Cardiac implantable electronic device remote monitoring surveillance in pediatric and congenital heart disease: Utility relative to frequency Brynn E. Dechert, MSN, CPNP, Gerald A. Serwer, MD, FHRS, David J. Bradley, MD, Macdonald Dick 2nd, MD, FHRS, Martin J. LaPage, MD, MS, FHRS From the Department of Pediatrics and Communicable Diseases, Division of Pediatric Cardiology, University of Michigan, Ann Arbor, Michigan. BACKGROUND Heart Rhythm Society expert consensus provides recommendations for surveillance monitoring of cardiac implantable electronic devices (CIEDs), but limited data are available for the pediatric and congenital heart disease population. OBJECTIVE The purpose of this study was to determine the rate of actionable events during CIED surveillance in this population, assess the utility of routine CIED remote monitoring, and assess the potential benefit from more frequent monitoring. METHODS This was a retrospective cohort study of all CIED patients followed at a pediatric and congenital heart center and enrolled in the Medtronic Carelink system with either (1) a chronic (implanted for 46 months) CIED followed between July 1, 2010, and July 1, 2012, on a bimonthly schedule; or (2) a new CIED (implanted o6 months) between July 1, 2008, and July 1, 2012, followed on a monthly schedule. RESULTS Aggregate mean age was 20 ⫾13.7 years. There were 608 interrogations on newly implanted CIEDs with an actionable event rate of 11 per 100 patient-years. There were 2614 interrogations of chronic CIEDs with an actionable event rate of 22 per 100 patient-
Introduction Cardiac implantable electronic device (CIED) surveillance monitoring is an important facet of patient care that ensures adequate device function, optimal programming, and identification of device or patient (ie, arrhythmia) problems.1,2 CIED surveillance has evolved considerably over the past decades.3 Currently, remote monitoring is the primary method by which the medical team evaluates CIED function. Remote monitoring transmissions provide extensive data on device function as well as patient information such as arrhythmia burden and markers of heart failure exacerbation.2 Most recently, certain CIED models have incorporated automated monitoring in which the device automatically transmits data when a problem is detected, thereby notifying Dr. Serwer is a consultant for Medtronic Inc. Address reprint requests and correspondence: Ms. Brynn Dechert, University of Michigan, 1540 E. Hospital Dr Ann Arbor, MI 48109. E-mail address: [email protected].
1547-5271/$-see front matter B 2015 Heart Rhythm Society. All rights reserved.
years. The odds of an actionable event on an asymptomatic remote monitoring transmission was lower than if symptomatic (odds ratio 0.04, 95% confidence interval 0.03–0.07). Tachyarrhythmia was the most common event. Predictors of actionable events were identified. CONCLUSION In this population of pediatric and congenital heart disease patients, the rate of actionable events was low, especially on asymptomatic interrogations. Most actionable events were due to tachyarrhythmia. A more frequent than every 90-day monitoring schedule does not appear to be of significant benefit. KEYWORDS Remote monitoring; Pediatric; Congenital heart disease; Pacemaker; Implantable cardioverter-defibrillator ABBREVIATIONS CI ¼ confidence interval; CIED ¼ cardiac implantable electronic device; ERI ¼ elective replacement indicator; ICD ¼ implantable cardioverter-defibrillator; OR ¼ odds ratio (Heart Rhythm 2015;12:117–122) I 2015 Heart Rhythm Society. All rights reserved.
the medical team of potentially asymptomatic problems before a routine CIED interrogation.4,5 As the ease of CIED surveillance has increased, the optimal frequency of remote monitoring remains questionable. The Heart Rhythm Society has published guidelines for adult patients with CIEDs, recommending pacemaker surveillance a minimum of every 3 to 12 months by in-office interrogation or remote monitoring transmission and implantable cardioverter-defibrillator (ICD) surveillance every 3 to 6 months by in-office interrogation or remote monitoring transmission.6 Additionally, newly implanted CIEDs are interrogated in person within 72 hours of the procedure and again within 2 to 12 weeks after implantation. Although these guidelines are based on a substantial body of evidence for adult patients, there is limited evidence to establish a monitoring frequency for the pediatric or congenital heart disease population. Considering that pediatric and congenital heart disease patients experience device http://dx.doi.org/10.1016/j.hrthm.2014.10.009
118 complications more frequently than the typical adult population, the ideal monitoring schedule for these patients may be different.7,8 The frequency of remote monitoring should be based primarily on the expected rate and frequency of CIED interrogations that require intervention. Although remote monitoring data are easily obtained and formatted for clinician review by industry databases, the workflow of processing, interpretation, patient follow-up, and reporting related to remote monitoring transmissions is significant. The University of Michigan Congenital Heart Center has routinely performed CIED surveillance, primarily by remote monitoring, on chronic CIEDs (leads implanted for 46 months) at 60-day intervals and for newly implanted CIEDs (leads implanted for o6 months) at 30-day intervals. The goals of this study were to determine the rate of actionable events during CIED surveillance in a population of pediatric and congenital heart disease patients, assess the utility of routine CIED remote monitoring in this population, and identify any benefit from more frequent monitoring than 90 days.
Methods This was a retrospective cohort study of all CIED patients followed at the University of Michigan Congenital Heart Center and enrolled in the Medtronic Carelink Remote Monitoring system. Two cohorts were analyzed: (1) patients with a chronic CIED (leads implanted for 46 months) followed between July 1, 2010, and July 1, 2012; and (2) patients with a newly implanted CIED (leads implanted for o6 months) implanted between June 1, 2008, and July 1, 2012. The time frame for the newly implanted cohort was longer in order to increase the number of patients in that cohort. The standard monitoring schedule at the University of Michigan Congenital Heart Center for chronic CIEDs during this time period was remote monitor transmissions every 60 days, with more frequent monitoring if required. CIEDs with newly implanted leads were scheduled for remote monitoring every 30 days for the first 6 months postimplant, with inoffice interrogation immediately postimplant and at 6 weeks postimplant. Patients without any remote monitoring transmissions were excluded from the study. The study was approved by the institutional review board. Patient and CIED data were collected from the medical records and from the Medtronic Carelink system by individual review of each record and remote monitoring transmission. CIED interrogations occurred as in-office interrogations and as remote monitoring transmissions sent via Carelink. Routine CIED interrogations were those expected to occur based on the surveillance schedule and were asymptomatic. Symptomatic interrogations were those in-office or remote monitoring transmissions performed specifically for patient symptoms. Remote monitoring transmissions for unknown reasons or provider requested followup were considered asymptomatic. In-office interrogations and symptomatic interrogations were considered to replace the routine remote transmission if they occurred within 7 days of an expected routine scheduled transmission.
