Ventricular contraction abnormalities in dilated cardiomyopathy: Effect ofbiventricular pacing to correct interventricular dyssynchrony

OBJECTIVE To measure ventricular contractile synchrony in patients with dil ated cardiomyopathy (DCM) and to evaluate the effects of biventricular paci ng on contractile synchrony and ejection fraction. BACKGROUND Dilated cardiomyopathy is characterized by abnormal ventricular activation and contraction. Biventricular pacing may promote a more coordin ated ventricular contraction pattern in these patients. We hypothesized tha t biventricular pacing would improve synchrony of right ventricular and lef t ventricular (RV/LV) contraction, resulting in improved ventricular ejecti on fraction. METHODS Thirteen patients with DCM and intraventricular conduction delay un derwent multiple gated equilibrium blood pool scintigraphy. Phase image ana lysis was applied to the scintigraphic data and mean phase angles computed for the RV and LV. Phase measures of interventricular (RV/LV) synchrony wer e computed in sinus rhythm and during atrial sensed biventricular pacing (B iV). RESULTS The degree of interventricular dyssynchrony present in normal sinus rhythm correlated with LV ejection fraction (r = -0.69, p < 0.01). During BiV, interventricular contractile synchrony improved overall from 27.5 +/- 23.1 degrees to 14.1 +/- 13 degrees (p = 0.01). The degree of interventricu lar dyssynchrony present in sinus rhythm correlated with the magnitude of i mprovement in synchrony during BiV (r = 0.83, p < 0.001). Left ventricular ejection fraction increased in all thirteen patients during BiV, from 17.2 +/- 7.9% to 22.5 +/- 8.3% (p < 0.0001) and correlated significantly with im provement in RV/LV synchrony during BiV (r = 0.86, p < 0.001). CONCLUSIONS Dilated cardiomyopathy with intraventricular conduction delay i s associated with significant interventricular dyssynchrony. Improvements i n interventricular synchrony during biventricular pacing correlate with acu te improvements in LV ejection fraction. (J Am Coll Cardiol 2000;35:1221-7) (C) 2000 by the American College of Cardiology.