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, 69.3Ϯ6.5 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% (PϽ0.0001), 6-minute walk distance by 30% (Pϭ0.01), peak V O 2 by 26% (Pϭ0.01), left ventricular end-diastolic diameter by 5% (Pϭ0.02), ejection fraction by 22% (Pϭ0.07), mitral regurgitation area by 40% (Pϭ0.01), and norepinephrine level by 37% (Pϭ0.04). 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.
Ž .Background: Beneficial effects of left ventricular LV -based pacing on acute hemodynamic parameters were reported in several series, but only a few studies examined the long-term effects of this new pacing procedure. Aims: To assess long-term Ž . effects of permanent LV-based pacing on LV function and mitral regurgitation MR in patients with refractory congestive Ž . heart failure CHF . Methods: A prospective evaluation of LV function and MR was performed in 23 patients with severe but Ž . stable CHF and left bundle branch block mean QRS: 186 " 31 ms by radionuclide and echocardiographic techniques at Ž . baseline and 6 months after implantation of a permanent LV-based LV alone: 13 patients; biventricular: 10 patients Ž . Ž . pacemaker programmed either in a DDD mode sinus rhythm; n s 14 or in a VVIR mode atrial fibrillation; n s 9 . Results: Compared to baseline, the 6 months follow-up visit demonstrated a significant increase in radionuclide derived LV ejection Ž . fraction from 23.3" 7 to 26.2" 7% P -0.01 and in echocardiographic LV fractional shortening from 13 " 4 to 16" 6% Ž . Ž P-0.05 , without any change in cardiac index, a significant decrease in LV end-diastolic diameter from 73.2" 6 to 71.2" 7 . Ž . Ž mm; P-0.05 , end-systolic diameter from 63.6" 6 to 60.2" 8 mm; P-0.05 and color Doppler MR jet area from 11.5" 6 1 . to 6.6" 4 cm ; P-0.001 . A comparison of patients with LV pacing alone and patients with biventricular pacing showed similar beneficial effects of pacing on MR severity in the two subgroups and a non-significant trend for a better improvement of LV function during biventricular pacing. Conclusion: Thus, in patients with severe CHF and left bundle branch block, permanent LV-based pacing may significantly improve LV systolic function and decrease MR. ᮊ
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