Expanding indications for defibrillators after myocardial infarction: risk stratification and cost effectiveness.

Practice guidelines have expanded to include a new Class IIa recommendation for implantable cardiac defibrillator (ICD) use in patients post-myocardial infarction (MI) with a left ventricular ejection fraction (LVEF) </=30% on the basis of the results of the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II). Given that over 3 million patients in North America meet these criteria and over 400,000 additional patients will meet these criteria every year, the potential costs to the healthcare system are substantial and possibly prohibitive. The results of MADIT II must be interpreted in the context of other studies. The benefits of ICD therapy may vary substantially across subgroups of MADIT II patients. Studies of amiodarone suggest that it may be useful if used in addition to beta-blockers, and the relative value of this therapy compared to ICD therapy remains to be elucidated. Subgroups of MADIT II patients with QRS duration >0.12 seconds or LVEF </=25% appear to derive the greatest benefit from ICD therapy. Cost-effectiveness depends on the magnitude of benefit expected and will differ across subgroups of patients with different levels of risk. Better risk stratification strategies are needed to predict which patients will benefit most. Results of ongoing studies will be crucial in determining the relative effectiveness of ICD compared to optimal medical therapy including the use of amiodarone and beta-blockers. Predictors of subsets of MADIT II patients most likely to benefit from ICD therapy are urgently needed in order to prioritize allocation of healthcare resources.