Study of Biventricular Pacing in Heart Patients

A European multi-center trial has validated the therapeutic interest in biventricular pacing as resynchronization therapy in patients with severe heart failure and major intraventricular conduction delay, and shown that it has improved exercise tolerance, symptoms, and quality of life in patients in sinus rhythm treated with atrio-biventricular pacing. The trial, called the Multi-Site Stimulation in Cardiomyopathy (MUSTIC), was conducted under the auspices of the European Society of Cardiology.

The trial involved two patient groups. The first was composed of patients with congestive heart failure, chronic left ventricular systolic dysfunction, and signs of major ventricular asynchrony. Patients were implanted with a standard dual-chamber pacemaker, with an atrial port connected to the left ventricular lead and the ventricular port to the right ventricular lead. Patients were paced on or off in both ventricles but did not know whether they received biventricular pacing or not.

Biventricular pacing resulted in a slight but significant improvement in exercise tolerance, but the patients' quality of life, hospitalization rates, and mortality were not significantly different between the two pacing modes. Afterward, 87% of the patients said they preferred biventricular pacing. The results of this part of the trial were presented at the 22nd Congress of the European Society of Cardiology in Paris (France).

The second group of patients, who had normal sinus rhythm and no conventional indication for permanent cardiac pacing, were implanted with an atrio-biventricular pacemaker connected to three transvenous leads. The exercise tolerance in this group increased by 23% between the no-pacing and the pacing period. Hospitalization rates were found to be three times lower than in the no-pacing period. Afterward, 86% of the patients chose biventricular pacing as their preferred mode of therapy. The results of this part of the trial were reported earlier, at the 21st Scientific Sessions of the North American Society of Cardiac Pacing and Electrophysiology.