Heart Rhythm, Vol 12, No 1, January 2015 The primary outcome was an actionable event discovered on remote monitoring or in-office interrogation. It was defined as those findings that resulted in a clinical intervention as determined by the managing team. Actionable events were categorized as (1) device/lead issue or (2) tachyarrhythmia. Interventions for device/lead findings were deemed major if device revision was required or minor if only device reprogramming or additional in-office clinical evaluation was needed. Nonsustained tachyarrhythmias and minor programming changes were not considered actionable.
Statistical analysis Statistical analysis included basic predictive value calculations, risk assessment by odds ratio (OR), multiple logistic regression analysis, and Kaplan–Meier time-to-event analysis performed using SAS 9.3 (SAS Institute, Cary, NC). Assessment of workload was based on a conservative estimation of staff and physician time for processing, interpreting, reporting, and patient notification of 15 minutes per remote monitoring transmission (similar to an adult study reporting a mean time spent per transmission of 11.5 minutes ⫾ 7.7 minutes).9
Results Surveillance of newly implanted CIEDs There were 91 newly implanted CIEDs in 89 patients between July 1, 2008, and July 1, 2012. Patient summary data are given in Table 1 and CIED interrogation summary data in Table 2. Of this cohort, 22 of 91 devices (24%) were enabled for wireless/automatic transmission of remote monitoring, although none of the remote monitoring transmissions reviewed for this cohort met “alert conditions” and therefore were not automatically transmitted. Actionable events were identified on 14 of the total 608 CIED interrogations in this cohort: 11 (79%) due to tachyarrhythmia and 3 (21%) due to device/lead malfunction. These data result in an overall risk of 15.7 actionable events per 100 patients followed, equaling a rate of 11 actionable events per 100 patient-years. Considering findings due to device/lead issues only, there were 3.4 actionable events per 100 patients followed, equaling a rate of actionable events of 0.8 per 100 patient-years. Only 2 actionable events required major Table 1
Patient demographics
No. of patients Age (years)* Congenital heart disease Brady pacemaker Antitachycardia pacemaker ICD
New CIED
Chronic CIED
89 17 ⫾ 14.6 59 (66%) 51 (57%) 13 (15%) 25 (28%)
286 21 ⫾ 13 196 (69%) 189 (66%) 31 (11%) 66 (23%)
Data are given as mean ⫾ SD or count (%). CIED ¼ cardiac implantable electronic device; ICD ¼ implantable cardioverter-defibrillator. * Mean age at study midpoint for cohort.
Dechert et al Table 2
CIED Surveillance in Pediatrics
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Interrogation summary data New CIED
Chronic CIED
No. of interrogations 608 2614 In-office interrogations 208 (34%) 792 (30%) Symptomatic 3 (1.4%) 11 (1.4%) Remote monitoring transmissions 400 (66%) 1822 (70%) Routine/asymptomatic 324 (81%) 1441 (79%) Symptomatic 37 (9.5%) 144 (8%) * 38 (9.5%) 237 (13%) Nonroutine/asymptomatic Interval between interrogation (days) 28.2 ⫾ 23 65.4 ⫾ 61.4 Remote transmissions per patient 4.4 ⫾ 2.2 6⫾6 In-office interrogations per patient 2.3 ⫾ 1.3 3⫾2 Data are given as mean ⫾ SD or count (%). CIED ¼ cardiac implantable electronic device. * Includes asymptomatic nonroutine transmissions, 8 automated transmissions, and follow-up transmissions requested by the medical team.
intervention in this cohort, and both occurred within 1 week of implantation (a symptomatic lead perforation 1 week postimplant and an asymptomatic lead dislodgment 1 day postimplant). There were 40 symptomatic CIED interrogations for patient symptoms: 31 (78%) were normal, and 9 (22%) revealed an actionable event (8 due to tachyarrhythmia). There were 568 routine, asymptomatic CIED interrogations. Of these, only 5 (1.3%) demonstrated an actionable event (3 tachyarrhythmias and 2 device/lead malfunctions). The positive and negative predictive values of symptoms to predict actionable events on any interrogation (remote or in-office) were 22.5% (95% confidence interval CI 10.9– 38.5) and 99.1% (95% CI 98–99.7), respectively, indicating that an asymptomatic routine interrogation is normal 99% of the time. In the 400 remote transmissions, there were 8 actionable events during the first 6 months postimplant, none due to device/lead issues. Only 1 asymptomatic transmission had an actionable event, which was due to arrhythmia requiring programming change. An asymptomatic routine remote monitor transmission had a positive predictive value of 0.3% (95% CI 0.05–1.5) for an actionable event.
