Comparison of left ventricular reverse remodeling induced by cardiac contractility modulation and cardiac resynchronization therapy in heart failure patients with different QRS durations.

BACKGROUND: Cardiac contractility modulation (CCM) is a new device-based therapy for advanced systolic heart failure with normal QRS duration and therefore not suitable for cardiac resynchronization therapy (CRT). Left ventricular (LV) reverse remodeling was reported in patients treated with CCM or CRT, however, the extent of response was not compared.

METHODS: This observational study consisted of three groups of patients with symptomatic heart failure and LV ejection fraction <35% despite optimal medical therapy. Group 1 included those received CCM with a QRS duration <120 ms (n=33), Group 2 included those received CRT with a QRS duration of 120-150 ms (n=43), and Group 3 included those received CRT with a QRS duration >150 ms (n=56). LV end-systolic volume (LVESV) was measured at baseline and 3 months later.

RESULTS: Age, gender, etiology of heart failure and baseline ejection fraction were comparable. A significant LV reverse remodeling was observed in each group. The degree of LVESV reduction was similar between Group 1 and Group 2 (-11.3 ± 1 1.8 vs. -13.6 ± 18.3%, p=0.833), however, it was greater in Group 3 (-25.0 ± 18.0%, both p<0.01). By using the reduction ≥ 15%, the responder rate was not different between Group 1 (39%) and Group 2 (42%), but significantly higher in Group 3 (68%) (χ(2)=9.514, p=0.009).

CONCLUSION: CCM exhibited a similar LV reverse remodeling response to CRT for patients with a mildly prolonged QRS, though the effect was less strong when compared to CRT for patients with a very wide QRS.