Although most patients who improve in clinical status after cardiac resynchronization therapy (CRT) also show a significant left ventricular (LV) reverse remodeling, some patients do not show echocardiographic improvement. The aim of the present study was to evaluate the degree of agreement between clinical and echocardiographic response to CRT in a large cohort of heart failure patients, and to evaluate the characteristics of patients with clinical response but without echocardiographic response.

In 440 consecutive heart failure patients (mean age 66 ± 11 years, 81% men) treated with CRT, agreement between clinical and echocardiographic responses at 6 months of follow-up were evaluated. The combined clinical response was defined as: ≥1-point New York Heart Association functional class improvement or ≥15% increase in 6-minute walk test. Echocardiographic response was defined by a reduction in LV end-systolic volume (LVESV) ≥15%.

At 6 months of follow-up, clinical response was observed in 84% (n = 370) of the patients. Significant reduction in LVESV was noted in 63% (n = 276). The majority of patients who improved clinically did show LV reverse remodeling (72%, n = 268). Importantly, 28% (n = 102) of patients who improved clinically did not show significant LV reverse remodeling. The patients with clinical response but without echocardiographic response had more often ischemic heart failure as compared to patients with positive clinical and echocardiographic response (69.6% vs 57.5%; P = .021). Moreover, patients with such discordant responses had more narrow QRS complex (148 ± 31 vs 159 ± 31 milliseconds; P = .004), and showed less LV dyssynchrony than patients with concordant positive responses (90 ± 77 vs 171 ± 105 milliseconds; P < .001).

Although there is a good concordance between echocardiographic and clinical response to CRT, up to 28% of the population experienced clinical response without significant LV reverse remodeling. Subjects with such discrepant responses have more frequently ischemic heart failure and show more narrow QRS complex and less LV dyssynchrony than patients with both clinical and echocardiographic response.