Surveillance of chronic CIEDs: Leads implanted Z6 months There were 366 patients with chronic CIEDs followed between July 1, 2010, and July 1, 2012. Excluded from the study were 80 patients without any remote monitoring transmissions sent during the study time frame. Summary data on the included 286 patients and 2614 CIED interrogations are given in Tables 1 and 2. Of this cohort, 33 of 286 devices (12%) were enabled for wireless/remote monitoring transmissions. However, only 8 automatic transmissions occurred during the study period: 2 for lead fracture, 3 for elective replacement indicator (ERI), and 3 for delivered shock. More frequent than every 60-day remote monitoring was scheduled for 58 patients (20%) during some portion of the study period per the discretion of the managing electrophysiologist, most commonly as devices approached ERI. Actionable events were discovered on 123 of the 2614
CIED interrogations (4.7%) : 58 (47%) related to arrhythmia, 37 (30%) due to device/lead malfunction, and 28 (23%) at ERI. Overall, the rate of actionable events in the chronic CIED cohort was 22 actionable events per 100 patient-years. The rate for device/lead malfunction was 6.5 actionable events per 100 patient-years. There were 155 symptomatic CIED interrogations, of which 106 (68%) were normal. The remaining 49 included 40 events (82%) due to tachyarrhythmia, 5 devices (10%) at ERI, and 4 (8%) related to device/lead malfunction. Three of the 4 device/lead issues required a major intervention. There were 2451 asymptomatic routine CIED interrogations, of which only 66 (2.7%) had an actionable event. Of these 66, 15 (23%) were due to tachyarrhythmia, 21 (32%) ERI, and 30 (45%) device/lead issues. There were 3 device/lead issues requiring major intervention. Minor interventions addressed 24 of the 51 events related to device/lead issues. The rate of asymptomatic actionable events was 11.5 per 100 patient-years and 5.2 per 100 patient-years for device/ lead malfunctions only. The positive and negative predictive values of symptoms to predict actionable event on any chronic CIED interrogation (remote or in-office) were 32% (95% CI 24–40) and 97% (CI 95% 96–98), respectively, indicating that an asymptomatic interrogation was normal 97% of the time. Asymptomatic remote transmissions in this cohort were also likely to be normal 98% of the time (95% CI 97%– 98.2%). The odds of an actionable event (excluding ICD shock) on a routine asymptomatic remote monitoring transmission were significantly lower than on a symptomatic remote monitoring transmission (OR 0.04, 95% CI 0.03–0.07).
Outcome and prediction of actionable events In total (newly implanted devices and chronic devices combined), there were 3214 interrogations reviewed (excluding the 8 automated transmissions). Of these, only 195 (6%) were symptomatic. The outcomes of all actionable events dichotomized by the presence or absence of symptoms are presented in Figures 1 and 2. The 3019 asymptomatic interrogations revealed 30 device/lead malfunctions (1%), of which 24 were corrected with reprogramming, including 10 lead polarity changes and 10 output adjustments. Overall, the positive predictive value of symptoms to predict actionable events was 29.7% (95% CI 23.4–36.7), and the negative predictive value was 97.7% (95% CI 97– 98.2), indicating that 97.7% of routine asymptomatic interrogations are normal. The likelihood of a chronic CIED patient having an arrhythmia or device/lead malfunction as an actionable event was modeled by multiple logistic regression based on the presence of congenital heart disease, age, and type of device (bradycardia pacemaker, antitachycardia pacemaker, or ICD). Predictive of arrhythmia were age 418 years (OR 4.5, 95% CI 1.2–16.4), presence of an antitachycardia pacemaker (OR 5.5, 95% CI 1.7–17.3), and presence of an ICD (OR 3.7, 95% CI 1.2–10.8). Pediatric patients (age o18
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Figure 1 Types and outcomes of symptomatic actionable findings: aggregate data from both newly implanted and chronic cardiac implantable electronic device (CIED) cohorts, excluding the 8 automated transmissions. *Includes lead fracture and failure to capture requiring output reprogramming. †Treatments included 18 external cardioversions, 2 treated with medication, and 1 device revision (replace fractured lead in previously abandoned device). ICD ¼ implantable cardioverter-defibrillator.
Figure 2 Types and outcomes of asymptomatic actionable findings: aggregate data from both newly implanted and chronic cardiac implantable electronic device (CIED) cohorts, excluding the 8 automated transmissions. *Includes lead fracture and failure to capture requiring output reprogramming. †Occurred 1 day and 3 years post implant. ‡Treatments included 10 reprogrammed, 6 external cardioversions, and 2 treated with medication. ERI ¼ elective replacement indicator.
Dechert et al
CIED Surveillance in Pediatrics
years) had an increased likelihood of device/lead malfunction (OR 2.5, 95% CI 1–5.9).
Compliance with routine CIED surveillance Overall compliance with monthly remote monitoring transmissions for the newly implanted CIED cohort was 71%, and only 16 patients (18%) were 100% compliant with all scheduled transmissions. Compliance with routine remote monitoring surveillance in the chronic CIED cohort was 58%, with only 21 patients (7%) being 100% compliant over the 2-year study period. Multiple logistic regression was used to assess possible predictors of compliance, including presence of congenital heart disease, age 418 years, and device type (antitachycardia pacemaker or ICD vs pacemaker). Higher compliance was arbitrarily set at o6 missed routine remote transmissions. Predictors of higher compliance were presence of congenital heart disease (OR 1.8, 95% CI 1–3) and presence of an ICD (OR 2, 95% CI 1.1–3.7).
Cost and workload Because the current reimbursement structure for device surveillance is based on a 90-day interval and the study was based on a 60-day interval, an assessment of workload differences between the 2 monitoring schedules was performed. It was assumed that patient compliance with a 90day interval would be similar to the compliance of 58% in the study, and the medical team workload was estimated to be 15 minutes per interrogation (including accessing, interpreting, reporting, and contacting patient). The total workload required for the expected remote monitoring transmissions of the patients in this study over a 2-year period for the 60day model was 635 hours compared to 413 hours in a 90-day model, resulting in a 35% reduction in workload with the 90day model. Kaplan–Meier time-to-event analysis was used to determine the timing of events relative to the previous interrogation. Based on this analysis, a 60-day interval surveillance schedule would require 25 interrogations to find 1 actionable event, whereas a 90-day interval would require 15 interrogations to find 1 actionable event.
