3-10-99
MUSTT: Multicenter Unsustained Tachycardia Trial

	Nonsustained ventricular tachycardia often
occurs in patients with coronary artery disease (CAD)
and left ventricular dysfunction. These patients have 
increased risk of sudden death but it is unclear whether 
anti-arrhythmic therapy is of any benefit. Some trials 
studying anti-arrhythmic drugs in heart attack patients,
such as the CAST trial, showed increased mortality, but
EAMIAT and CAMIAT showed no benefit. MADIT was the first 
study to show a mortality benefit in patients with CAD
and left ventricular systolic dysfunction, using anti-
arrhythmic therapy besides beta-blockers. (ICDs)
	Dr. Alfred Buxton from Temple University School
of Medicine in Philadelphia and others from 85 sites in 
the USA and Canada did the Multicenter Unsustained 
Tachycardia Trial (MUSTT). The purpose was to see
whether anti-arrhythmic therapy guided by an 
electrophysiology (EP) study lowers risk of arrhythmic 
death and heart attack in patients with nonsustained 
ventricular tachycardia, EF less than 40%, and CAD.
	Patients all had an EP study to see if they had 
inducible sustained ventricular tachycardia. If they 
did, they were randomized to either conservative 
treatment (with ACE inhibitor and/or beta-blocker) or 
EP-guided treatment using the following drug sequence: 
1 - propafenone or sotalol
2 - Type IA agent and mexiletine or ICD or another round 
one agent
3 - amiodarone, ICD, or another round 1 or 2 agent. 
	Patients proceeded to the next round if a repeat 
EPS induced ventricular tachycardia, until it could no 
longer be induced. All patients received ACE inhibitors 
and beta-blockers. The primary endpoints were arrhythmic 
death or cardiac arrest. The secondary endpoints were 
overall mortality and cardiac mortality.
	704 patients were randomized to either the 
conservative group (353) or anti-arrhythmic therapy group
(351). Average patient age was 67 years and average EF 30%.
95% had a previous heart attack and 56% had previous bypass
surgery. In the anti-arrhythmic therapy group, 45% received
anti-arrhythmic drugs, 46% received an ICD, and 7% received
no therapy. The average follow-up was 39 months.
	RESULTS: Mortality rate at 24 and 60 month follow-up
showed that the anti-arrhythmic therapy group did better 
than the conservative group, with a 23% relative risk 
reduction. Patients who received an ICD clearly performed
better than any other group, with 92% being alive at 60 
months. In fact, when the ICD patients were removed from 
the anti-arrhythmic therapy group, there was no significant
difference between the 2 groups.
	CONCLUSIONS: In patients with asymptomatic 
nonsustained ventricular tachycardia, CAD, EF less than 40%
and sustained inducible ventricular tachycardia, ICDs 
appear to have a mortality benefit and reduce risk of 
arrhythmic death and cardiac arrest. Given the high cost of
EP testing and the enormous number of similar patients, it 
is unclear whether the healthcare system will be able to 
shoulder the financial burden if all these patients were to 
be studied and treated.