MUSTT: defibrillators work, antiarrhythmics don't, in inducible sustained VT

Laurent Castellucci

December 16, 1999

Boston, MA - Patients with inducible, sustained tachyarrhythmias can be helped by implantable defibrillators, but not with antiarrhythmic drugs. The Multicenter Unsustained Tachycardia Trial (MUSTT) data appear in the New England Journal of Medicine's December 16 issue[1].

Led by Alfred Buxton (Brown University, Providence, RI), the MUSTT researchers randomized 704 patients with ejection fractions<40%, known CAD, spontaneous nonsustained ventricular tachycardia, and inducible sustained VT to receive either electrophysiologic-guided antiarrhythmic (AA) therapy or no AA therapy. 1435 patients with all of the above but without inducible sustained VT were enrolled in a registry to be followed.

Patients receiving EP-guided AA therapy had lower rates of arrhythmic death and cardiac arrest compared with those not receiving AA therapy, an effect due entirely to the implantation of defibrillators. In a previous interview with heartwire , Buxton said, "The patients who were treated with pharmacologic antiarrhythmic therapy had a survival curve that was almost identical to that of the patients randomized to no antiarrhythmic therapy."

Mortality at 5 years after receiving EP-guided AA therapy

Outcome AA therapy (n=351), % No AA therapy (n=353), % p-value
Cardiac arrest or death from arrhythmia 25 32 0.04
Total mortality 42 48 0.06
Death from cardiac causes 34 40 0.05

Mortality at 5 years: defibrillators vs AA drugs

Outcome Defibrillators( n=161), % AA drugs (n=158), % p-value
Cardiac arrest or death from arrhythmia 9 37 <0.001
Total mortality 24 55 <0.001

The authors stress that the trial was designed to assess the usefulness of electrophysiologic testing to guide antiarrhythmic therapy and not to compare different types of AA therapy. The patients who received defibrillators were not assigned randomly, and the true size of the benefit cannot be determined from these conditions.

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