News Release

Noninvasive cardiac T-Wave test

May identify best patient candidates for ICD implant

Peer-Reviewed Publication

American College of Cardiology

Patients who experience abnormal heart rhythm, known as arrhythmia, are often treated with an implantable cardioverter defibrillator (ICD), which is used to correct the abnormal rhythmic episodes. However, not all patients will benefit from the implant, and researchers are seeking improved methods to identify – within a group of potential candidates – those patients who are most likely to respond successfully to the ICD, as well as those who are unlikely to benefit from the intervention.

According to a study presented today at the American College of Cardiology's 56th Annual Scientific Session, a new test called an abnormal T-Wave Alternans (TWA) test may be able to identify heart failure patients with stage II and III nonischemic cardiomyopathy (defining moderate levels of heart muscle tissue damage), who are likely to benefit from the use of an ICD. ACC.07 is the premier cardiovascular medical meeting, bringing together cardiologists and cardiovascular specialists to further breakthroughs in cardiovascular medicine.

A TWA test is a non-invasive measure of the heart's electrical activity, usually performed during an exercise test. The presence of alternating patterns of the T-wave (a component of the electrocardiogram) is considered abnormal and thereby identifies individuals at a higher risk of life-threatening arrhythmias. The study, known as ALPHA (T-wave ALternans in Patients with Heart fAilure Trial), was conducted among 446 stage II and III heart failure patients with cardiomyopathy of nonischemic origin (with normal or near normal coronary arteries), all of whom had left ventricle ejection fraction of less than 40 percent and no previous malignant arrhythmias. The patients underwent a TWA test and were followed for 18 to 24 months to assess the combined rates of cardiac death plus life-threatening arrhythmias, as well as rates of total mortality and of sudden death plus life-threatening arrhythmias.

The prognostic value of TWA among the study participants suggests that patients with an abnormal TWA test (65 % of patients) have a four-fold higher risk (HR=4.0) of cardiac death and life-threatening arrhythmias. The study also demonstrated that stage II and III nonischemic cardiomyopathy patients with a normal TWA test (35 % of patients) have a very good prognosis and are therefore unlikely to benefit from an ICD.

“The ability to determine if heart failure patients are at high risk of life-threatening arrhythmias is essential to determining the best method of treatment, including the option of using an ICD or maintaining pharmacologic therapy. The predictive value of a TWA test among this population demonstrated accuracy in identifying high-risk patients that will likely see benefit from an ICD device,” said Gaetano M De Ferrari, M.D., of the Department of Cardiology of the San Matteo Hospital in Pavia, Italy, and contributing author of the study. “Presently, all patients with stage II and III disease with left ventricle ejection fraction of less than 35 percent are considered candidates to an ICD. The ALPHA study strongly suggests that one third of these patients will have a normal TWA test and will not benefit from the ICD. Knowing this, we are able to better treat the two thirds of patients that really need the device.”

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Dr. De Ferrari will present this study, “Prognostic Value of T-Wave Alternans in Patients With Heart Failure Due to Nonischemic Cardiomyopathy: Results of the T-Wave Alternans in Patients With Heart Failure (ALPHA) Study,” on Sunday, March 25 at 8:30 a.m. in Hall A.

The American College of Cardiology (www.acc.org) represents the majority of board certified cardiovascular physicians in the United States. Its mission is to advocate for quality cardiovascular care through education, research, promotion, development and application of standards and guidelines- and to influence health care policy. ACC.07 and the i2 Summit is the largest cardiovascular meeting, bringing together cardiologists and cardiovascular specialists to share the newest discoveries in treatment and prevention, while helping the ACC achieve its mission to address and improve issues in cardiovascular medicine


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