The need for European Registries in inherited cardiomyopathies

We read with interest the clinical perspective ‘Is prophylaxis the best use of the ICD?’ by Nisam and Farre. There is no doubt that ICDs save lives and are certainly a great advance in the treatment of heart disease in this century. The MADIT-II results were published recently and are likely to bring about an exponential increase in the use of the device. However, some of the aspects of MADIT-II deserve a closer look before the results of the study are applied to all patients with prior myocardial infarction and left ventricular dysfunction. In MADIT-I, the authors had used an antiarrhythmic drug (amiodarone) limb, in which 7% were also given beta-blockers vs 27% in the AICD limb; there was a high withdrawal rate of antiarrhythmic drug, many patients being left on no therapy. In MADIT-II, curiously, placebo replaced the amiodarone treatment limb. There have been data suggesting that amiodarone and betablockers combined may be synergistic on arrhythmic events as revealed in the EMIAT and CAMIAT studies. Should a combination arm of beta blockers and amiodarone have served a more reasonable control group than placebo in MADIT-II ? Secondly, it is not clear why patients with prior revascularization in the previous 3 months were excluded in MADIT-II. Increasingly, most MADIT-II type patients now undergo revascularization, usually in close proximity to their infarct. The CABGPatch trial showed that in such patients there is no survival benefit with the AICD emphasizing the benefit of coronary revascularization. There is no doubt that treating large territory inducible ischemia with percutaneous or surgical revascularization would decrease the risk of life threatening ventricular arrhythmias. Conversely, not treating the ischemic burden with revascularization therapy is likely to cause the magnitude of the beneficial effect of the ICD to be exaggerated, as these patients are likely to suffer a greater incidence of life threatening ventricular arrhythmias. Would the results of MADIT-II have reached statistical significance (showing benefit from AICD) if all the patients had been offered revascularization therapy (by percutaneous intervention or surgery, as appropriate) after their myocardial infarction and if the control limb had been given the benefit of amiodarone and beta-blocker therapy? Maybe, we should await the outcome of the ongoing SCD-HEFT study, in which the effects of placebo, amiodarone, and the AICD therapy are being compared in a similar population.