MUSTT
The Multicenter Unsustained Ventricular Tachycardia Trial (MUSTT) was presented by Dr. Alfred Buxton, the principal investigator. It tested the hypothesis that antiarrhythmic therapy, guided by electrophysiologic testing (EPT), would decrease cardiac deaths in patients with coronary artery disease, systolic dysfunction (EF < 40%), and nonsustained ventricular tachycardia (VT). EPT was done to detect inducible sustained VT. If none was found, the patient went into a registry. If they had inducible VT, they were randomized to an ACE inhibitor plus beta-blocker or antiarrhythmic therapy. Antiarrhythmic therapy was EPT guided: round 1, propafenone or sotalol; round 2, type IA and mexilitine or implanted cardioverter/defibrillator (ICD); round 3, amiodarone, ICD, or another round of 1 or 2 agents. The primary end point was arrhythmia death or cardiac arrest; secondary end points were all-cause mortality and cardiac death. A total of 2202 patients were enrolled; 35% had a positive EPT and 92% of these were randomized: 351 to antiarrhythmic therapy and 352 to conservative therapy. Patient characteristics were well matched between the groups: EF averaged 30%, two-thirds were NYHA class II-III, 95% had a prior MI, and 56% had a prior CABG. In the conservative group, 70% were on an ACE inhibitor and 45% on a beta-blocker; in the aggressive group, 46% had an ICD and 45% were on antiarrhythmic drugs. The median follow-up was 39 months (up to 5 years maximum).
Event-free survival was significantly better in the EPT-guided therapy group: the primary end point at 24 months was 12% vs. 18% and 25% vs. 32% at 60 months. The hazard ratio was 0.73 for EPT. Total mortality was less in the EPT group (HR = 0.8; P = 0.06). Subgroup analysis showed that patients with ICD did the best, with 92% alive at 60 months. The investigators concluded that in patients with asymptomatic nonsustained VT, CAD, reduced LVEF, and inducible sustained VT at EPT, ICD therapy reduces arrhythmic deaths. Antiarrhythmic therapy without ICD was not better than conservative therapy of ACE inhibitor and beta-blocker.
Comment by Michael H. Crawford, MD
These results are not surprising and confirm the results of MADIT, which showed that mortality was reduced in post-MI patients with LV dysfunction using an ICD vs. conservative therapy. The major issues with both studies are the resources required to study patients with CAD and LV dysfunction by EPT and treat appropriate ones with ICD and expensive antiarrhythmic drugs. It is dubious whether the health care system can afford this. Thus, further analysis of these trials and future, more focused studies are required to be selective in applying this expensive approach. Nonetheless, the mortality reductions are impressive and hard to ignore.
Dr. Abrams is Professor of Medicine, Division of Cardiology, University of New Mexico, Albuquerque.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content