"This is where this paper extends our knowledge," Rosenbaum said. "It shows that the two [irregularities] have a synergistic effect in a post-myocardial infarction [heart attack] population."
One application of the two-in-one testing could be in selecting persons who would be best helped by an implantable defibrillator, a device that delivers a shock to keep the heart beating normally when necessary. In the majority of cases today, Rosenbaum said, an implanted defibrillator just sits in the chest, because its emergency activity is never needed.
Exner said: "We have two large studies planned. One is where we have patients who are not indicated for defibrillators post-MI [myocardial infarction]. It is starting in May. The other study will include patients getting defibrillators because of a low ejection fraction," a weakened ability to pump blood.
Until these and other studies are done, "it's too early to start making treatment decisions" on the basis of the two combined tests, Exner said.
Rosenbaum said the new study does show "that when you combine these tests, you get a fairly robust prediction of outcomes. But like all good studies, it raises a lot of questions. It also requires validation in prospective trials."
To learn more about implantable defibrillators, visit the American Heart Association.
SOURCES: Derek V. Exner, M.D., associate professor of medicine, University of Calgary, Canada; David S. Rosenbaum, M.D., professor, medicine and biomedical engineering, Case Western Reserve University, Cleveland; Dec. 11, 2007, Journal of the Amer
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