Clinical, echocardiographic, and neurohormonal response to cardiac resynchronization therapy: are they interchangeable?

BACKGROUND The relationship between changes in N-terminal pro-brain natriuretic peptide (NT-proBNP) and echocardiographic or clinical definitions of response to cardiac resynchronization therapy (CRT) has not been evaluated. The aims of the present evaluation were to assess: (1) the relationship between changes in NT-proBNP after 6 months of CRT and clinical and echocardiographic responses; (2) the association between NT-proBNP changes and long-term outcome. METHODS In 170 patients treated with CRT (age 61 ± 11 years, 75% male), clinical and echocardiographic parameters and circulating NT-proBNP levels were assessed at baseline and 6 months after CRT. At 6 months follow-up, improvement in New York Heart Association class ≥ 1 point, decrease in left ventricular end-systolic volume ≥ 15%, and decrease in NT-proBNP ≥ 15% defined clinical, echocardiographic, and neurohormonal CRT response, respectively. All-cause mortality data were collected and related to neurohormonal response. RESULTS Neurohormonal, echocardiographic, and clinical response rates were 54%, 58%, and 66%, respectively. The majority of patients (71%) showing echocardiographic response had NT-proBNP reduction ≥ 15%. In contrast, only 58% of patients who showed clinical response also had NT-proBNP reduction ≥ 15%. During a median follow-up of 32 months, 40 patients died. Patients with neurohormonal response demonstrated a superior long-term outcome compared to patients without neurohormonal response (log-rank P = 0.02). CONCLUSIONS NT-proBNP reduction ≥ 15% showed better agreement with echocardiographic response compared to clinical response. Neurohormonal response was associated with superior long-term outcome compared to insufficient reduction in NT-proBNP levels.