Predicting Cardiac Resynchronization Therapy Response with Speckle-Tracking Echocardiography: A Systematic Review and...

Nearly 30% of patients with cardiac resynchronization therapy (CRT) are nonresponders. Speckle-tracking echocardiography (STE) parameters are able to evaluate electromechanical dyssynchrony that could improve outcomes. We aim to examine the association between various STE parameters with CRT response and clinical outcomes in heart failure patients. Searching was done on 3 medical databases. The STE parameters assessed are dyssynchrony index (time delay of peak strain between walls > 130 msec), myocardial work indices (global constructive and wasted work), and strain patterns. Meta-analysis with a random-effect model was used to pool the effect sizes. Fifty-one observational studies comprising 11,491 patients ranging from 63 to 71 years old were included. Dyssynchrony index with radial strain is not associated with CRT response but with risk reduction of clinical outcome (hazard ratio [HR] = 0.51; CI, 0.39-0.67). This association is also found in unfavorable electrocardiogram (HR = 0.77), and non-left bundle branch block (HR = 0.47) populations. Meta-regression result did not show an association of LBBB, ischemic heart disease, or QRS duration as covariates to the outcomes. Global wasted work is associated with an increased odds of CRT response (odds ratio = 4.78) and risk reduction of clinical outcomes (HR = 0.44). Deformation strain pattern 1/2 and typical LBBB strain are associated with increased odds of CRT response (odds ratio = 8.26 and 5.07), while deformation pattern 3 and absence of typical LBBB strain pattern are associated with increased risk of clinical outcome (HR = 3.22 and 2.77). Various STE parameters could be used to improve CRT response and clinical outcome in heart failure patients.