A costly heart device similar to a pacemaker given to many heart attack patients is unnecessary in a third of them, and a simple treadmill test can tell between the two, according to a new study.
Researchers enrolled 768 heart attack patients whose hearts had been permanently weakened by the lack of oxygen they experienced during the attack, a condition known as ischaemic cardiomyopathy.
All of the patients underwent a test of their heart's rhythm, a microvolt T-wave alternans (MTWA) test, and half were then given an implantable cardioverter defibrillator, which is designed to shock their hearts back into rhythm.
Positive or inconclusive test results were seen in two thirds of the patients, while the other third tested negative.
The researchers calculated that the defibrillator halved the risk of death in the patients with positive or inconclusive results, but failed to improve the survival of those with negative results.
The authors hope that all patients who would otherwise have an implantable cardioverter defibrillator will undergo MTWA testing as a result of the findings.
Journal of the AmericanCollege of Cardiology (2007) 49: 50-58