Alternating T waves on ECG identify patients who may benefit from ICD

March 25, 2007

An abnormal T-wave alternans test may identify those patients with stage II and III heart failure due to nonischemic cardiomyopathy who are likely to benefit from an implantable cardioverter defibrillator (ICD), said Gaetano M. De Ferrari, MD, at the American College of Cardiology's 56th annual scientific session.

An abnormal T-wave alternans test may identify those patients with stage II and III heart failure due to nonischemic cardiomyopathy who are likely to benefit from an implantable cardioverter defibrillator (ICD), said Gaetano M. De Ferrari, MD, left, at the American College of Cardiology's 56th annual scientific session.

"There is a strong need to identify reliable risk stratifiers among heart failure patients for ICD prophylaxis," he said. "This is particularly true for patients with heart failure of nonischemic origin."

The presence of alternating patterns of the T wave on the electrocardiogram during exercise is considered abnormal. Absence of T-wave alternans appears to identify a low-risk subset of patients who have had a myocardial infarction with depressed left ventricular ejection fraction (LVEF). Its predictive role in nonischemic cardiomyopathy is unclear.

In a study known as ALPHA (T-wave Alternans in Patients with Heart Failure), 446 patients with stage II and III heart failure of nonischemic origin who had an LVEF 40% and no previous malignant arrhythmias underwent a T-wave alternans test and were followed for 18 to 24 months. The primary endpoint was a combination of cardiac death and life-threatening arrhythmias; total mortality and sudden death plus life-threatening arrhythmias were secondary endpoints.

Sixty-five percent of the patients had an abnormal T-wave alternans test.

There were 28 deaths overall-3 in the group with normal T-wave alternans tests and 25 in the group with abnormal tests (p = 0.002). An abnormal T-wave alternans test was associated with a 4-fold higher risk (p = 0.002) of the primary endpoint (cardiac death/life-threatening arrhythmias). The endpoint of arrhythmic death plus life-threatening arrhythmias was increased by more than five times (p =0.004) with an abnormal test.

ICDs are offered to few patients who would derive benefit, as established by criteria endorsed by guidelines writers from most countries, said Dr. De Ferrari, head of the cardiac intensive care unit at Fondazione IRCCS Policlinico San Matteo, Pavia, Italy. The T-wave alternans test may have "practical significance" to prioritize ICD use by identifying those patients most likely to suffer life-threatening events without an ICD, he said.