RV Pacing-Induced Cardiomyopathy With Preserved EF
What are the incidence and predictors of right ventricular (RV) pacing-induced cardiomyopathy (PICM) in complete heart block (CHB) with preserved left ventricular ejection fraction (LVEF)?
This was a retrospective analysis of 823 consecutive patients with CHB and LVEF >50% who underwent permanent pacemaker (PPM) placement at Cleveland Clinic over a span of 14 years. Cardiac resynchronization therapy (CRT) response was defined by LVEF increase ≥10% or LV end-systolic volume decrease ≥15%.
Over the mean follow-up of 4.3 years, 101 (12.3%) patients developed PICM, with post-PPM LVEF being 33.7% in patients with PICM versus 57.6% in patients without PICM (p < 0.001). Lower pre-PPM LVEF and RV pacing percentage both as a continuous and as a categorical (<20% or ≥20% RV pacing) variable were independently associated with PICM on multivariable analysis. Only 29 patients with PICM (28.7%) received CRT upgrade despite an 84% responder rate (LVEF increase 18.5% and LV end-systolic volume decrease 45.1% in responders).
The authors concluded that PICM is not uncommon in patients receiving PPM for CHB with preserved LVEF and is strongly associated with RV pacing burden >20%. CRT response rate is high in PICM, but is perhaps underutilized.
In order to minimize false positives, the authors chose an EF threshold of ≤40% to denote post RV-pacing cardiomyopathy. While prior literature suggested that RV pacing ≥40% was associated with risk of LV dysfunction, the present study suggests that the threshold may be much lower at ≥20%. The findings of this study suggest that LV function should be periodically assessed in patients who RV pace a significant percentage of the time (i.e., ≥20%), and be considered for CRT upgrade once LVEF falls. Importantly, 84% of patients who underwent CRT upgrade experienced significant improvement in their LVEF. Unfortunately, only a minority of eligible patients (~30%) was offered CRT upgrade in this cohort, especially if the post-pacing LVEF was >35%, suggesting that this intervention may be significantly underutilized. Of note, the 12.3% incidence of cardiomyopathy post-PPM implantation at 3.7 years may be a significant underestimate, because by that point, >50% of patients were lost to follow-up.
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