Efficacy of optimal medical therapy and cardiac resynchronization therapy upgrade in patients with pacemaker-induced cardiomyopathy.

Purpose: The aim of our study was to assess the prevalence of pacemaker-induced cardiomyopathy (PMiCMP) and its response to biventricular stimulation and optimal medical therapy.

Methods: To identify patients with PMiCMP, we screened all patients that presented for pacemaker interrogation in our outpatient clinic in 2012 and 2013 (n = 615). Left ventricular (LV) function was assessed by transthoracic echocardiography. PMiCMP was defined as deterioration of left ventricular ejection fraction (LVEF) <45% unexplained by other cardiac disease under a right ventricular (RV) pacing percentage ≥90%. If symptoms and LV dysfunction persisted under heart failure medication, patients were offered to receive an upgrade to biventricular stimulation (cardiac resynchronization therapy, CRT). CRT response was defined as a decrease of the LV end-systolic volume (LVESV) of ≥15%.

Results: Thirty-seven patients were found to have a PMiCMP. The prevalence of PMiCMP in our total cohort was 6.0%. In 20 PMiCMP patients, an upgrade to a CRT device was performed after a minimum of 3 months of optimal medical therapy. The remaining PMiCMP patients either refused an upgrade or were in good functional status. The LVEF before CRT upgrade was 33.3 ± 5.2% and improved to 47.6 ± 9.3% (P < 0.001) within 6 months. Positive response to CRT was observed in 17 patients (85%). In the group without device upgrade, LVEF was 40.5 ± 5% and did not change during the follow-up period of 1 year.

Conclusions: Optimal medical therapy lacks efficacy in PMiCMP patients. The response rate to CRT was significantly higher in PMiCMP patients compared to average CRT patients.