Abstract 11865: Electrical Reverse Remodeling Associated with Improvements in Mechanical Dyssynchrony and Ventricular Function After Cardiac Resynchronization Therapy
Background: Although cardiac resynchronization therapy (CRT) has been shown to benefit heart failure (HF) patients with widened QRS and mechanical dyssynchrony by left ventricular (LV) reverse remodeling, effects on electrical reverse remodeling are not clear. Our objective was to test the hypothesis that CRT may improve electrical repolarization along with LV chamber remodeling and improvements in mechanical dyssynchrony.
Methods: We studied 148 consecutive HF patients referred for CRT with ejection fraction of 24±6% and QRS of 159±29ms. Twelve-lead electrocardiogram (ECG) and echocardiogram were examined before and 7±4 months after the CRT. Repolarization was determined as the rate corrected maximum QT interval (QTc; ms) and dispersion of QTp (QRS to T-wave peak; ms) in 12-leads (QTpd: maximum - minimum QTp; ms). Dyssynchrony was assessed by speckle tracking radial strain delay between anterior-septum to posterior wall >130ms and interventricular mechanical delay (IVMD) >40ms. CRT response was defined as a relative decrease in end-systolic volume (ESV) >10% at chronic follow-up.
Results: In ESV responders (n=89), the repolarization abnormality QTpd decreased significantly after CRT (69±17ms to 43±19ms, p<0.001). QTc did not change (495±45ms to 496±40ms, NS). In contrast, 59 non-responders without ESV reverse remodeling, had QTc prolongation (481±40ms to 513±41ms, p<0.001) while QTpd was unchanged (64±19ms to 62±21ms, NS). Overall, chronic QTpd was significantly less in ESV responders than in the non-responders (p<0.001). Patients who had radial dyssynchrony or IVMD had larger improvements in ESV and QTpd than in the patients with no dyssynchrony (p<0.02, respectively).
Conclusions: Improvements in repolarization following CRT were associated with improvements in LV structural remodeling. CRT has the potential to improve both structural and electrical remodeling in the HF patients with mechanical dyssynchrony.
- © 2011 by American Heart Association, Inc.