Myocardial Contractile Reserve Accurately Predicts Positive Response to Cardiac Resynchronization Therapy

Background- Up to 30% of patients with heart failure fail to respond to cardiac resynchronization therapy. This study was aimed at assessing the role of low-dose dobutamine stress echocardiography along with tissue Doppler imaging indices to predict response to cardiac resynchronization therapy. Methods- Twenty-one consecutive patients with systolic heart failure who were candidates for cardiac resynchronization therapy were prospectively included. Contractile reserve was assessed by low-dose dobutamine stress echocardiography (cut-off: 5 and 10%). Interventricular and intraventricular dyssynchrony (using 6 basal, 6 mid-segmental models) was assessed. Acute post-cardiac resynchronization therapy response was defined by 15% or more decrease in the left ventricular end systolic volume. Sensitivity, specificity, predictive values, and likelihood ratios were calculated for the tests singly and in combination. Results- Low-dose dobutamine stress echocardiography had the highest specificity (80%) and positive likelihood ratio (2.5), but interventricular dyssynchrony exhibited the highest sensitivity (83.3%) and the lowest negative likelihood ratio (0.4) for predicting positive response to CRT. Conclusion- Inotropic contractile reserve assessed by low-dose dobutamine stress echocardiography strongly predicts acute response to cardiac resynchronization therapy (Iranian Heart Journal 2010; 11 (3): 29-36).