Aims: Cardiac resynchronization therapy (CRT) improves functional capacity and survival in heart failure. However, one-third of patients fail to respond to CRT. Resting left ventricular (LV) dyssynchrony assessed by echocardiography (ECHO) showed discordant results in identifying CRT responders. LV dyssynchrony can totally change during exercise. Aim of this study was to evaluate whether exercise dyssynchrony could select responders to CRT.
Methods and results: Sixty-four patients scheduled for CRT implantation performed bicycle exercise ECHO in semi-supine position on an exercise tilting table before and 6 months after CRT implantation. Tissue Doppler imaging (TDI) was acquired both at rest and during exercise to detect LV mechanical dyssynchrony. Predictive values for CRT response were 70% for rest TDI and 89% for exercise TDI (P = 0.01). Exercise LV dyssynchrony was the only parameter independently associated with follow-up improvement of rest ejection fraction and LV volume during multivariable analysis (P < 0.001). Functional improvement at 6-min walking test was statistically higher in patients with exercise dyssynchrony (P = 0.005), and not different considering rest dyssynchrony (P = 0.30).
Conclusion: Exercise intraventricular dyssynchrony assessed by exercise TDI ECHO is a strong independent predictor of CRT response. It could be used to select candidates for CRT, thus reducing ineffective implantations of biventricular pacemakers.