Performance of left ventricular versus biventricular pacing in chronic heart failure assessed by stress...

Acute hemodynamic studies suggest that resynchronization therapy using single-site left ventricular pacing (LVP) is equivalent to biventricular pacing (BIVP). The aim of this study was to assess the performance of LVP versus BIVP during exercise by means of stress echocardiography. A total of 28 patients (25 men and 3 women, mean age 60.9 +/- 8 years) with advanced chronic heart failure and impaired ventricular conduction (QRS > 150 ms) were studied. Patients were randomly allocated to either BIVP or LVP mode with a crossover on the next day and cardiac output was estimated at rest and during each stage of bicycle ergometry in supine position by means of velocity time integral formula. Maximum exercise level was comparable for both pacing modes (up to 100 W) and no significant differences were revealed either in heart rate or in blood pressure at rest and during any step of exercise. LVP was associated with significantly higher cardiac output at rest (3.2 +/- 0.5 vs 2.8 +/- 0.6 l/min, P < 0.01) and during low level exercise (4.4 +/- 0.8 vs 3.9 +/- 0.8 l/min at 25 W, P < 0.05) as compared with BIVP. There was a trend towards higher cardiac output for LVP even at higher levels of exercise. These effects were predominantly confined to patients with idiopathic dilated cardiomyopathy. It is concluded that cardiac resynchronization therapy using single-site LVP results in better hemodynamic response as compared with BIVP, both at rest and during physical exercise.