EDITORIAL
Primary prevention: prime time? ICD trials (and tribulations) There can be little doubt as to the role of the implantable defibrillator (ICD) in secondary prevention of arrhythmic death (SCD). Landmark trials demonstrated the benefit of ICD implantation on survival in patients who had survived cardiac arrest or haemodynamically compromising VT unequivocally, both with and without coronary artery disease (CAD) or heart failure (CHF).' VVhile exclusion of a reversible cause of the index event and specific management of minority groups such as patients with long-QT syndrome remain caveats, the vast majority ofsecondary prevention indications for ICD implantation are now relatively straightforward. In the wake of the success in preventing 'recurrence' of SCD, it was a logical step to look towards primary prevention in selected groups of patients at high risk of malignant ventricular tachyarrhythmias. From the outset, however, this has been precisely the Achilles heel of primary prevention: we do not exactly know who is at risk. Simply put, a patient with a remote, small inferior myocardial infarction (MI) may die of ventricular fibrillation, while another with a large anterior MI may succumb to progressive heart failure without ever experiencing a ventricular arrhythmia. Having said this, patients with poor ventricular function have, as a group, long been recognised to be at greater risk of SCD. It is thus hardly surprising that left ventricular ejection fraction (LVEF) has been pivotal in all primary prevention trials to date. Given the large numbers involved and the lack of specificity of LVEF alone in identifying patients at greatest risk, however, the majority oftrials recognised the need for some additional parameter. This effectively divides the primary prevention studies into two camps: the heart failure driven and the electrophysiological study (EPS) driven.
Until very recently, the indication for a prophylactic ICD in a post-MI patient was decided according to guidelines based on two studies published in 1996 and 1999, MADIT (I) and MUSTT.45 Both included patients with prior MI, reduced LVEF (MADIT
Primary prevention: prime time? ICD trials (and tribulations) There can be little doubt as to the role of the implantable defibrillator (ICD) in secondary prevention of arrhythmic death (SCD). Landmark trials demonstrated the benefit of ICD implantation on survival in patients who had survived cardiac arrest or haemodynamically compromising VT unequivocally, both with and without coronary artery disease (CAD) or heart failure (CHF).' VVhile exclusion of a reversible cause of the index event and specific management of minority groups such as patients with long-QT syndrome remain caveats, the vast majority ofsecondary prevention indications for ICD implantation are now relatively straightforward. In the wake of the success in preventing 'recurrence' of SCD, it was a logical step to look towards primary prevention in selected groups of patients at high risk of malignant ventricular tachyarrhythmias. From the outset, however, this has been precisely the Achilles heel of primary prevention: we do not exactly know who is at risk. Simply put, a patient with a remote, small inferior myocardial infarction (MI) may die of ventricular fibrillation, while another with a large anterior MI may succumb to progressive heart failure without ever experiencing a ventricular arrhythmia. Having said this, patients with poor ventricular function have, as a group, long been recognised to be at greater risk of SCD. It is thus hardly surprising that left ventricular ejection fraction (LVEF) has been pivotal in all primary prevention trials to date. Given the large numbers involved and the lack of specificity of LVEF alone in identifying patients at greatest risk, however, the majority oftrials recognised the need for some additional parameter. This effectively divides the primary prevention studies into two camps: the heart failure driven and the electrophysiological study (EPS) driven.
Until very recently, the indication for a prophylactic ICD in a post-MI patient was decided according to guidelines based on two studies published in 1996 and 1999, MADIT (I) and MUSTT.45 Both included patients with prior MI, reduced LVEF (MADIT
