First-in-man studies of leadless pacemakers have demonstrated high rates of implant success, and safety and efficacy objectives were achieved. Outside of the investigational setting, there are concerns, particularly over cardiac effusion and perforation, device dislodgement, infection, telemetry, and battery issues. The acute performance of the Micra transcatheter pacemaker from a worldwide Post-Approval Registry is reported. The registry is an ongoing prospective single-arm observational study designed to assess the safety and effectiveness of Micra in the post-approval setting. The safety end point was system- or procedure-related major complications at 30 days post implant. We compared the major complication rate with that of the 726 patients from the investigational study. Electrical performance was also characterized. The device was successfully implanted in 792 of 795 registry patients (99.6%) by 149 implanters at 96 centers in 20 countries. Through 30 days post implant, a total of 13 major complications occurred in 12 patients, for a major complication rate of 1.51% (95% confidence interval, 0.78%-2.62%). Major complications included cardiac effusion/perforation (1, 0.13%), device dislodgement (1, 0.13%), and sepsis (1, 0.13%). After adjusting for baseline differences, the rate of major complications in the registry trended lower than the investigational trial (odds ratio, 0.58, 95% confidence interval, 0.27-1.25; P = .16). Early pacing capture thresholds were low and stable. Performance of the Micra transcatheter pacemaker in a real-world setting demonstrates a high rate (99.6%) of implant success and low rate (1.51%) of major complications through 30 days post implant. In particular, the rates of pericardial effusion, device dislodgement, and infection were low, reinforcing the positive results seen in the investigational study.

Micra is a leadless pacemaker that is implanted in the right ventricle and provides rate response via a 3-axis accelerometer (ACC). Custom software was developed to detect atrial contraction using the ACC enabling atrioventricular (AV) synchronous pacing. The purpose of this study was to sense atrial contractions from the Micra ACC signal and provide AV synchronous pacing. The Micra Accelerometer Sensor Sub-Study (MASS) and MASS2 early feasibility studies showed intracardiac accelerations related to atrial contraction can be measured via ACC in the Micra leadless pacemaker. The Micra Atrial TRacking Using A Ventricular AccELerometer (MARVEL) study was a prospective multicenter study designed to characterize the closed-loop performance of an AV synchronous algorithm downloaded into previously implanted Micra devices. Atrioventricular synchrony (AVS) was measured during 30 minutes of rest and during VVI pacing. AVS was defined as a P wave visible on surface ECG followed by a ventricular event <300 ms. A total of 64 patients completed the MARVEL study procedure at 12 centers in 9 countries. Patients were implanted with a Micra for a median of 6.0 months (range 0-41.4). High-degree AV block was present in 33 patients, whereas 31 had predominantly intrinsic conduction during the study. Average AVS during AV algorithm pacing was 87.0% (95% confidence interval 81.8%-90.9%), 80.0% in high-degree block patients and 94.4% in patients with intrinsic conduction. AVS was significantly greater (P <.001) during AV algorithm pacing compared to VVI in high-degree block patients, whereas AVS was maintained in patients with intrinsic conduction. Accelerometer-based atrial sensing is feasible and significantly improves AVS in patients with AV block and a single-chamber leadless pacemaker implanted in the right ventricle.

Background and Purpose—: Atrial fibrillation (AF) is increasingly prevalent in the elderly, but such patients tend to be under-represented in clinical trials. Increasing age confers a higher risk of stroke and bleeding when antithrombotic therapy is used. We examined risk factors for stroke and bleeding among elderly (age, >75 years) patients within a real world hospitalized cohort from the Loire Valley AF project. Methods—: We identified elderly (age, >75 years) patients with AF, assessed their risk factors, and followed up for stroke, thromboembolism, death, or major bleeding. The effect of vitamin K antagonist (VKA) use on these end points was assessed. Results—: We studied 8962 patients with AF, and we identified 4130 elderly (age, ≥75 years) patients. Using Kaplan–Meier analyses, event rates of death, stroke/thromboembolism, the composite of stroke/thromboembolism/death, and major bleeding increased with increasing age. For mortality, VKA-treated patients did better than non-VKA–treated patients. The risk of death and stroke/thromboembolism/death increased with increasing age. The risk of major bleeding did not increase with increasing age strata. VKA treatment was associated with lower mortality in those aged <75 years (adjusted hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.45–0.72), and the effect size was maintained with increasing age strata ( P _int =0.67). For stroke/thromboembolism/death, VKA also has a significant benefit in those aged <75 years (adjusted HR, 0.69; [0.57–0.83]), and the effect size was maintained with increasing age strata ( P _int =0.58). For major bleeding, there was no statistically significant difference between age strata ( P _int =0.67). In elderly patients, age and previous stroke emerged as the main predictors of stroke and thromboembolism. Renal impairment and VKA use were predictors of major bleeding. Conclusions—: Elderly patients with AF have a higher risk of stroke and bleeding, but the benefits of VKA therapy for stroke/thromboembolism or mortality were present regardless of increasing age.

Whether statins may prevent atrial fibrillation remains a subject of debate. An updated systematic review of randomized controlled trials with statins that collected data on the incidence or recurrence of atrial fibrillation was performed. Thirty-two published studies with 71 005 patients were included in the analysis. Overall, the use of statins was significantly associated with a decreased risk of atrial fibrillation compared with controls [odds ratio (OR) 0.69, 95% confidence interval (CI) 0.57-0.83, P < 0.0001] with heterogeneous results. The benefit of statin therapy appeared highly significant for the prevention of postoperative atrial fibrillation (homogeneous OR 0.37, 95% CI 0.28-0.51, P < 0.00001). Benefit was not apparent for the prevention of new-onset atrial fibrillation (OR 1.00, 95% CI 0.86-1.15, P = 0.95) but was significant for secondary prevention of atrial fibrillation (OR 0.57, 95% CI 0.36-0.91, P = 0.02 with significant heterogeneity). There was no reduction in the risk of atrial fibrillation with more intensive vs. standard statin regimens (OR 1.01, 95% CI 0.77-1.32, P = 0.96). The use of statins was significantly associated with a decreased risk of atrial fibrillation in patients with sinus rhythm. The highest benefit was seen for the prevention of postoperative atrial fibrillation and in secondary prevention of atrial fibrillation, with a heterogeneity that deserves further clarification.