Introduction: In the patients with left ventricular systolic dysfunction and narrow QRS complex, cardiac-resynchronization therapy (CRT) benefits were restrictive.
Methods: Twenty-eight chronic heart failure patients were examined for acute effects in a bi-ventricular pacing study using external pacemakers. Twenty-five patients who had acute positive hemodynamic effects were classified into three groups according to QRS duration; group A (N=7, <120 msec), group B (N=10, 120-150 msec) and group C (N=8, >150 msec). The echocardiography examined before and after CRT device implantation.
Results: The changes of the acute hemodynamic state were similar among three groups. The CRT responders were observed in 6 patients of group A (85.7%), in 7 patients of group B (70.0%) and in 6 patients of group C (75.0%). The changes of ejection fraction were as good as the three groups (Group A; +16.3 ± 13.3%, Group B; +8.3 ± 4.3%, Group C; +9.3 ± 7.9%).
Conclusions: In the heart failure patients with narrow QRS complex, acute positive hemodynamic effects using bi-ventricular pacing study were expected in CRT responders.