Discussion This is the largest study of CIED surveillance data including remote monitoring on pediatric and congenital heart disease patients to date, including more than 3000 CIED interrogations. Currently no guidelines specific to this population exist regarding the frequency of surveillance monitoring. The important findings of this study are as follows. (1) The rate of actionable events identified by CIED surveillance monitoring is low: 22 per 100 patient-years for chronic CIEDs and 11 per 100 patient-years for newly implanted devices. (2) Actionable events are unlikely to be found on routine asymptomatic CIED interrogation. (3) Tachyarrhythmias were the most common actionable event found on CIED interrogation. (4) There are identifiable predictors of patients at increased risk for an actionable event. (5) The
121 benefit to more frequent than every 90-day CIED interrogation for this population appears minimal. Previous studies on CIED surveillance tend to report the incidence of actionable events per total interrogations. We found that among interrogations of chronic systems evaluated over a 2-year period, only 4.7% of revealed an actionable event, similar to an adult study reporting 4.2% of remote interrogations (n = 500) over a 2-week period requiring intervention.9 The only published pediatric study reported 16% of transmissions had true adverse events, leading to 11% requiring action.10 The incidence of actionable events is directly related to the frequency of monitoring and patient compliance, both of which impact the total number of interrogations (ie, the denominator). We present the rate of actionable events in this patient population. The rate can most easily be translated between studies with varying monitoring frequencies and patient compliance. For example, a center with 100 patients who are 50% compliant with a 90-day monitoring interval would expect a total of 200 interrogations in 1 year; applying the rate (22 actionable events per 100 patient-years) results in an 11% incidence of actionable events. Knowledge of the expected rate of events will be useful for guideline development or center-specific CIED monitoring practices. This is the first study to specifically evaluate the occurrence of actionable events during the first 6 months after CIED implantation. This dataset is unique because of the increased frequency of monitoring during the first 6 months postimplantation at our center, which allows more precise assessment of the timing of actionable events. Importantly, actionable events during this time period were infrequent and, in fact, less than the rate in the chronic group. Increased frequency of CIED monitoring may be considered desirable early after implant because of concerns of lead dislodgment. However, these data show it to be extremely rare and identified by symptoms more readily than by monitoring. The role of increased monitoring during the acute phase is not supported by these data. Although remote monitoring allows for early identification of actionable events, the overall rate of actionable events found on routine asymptomatic interrogations is low. The predictive values reported here show that if the patient is asymptomatic, the chance of a normal CIED interrogation is 98%. This is similar to a published adult study and a smaller pediatric study, both of which reported a higher incidence of actionable events on unscheduled and symptomatic transmissions.9,10 The pediatric study of 461 remote monitoring transmissions found 13% of routine remote monitoring transmissions had actionable events compared to 27% of symptomatic remote monitoring transmissions.10 Despite the false-positive risk with symptoms, patients with concerning symptoms should be encouraged to send remote monitoring transmissions for review. Tachyarrhythmias (including ICD shock) accounted for 78% of actionable events in patients with newly implanted devices and 47% of actionable events in patients with a chronic device, consistent with currently published adult and
122 pediatric studies reporting tachyarrhythmias accounting for 56% to 79% of all actionable events.9–11 Excluding ICD shocks, 44 of 137 actionable events (32%) were due to tachyarrhythmia. Although these tachyarrhythmias typically were symptomatic, 41% were asymptomatic and discovered on routine interrogation. This may support a role for more frequent monitoring in patients at risk for asymptomatic tachyarrhythmias, primarily patients with congenital heart disease. Predictive of arrhythmia in this population were age 418 years, presence of an antitachycardia pacemaker, and presence of an ICD. In this population of 69% patients with congenital heart disease, arrhythmia is a common concern for patients as they age. Patients with antitachycardia pacemakers and ICDs are likely to have a history of tachyarrhythmia as the indication for the device, although these clinical data were not specifically explored in this study. Pediatric patients are more likely to have a device/lead malfunction. This finding is similar to a large, multicenter pediatric study of ICD leads that found increased risk of lead failure with younger age at implantation.7 Any benefit to 60-day monitoring compared to a 90-day monitoring schedule is minimal considering the very low rate of actionable events on asymptomatic interrogations. There is a substantial decrease in workload with a 90-day schedule. In addition, because the 60-day interval allows only 50% of the interrogations to be reimbursed vs 100% in the 90-day model, the reimbursement per workload hour is increased. Although certain patients may require more frequent monitoring, it appears that routine monitoring more often than every 90 days may not be justified. As technology improves and incorporates more wireless and automated surveillance into all CIEDs, routine scheduling of remote monitoring may be necessary only for those at risk for asymptomatic arrhythmias. Patients with symptoms can manually send transmissions, and asymptomatic patients would have automatic notification of device/lead issues. Depending on the recording capabilities and programming of the device, the automatic/wireless system can also monitor for certain types of arrhythmia. Therefore, the role of the wireless system may improve patient surveillance while minimizing the effort of the care team. Patient compliance with the routine remote monitoring is suboptimal but comparable to previously reported compliance in a large adult study.9 We attempted to identify predictors of compliance with remote monitoring and found that patients with congenital heart disease or an ICD were less likely to miss routine transmissions. We speculate that these circumstances improve compliance because patients with congenital heart disease are more likely to have ongoing medical concerns or problems that prompt them to send routine transmissions, and patients or parents of patients with an ICD may send more frequently because of anxiety associated with that device. Remote monitoring provides
Heart Rhythm, Vol 12, No 1, January 2015 peace of mind, which may improve compliance in these patients. Because this was a retrospective study, ascertainment of patient symptoms was only as complete as the documentation in the medical records. This study was limited to patients enrolled in the Medtronic Carelink system because these patients make up the vast majority of device patients at our center; older devices that cannot be remotely monitored and those from other manufacturers may have different rates of actionable events. Patient compliance was suboptimal and may have affected the timing of presentation for asymptomatic actionable events.
Conclusion The rate of actionable events for patients with chronic or newly implanted CIEDs is low, especially in asymptomatic patients, suggesting that the benefit of frequent CIED surveillance is minimal. Many actionable events were due to arrhythmia; patients at risk from asymptomatic arrhythmia may require increased surveillance. However, for this population, a more frequent than every 90-day monitoring schedule does not appear to be of significant benefit. These data may serve to support the development of specific pediatric and congenital heart disease CIED monitoring guidelines.
