Midterm Benefits of Left Univentricular Pacing in Patients With Congestive Heart Failure

Background—Resynchronization therapy by simultaneous pacing of the right and left ventricles has gained wide acceptance as a useful treatment for patients with severe congestive heart failure. Several short-term hemodynamic studies in humans and animals failed to demonstrate any benefit of biventricular pacing over left univentricular pacing, but long-term studies on this pacing mode are lacking. The objective of this study was to assess the outcome over a 1-year period of patients paced exclusively in the left ventricle. Methods and Results—Clinical, angiographic, echocardiographic, and ergometric data were collected at baseline and after 12 months in 22 patients (age, 69.3±6.5 years) with NYHA class III or IV (10 patients), sinus rhythm, left bundle-branch block, and no bradycardia indication for pacing. After 12 months, compared with baseline values, NYHA class improved significantly by 40% (P <0.0001), 6-minute walk distance by 30% (P =0.01), peak &OV0312;O2 by 26% (P =0.01), left ventricular enddiastolic diameter by 5% (P = 0.02), ejection fraction by 22% (P = 0.07), mitral regurgitation area by 40% (P = 0.01), and norepinephrine level by 37% (P = 0.04). Conclusions—In patients with severe congestive heart failure, sinus rhythm, and left bundle-branch block despite optimal pharmacological treatment, left univentricular pacing is feasible and results in significant midterm benefit in exercise tolerance and left ventricular function.