Does ventricular dyssynchrony on echocardiography predict response to cardiac resynchronisation therapy? A randomised controlled study

Objective To determine the value of echocardiography in predicting response to cardiac resynchronisation therapy (CRT). Methods This is a prospective randomised study that recruited patients with (group 1) and without (group 2) echocardiographic evidence of mechanical dyssynchrony. 73 heart failure patients (NYHA III-IV) with a requirement for an implantable cardioverter defibrillator, QRS >= 120 ms and LV ejection fraction (EF) < 35% were studied. Group 1 patients received CRT-D (26 patients). Group 2 patients were randomised to CRT-D (group 2a: 23 patients) or implantable cardioverter defibrillator (group 2b: 21 patients). Main outcome measures were peak oxygen consumption (VO(2)max), NYHA class, and echocardiography at baseline and at 6 months. Results 62% of group 1 patients achieved >= 1 ml/kg/min increase in VO2max at 6 months versus 50% in group 2a and 21% in group 2b (p=0.04). Group 1 patients showed significant improvements in VO2max (15.8 +/- 2 to 18.0 +/- 4 ml/kg/min, p=0.01), NYHA class (3.1 +/- 0.3 to 1.9 +/- 0.7, p<0.001) and EF (22 +/- 7% to 26 +/- 9%, p=0.02). Group 2a showed significant improvement in NYHA class (3.1 +/- 0.3 to 2.2 +/- 0.7, p<0.001) but no change in EF or VO(2)max. Group 2b showed no change in NYHA class or EF with a decline in VO(2)max (16.4 +/- 4 to 14.1 +/- 4, p=0.03). A significantly higher proportion of patients in group 2b showed >= 1 ml/kg/min deterioration in VO(2)max compared to group 2a (68% vs 23%, HR for group 2b: 2.4, 95% CI 1.2 to 4.8, p=0.005). Conclusions The presence of echocardiographic dyssynchrony identifies patients who derive the most improvement from CRT. Patients without dyssynchrony also show more benefit and less deterioration with CRT than without and should not be denied CRT.