Cardiopulmonary exercise testing (CPET) in the identification of candidate for cardiac resynchronisation therapy (CRT)

Abstract

Aim. To assess in patients with heart failure the effect of CRT over 12 months' follow up on functional class, cardiac function, CPET and neurohormonal indices, the time course and to identify responders to CRT. Methods. 89 patients with a left ventricular (LV) ejection fraction <35% and a left bundle branch block (QRS duration of >150 ms) were prospectively evaluated either in the control (n=45) or CRT group (n=44). All patients (74.1±1 years) were in stable NYHA class III or IV after receiving optimal medical treatment. Results. In the CRT group vs. control group, improvement of cardiac indices (LVEF, LVEDD, Mitral DT) and CPET indices (peak VO2, Ve/VCO2, duration) NYHA class was evident in a medium term (over 6 months) follow up, which persisted on a long term (12 months) (all P<0.05). An inhibitory medium–long term effect of CRT on neurohormonal activation with an increase in HRV after 6 month and decrease of plasma BNP (all P<0.05). We identified 26 responders to CRT vs. 18 non responders according to changes in cardiac ejection fraction and diameters. Responders presented more preserved clinical (NYHA class 2.1±0.1 vs. 3.2±0.2), haemodynamic (LVEF27±1 vs. 21±0.1%), and functional indices (PeakVO2 10±0.3 vs. 6±0.4 ml/kg/min) (all P<0.05). In the multivariate analysis, CPET indices were the strongest predictors of responders. Conclusion. Less depressed haemodynamic and functional status was the strongest predictor of responders to CRT.