Regional correlation by color-coded tissue Doppler to quantify improvements in mechanical left ventricular synchrony after biventricular pacing therapy.

Cardiac resynchronization therapy (CRT) can improve cardiac function in patients with heart failure and left bundle branch block. To test a new synchrony index derived from mitral annular velocity by color tissue Doppler, 19 subjects were studied: 9 patients with heart failure and left bundle branch block at baseline and at 1, 3 and 6 months after CRT and 10 normal controls. The synchrony index in patients with heart failure was less than that in controls at baseline (r = 0.60 +/- 0.13 vs 0.94 +/- 0.02; p <0.01), but improved at 6 months after CRT (r = 0.77 +/- 0.09; p <0.05 vs baseline).