References 1. Movsowitz C, Mittal S. Remote patient management using implantable devices. J Interv Card Electrophysiol 2011;31:81–90. 2. Bonnell S, Mittal S. Clinical guidelines for remote monitoring. Card Electrophysiol Clin 2013;5:283–291. 3. Burri H, Varma N. Remote device management in patients with cardiac complaints. Card Electrophysiol Clin 2013;5:337–347. 4. Crossley GH, Chen J, Choucair W, Cohen TJ, Gohn DC, Johnson B, Kennedy EE, Mongeon LR, Serwer GA, Qiua H, Wilkofff BL. Clinical benefits of remote versus transtelephonic monitoring of implanted pacemakers. J Am Coll Cardiol 2009;54:2012–2019. 5. Crossley GH, Boyle A, Vitense H, Chang Y, Mead RH. The CONNECT (clinical evaluation of remote notification to reduce time to clinical decision) trial. J Am Coll Cardiol 2011;57:1181–1189. 6. Wilkoff BL, Auricchio A, Brugada J, et al. HRS/EHRA expert consensus on the monitoring of cardiovascular electronic devices (CIEDs): description of techniques, indications, personnel, frequency and ethical considerations. Heart Rhythm 2008;5:907–925. 7. Atallah J, Erickson CC, Cecchin F, Dubin AM, Law IH, Cohen MI, LaPage MJ, Cannon BC, Chun TU, Freedenberg V, Gierdalski M, Berul CI. Multiinstitutional study of implantable defibrillator lead performance in children and young adults: results of the pediatric lead extractability and survival evaluation (PLEASE) study. Circulation 2013;127:2393–2402. 8. Kremers MS, Hammill SC, Berul CL, et al. The national ICD registry report: version 2.1 including leads and pediatrics for years 2010 and 2011. Heart Rhythm 2013;10:e59–e65. 9. Cronin EM, Ching EA, Varma N, Martin DO, Wilkoff BL, Lindsay BD. Remote monitoring of cardiovascular devices: a time and activity analysis. Heart Rhythm 2012;9:1947–1951. 10. Malloy LE, Gingerich J, Olson MD, Atkins DL. Remote monitoring of cardiovascular implantable devices in the pediatric population improves detection of adverse events. Pediatr Cardiol 2014;35:301–306. 11. Ricci RP, Morichelli L, D’Onofrio A, Calo L, Vaccari D, Zanotto G, Curnis A, Buja G, Rovai N, Gargaro A. Effectiveness of remote monitoring of CIEDs in detection and treatment of clinical and device-related cardiovascular events in family practice: the HomeGuide registry. Europace 2013;15:970–977.
Introduction Cardiac implantable electronic device (CIED) surveillance monitoring is an important facet of patient care that ensures adequate device function, optimal programming, and identification of device or patient (ie, arrhythmia) problems.1,2 CIED surveillance has evolved considerably over the past decades.3 Currently, remote monitoring is the primary method by which the medical team evaluates CIED function. Remote monitoring transmissions provide extensive data on device function as well as patient information such as arrhythmia burden and markers of heart failure exacerbation.2 Most recently, certain CIED models have incorporated automated monitoring in which the device automatically transmits data when a problem is detected, thereby notifying Dr. Serwer is a consultant for Medtronic Inc. Address reprint requests and correspondence: Ms. Brynn Dechert, University of Michigan, 1540 E. Hospital Dr Ann Arbor, MI 48109. E-mail address: [email protected].
1547-5271/$-see front matter B 2015 Heart Rhythm Society. All rights reserved.
years. The odds of an actionable event on an asymptomatic remote monitoring transmission was lower than if symptomatic (odds ratio 0.04, 95% confidence interval 0.03–0.07). Tachyarrhythmia was the most common event. Predictors of actionable events were identified. CONCLUSION In this population of pediatric and congenital heart disease patients, the rate of actionable events was low, especially on asymptomatic interrogations. Most actionable events were due to tachyarrhythmia. A more frequent than every 90-day monitoring schedule does not appear to be of significant benefit. KEYWORDS Remote monitoring; Pediatric; Congenital heart disease; Pacemaker; Implantable cardioverter-defibrillator ABBREVIATIONS CI ¼ confidence interval; CIED ¼ cardiac implantable electronic device; ERI ¼ elective replacement indicator; ICD ¼ implantable cardioverter-defibrillator; OR ¼ odds ratio (Heart Rhythm 2015;12:117–122) I 2015 Heart Rhythm Society. All rights reserved.
the medical team of potentially asymptomatic problems before a routine CIED interrogation.4,5 As the ease of CIED surveillance has increased, the optimal frequency of remote monitoring remains questionable. The Heart Rhythm Society has published guidelines for adult patients with CIEDs, recommending pacemaker surveillance a minimum of every 3 to 12 months by in-office interrogation or remote monitoring transmission and implantable cardioverter-defibrillator (ICD) surveillance every 3 to 6 months by in-office interrogation or remote monitoring transmission.6 Additionally, newly implanted CIEDs are interrogated in person within 72 hours of the procedure and again within 2 to 12 weeks after implantation. Although these guidelines are based on a substantial body of evidence for adult patients, there is limited evidence to establish a monitoring frequency for the pediatric or congenital heart disease population. Considering that pediatric and congenital heart disease patients experience device http://dx.doi.org/10.1016/j.hrthm.2014.10.009
118 complications more frequently than the typical adult population, the ideal monitoring schedule for these patients may be different.7,8 The frequency of remote monitoring should be based primarily on the expected rate and frequency of CIED interrogations that require intervention. Although remote monitoring data are easily obtained and formatted for clinician review by industry databases, the workflow of processing, interpretation, patient follow-up, and reporting related to remote monitoring transmissions is significant. The University of Michigan Congenital Heart Center has routinely performed CIED surveillance, primarily by remote monitoring, on chronic CIEDs (leads implanted for 46 months) at 60-day intervals and for newly implanted CIEDs (leads implanted for o6 months) at 30-day intervals. The goals of this study were to determine the rate of actionable events during CIED surveillance in a population of pediatric and congenital heart disease patients, assess the utility of routine CIED remote monitoring in this population, and identify any benefit from more frequent monitoring than 90 days.
