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[Primary prophylaxis with the implantable cardioverter-defibrillator in heart failure: a clinical point of view].

The implantable cardioverter-defibrillator (ICD) is one of the great inventions of modern cardiology. Its use for the prevention of sudden death in patients with left ventricular dysfunction has meant that clinical cardiologists are now fully involved in decision-making on the implantation of these devices. The majority of clinical trials, which have used low ejection fraction as the only or main criterion for patient recruitment, have shown that ICD use leads to a significant improvement in survival. Three trials, two of which were carried out soon after myocardial infarction and one of which was performed at the same time as surgical revascularization, were exceptions. However, it is important to be aware that the improvements observed in the most recent trials have not been as large as those seen in the initial studies. Reduced efficacy has meant that in the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), for instance, 25 ICDs had to be implanted to save one life over a 2-year period. The most likely explanation for this observation is that the better prognosis achieved by present-day pharmacologic treatment of heart failure has reduced the margin of benefit associated with ICD use. Another consequence is that depressed left ventricular ejection fraction has lost some of its specificity in predicting sudden death. New predictive variables are needed to improve risk stratification in this population. Without these variables, the use of ICDs in the primary prevention of sudden death in patients with left ventricular dysfunction will not seem a very attractive option from the point of view of good clinical practice.