Occurrence and long-term outcomes of pacing-induced cardiomyopathy in a large leadless pacemaker cohort

Background

Ventricular leadless pacemakers reduce complication and reintervention rates by half compared to transvenous systems.1 However, their limitation to right ventricular (RV) pacing only may increase the risk of development of pacing-induced cardiomyopathy (PICM). Long-term data on PICM incidence in patients implanted with Micra Transcatheter Pacing System (Micra TPS, Medtronic, US) remain lacking, limiting optimal device selection in clinical practice.

Purpose

To assess the long-term incidence and clinical management of PICM in a single-center cohort of Micra TPS patients. A minimal follow-up of 6 months was required for analysis.

Methods

A total of 406 patients benefited from a Micra implantation from July 2015 to March 2025 (261 Micra VR and 145 Micra AV). Cardiomyopathy development or progression was defined as a >10% reduction in left ventricular ejection fraction (LVEF) leading to LVEF <50%. PICM was withheld as a cause for cardiomyopathy in patients with >20% ventricular pacing (VP), where RV pacing was considered the likely etiology (i.e. no clear alternative cause) or a possible etiology (i.e. alternative cause equally likely).

Results

Micra patients were old (mean age 78 ± 11 years), 66.3% male and frequently had a history of ischemic heart disease (38.2%), valve repair/replacement (29.8%) or severe renal dysfunction/dialysis (15.6%). Mean LVEF at baseline was 54.5±6.3%. Median follow-up was 32.4 months (IQR 11.2-52.4) and median VP% was 58.9% (IQR 18.4-94.1%). Any kind of cardiomyopathy occurred in 51 patients (12.6%) (Figure 1). Twenty-two patients (5.4%) were classified as PICM (11 likely, 11 possible), of whom 15 (3.7%) had no history of systolic heart failure or LVEF <50% before implantation. PICM patients had a median VP% of 90.1% (IQR 72.2-97.5%). In our cohort, the PICM risk was not significantly lower in patients implanted with Micra AV compared to Micra VR (HR 2.3, p = 0.10).

Most PICM cases (90.9%) were managed with optimal medical therapy alone, while 2 patients (9.1%) underwent cardiac resynchronization therapy (CRT) upgrade. In 19/20 medically treated patients, follow-up echocardiogram >6 months after PICM diagnosis was available (1 had recent diagnosis). Among them, 9 (47.4%) showed >10% LVEF improvement, 8 (42.1%) showed stabilization, and 2 (10.5%) had further LVEF decline at last follow-up (Figure 2).

Conclusion

Occurrence of new or progressive cardiomyopathy is frequent in patients implanted with Micra TPS (12.6%), but the long-term incidence of PICM remains relatively low (5.4%). In this old population with high comorbidity, most PICM were only treated with optimal medication and only 2 CRT upgrades were required.Figure 1Figure 2