Methods This was a retrospective cohort study of all CIED patients followed at the University of Michigan Congenital Heart Center and enrolled in the Medtronic Carelink Remote Monitoring system. Two cohorts were analyzed: (1) patients with a chronic CIED (leads implanted for 46 months) followed between July 1, 2010, and July 1, 2012; and (2) patients with a newly implanted CIED (leads implanted for o6 months) implanted between June 1, 2008, and July 1, 2012. The time frame for the newly implanted cohort was longer in order to increase the number of patients in that cohort. The standard monitoring schedule at the University of Michigan Congenital Heart Center for chronic CIEDs during this time period was remote monitor transmissions every 60 days, with more frequent monitoring if required. CIEDs with newly implanted leads were scheduled for remote monitoring every 30 days for the first 6 months postimplant, with inoffice interrogation immediately postimplant and at 6 weeks postimplant. Patients without any remote monitoring transmissions were excluded from the study. The study was approved by the institutional review board. Patient and CIED data were collected from the medical records and from the Medtronic Carelink system by individual review of each record and remote monitoring transmission. CIED interrogations occurred as in-office interrogations and as remote monitoring transmissions sent via Carelink. Routine CIED interrogations were those expected to occur based on the surveillance schedule and were asymptomatic. Symptomatic interrogations were those in-office or remote monitoring transmissions performed specifically for patient symptoms. Remote monitoring transmissions for unknown reasons or provider requested followup were considered asymptomatic. In-office interrogations and symptomatic interrogations were considered to replace the routine remote transmission if they occurred within 7 days of an expected routine scheduled transmission.
Heart Rhythm, Vol 12, No 1, January 2015 The primary outcome was an actionable event discovered on remote monitoring or in-office interrogation. It was defined as those findings that resulted in a clinical intervention as determined by the managing team. Actionable events were categorized as (1) device/lead issue or (2) tachyarrhythmia. Interventions for device/lead findings were deemed major if device revision was required or minor if only device reprogramming or additional in-office clinical evaluation was needed. Nonsustained tachyarrhythmias and minor programming changes were not considered actionable.
Statistical analysis Statistical analysis included basic predictive value calculations, risk assessment by odds ratio (OR), multiple logistic regression analysis, and Kaplan–Meier time-to-event analysis performed using SAS 9.3 (SAS Institute, Cary, NC). Assessment of workload was based on a conservative estimation of staff and physician time for processing, interpreting, reporting, and patient notification of 15 minutes per remote monitoring transmission (similar to an adult study reporting a mean time spent per transmission of 11.5 minutes ⫾ 7.7 minutes).9
Results Surveillance of newly implanted CIEDs There were 91 newly implanted CIEDs in 89 patients between July 1, 2008, and July 1, 2012. Patient summary data are given in Table 1 and CIED interrogation summary data in Table 2. Of this cohort, 22 of 91 devices (24%) were enabled for wireless/automatic transmission of remote monitoring, although none of the remote monitoring transmissions reviewed for this cohort met “alert conditions” and therefore were not automatically transmitted. Actionable events were identified on 14 of the total 608 CIED interrogations in this cohort: 11 (79%) due to tachyarrhythmia and 3 (21%) due to device/lead malfunction. These data result in an overall risk of 15.7 actionable events per 100 patients followed, equaling a rate of 11 actionable events per 100 patient-years. Considering findings due to device/lead issues only, there were 3.4 actionable events per 100 patients followed, equaling a rate of actionable events of 0.8 per 100 patient-years. Only 2 actionable events required major Table 1
Patient demographics
No. of patients Age (years)* Congenital heart disease Brady pacemaker Antitachycardia pacemaker ICD
New CIED
Chronic CIED
89 17 ⫾ 14.6 59 (66%) 51 (57%) 13 (15%) 25 (28%)
286 21 ⫾ 13 196 (69%) 189 (66%) 31 (11%) 66 (23%)
Data are given as mean ⫾ SD or count (%). CIED ¼ cardiac implantable electronic device; ICD ¼ implantable cardioverter-defibrillator. * Mean age at study midpoint for cohort.
Dechert et al Table 2
CIED Surveillance in Pediatrics
119
Interrogation summary data New CIED
Chronic CIED
No. of interrogations 608 2614 In-office interrogations 208 (34%) 792 (30%) Symptomatic 3 (1.4%) 11 (1.4%) Remote monitoring transmissions 400 (66%) 1822 (70%) Routine/asymptomatic 324 (81%) 1441 (79%) Symptomatic 37 (9.5%) 144 (8%) * 38 (9.5%) 237 (13%) Nonroutine/asymptomatic Interval between interrogation (days) 28.2 ⫾ 23 65.4 ⫾ 61.4 Remote transmissions per patient 4.4 ⫾ 2.2 6⫾6 In-office interrogations per patient 2.3 ⫾ 1.3 3⫾2 Data are given as mean ⫾ SD or count (%). CIED ¼ cardiac implantable electronic device. * Includes asymptomatic nonroutine transmissions, 8 automated transmissions, and follow-up transmissions requested by the medical team.
intervention in this cohort, and both occurred within 1 week of implantation (a symptomatic lead perforation 1 week postimplant and an asymptomatic lead dislodgment 1 day postimplant). There were 40 symptomatic CIED interrogations for patient symptoms: 31 (78%) were normal, and 9 (22%) revealed an actionable event (8 due to tachyarrhythmia). There were 568 routine, asymptomatic CIED interrogations. Of these, only 5 (1.3%) demonstrated an actionable event (3 tachyarrhythmias and 2 device/lead malfunctions). The positive and negative predictive values of symptoms to predict actionable events on any interrogation (remote or in-office) were 22.5% (95% confidence interval CI 10.9– 38.5) and 99.1% (95% CI 98–99.7), respectively, indicating that an asymptomatic routine interrogation is normal 99% of the time. In the 400 remote transmissions, there were 8 actionable events during the first 6 months postimplant, none due to device/lead issues. Only 1 asymptomatic transmission had an actionable event, which was due to arrhythmia requiring programming change. An asymptomatic routine remote monitor transmission had a positive predictive value of 0.3% (95% CI 0.05–1.5) for an actionable event.
