Clinical and echocardiographic predictors of nonresponse to cardiac resynchronization therapy.

Background: Lack of response to cardiac resynchronization therapy (CRT) ranges between 30% to 40% of heart failure (HF) patients. The present study aimed to evaluate the clinical and echocardiographic determinants of nonresponse to CRT.

Methods: A total of 581 patients (66.4 ± 10.0 years, 77.9% male) with advanced HF scheduled for CRT implantation were included. Clinical and echocardiographic evaluations were performed at baseline and 6 months of follow-up. Nonresponse was defined as no improvement in the New York Heart Association functional class, death from worsening HF or heart transplantation, and <15% reduction in left ventricular (LV) end-systolic volume.

Results: At 6 months of follow-up, 254 patients (44%) did not respond to CRT. The nonresponders were more frequently male (81.9% vs 74.3%, P = .030) and had ischemic cardiomyopathy (69.7% vs 53.2%, P < .001), shorter QRS duration (150.6 ± 29.9 milliseconds vs 156.0 ± 32.5 milliseconds, P = .041), worse New York Heart Association functional class (2.8 ± 0.6 vs 2.7 ± 0.6, P = .008) and shorter 6-minute walk distance (297.9 ± 110.7 m vs 331.8 ± 112.6 m, P = .001), larger left atrial volumes (44.9 ± 16.9 mL/m(2) vs 40.9 ± 17.6 mL/m(2), P = .006), less baseline LV dyssynchrony (56.2 ± 41.3 milliseconds vs 69.1 ± 39.9 milliseconds, P < .001), and, more frequently, anterior LV lead position (12.4% vs 4.0%, P = .007). At multivariate analysis, only the ischemic etiology of HF (odds ratio [OR] 2.264, P = .005), shorter 6-minute walk distance at baseline (OR 0.998, P = .030), less baseline LV dyssynchrony (OR 0.989, P < .001), and anterior LV lead position (OR 3.713, P < .010) remained independent predictors of nonresponse to CRT.

Conclusions: Ischemic etiology of HF, shorter baseline 6-minute walk distance, less baseline LV dyssynchrony, and anterior LV lead position are independent determinants of nonresponse to CRT.