One-Year Outcomes of the First 1000 Patients Implanted With the Medtronic Micra AV Leadless Pacing System in France:...

Evidence supporting the Micra AV leadless pacing system has largely derived from highly experienced centers, potentially limiting generalizability to routine clinical practice.

The AV-CESAR study (French Cohort Evaluating the Effectiveness of Atrioventricular Synchrony by the micRa AV) is a nationwide retrospective cohort, including the first 1000 patients implanted with a Medtronic Micra AV leadless pacemaker in France (2020-2024). Mean follow-up was 13.4±10.6 months. Primary end points were early (in-hospital) and late (postdischarge) device-related major complications; pacemaker syndrome and need for implantation of a new pacing system were centrally adjudicated.

Among 1003 patients, device implantation was successful in 1000 (99.7%). Mean age was 72.0±15 years; 62.8% were men, 44.0% had ≥2 comorbidities, and 62.4% were unsuitable for transvenous pacemakers. The primary indication was permanent complete atrioventricular block with preserved sinus rhythm (78.0%). Early major complications occurred in 2.4%, including pericardial effusion (0.8%; 3 requiring surgery), access-site complications (0.8%), and thromboembolism (0.3%). Late major complications included pacemaker syndrome (2.5%), pacing-induced cardiomyopathy (1.2%), high thresholds (>4 V/0.24ms, 0.3%), and premature battery depletion (0.2%). No device infections or dislodgements were observed. Overall, 2.5% of patients required implantation of a new pacing system (pacing-induced cardiomyopathy n=11; pacemaker syndrome n=7; high threshold n=3; battery/software failure n=3; tricuspid regurgitation n=1) and 12.7% were permanently reprogrammed to ventricular paced/sensed, inhibited (VVI) mode. In pacing-dependent patients with ambulatory Holter monitoring (>3.4 million paced cycles), mean atrioventricular synchrony was 67.6±17.3% and correlated with device-reported AM-VP (74.8±17.1%; R²=0.92; P<0.001). Atrioventricular synchrony declined at heart rates >90 beats per minute (5.6% of monitored time). All-cause mortality was 13.8%, with 0.2% directly device-related; 41.7% of deaths were cardiovascular.

The Micra AV system is primarily used as an alternative when dual-chamber conventional pacemakers are not feasible. It demonstrated acceptable safety and clinical performance in a high-risk population. The marked reduction in atrioventricular synchrony at higher heart rates may suggest limited clinical benefit in patients with higher exertional heart rates.

URL: https://clinicaltrials.gov/study/NCT05953558; Unique identifier: NCT05953558.