Surveillance of chronic CIEDs: Leads implanted Z6 months There were 366 patients with chronic CIEDs followed between July 1, 2010, and July 1, 2012. Excluded from the study were 80 patients without any remote monitoring transmissions sent during the study time frame. Summary data on the included 286 patients and 2614 CIED interrogations are given in Tables 1 and 2. Of this cohort, 33 of 286 devices (12%) were enabled for wireless/remote monitoring transmissions. However, only 8 automatic transmissions occurred during the study period: 2 for lead fracture, 3 for elective replacement indicator (ERI), and 3 for delivered shock. More frequent than every 60-day remote monitoring was scheduled for 58 patients (20%) during some portion of the study period per the discretion of the managing electrophysiologist, most commonly as devices approached ERI. Actionable events were discovered on 123 of the 2614
CIED interrogations (4.7%) : 58 (47%) related to arrhythmia, 37 (30%) due to device/lead malfunction, and 28 (23%) at ERI. Overall, the rate of actionable events in the chronic CIED cohort was 22 actionable events per 100 patient-years. The rate for device/lead malfunction was 6.5 actionable events per 100 patient-years. There were 155 symptomatic CIED interrogations, of which 106 (68%) were normal. The remaining 49 included 40 events (82%) due to tachyarrhythmia, 5 devices (10%) at ERI, and 4 (8%) related to device/lead malfunction. Three of the 4 device/lead issues required a major intervention. There were 2451 asymptomatic routine CIED interrogations, of which only 66 (2.7%) had an actionable event. Of these 66, 15 (23%) were due to tachyarrhythmia, 21 (32%) ERI, and 30 (45%) device/lead issues. There were 3 device/lead issues requiring major intervention. Minor interventions addressed 24 of the 51 events related to device/lead issues. The rate of asymptomatic actionable events was 11.5 per 100 patient-years and 5.2 per 100 patient-years for device/ lead malfunctions only. The positive and negative predictive values of symptoms to predict actionable event on any chronic CIED interrogation (remote or in-office) were 32% (95% CI 24–40) and 97% (CI 95% 96–98), respectively, indicating that an asymptomatic interrogation was normal 97% of the time. Asymptomatic remote transmissions in this cohort were also likely to be normal 98% of the time (95% CI 97%– 98.2%). The odds of an actionable event (excluding ICD shock) on a routine asymptomatic remote monitoring transmission were significantly lower than on a symptomatic remote monitoring transmission (OR 0.04, 95% CI 0.03–0.07).
Outcome and prediction of actionable events In total (newly implanted devices and chronic devices combined), there were 3214 interrogations reviewed (excluding the 8 automated transmissions). Of these, only 195 (6%) were symptomatic. The outcomes of all actionable events dichotomized by the presence or absence of symptoms are presented in Figures 1 and 2. The 3019 asymptomatic interrogations revealed 30 device/lead malfunctions (1%), of which 24 were corrected with reprogramming, including 10 lead polarity changes and 10 output adjustments. Overall, the positive predictive value of symptoms to predict actionable events was 29.7% (95% CI 23.4–36.7), and the negative predictive value was 97.7% (95% CI 97– 98.2), indicating that 97.7% of routine asymptomatic interrogations are normal. The likelihood of a chronic CIED patient having an arrhythmia or device/lead malfunction as an actionable event was modeled by multiple logistic regression based on the presence of congenital heart disease, age, and type of device (bradycardia pacemaker, antitachycardia pacemaker, or ICD). Predictive of arrhythmia were age 418 years (OR 4.5, 95% CI 1.2–16.4), presence of an antitachycardia pacemaker (OR 5.5, 95% CI 1.7–17.3), and presence of an ICD (OR 3.7, 95% CI 1.2–10.8). Pediatric patients (age o18
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Heart Rhythm, Vol 12, No 1, January 2015
Figure 1 Types and outcomes of symptomatic actionable findings: aggregate data from both newly implanted and chronic cardiac implantable electronic device (CIED) cohorts, excluding the 8 automated transmissions. *Includes lead fracture and failure to capture requiring output reprogramming. †Treatments included 18 external cardioversions, 2 treated with medication, and 1 device revision (replace fractured lead in previously abandoned device). ICD ¼ implantable cardioverter-defibrillator.
Figure 2 Types and outcomes of asymptomatic actionable findings: aggregate data from both newly implanted and chronic cardiac implantable electronic device (CIED) cohorts, excluding the 8 automated transmissions. *Includes lead fracture and failure to capture requiring output reprogramming. †Occurred 1 day and 3 years post implant. ‡Treatments included 10 reprogrammed, 6 external cardioversions, and 2 treated with medication. ERI ¼ elective replacement indicator.
Dechert et al
CIED Surveillance in Pediatrics
years) had an increased likelihood of device/lead malfunction (OR 2.5, 95% CI 1–5.9).
Compliance with routine CIED surveillance Overall compliance with monthly remote monitoring transmissions for the newly implanted CIED cohort was 71%, and only 16 patients (18%) were 100% compliant with all scheduled transmissions. Compliance with routine remote monitoring surveillance in the chronic CIED cohort was 58%, with only 21 patients (7%) being 100% compliant over the 2-year study period. Multiple logistic regression was used to assess possible predictors of compliance, including presence of congenital heart disease, age 418 years, and device type (antitachycardia pacemaker or ICD vs pacemaker). Higher compliance was arbitrarily set at o6 missed routine remote transmissions. Predictors of higher compliance were presence of congenital heart disease (OR 1.8, 95% CI 1–3) and presence of an ICD (OR 2, 95% CI 1.1–3.7).
Cost and workload Because the current reimbursement structure for device surveillance is based on a 90-day interval and the study was based on a 60-day interval, an assessment of workload differences between the 2 monitoring schedules was performed. It was assumed that patient compliance with a 90day interval would be similar to the compliance of 58% in the study, and the medical team workload was estimated to be 15 minutes per interrogation (including accessing, interpreting, reporting, and contacting patient). The total workload required for the expected remote monitoring transmissions of the patients in this study over a 2-year period for the 60day model was 635 hours compared to 413 hours in a 90-day model, resulting in a 35% reduction in workload with the 90day model. Kaplan–Meier time-to-event analysis was used to determine the timing of events relative to the previous interrogation. Based on this analysis, a 60-day interval surveillance schedule would require 25 interrogations to find 1 actionable event, whereas a 90-day interval would require 15 interrogations to find 1 actionable event.
