Sept 22, 2015 | Mrinal Yadava, MD
Education

In keeping with triennial tradition, the city of Boston played host to the 36th Annual Scientific Sessions of the Heart Rhythm Society from May 13 – 16. As electrophysiologists from across the globe congregated to share their science and interface with industry, there was a palpable excitement for the potentially practice-changing results that lay in prospect. As expected, atrial fibrillation (AFib) related research dominated the landscape, bearing testimony to the fact that AFib indeed lies at the epicenter of the current electrophysiology milieu.

The following is an overview of the key studies presented at this year’s meeting; to inform practice and fuel scientific inquiry of the fellow in training:

1. Aggressive Risk Factor Control Improves Long-Term Success of AFib Ablation (ARREST-AF)
   Presented by Prash Sanders, MBBS, PhD, of the University of Adelaide, this study provided substantial evidence that aggressive modification of cardiac risk factors such as weight, blood pressure, blood sugar and lipid profile is associated with lower AFib frequency, duration, symptoms, and symptom severity following ablation. Single-procedure (p<0.001) and multiple-procedure (p<0.001) arrhythmia-free survival was markedly better in patients with risk factor modification (RFM) compared to controls. RFM was also found to be an independent predictor of arrhythmia-free survival (hazard ratio 4.8 [95% CI: 2.04 to 11.4]; p<0.001).¹
2. Promising Results For the World’s Smallest Pacemaker
   Interim data from the first-in-human trial of the world’s smallest pacemaker, Medtronic’s MircaTM transcatheter pacing system, was presented by Philipe Ritter, MD, of the Hôpital Haut-Lévêque in Bordeaux, France. At one-tenth the size of a conventional pacemaker, or the size of a large vitamin pill, the leadless device is implanted in the endomyocardium via a percutaneous approach. Data from the first 60 patients demonstrated efficacy and safety of the device, with a 5.7 percent rate of serious adverse events, comparable to traditional systems. (Preliminary data; awaiting publication)
3. Effects of Exercise in Patients With Paroxysmal AFib
   In a meta-analysis of 380,000 patients with paroxysmal AFib, moderate and vigorous exercise was associated with a reduction in the risk of AFib recurrence in women. In males, while moderate exercise was beneficial, vigorous exercise was associated with a 90 percent increase in AFib. (Preliminary data; awaiting publication)
4. Emergency Room Protocol For AFib Lowers Hospital Admissions and Length-of-Stay
   A new emergency room-initiated protocol for the evaluation and treatment of AFib was piloted at a single center in Michigan. The pathway emphasized early involvement of the cardiac electrophysiology team, with cardioversion (when appropriate), and institution of novel oral anticoagulants for stroke prophylaxis. The strategy was associated with a comparatively lower rate of hospital admissions, and a shorter length of stay (32.4 vs 88.9 hours; p=0.004).²
5. Lower AF burden in patients with Botulinum toxin injection during coronary artery bypass grafting (CABG)
   Epicardial fat continues to generate considerable interest in the pathogenesis of AF. In this study, intraoperative injection of botulinum toxin in the epicardial fat pads was associated with a decrease in perioperative AF burden. Of particular interest was that these patients had a lower rate of AF even 1-year after the procedure, well after the toxin should have lost its effect.³
6. HeartLight Meets Primary Safety and Efficacy Endpoints
   HeartLight (Cardiofocus) is an endoscopic ablation system that allows for the application of laser energy to produce lesions under direct visualization using a balloon with a camera. In this investigational-device-exemption (IDE) study for the U.S. Food and Drug Administration, the HeartLight laser-balloon catheter was found to be as safe and effective as the Thermocool catheter (Biosense Webster), meeting the primary endpoint for non-inferiority.

This post was authored by Mrinal Yadava, MD, a fellow in training at the Knight Cardiovascular Institute, Oregon Health and Science University in Portland, OR.

References

1. Pathak RK, Middeldorp ME, Lau DH, Mehta AB, Mahajan R, Twomey D, et al. Aggressive risk factor reduction study for atrial fibrillation and implications for the outcome of ablation: the ARREST-AF cohort study. J Am Coll Cardiol. 2014 Dec 2;64(21):2222–31.
2. Elmouchi DA, VanOosterhout S, Muthusamy P, Khan M, Puetz C, Davis AT, et al. Impact of an emergency department-initiated clinical protocol for the evaluation and treatment of atrial fibrillation. Crit Pathw Cardiol. 2014 Jun;13(2):43–8.
3. Pokushalov E, Kozlov B, Romanov A, Strelnikov A, Bayramova S, Sergeevichev D, et al. Botulinum toxin injection in epicardial fat pads can prevent recurrences of atrial fibrillation after cardiac surgery: results of a randomized pilot study. J Am Coll Cardiol. 2014 Aug 12;64(6):628–9.