Last year, about 170,000 people in North America had devices surgically implanted to stop potentially fatal arrhythmias. For many, these were life-saving, but for others they were unnecessary, uncomfortable, and sometimes dangerous.
Now a new, noninvasive test may help determine which patients are most likely to benefit from the device, known as implantable cardiac defibrillator (ICD). A large, multicenter, NIH-sponsored study coordinated by Columbia University Medical Center researchers reported on the accuracy of the test was and was published in the latest issue of the Journal of the American College of Cardiology.
The test, known as the Microvolt T-wave Alternans (MTWA) test, measures the electrical activity in the heart while the patient is performing light exercise on a stationary bicycle or treadmill. It can detect an electrical signal that can identify a heart likely to generate a life-threatening rhythm disturbance, a signal too slight to be detected by the traditional electrocardiogram (ECG). The MWTA test will be most helpful for patients who are at risk but have not yet had a cardiac arrest. If an arrhythmia occurred in a patient who had an ICD, the device would deliver a pulse of electrical current through the heart in order to stop the potentially fatal arrhythmia.