The role of EP-guided therapy in ventricular arrhythmias: Beta-blockers, sotalol, and ICD's

Arrhythmic death can be reduced by antiarrhythmic drugs to a range of 2-4%. Electrophysiologic study by testing noninducibility of ventricular arrhyth mia represents the classic method for evaluating the effectiveness of drug therapy. Several clinical studies have shown thaat sotalol suppresses VT induction a nd prevents arrhythmias recurrences at long term follow-up in 23% to 67% of patients. The efficacy of sotalol EP guided therapy in preventing VT/VF is not necessarily related to prevention of sudden death. In the ESVEM study the superiority of d,l-sotalol to other antiarrhythmic drugs was confirmed. The response to programmed ventricular stimulation was found to be strongl y predictive for arrhythmia free state while the failure of sotalol therapy to suppress VT at the EP study was associated with an high recurrence rate (40%). However, EP study failes to predict freedom from sudden death. The beta-blocking activity of racemic sotalol may account for some of the obser ved survival benefit. Beta-blockers therapy reduces mortality in patients after myocardial infarc tion primarily by a reduction of sudden death. A reduction of death, worsen ing heart failure and life threatening ventricular arrhythmias was shown in a recent study on carvedilol. In the prospective study of Steinbeck the EP guided-therapy did not improve the overall outcome when compared to metopr olol. Suppression of inducible arrhythmias by antiarrhythmic drugs was asso ciated with a better outcome. The effectiveness of defibrillator therapy in reducing overall mortality, has been uncertain since great clinical trials have been concluded. MADIT, AVID and CASH trials confirmed the superiority of ICD therapy over antiarrhythmic drugs therapy: ICD should be considered the first choice therapy in post-cardiac arrest patients. The ongoing BEST Trial will give us further responses about the interaction between EP study and metoprolol effect compared to ICD in patients post my ocardial infarction also focusing on tolerability and compliance of the bet a-blocking therapy in patients with low ejection fraction. In this study wi ll be useful to optimize therapy in patients at high risk of sudden death.