Aims: The MicraTM transcatheter pacing system (TPS) (Medtronic) is the only leadless pacemaker that promotes atrioventricular (AV) synchrony via accelerometer-based atrial sensing. Data regarding the real-world experience with this novel system are currently lacking. We sought to characterize patients undergoing MicraTM -AV implants, describe percentage AV synchrony achieved, and analyze the causes for suboptimal AV synchrony. Methods: In this retrospective cohort study, electronic medical records from 56 consecutive patients undergoing MicraTM -AV implants at the Mayo Clinic sites in Minnesota, Florida, and Arizona with a minimum follow-up of 3 months were reviewed. Demographic data, comorbidities, echocardiographic data, and clinical outcomes were compared among patients with and without atrial synchronous-ventricular pacing (AsVP) ≥70%. Results: Fifty-six percent of patients achieved AsVP ≥70%. Patients with adequate AsVP had smaller body mass indices, a lower proportion of congestive heart failure and pulmonary hypertension. Echocardiographic parameters and procedural characteristics were similar across the two groups. Active device troubleshooting was associated with higher AsVP. The likely reasons for low AsVP were persistent atrial arrhythmias, small A4-wave amplitude, and inadequate device reprogramming. Importantly, in patients with low AsVP, subjective clinical worsening was not noted during follow-up. Conclusion: With the increasing popularity of leadless PM, it is paramount for device implanting teams to be familiar with common predictors of AV synchrony and troubleshooting with MicraTM -AV devices.

Background: It is unknown whether cryoballoon technology for persistent atrial fibrillation (AF) is a reasonable initial strategy for patients with persistent AF (perAF). Methods: 390 consecutive procedures using cryoballoon for initial AF ablation were evaluated and divided first by clinical presentation: paroxysmal AF (PAF) or perAF, and then whether PV potentials associated PV pacing (PV capture) were identified after ablation. Patients were followed for recurrent AF (median 20 months). Results: PV capture was identified in patients with PAF and perAF (PAF: 20.3% vs. perAF: 14.6%; p < 0.05). No patient charactieristic differences were identified between those patients with or without PV capture. The presence of PV capture was not associated with different outcomes in patients with PAF. However, in patients with perAF, the presence of PV capture was associated with long-term outcomes similar to patients with PAF and significantly better than patients with perAF without PV capture (p < 0.001). In patients with perAF and PV capture, a strategy of reisolation of the PVs only for recurrent AF resulted in 20/23 (87%) patients in sinus rhythm off antiarrhythmic medications at study completion. In patients with PV capture, specific electrophysiologic properties of PV tissue did not have an impact on AF recurrence. Conclusion: PV capture (and not specific PV electrophysiologic characteristics) was associated with decreased recurrent AF in patients with perAF. PV capture may identify those patients with perAF in whom PV isolation alone is sufficient at initial ablation procedure and also as the primary ablation strategy for recurrent AF.