Abstract 11902: Evaluating Right Ventricular Pacing Burden Leading to Pacing Induced Cardiomyopathy

Introduction: Pacing induced cardiomyopathy (PICM) is defined as a drop in left ventricular ejection fraction (LVEF) due to high amount of right ventricular (RV) pacing. Although PICM occurs with chronic, and occasionally, acute high burden RV pacing, the minimum burden of RV pacing inducing PICM is not widely established. Hypothesis: Based on multiple cases at our hospital, we hypothesize that >40% RV pacing would induce PICM. Methods: A single center retrospective analysis was done on patients undergoing permanent pacemaker (PPM) placement between January 2019 and April 2020 at our hospital. Data for 88 patients was collected and analyzed using paired student’s t test, comparing mean LVEF in the two groups. Results: Out of 88 patients, 6 patients with cardiac ischemia and 9 patients with biventricular PPM were excluded. 40 out of the remaining 73 (54.8%) patients had >40% RV pacing, out of which 36 patients had pre-PPM and post-PPM implantation echocardiograms and were included in the final analysis. 33 patients (45.2%) had <40% RV pacing, out of which 30 patients had pre-PPM and post-PPM implantation echocardiograms and were included in the final analysis. Median duration of pacing at the time of analysis was 418 days. There was a statistically significant decrease in LVEF in patients with >40% RV pacing [pre-PPM LVEF= 55.4861%, post-PPM LVEF= 51.5972%, mean difference between post-PPM and pre-PPM LVEF= -3.8889% (p=0.032)], but not in patients with <40% pacing [pre-PPM LVEF= 57.1167%, post-PPM LVEF= 57.4833%, mean difference= 0.3666% (p=0.810)] (Image 1; ns: not significant). Conclusion: Our findings showed a statistically significant decrease in LVEF for patients with >40% RV pacing, but not for patients with <40% RV pacing, suggesting that 40% RV pacing is the likely threshold for producing LV systolic dysfunction and cardiomyopathy. Although this difference is statistically significant, clinical significance of this difference varies case-by-case.