Myocardial Scar Burden Independently Predicts Response to Cardiac Resynchronization Therapy

Abstract

Objectives: Cardiac resynchronization therapy (CRT) has been shown to improve quality of life and reduce mortality in patients with heart failure. Around 30 - 45%   are non-responders to CRT. Determinants of response to CRT have been extensively studied. Faithful efforts were exerted to improve selection criteria for CRT beyond standard measures of electrical dyssynchrony. We aimed to assess the predictive value of amount and distribution of myocardial fibrosis to identify responders to CRT compared to conventional measures.

Methodology: 58 patients who underwent CRT implantation on the basis of standard indication were studied. All patients had available myocardial imaging (cardiac MRI or nuclear scan) prior to CRT. Images were analyzed for scar quantification and distribution. Multiple variables were studied. Receiver operator characteristic (ROC) curve analysis was used to evaluate the ability of Global scar to predict response to CRT.

Results: 30 patients of 58 were non-responders to CRT. 27 patients had non-ischemic cardiomyopathy, while 31 patients had ischemic cardiomyopathy. 19 patients (70.3%) in the non-ischemic group, and 9 patients (32.2%) in the ischemic group were responders to CRT, with a statistically significant difference, p- value: 0.002. A cutoff threshold of myocardial scar at 22.9% independently predicted response to CRT with a sensitivity of 70% and a specificity of 92.9%.

Conclusion: Global myocardial scar burden predicted response to CRT independent of etiology, regional distribution, and measures of electrical dyssynchrony