Effect of cardiac resynchronization therapy in patients with moderate left ventricular systolic dysfunction and wide QRS complex: a prospective study.

BACKGROUND: We sought to investigate the effect of cardiac resynchronization therapy (CRT) on disease progression in patients with moderate left ventricular (LV) systolic dysfunction.

METHODS AND RESULTS: This is a prospective study to explore the effect of CRT in 15 optimally treated patients (age: 66.1 +/- 12.8 years; male = 13) with New York Heart Association (NYHA) class III, LV ejection fraction >35% and <45% and QRS duration >120 msec. Echocardiographic examination and standard heart failure assessment was performed before and 3 months after CRT implantation. The magnitude of echocardiographic remodeling measurements was compared with 30 age, sex, NYHA class, and heart failure etiology matched patients with conventional CRT indication. There were significant reductions in LV end-systolic (86.2 +/- 24.1 to 69.7 +/- 22.2 mL, P < 0.01)/end-diastolic (135.5 +/- 36.8 to 120.5 +/- 34.6 mL, P < 0.01) volumes, improvement in LV ejection fraction (39.1 +/- 2.2 to 44.2 +/- 5.5%, P = 0.01), and NYHA class (3.0 +/- 0.0 to 2.07 +/- 0.46, P < 0.001). There was no difference in changes in LV volumes, ejection fraction, NYHA class, and exercise capacity before and after CRT between the study and conventional groups except for greater improvement in the quality of life score in the conventional group.

CONCLUSION: In this prospective study, significant LV reverse remodeling by CRT in those with a wide QRS complex and moderate LV systolic dysfunction was observed. Further studies to explore the benefit of CRT in patients with less severe heart failure are recommended.