A Real-world Experience of Atrioventricular Synchronous Pacing with Leadless Ventricular Pacemakers

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.

A new leadless pacemaker with atrioventricular synchronous pacing replacing a still working VVI leadless pacemaker: a case report

Background A new intracardiac leadless pacemaker (ILP) has been developed to ensure atrioventricular synchrony during ventricular pacing. Recent studies have shown feasibility and safety of accelerometer-based atrial sensing and an improvement in atrioventricular synchrony among patients with atrioventricular block implanted with the Micra AV ILP (Medtronic Inc, Minneapolis, Minnesota, US). However, no data exists about the benefits of a VDD ILP in patients wearing a still working VVI Nanostim ILP (St Jude Medical, St Paul, Minnesota, US). We describe the feasibility of the procedure and the absence of device-related adverse events in the short-term follow-up. Case summary We present the case of a 72-year-old man implanted with a VVI ILP (Nanostim, St Jude Medical, St Paul, MN) on May 2014, who has developed symptomatic high percentage of VVI asynchronous pacing and was treated with an upgrade to synchronous AV PM ILP—Micra AV (Medtronic Inc, Minneapolis, Minnesota, US), which has improved symptoms and functional class. Discussion ILPs represent the best current option for patients requiring pacemaker implantation who are at high risk of infection and bleeding. Our case shows that the new AV synchronous ILP is a good alternative to VVI ILP in patients with sinus rhythm and a strong need for ventricular pacing.

TTE guided synchronization to optimize AV synchronous leadless pacemaker programming

Transvenous pacemakers are associated with major complications [1]. Transcatheter leadless pacemaker has reduced the incidence of these complications and the recent accelerometer based atrial sensing algorithm permits restoration of atrioventricular synchrony [1]. We report utilizing cardiac output measurements using Transthoracic Echocardiography (TTE) to determine optimal programming for leadless pacemaker.

What do we do about atrial high rate episodes?

Atrial high rate episodes (AHREs) are defined as asymptomatic atrial tachyarrhythmias detected by cardiac implantable electronic devices with atrial sensing, providing automated continuous monitoring and tracings storage, occurring in subjects with no previous clinical atrial fibrillation (AF) and with no AF detected at conventional electrocardiogram recordings. AHREs are associated with an increased thrombo-embolic risk, which is not negligible, although lower than that of clinical AF. The thrombo-embolic risk increases with increasing burden of AHREs, and moreover, AHREs burden shows a dynamic pattern, with tendency to progression along with time, with potential transition to clinical AF. The clinical management of AHREs, in particular with regard to prophylactic treatment with oral anticoagulants (OACs), remains uncertain and heterogeneous. At present, in patients with confirmed AHREs, as a result of device tracing analysis, an integrated, individual and clinically-guided assessment should be applied, taking into account the patients’ risk of stroke (to be reassessed regularly) and the AHREs burden. The use of OACs, preferentially non-vitamin K antagonists OACs, may be justified in selected patients, such as those with longer AHREs durations (in the range of several hours or ≥24 h), with no doubts on AF diagnosis after device tracing analysis and with an estimated high/very high individual risk of stroke, accounting for the anticipated net clinical benefit, and informed patient’s preferences. Two randomized clinical trials on this topic are currently ongoing and are likely to better define the role of anticoagulant therapy in patients with AHREs.