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

In this review, we summarise Vaughan Williams' classification of antiarrhyt hmic agents and the trials that have explored their efficacy in reducing mo rtality after myocardial infarction (MI). After analysing the data, it is c lear that there is no role for class I antiarrhythmic agents as prophylaxis after MI since their use has been associated with increased mortality. Cla ss II agents, i.e. beta-blockers, have demonstrated a reduction in mortalit y 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 p ossible benefit, whereas its isomer without any beta-blocking properties, d exsotalol, has been shown to increase the incidence of arrhythmias. Amiodar one appears to reduce the incidence of deaths due to arrhythmia and sudden deaths without changing overall mortality. As a group, the calcium antagoni sts, class IV agents, have not been shown to reduce mortality and, in the c ase of nifedipine, may even increase it. Verapamil has been shown to be ben eficial in one large study and may have a role in those patients in whom th e 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 cert ain high risk patient subsets. Future efforts will need to focus on more ac curate risk stratification of post-MI patients and the role of both defibri llators and, possibly, amiodarone in improving survival. Multiple arrhythmias can accompany acute myocardial infarction (MI). These include tachyarrhythmias - both supraventricular and ventricular sinus brad ycardia, accelerated idioventricular rhythms and varying degrees of heart b lock. Each requires appropriate management for an individual patient. Follo wing the acute event, the greatest management dilemmas have surrounded thos e patients with persistent frequent premature ventricular contractions and nonsustained ventricular tachyarrhythmias. Ventricular arrhythmias followin g acute MI were first noted to be associated with increased post MI mortali ty in the 1960s.([1,2]) Following this, several observational studies were performed confirming that those patients with complex ventricular premature beats (VPBs) on I hour ECG and 6- and 24-hour holter monitors had a higher mortality rate than those with only simple VPBs or none at all.([3-5]) Sev eral of these studies also demonstrated an increased risk of sudden death i n these patients, suggesting that mortality after acute MI would be reduced if these arrhythmias could be suppressed. This review focuses on the trial s of aritiarrhythmic therapy in patients with MI with emphasis on trials wh ich attempted to determine if control of ventricular arrhythmias is associa ted with improved survival.