Persistence of secondary mitral regurgitation and response to cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) improves survival and quality of life in advanced heart failure (HF). Although mitral regurgitation (MR) reduction has been reported, its presence has been associated with non-response to CRT. This study was undertaken to assess the potential role of significant mitral regurgitation (SMR) persistence after CRT on clinical outcome, major arrhythmic events, and echocardiographic response in the mid-long term.

Seventy-six patients (28.9% women, 63 +/- 11 years) with dilated cardiomyopathy in advanced HF were included. SMR, defined as regurgitant orifice area > or =0.20 cm(2), was assessed at baseline and its evolution 6 months after CRT. Clinical outcome (cardiovascular death/HF readmission), major arrhythmic events, and echocardiographic response (reverse remodelling) were recorded on follow-up. Thirty-two patients (42.1%) presented baseline SMR, becoming non-significant in 11 of the 32 patients (34.3%) 6 months after CRT. Its persistence was associated with higher rates of clinical events (46.4 vs. 18.7%, P = 0.011), arrhythmic events (35.7 vs. 14.5%, P = 0.034), and less reverse remodelling (28.5 vs. 83.3%, P < 0.001).

CRT can reduce moderate or severe baseline MR to non-significant in one-third of patients. However, its persistence was associated with worse clinical evolution, greater incidence of arrhythmic events, and less reverse remodelling.