The MUSTT study: Evaluating testing and treatment

The multicenter unsustained tachycardia trial (MUSTT) tested the value of e lectrophysiologically guided antiarrhythmic drug therapy against no therapy in high risk coronary artery disease with poor left ventricular function ( LV-EF less than or equal to 40%) and nonsustained ventricular tachycardia. Risk assessment was performed by testing inducibility of a sustained ventri cular tachycardia. The primary endpoint of the study was sudden arrhythmic death or cardiac arrest. Significant information on risk stratification was gathered by the follow-up of patients that were noninducible. Although MUS TT was not a specific ICD trial for primary prevention of SCD the results o f the trial revealed that only with ICD back-up-a significant reduction of arrhythmic death or cardiac arrest can be achieved. EP-guided antiarrhythmic drug treatment had a lower incidence of SCD/CA com pared to no treatment (12% versus 25%, p = 0.043, hazard ratio 0.73 after 2 4 months and 18% versus 32% after 60 months). A subgroup analysis showed th at the benefit of antiarrhythmic treatment was only due to ICD implantation . No difference was found between those inducible pts treated exclusively w ith antiarrhythmic drugs and those who were randomized to no drug treatment . Patients who were not inducible did significantly better than pts who wer e inducible wether or not treated with antiarrhythmic drugs. MUSTT results strengthen the data of the MADIT study. They confirm the indu cibility testing as the most accurate risk stratifier. MUSST demonstrated t he poor value of serial EP drug testing as well as the risk of "stand alone " antiarrhythmic drug treatment.