Incidence and Clinical Outcomes of Pacing Induced Cardiomyopathy in Patients with Preserved Left Ventricular Systolic Function and Atrioventricular Block

Background: Patients with preserved left ventricular ejection function (LVEF) and atrioventricular block (AVB) who are anticipated for high burden of right ventricular (RV) pacing possess a risk to develop pacing induced cardiomyopathy (PICM) and adverse clinical outcomes.

Objective: To evaluate the incidence, predictors and outcomes of RV-PICM in patients with preserved LVEF, AVB and high-burden RV pacing.

Methods: 1013 patients with advanced AVB underwent pacemaker (PM) implantation between January 2002 and August 2016. A total of 203 patients with a newly implanted PM, normal baseline LVEF, and high-burden RV pacing were included in the present analysis. Follow-up echocardiography was examined for a new decrease in LVEF of 10% or greater. Patients who were not referred to an echocardiography during that period were included in the control arm, in order to avoid referral bias and over diagnosis of PICM as a result of more referrals of subjects with PICM and heart failure symptoms to an echocardiography.

Alternative causes for cardiomyopathy were excluded. Patient characteristics, echocardiographic measurements, device clinic data, mortality and hospitalizations for heart failure (HF) were collected and compared between PICM and non-PICM groups.

Results: 51 patients (25%) developed left ventricular dysfunction with 22 patients (11%) showing LVEF < 40%. Coronary artery disease and left ventricular end diastolic diameter were independently associated with future PICM. During mean follow-up of 49.2 months, the risk of HF hospitalization or all-cause mortality was significantly higher in the PICM group vs. non-PICM group (35.3% vs. 19.1%, p=0.009).

Conclusion: The incidence of PICM in patients with normal LVEF and AVB, who are anticipated for high-burden RV pacing is alarmingly high. PICM in patients with a previously normal left ventricular function is associated with unfavorable long-term clinical outcomes including higher rates of HF hospitalizations and all-cause mortality.