Cardiac resynchronisation therapy (CRT) is now a recommended treatment in patients with advanced heart failure despite optimal drug treatment, left ventricular systolic dysfunction, enlarged left ventricle, and cardiac dyssynchrony defined by a QRS duration ⩾120 ms on 12 lead surface ECG and normal sinus rhythm.1 2 These recommendations are based on the inclusion criteria of major clinical trials which validated the concept of CRT using sequential or simultaneous biventricular pacing.^w1–6 These clinical trials excluded patients with permanent atrial fibrillation, patients with conventional pacemaker indication, and finally patients previously paced in the right ventricle.^w1–6 However, the question of the upgrade from right ventricular pacing to biventricular pacing is an important question in daily practice. According to the current guidelines, there is no clear indication for CRT in patients already implanted with a VVI or DDD pacemaker.1 2 The purpose of this article is to review the rationale and the potential benefits of the upgrading from right ventricular pacing to biventricular pacing.

HEART FAILURE AND CARDIAC PACING: IMPORTANCE OF THE PROBLEM

The EuroHeart Failure survey screened more than 11 000 patients with suspected or confirmed heart failure over a 6 week period in 115 hospitals from 24 European countries.3 Eight per cent of the studied population had a pacemaker implanted for conventional indications.3 Thackray et al assessed the prevalence of heart failure and asymptomatic ventricular systolic dysfunction in a chronically paced population.4 From the 307 patients screened, 27% had symptoms of heart failure (New York Heart Association (NYHA) functional class II–IV) and a left ventricular ejection fraction (LVEF) <40%, and 20% had symptoms of heart failure (NYHA class III–IV) and an LVEF <35% and thus were potential candidates for CRT.4 In the Italian InSync registry, which included more than 300 patients implanted with a CRT pacemaker or implantable cardioverter-defibrillator (ICD), 20% of patients were …