Abstract 1603: Factors and Mechanisms Associated with Improved Cardiopulmonary Performance after Cardiac Resynchronization Therapy. An Exercise Echocardiography Study.
Background: Cardiac resynchronization therapy (CRT) leads to better cardiopulmonary performance in congestive heart failure (CHF) patients (pts). Mechanisms underlying the benefits are not fully elucidated.
Aim: To investigate factors and mechanisms associated with improved cardiopulmonary performance after CRT.
Methods: Twenty-three pts (EF 26±7%, QRS complex 170±26 msec) were studied by simultaneous quantitative semi-supine exercise echocardiography and cardiopulmonary exercise testing before and 3 months after CRT. Pts with an increase (Δ) in peak VO2≥1.1 ml/kg/min were considered clinical responderes. Effective regurgitant orifice (ERO) of the mitral regurgitation (MR) was assessed using the PISA method.
Results: In the entire population, CRT was associated with a decrease in LV dyssynchrony from 53±2 to 23±9 msec (p<0.001), increase LV ejection fraction (EF) from 26±7 to 36±9% (p<0.001) and ERO reduction from 0.24±0.11 to 0.13±0.06 cm2 (p<0.001) In addition, peak VO2 increased from 11.6±2.3 to 12.9±3.6 ml/kg/min (p<0.01) and Nt-pro BNP decreased from 2795±1644 to 2021±1353 pg/ml (p<0.05). At follow-up (Table⇓), ERO at rest was similar but exercise-induced ERO and Nt-pro BNP were significantly lower in responders vs nonresponders. Change in peak VO2 correlated inversely with the extent of exercise-induced MR at follow-up (r=−0.47, p<0.05), with baseline Nt-pro BNP levels (r=−0.53, p<0.05) and change in LVESV (r=−0.49, p<0.05).
Conclusions. Improved cardiopulmonary performance after CRT is related to changes in exercise-induced MR rather than resting MR. Thus, effects on the exercise-induced MR in parallel to reverse LV remodelling appear to contribute to improved cardiopulmonary performance and clinical benefits of the CRT.