T-Wave Pattern Can Prioritize HF Patients for ICD Placement

Internal Medicine World Report, September 2007, Volume 0, Issue 0

By Wayne Kuznar

NEW ORLEANS—An alternating pattern of T waves on electrocardiography (ECG) may identify patients with heart failure due to nonischemic cardiomyopathy who are most likely to benefit from an implantable cardioverter defibrillator (ICD), said Gaetano M. De Ferrari, MD, at the American College of Cardiology annual meeting.

"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 EGC (an abnormal T-wave alternans test) during exercise is considered abnormal, identifying individuals at increased risk of arrhythmias.

An absence of T-wave alternans appears to identify a low-risk subset of patients who have had a myocardial infarction with depressed left ventricular (LV) ejection fraction. Its predictive role in nonischemic cardiomyopathy is currently unclear.

Dr De Ferrari, head of the cardiac intensive care unit at Fondazione IRCCS Policlinico San Matteo, Pavia, Italy, performed T-wave alternans tests in 446 patients with New York Heart Association (NYHA) class II or III heart failure of nonischemic origin who had an LV ejection fraction ≤40% and no previous malignant arrhythmias. Patients were followed for 18 to 24 months after the test.

The primary end point was a combination of cardiac death and life-threatening arrhythmias; total mortality and sudden death plus life-threatening arrhythmias were secondary end points. A total of 65% of the patients had an abnormal T-wave alternans test.

Overall, 28 deaths occurred: 3 were in the group with normal T-wave alternans tests and 25 were in the group with abnormal tests (P = .002). An abnormal test result was associated with a 4-fold greater risk (P = .002) of the primary end point (ie, cardiac death/life-threatening arrhythmias).

The risk of arrhythmic death, life-threatening arrhythmias, and hospitalization was increased by more than5-fold (P = .004) in patients with an abnormal test result (Table).

Table. Cardiac events relative to T-wave pattern

Event

All patients

(n=446)

Abnormal TWA

(n=292)

Normal TWA

(n=154)

All-cause death

Cardiac death

Arrhythmic death

28

18

7

25

16

7

3

2

0

Systematic sustained

VT or VF

11

9

2

Documented VF

4

4

0

Sustained Vt

revealed by devices

4

4

0

Hospitalization

85

61

24

TWA = T-wave alternans; VT = ventricular tachycardia; VF = ventricular fibrillation

Presently, all patients with NYHA class II and III disease with an LV ejection fraction <35% are considered candidates for an ICD, said Dr De Ferrari.

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. "Our study suggests that about one third of these patients will have a normal T-wave alternans test and will not benefit from ICD placement."