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.