Controversies in the Prevention of Sudden Death

Journal of Clinical and Basic Cardiology 2001; 4 (4): 275-278

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Keywords: Elektrophysiologie,  Herzinsuffizienz,  implantierbarer Defibrillator,  plötzlicher Herztod,  ventrikuläre Tachykardie,  electrophysiological study,  heart failure,  implantable defibrillators,  sudden cardiac death,  unsustained ventricular tachycardia

Implantable cardioverter defibrillator (ICD) has been demonstrated effective in preventing sudden cardiac death in high risk patients. However, individual prognostic stratification is needed in order to optimise cost-effectiveness ratio. Depressed left ventricular ejection fraction (LVEF) is the most powerful predictor of total mortality and sudden death. In particular, subgroup analysis of ICD trials demonstrated that the patients with very low LVEF (> 0.26) may benefit the most from ICD implantation. Among other risk indexes in the post-infarction period, the occurrence of premature ventricular complexes > 10/h in the pre-thrombolytic era and > 30/h in the thrombolytic era were associated to significantly increased risk. Ventricular late potentials showed an high negative predictive power, while the positive predictive power was very low. Heart rate variability and baroreflex sensitivity, individually or in combination, significantly discriminated patients at higher or lower risk. However, only inclusion of LVEF in the analysis allowed identification of patients at very high risk. Invasive electrophysiological study combined with depressed LVEF and unsustained ventricular tachycardia selected very high risk patients in MADIT and MUSTT trials. In spite of that, in the MUSTT registry not inducible patients showed a 24 % sudden death rate after 5 years. As a matter of fact, the major challenge for the future is the improvement of sensitivity in patient stratification, considering that the actual number of deaths is higher in the so called "low risk" groups.