The MUSTT study: Evaluating testing and treatment

The multicenter unsustained tachycardia trial (MUSTT) tested the value of electrophysiologically 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 ventricular 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 MUSTT was not a specific ICD trial for primary prevention of SCD the results of 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 compared to no treatment (12% versus 25%, p = 0.043, hazard ratio 0.73 after 24 months and 18% versus 32% after 60 months). A subgroup analysis showed that the benefit of antiarrhythmic treatment was only due to ICD implantation. No difference was found between those inducible pts treated exclusively with antiarrhythmic drugs and those who were randomized to no drug treatment. Patients who were not inducible did significantly better than pts who were inducible wether or not treated with antiarrhythmic drugs. MUSTT results strengthen the data of the MADIT study. They confirm the inducibility testing as the most accurate risk stratifier. MUSST demonstrated the poor value of serial EP drug testing as well as the risk of "stand alone" antiarrhythmic drug treatment.