Additive Prognostic Value of Echocardiographic Global Longitudinal and Global Circumferential Strain to Electrocardiographic Criteria in Patients With Heart Failure Undergoing Cardiac Resynchronization Therapy

Background-Response to cardiac resynchronization therapy is most favorable in patients with heart failure with QRS duration >= 150 ms and left bundle branch block and less predictable in those with QRS width 120 to 149 ms or non-left bundle branch block. Methods and Results-We studied 205 patients with heart failure referred for cardiac resynchronization therapy with QRS >= 120 ms and ejection fraction <= 35%. We tested the hypothesis that contractile function using speckle-tracking echocardiographic global circumferential strain (GCS) from 2 short-axis views and global longitudinal strain (GLS) from 3 apical views add prognostic value to electrocardiographic criteria. There were 112 patients (55%) with GLS >-9% and 136 patients (66%) with GCS >-9%. During 4 years, 81 patients reached the combined primary end point (death, circulatory support, or transplant) and 120 reached the secondary end point (heart failure hospitalization or death). Both GLS >-9% and GCS >-9% were associated with increased risk of unfavorable events as follows: for the primary end point (hazard ratio = 2.91; 95% confidence interval, 1.88-4.49; P < 0.001) and (hazard ratio= 3.73; 95% confidence interval, 2.39-5.82; P< 0.001) for the secondary end point (hazard ratio= 2.10; 95% confidence interval, 1.45-3.05; P < 0.001) and (hazard ratio = 3.25; 95% confidence interval, 2.23-4.75; P < 0.001). In a prespecified subgroup of 120 patients with QRS 120 to 149 ms or non-left bundle branch block, significant associations of baseline GLS and GCS and outcomes remained: P = 0.014 and P = 0.002 for the primary end point and P = 0.049 and P = 0.001 for the secondary end point. Global strain measures had additive prognostic value to routine clinical or electrocardiographic parameters (P < 0.001). Conclusions-Baseline GCS and GLS were significantly associated with long-term outcome after cardiac resynchronization therapy and had additive prognostic value to routine clinical and electrocardiographic selection criteria for cardiac resynchronization therapy.