According to a study at the University of Michigan Medical Center, as many as a third of Americans who get implantable defibrillators to correct heartbeat irregularities may not need them. The study found that better answers of who is a candidate for a defibrillator implant may come from a test that provides precise information on how well the heart pumps blood. The report was published in the January issue of the Journal of the American College of Cardiology.
The test, known as MTWA, for microvolt T-wave alternans, measures changes in calcium levels in the heart. It costs about $400 and is conducted much like a treadmill stress test, only less vigorously.
