AF News Section Editor: Shih-Ann Chen, M.D.
Approaches to catheter ablation for persistent atrial fibrillation. Verma A, et al. Star AF II Investigators. N Engl J Med 2015;372:1812–1822. PMID: 25946280. Catheter ablation is less successful for persistent atrial fibrillation (AF) than for paroxysmal AF. Guidelines suggest that adjuvant substrate modification in addition to pulmonary-vein (PV) isolation is required in persistent AF. The Star AF II trial aimed to answer the effect of the substrate modification in persistent AF. The study randomly assigned 589 patients in a 1:4:4 ratio to ablation with PV isolation alone, PV isolation plus complex fractionated electrogram ablation, or PV isolation plus additional linear ablation (roof and mitral isthmus). The results showed that procedure time was significantly shorter for PV isolation alone than for the other 2 procedures (P < 0.001). After following up for 18 months, 59% of patients assigned to PV isolation alone were free from recurrent AF, as compared with 49% of patients assigned to PV isolation plus complex electrogram ablation, and 46% of patients assigned to PV isolation plus linear ablation (P = 0.15). There were no significant differences among the three groups for the secondary end points (freedom from AF after 2 procedures and freedom from any atrial arrhythmia). Conclusions: Among patients with persistent AF, there was no reduction in the rate of recurrent AF when either linear ablation or ablation of complex fractionated electrograms was performed in addition to PV isolation. Atrial fibrillation and risk of ST-segment elevation versus non-ST segment elevation myocardial infarction: The atherosclerosis risk in communities (ARIC) study. Soliman EZ, et al. Wake Forest School of Medicine, Winston Salem, NC, USA. Circulation 2015 [Epub ahead of print]. PMID: 25918127. It has recently been reported that AF is associated with an increased risk of myocardial infarction (MI). The ARIC study aimed to evaluate the relationship of AF with type of MI (ST elevation [STEMI] vs. non-ST elevation MI [NSTEMI]). The study examined the association between AF and incident MI in 14,462 patients from ARIC study who were free of coronary heart disease at baseline (1987–1989) with followup through the end of 2010. Over a median follow-up of 21.6 years, 1,374 MI events occurred (829 NSTEMI, 249 STEMI, and 296 unclassifiable). In a multivariable adjusted J Cardiovasc Electrophysiol, Vol. 26, pp. 912-913, August 2015. Li-Wei Lo, M.D. and Tze-Fan Chao, M.D. are co-authors with Shih-Ann Chen, M.D. Disclosures: None. Address for correspondence: Shih-Ann Chen, M.D., Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, 201, Sector 2, Shih-Pai Road, Taipei, Taiwan. Fax: 886-2-2873-5656; E-mail: [email protected]
model, AF (n = 1,545) as a time-varying variable was associated with a 63% increased risk of MI (HR [95% CI]: 1.63 [1.32–2.02]). However, AF was associated with NSTEMI (HR [95% CI]: 1.80 [1.39-2.31]) but not STEMI (HR [95% CI]: 0.49 [0.18–1.34]). The association between AF and MI was stronger in women than in men. Conclusions: AF is associated with an increased risk of incident MI, especially in women. This association is limited to NSTEMI. MicroRNA profiling of atrial fibrillation in canines: MiR206 modulates intrinsic cardiac autonomic nerve remodeling by regulating SOD1. Zhang Y, et al. PLoS One 2015; 10:e0122674. School of Medicine, Shandong University, China. PMID: 25816284. Numerous Micro RNAs (miRNAs) are involved in diseases of the nervous and cardiovascular systems. The study aimed to assess the underlying role of miRNAs in regulating cardiac autonomic nerve remodeling (ANR) in right atrial tachypacing (A-TP) canines. Following 4-week A-TP, the superior left ganglionated plexuses were subjected to miRNA expression profiling to screen preferentially expressed miRNAs. Sixteen miRNAs showed significantly differential expression between the control and A-TP groups, including miR-206, miR-203, miR-224, and miR-137, especially miR206 (10-fold elevation). Forced expression of miR-206 through lentiviral infection based on A-TP in vivo significantly shortened the atrial effective refractory period (81 ± 7 vs. 98 ± 7 milliseconds, P < 0.05). The expression of superoxide dismutase 1 (SOD1) was