Abstract 3076: Effects of Exercise on Ventricular Mechanical Dyssynchrony in Patients with Heart Failure Currently not Recommended for Resynchronization - Results from the Dyssynchrony Induced by Ventricular Exertion in Heart Failure (DIVE-HF) Study.
Background. Resynchronization therapy has been proven to improve exercise tolerance only in heart failure (HF) patients (pts) with profoundly impaired left ventricular ejection fraction (LVEF). Whether it could be useful to other spectrum of HF pts may depend on the existence of ventricular dyssynchrony, either at rest or exercise-induced.
Methods. We studied clinical features, ECG, and echocardiography coupled with tissue Doppler imaging (TDI) in 70 pts (38 men and 32 women, mean age 62±13 years). Among them, 60 pts with compensated HF (functional class II–III) for at least 3 months were grouped into systolic HF (SHF; EF=35–50 %, N=30) and diastolic HF (DHF; EF=50 % plus diastolic dysfunction, N=30) groups. The other 10 pts had no systolic or diastolic dysfunction are the control group. Six-minutes (stage 2) treadmill exercise tests were performed for SHF pts by modified Bruce protocol and for DHF and control pts by Bruce protocol. Dyssynchrony index (DI) represented by standard deviation of electromechanical delays of 12 LV segments was measured before and immediately after exercise.
Results. Except for diverse clinical features and conventional echo-parameters as expected, the QRS duration was similar (mean: 93±16 ms) between the 3 groups. TDI studies showed that baseline synchronized LV contraction remained unchanged after exercise (DI: 12.4±3.6 vs. 11.8±2.9 ms, p=ns) in control group. With regard to the DHF group, the preexisting ventricular dyssynchrony got significantly exacerbated (DI: 52.4±10.0 vs. 62.4±12.8 ms, p<0.001) including 21 pts (70%) with a ≥ 10% increase of DI after exercise provocation. With a more complex response to exercise, the DI in SHF pts didn’t worsen significantly (27.0±19.2 vs. 32.8±20.6 ms, p<0.06). However, the proportion of DI>33 ms, considered as presence of dyssynchrony, increased from 37% at baseline to 50% after exercise, including 6 pts (20%) with post-exercise new development and 2 pts (7%) with post-exercise disappearance of ventricular dyssynchrony.
Conclusions. Exercise-exacerbated ventricular dyssynchrony in DHF pts, and a 50% incidence of post-exercise dyssynchrony in SHF pts with LVEF between 35 to 50% may support the potential utility of resynchronization therapy to these non-indicated HF groups.