EP News: Clinical N.A. Mark Estes III, MD, FHRS From the Tufts University School of Medicine, Boston, Massachusetts.

Permanent leadless cardiac pacing Reddy et al (Circulation 2014;129(14):1466-71, PMID 24664277) evaluated the safety and performance of a novel completely self-contained leadless cardiac pacemaker (LCP). The primary safety end point was freedom from complications at 90 days. Secondary end points included implant success rate, implant time, and measures of device performance (pacing/sensing thresholds and rate-responsive performance). The most common indication for cardiac pacing was permanent atrial fibrillation with atrioventricular block (n ¼ 22 [67%]). The implant success rate was 97% (n ¼ 32). Five (15%) patients required the use of 41 LCP during the procedure. The overall complication-free rate was 94% (31 of 33). After 3 months of follow-up, the measures of pacing performance either improved or were stable. The authors conclude that the LCP has shown to be safe and feasible, representing a paradigm shift in cardiac pacing.

Permanent pacemaker implantation after transcatheter aortic valve implantation Urena et al (Circulation 2014;129(11):1233-43, PMID 24370552) evaluated the effect of permanent pacemaker implant (PPI) after transcatheter aortic valve implantation (TAVI). Of 1556 consecutive patients without prior PPI, 239 (15.4%) required a PPI immediately after TAVI. No association was observed between PPI and all-cause mortality (hazard ratio [HR] 0.98; P ¼ .871), cardiovascular mortality (HR 0.81; P ¼ .270), and all-cause mortality or hospitalization for heart failure (HR 1.00; P ¼ .980). A lower rate of sudden death was observed in patients with PPI (HR 0.31; P ¼ .023). Patients with PPI had a poorer evolution of left ventricular ejection fraction over time (P ¼ .017). PPI was an independent predictor of left ventricular ejection fraction decrease (P ¼ .013). The authors conclude that the need for PPI was a frequent complication of TAVI. It was not associated with any increase in overall or cardiovascular death or rehospitalization for heart failure. PPI was a protective factor for the occurrence of sudden death. However, PPI had a negative effect on left ventricular function over time.

Apixaban after cardioversion for atrial fibrillation Flaker et al (J Am Coll Cardiol 2014;63:1082, PMID 24211508) evaluated the risk of major clinical and

thromboembolic events after cardioversion (CV) for atrial fibrillation in patients treated with apixaban compared with patients treated with warfarin. Using data from the ARISTOTLE trial, the investigators conducted a post hoc analysis of patients undergoing CV. A total of 743 CVs were performed in 540 patients: first CVs in 265 patients assigned to apixaban and in 275 patients assigned to warfarin. No stroke or systemic emboli occurred in the 30-day follow-up period. Myocardial infarction occurred in 1 (0.2%) patient receiving warfarin and 1 patient receiving apixaban (0.3%). Major bleeding occurred in 1 (0.2%) patient receiving warfarin and 1 patient receiving apixaban (0.3%). Death occurred in 2 (0.5%) patients receiving warfarin and 2 (0.6%) patients receiving apixaban. The authors conclude that major cardiovascular events after CV are rare and comparable between warfarin and apixaban.

Coupling interval variability differentiates origin of ventricular ectopic complexes Bradfield (J Am Coll Cardiol 2014;Epub, PMID 24657687) evaluated whether premature ventricular contractions (PVCs) arising from the aortic sinuses of Valsalva (SOVs) and great cardiac veins (GCVs) have coupling interval (CI) characteristics that differentiate them from other ectopic foci. Seventy-three consecutive patients referred for PVC ablation were assessed. The ΔCI (maximum CI  minimum CI) was measured. In 73 patients, PVC origin was right ventricular (RV) in 29 (40%), left ventricular (LV) in 17 (23%), SOV 21 (29%), and GCV in 6 (8%). There was a significant difference between the mean ΔCI of RV/LV and that of SOV/GCV PVCs (33 ⫾ 15 ms vs 116 ⫾ 52 ms; P o .0001). A ΔCI of 460 ms demonstrated a sensitivity of 89%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 94%. Cardiac events were more common in the SOV/GCV group than in the RV/LV group (7 of 27 [26%] vs 2 of 46 [4%]; P o .02). The authors conclude that ΔCI is more pronounced in PVCs originating from the SOV or GCV. A ΔCI of 60 ms helps discriminate the origin of PVCs and may be associated with an increased frequency of cardiac events.

Address reprint requests and correspondence: Dr N.A. Mark Estes, Tufts University School of Medicine, 800 Washington St Boston, MA 02111. E-mail address: [email protected]

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EP News Clinical April 2014.

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