Discussion This is the largest study of CIED surveillance data including remote monitoring on pediatric and congenital heart disease patients to date, including more than 3000 CIED interrogations. Currently no guidelines specific to this population exist regarding the frequency of surveillance monitoring. The important findings of this study are as follows. (1) The rate of actionable events identified by CIED surveillance monitoring is low: 22 per 100 patient-years for chronic CIEDs and 11 per 100 patient-years for newly implanted devices. (2) Actionable events are unlikely to be found on routine asymptomatic CIED interrogation. (3) Tachyarrhythmias were the most common actionable event found on CIED interrogation. (4) There are identifiable predictors of patients at increased risk for an actionable event. (5) The
121 benefit to more frequent than every 90-day CIED interrogation for this population appears minimal. Previous studies on CIED surveillance tend to report the incidence of actionable events per total interrogations. We found that among interrogations of chronic systems evaluated over a 2-year period, only 4.7% of revealed an actionable event, similar to an adult study reporting 4.2% of remote interrogations (n = 500) over a 2-week period requiring intervention.9 The only published pediatric study reported 16% of transmissions had true adverse events, leading to 11% requiring action.10 The incidence of actionable events is directly related to the frequency of monitoring and patient compliance, both of which impact the total number of interrogations (ie, the denominator). We present the rate of actionable events in this patient population. The rate can most easily be translated between studies with varying monitoring frequencies and patient compliance. For example, a center with 100 patients who are 50% compliant with a 90-day monitoring interval would expect a total of 200 interrogations in 1 year; applying the rate (22 actionable events per 100 patient-years) results in an 11% incidence of actionable events. Knowledge of the expected rate of events will be useful for guideline development or center-specific CIED monitoring practices. This is the first study to specifically evaluate the occurrence of actionable events during the first 6 months after CIED implantation. This dataset is unique because of the increased frequency of monitoring during the first 6 months postimplantation at our center, which allows more precise assessment of the timing of actionable events. Importantly, actionable events during this time period were infrequent and, in fact, less than the rate in the chronic group. Increased frequency of CIED monitoring may be considered desirable early after implant because of concerns of lead dislodgment. However, these data show it to be extremely rare and identified by symptoms more readily than by monitoring. The role of increased monitoring during the acute phase is not supported by these data. Although remote monitoring allows for early identification of actionable events, the overall rate of actionable events found on routine asymptomatic interrogations is low. The predictive values reported here show that if the patient is asymptomatic, the chance of a normal CIED interrogation is 98%. This is similar to a published adult study and a smaller pediatric study, both of which reported a higher incidence of actionable events on unscheduled and symptomatic transmissions.9,10 The pediatric study of 461 remote monitoring transmissions found 13% of routine remote monitoring transmissions had actionable events compared to 27% of symptomatic remote monitoring transmissions.10 Despite the false-positive risk with symptoms, patients with concerning symptoms should be encouraged to send remote monitoring transmissions for review. Tachyarrhythmias (including ICD shock) accounted for 78% of actionable events in patients with newly implanted devices and 47% of actionable events in patients with a chronic device, consistent with currently published adult and
122 pediatric studies reporting tachyarrhythmias accounting for 56% to 79% of all actionable events.9–11 Excluding ICD shocks, 44 of 137 actionable events (32%) were due to tachyarrhythmia. Although these tachyarrhythmias typically were symptomatic, 41% were asymptomatic and discovered on routine interrogation. This may support a role for more frequent monitoring in patients at risk for asymptomatic tachyarrhythmias, primarily patients with congenital heart disease. Predictive of arrhythmia in this population were age 418 years, presence of an antitachycardia pacemaker, and presence of an ICD. In this population of 69% patients with congenital heart disease, arrhythmia is a common concern for patients as they age. Patients with antitachycardia pacemakers and ICDs are likely to have a history of tachyarrhythmia as the indication for the device, although these clinical data were not specifically explored in this study. Pediatric patients are more likely to have a device/lead malfunction. This finding is similar to a large, multicenter pediatric study of ICD leads that found increased risk of lead failure with younger age at implantation.7 Any benefit to 60-day monitoring compared to a 90-day monitoring schedule is minimal considering the very low rate of actionable events on asymptomatic interrogations. There is a substantial decrease in workload with a 90-day schedule. In addition, because the 60-day interval allows only 50% of the interrogations to be reimbursed vs 100% in the 90-day model, the reimbursement per workload hour is increased. Although certain patients may require more frequent monitoring, it appears that routine monitoring more often than every 90 days may not be justified. As technology improves and incorporates more wireless and automated surveillance into all CIEDs, routine scheduling of remote monitoring may be necessary only for those at risk for asymptomatic arrhythmias. Patients with symptoms can manually send transmissions, and asymptomatic patients would have automatic notification of device/lead issues. Depending on the recording capabilities and programming of the device, the automatic/wireless system can also monitor for certain types of arrhythmia. Therefore, the role of the wireless system may improve patient surveillance while minimizing the effort of the care team. Patient compliance with the routine remote monitoring is suboptimal but comparable to previously reported compliance in a large adult study.9 We attempted to identify predictors of compliance with remote monitoring and found that patients with congenital heart disease or an ICD were less likely to miss routine transmissions. We speculate that these circumstances improve compliance because patients with congenital heart disease are more likely to have ongoing medical concerns or problems that prompt them to send routine transmissions, and patients or parents of patients with an ICD may send more frequently because of anxiety associated with that device. Remote monitoring provides
Heart Rhythm, Vol 12, No 1, January 2015 peace of mind, which may improve compliance in these patients. Because this was a retrospective study, ascertainment of patient symptoms was only as complete as the documentation in the medical records. This study was limited to patients enrolled in the Medtronic Carelink system because these patients make up the vast majority of device patients at our center; older devices that cannot be remotely monitored and those from other manufacturers may have different rates of actionable events. Patient compliance was suboptimal and may have affected the timing of presentation for asymptomatic actionable events.
Conclusion The rate of actionable events for patients with chronic or newly implanted CIEDs is low, especially in asymptomatic patients, suggesting that the benefit of frequent CIED surveillance is minimal. Many actionable events were due to arrhythmia; patients at risk from asymptomatic arrhythmia may require increased surveillance. However, for this population, a more frequent than every 90-day monitoring schedule does not appear to be of significant benefit. These data may serve to support the development of specific pediatric and congenital heart disease CIED monitoring guidelines.
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