Abstract 11834: Impact of Mechanical Dyssynchrony on Long Term Outcome in Patients with Non Left Bundle Branch Block After Cardiac Resynchronization Therapy
Background: Although cardiac resynchronization therapy (CRT) has been shown to benefit heart failure (HF) patients with wide QRS, recent trials reported the greatest benefit to those with left bundle branched block (LBBB) and lesser benefit to those with non-LBBB. Our objective was to test the hypothesis that mechanical dyssynchrony may be associated with response to CRT in non-LBBB patients.
Methods: We studied 248 NYHA III/IV heart failure patients for CRT with ejection fraction (EF) of 24±6%, and QRS 159±27ms; 124 had LBBB and 124 had non-LBBB (80 with non-specific intraventricular conduction disturbance and 44 with RBBB). Dyssynchrony was assessed by speckle tracking radial strain delay (anterior-septum to posterior wall >130ms). After CRT, we assessed changes in EF and long-term outcome pre-specified as freedom from death, heart transplant or left ventricular assist device over 4 years.
Results: Radial dyssynchrony was observed in 85% of patients with LBBB, and 53% with non-LBBB (p<0.01). LBBB patients had greater improvements in EF (23±6 to 34±12%, p<0.01) and a more favorable long-term survival than non-LBBB patients (p<0.01). Only the non-LBBB patients with dyssynchrony significantly improved their EFs (23±6 to 31±10%, p<0.01) whereas those without dyssynchrony had no EF improvement (25±6 to 27±8%, p=NS). Importantly, non-LBBB patients with baseline dyssynchrony had a more favorable long-term event-free survival than non-LBBB patients without dyssynchrony (p<0.01).
Conclusions: Although LBBB patients derive the greatest benefit from CRT, dyssynchrony in patients with non-LBBB QRS morphology was significantly associated with outcome following CRT.
- © 2011 by American Heart Association, Inc.