Long-term benefits of biventricular pacing in congestive heart failure: results from the MUltisite STimulation in cardiomyopathy (MUSTIC) study

Objectives The main objective of this study was to assess if the benefits of biventricular (BiV) pacing observed during the crossover phase were sustained over 12 months. Background MUltisite STimulation In Cardiomyopathies (MUSTIC) is a randomized controlled study intended to evaluate the effects of BiV pacing in patients with New York Heart Association (NYHA) class III heart failure and intraventricular conduction delay. Methods Of 131 patients included, 42/67 in sinus rhythm (SR) and 33/64 in atrial fibrillation (AF) were followed up longitudinally at 9 and 12 months by 6-min walked distance, peak oxygen uptake (peak VO2), quality of life by the Minnesota score, NYHA class, echocardiography, and left ventricular ejection fraction by radionuclide technique. Results At 12 months, all SR and 88% of AF patients were programmed to BiV pacing. Compared with baseline, the 6-min walked distance increased by 20% (SR) (p = 0.0001) and 17% (AF) (p = 0.004); the peak VO2 by 11% (SR) and 9% (AF); quality of life improved by 36% (SR) (p = 0.0001) and 32% (AF) (p = 0.002); NYHA class improved by 25% (SR) (p = 0.0001) and 27% (AF) (p = 0.0001). The ejection fraction improved by 5% (SR) and 4% (AF). Mitral regurgitation decreased by 45% (SR) and 50% (AF). Conclusions The clinical benefits of BiV pacing appeared to be significantly maintained over a 12-month follow-up period.