repressed by miR206 overexpression, indicative of SOD1 as a direct target of miR-206. Overexpression of miR-206 increased reactive oxygen species (ROS) levels in vitro and in vivo, whereas miR-206 silencing attenuated irradiation- or A-TP-induced ROS. Conclusions: The study demonstrated the differential expression of miRNAs in response to ANR in AF, suggesting the novel molecular mechanism of ANR and a potential therapeutic target for AF. Higher circulating adiponectin levels are associated with increased risk of atrial fibrillation in older adults. Macheret F, et al., Penn Presbyterian Medical Center, University of Pennsylvania School of Medicine, Philadelphia, PA, USA. Heart 2015, doi: 10.1136/heartjnl-2014307015 [Epub ahead of print]. PMID: 25855796. Adiponectin has cardioprotective properties. However, higher adiponectin has been linked to greater incidence of adverse outcomes associated with AF. The author postulated that higher adiponectin would be linked to increased risk for AF in older adults in a U-shaped manner. In this population-based cohort study of older adults (n = 3,190; age = 74 ± 5 years) for 11.4 years, there were 886 incident AF events. There is a linear association between adiponectin and incident AF. After adjusting for potential confounders, the HR (95% CI) for AF per SD increase in total adiponectin
was 1.14 (1.05–1.24), while that for high-molecular-weight adiponectin was 1.17 (1.08–1.27). Conclusions: The findings demonstrate that higher, not lower, levels of adiponectin are independently associated with increased risk of AF in older adults. Additional work is necessary to determine if adiponectin is a marker of failed counter-regulatory pathways or whether it is directly harmful in the setting of or as a result of advanced age. Atrial ectopy predicts late recurrence of atrial fibrillation after pulmonary vein Isolation. Gang UJ, et al., Gentofte University Hospital, Department of Cardiology, Copenhagen, Denmark. Circ Arrhythm Electrophysiol 2015 [Epub ahead of print]. PMID: 25904494. Late recurrence of AF following radiofrequency ablation (RFA) remains significant. The presence of premature atrial complex (PAC) is not uncommon after RFA. This study aimed to evaluate the prognostic value of PAC occurrence in regards to the risk of late AF recurrence after RFA. The study enrolled 124 patients with 7-day Holter recordings at 6 months post-RFA for AF without recurrence prior to this time. During a follow-up of 4.2 years (1st Quartile–3rd Quartile [Q1–Q3] = 1.6–4.5), 32 patients (26%) had late recurrences of AF at a median of 462 days (Q1–Q3 = 319—1,026) post-RFA. Multivariate analysis of the risk of late AF recurrence found PAC 142 per 24 hours to have a hazard ratio of HR = 2.84 (CI 1.26–6.43), P = 0.01.
Conclusions: This study showed that occurrence of 142 PACs per day at 6 months after PV isolation was independently associated with a significantly increased risk of late AF recurrence. Surgical ablation of atrial fibrillation during mitral-valve surgery. Gillinov AM, et al. CTSN Investigators. N Engl J Med 2015;382:1399–1409. PMID: 25853744. Thirty to 50% patients are found to have AF during mitralvalve surgery. This study aimed to investigate the safety and effectiveness of AF surgical ablation during mitral-valve surgery. The study randomly assigned 260 patients with persistent or longstanding persistent AF who required mitralvalve surgery to undergo either surgical ablation (ablation group) or no ablation (control group) during the mitralvalve operation. More patients in the ablation group than in the control group were free from AF at both 6 and 12 months (63.2% vs. 29.4%, P < 0.001). There was no significant difference in the AF-free rate between patients who underwent PV isolation and those who underwent the biatrial maze procedure. Ablation was associated with more implantations of a permanent pacemaker than was no ablation (21.5 vs. 8.1 per 100 patient-years, P = 0.01). There were no significant differences between 2 groups in major adverse events. Conclusions: The addition of AF ablation to mitral-valve surgery significantly increased the AF-free rate at 1 year among patients with persistent or longstanding persistent AF, but the risk of implantation of a permanent pacemaker was also increased.