Published: Mar. 30, 2008
Updated: Mar. 31, 2008
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By Duke Medicine News and Communications
CHICAGO – Risk of sudden cardiac death increases following a heart attack, but researchers at the Duke Clinical Research Institute say the factors that predict such deaths change over time. The findings were presented today at the annual meeting of the American College of Cardiology.
Duke investigators reviewed the records of 14,703 patients enrolled in the VALIANT trial (Valsartan in Acute Myocardial Infarction Trial), a study that showed that risk of sudden death is greatest in the first 30 days after a heart attack.
"Patients who die in the first few weeks after a heart attack can experience abnormal heart rhythms that can lead to sudden death," says Dr. Jonathan Piccini, a cardiology fellow at Duke and the lead author of the study. "Ironically, however, multiple studies show that implantable defibrillators – devices that can stop life-threatening heart rhythms – don't really seem to alter death rates during that period. So it occurred to us that there may be other important risk factors for sudden death and that these risk factors may change with time."
Piccini and colleagues examined patient outcomes during four time periods in the VALIANT trial: in-hospital to discharge, discharge to 30 days, 30 days to six months and six months to three years.
They found that by 30 months, 7.3 percent of the patients had died of sudden cardiac death, and that those who died tended to be older, were more likely to have diabetes, had not been prescribed a beta-blocker and had experienced a heart attack before enrolling in the VALIANT trial.
"We also found that while low blood pressure and a high resting heart rate are strong initial predictors of sudden cardiac death, over time, heart failure and an earlier heart attack were even more robust predictors," says Piccini.
One risk factor that was consistently predictive over time was impaired kidney function. Piccini says the reasons why are not clear, but poor kidney function appears to be associated with higher likelihood of arrhythmia in general, but particularly in patients who have suffered a heart attack.
"These results are important because they may help cardiologists better understand their patients' risks for abnormal heart rhythms after a heart attack. This, in turn, could lead to more appropriate and better care," says Piccini.