Proper use of antiarrhythmic therapy for reduction of mortality after myocardial infarction

In this review, we summarise Vaughan Williams' classification of antiarrhythmic agents and the trials that have explored their efficacy in reducing mortality after myocardial infarction (MI). After analysing the data, it is clear that there is no role for class I antiarrhythmic agents as prophylaxis after MI since their use has been associated with increased mortality. Class II agents, i.e. beta-blockers, have demonstrated a reduction in mortality in combined and individual trials which extended for up to 6 years after the initial event. The class III drug, d,l-sotalol has been shown to have possible benefit, whereas its isomer without any beta-blocking properties, dexsotalol, has been shown to increase the incidence of arrhythmias. Amiodarone appears to reduce the incidence of deaths due to arrhythmia and sudden deaths without changing overall mortality. As a group, the calcium antagonists, class IV agents, have not been shown to reduce mortality and, in the case of nifedipine, may even increase it. Verapamil has been shown to be beneficial in one large study and may have a role in those patients in whom the use of beta-blockers is contraindicated. At this time, we recommend early implementation of beta-blockers for all patients without contraindications after MI. Further studies evaluating implantable defibrillators as primary and secondary prevention have provided significant risk reductions in certain high risk patient subsets. Future efforts will need to focus on more accurate risk stratification of post-MI patients and the role of both defibrillators and, possibly, amiodarone in improving survival.