Progression of heart failure in right univentricular pacing compared to biventricular pacing.

BACKGROUND Cardiac resynchronization therapy (CRT) improves hemodynamics and symptoms of heart failure by reducing ventricular dyssynchronity. Conversely, recent studies have demonstrated that right univentricular pacing in patients with an ejection fraction below 40% aggravates heart failure. In this retrospective study, we compared progression of disease in patients with mild to moderate heart failure that were treated with a right univentricular pacing device and patients with congestive heart failure that were treated with a biventricular system. METHODS 107 patients were included. 59 received a right ventricular pacing device and 48 a biventricular system. Patients were assessed after 1 and 6 months by NYHA class, echocardiographic parameters (EF, LVEDD) and hospitalization for heart failure. RESULTS Hospitalization for heart failure after implantation of the devices was more frequent in patients that received a conventional pacemaker with a single lead in the right ventricle than in patients that were treated with a CRT system (12% vs. 6%, p<0.05), although heart failure was more advanced in the CRT group at baseline. Ejection fraction in the right ventricular pacing group further decreased from 43%+/-4 at baseline to 38%+/-4 after 6 months (p<0.05). Left ventricular enddiastolic diameter (LVEDD) was 51+/-7 mm and 58+/-6 mm (p<0.05) at 6 months. In the CRT group, EF was 23%+/-4 at baseline and 31%+/-7 after 6 months (p<0.05.). LVEDD improved from 56+/-4 mm before implantation to 52+/-7 mm and 6 months (p<0.05). CONCLUSION Progression of heart failure symptoms in the right univentricular pacing group was more pronounced compared to the CRT group, despite the fact that patients assigned to the CRT group had more severe symptoms of heart failure at baseline. Biventricular pacing relieved symptoms of heart failure, whereas right univentricular pacing with subsequent conduction delay of the left ventricle further deteriorated pre-existing heart failure. Therefore, patients with an indication for pacemaker therapy because of bradycardia and co-existing mild to moderate heart failure might benefit from early implantation of a CRT system.