Implantable cardioverter-defibrillator treatment and resynchronisation in heart failure.

Correspondence to: Cecilia Linde MD, Department of Cardiology, Karolinska Hospital, 171 76 Stockholm, Sweden; [email protected] _________________________ P atients with severe heart failure in New York Heart Association (NYHA) functional class III– IV, low left ventricular ejection fraction, and broad QRS have been shown to benefit from biventricular pacing in randomised crossover and parallel trials concerning symptomatic improvement such as exercise tolerance and quality of life (tables 1 and 2). The results are less clear for those with mild heart failure where further studies are needed. However, the evidence at large is based on sample size calculations made for six month follow up. Therefore it remains unknown whether the effects on biventricular pacing are long lasting in terms of years and whether morbidity and mortality is influenced. Although observational and controlled studies have demonstrated a reduced need for heart failure related hospitalisations during biventricular pacing, no study as yet with mortality as the primary outcome has been published. Therefore, whether cardiac resynchronisation therapy influences survival remains to be demonstrated in the recently concluded COMPANION and the ongoing CARE-HF study. These both have hospitalisations and mortality as the primary outcome. The MUSTIC trial was not designed as a mortality study. Nevertheless, the two year survival rate in 104 patients on biventricular pacing was reported to be 80%. The annual mortality rate was 10%, which is lower than could be expected in these former NYHA class III patients. The causes of death were sudden (40%) and heart failure death (40%), and other causes (20%). There is thus no direct evidence to date that the risk for sudden cardiac death is reduced by biventricular pacing. Recently the use of prophylactic implantable cardioverter-defibrillators (ICD) has been suggested in patients with coronary artery disease and reduced left ventricular ejection fraction. 11 In one study the benefit of a prophylactic defibrillator was greater in those with broad QRS. Therefore, it could be speculated that a prophylactic defibrillator should be added to a biventricular pacemaker in the treatment of the severe heart failure patient with intraventricular conduction disturbance. The aim of this paper is to discuss the evidence for this.