Background: Sustained right ventricular (RV) pacing can cause cardiomyopathy due to electrical dyssynchrony. Cardiac resynchronization therapy (CRT) can lead to reverse left ventricular (LV) remodeling by minimizing conduction delay. We hypothesized that CRT in pacemaker induced cardiomyopathy (PICM) would result in a greater improvement in EF compared to other causes of cardiomyopathy.
Objective: To determine the change in ejection fraction after CRT upgrade in patients with PICM.
Methods: A retrospective EMR review was conducted for individuals who underwent CRT upgrade between January 1, 2010 and January 31, 2016. Inclusion criteria were normal EF prior to pacemaker placement, RV pacing ≥ 80% and EF ≤ 45% prior to CRT upgrade. Frequency of improvement in EF of greater than or equal to 5% and 10% were calculated.
Results: The study population included 22 patients with average age 69.7 ± 13.1 and average EF of 36.8 ± 6.9% at the time of CRT upgrade. Eight patients had aortic stenosis prior to CRT upgrade. Sixteen patients (73%) experienced at least 5% improvement in EF one year after upgrade to CRT and 12 patients (55%) improved by at least 10%. Average change in EF was 9.2 ± 12.3% compared to 4.6% improvement in all-comers with heart failure in the MIRACLE study. Ninety-two percent of participants without aortic stenosis had improvement in EF of at least 10% or to greater than 50% compared to only 8.3% of participants with aortic stenosis experiencing this degree of improvement (p=0.002).
Conclusion: In patients with PICM, EF improvement after CRT upgrade is higher than in all-comers. Furthermore, the presence of concomitant aortic stenosis was associated with an attenuated improvement in EF.