Methods Determine If Defibrillator Will Benefit Patient

Non-invasive and invasive methods identify patients at risk of sudden death

TUESDAY, Feb. 3 (HealthDay News) -- Non-invasive microvolt T-wave alternans (MTWA) and electrophysiological study (EPS) are effective in identifying patients with cardiac disease who may benefit from an implantable cardioverter-defibrillator, according to a report in the Feb. 10 issue of the Journal of the American College of Cardiology.

Otto Costantini, M.D., from Case Western Reserve University in Cleveland, and colleagues compared the ability of non-invasive MTWA and EPS to identify patients who would benefit from implantable cardioverter-defibrillators in 566 patients with ischemic cardiomyopathy and non-sustained ventricular tachycardia.

After a median of 1.9 years, the researchers found that 7.5 percent of patients either had an appropriate implantable cardioverter-defibrillator discharge or sudden death at one year. MTWA and EPS had similar positive (9 and 11 percent, respectively) and negative (95 percent for both) predictive values. At the one-year end point, the risk of an event was significantly higher in patients with a positive MTWA-directed strategy (hazard ratio 2.1) and a positive EPS-directed strategy (hazard ratio 2.4), the investigators found. The event rate was significantly lower in patients where both tests were negative compared with patients where both tests were positive (2 versus 12 percent), the report indicates.

The data "should not be taken as evidence that MTWA can replace EPS or as proof that the two are reasonably equivalent," Gregory K. Feld, M.D., from the University of California San Diego, and Paul Clopton, from the Veterans Affairs San Diego Healthcare System, write in an accompanying editorial. "The current data are best taken as suggesting that MTWA should be studied further to determine its role in identification of patients with ischemic heart disease and reduced left ventricular ejection fraction who are at highest risk for sudden cardiac death and in whom implantable cardioverter-defibrillator implantation might be warranted."

Authors of the study and editorial have financial relationships with pharmaceutical and medical companies.

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