ST. LOUIS, July 12 (UPI) -- It's well known depression increases the risk of death after a heart attack, but now U.S. researchers have determined why it does so.
Behavioral medicine specialists at the Washington University School of Medicine in St. Louis discovered abnormal heart rate variability is partially responsible for depression's effects in heart patients.
The researchers say treatments to alleviate symptoms of depression and correct defects in heart rate variability offer the best hope for improved survival in depressed patients with coronary heart disease.
The study compared 311 depressed heart patients with 367 non-depressed heart patients. Both groups were followed for about 2 1/2 years.
"Depressed patients were nearly three times as likely to die during the study period as comparable, non-depressed heart patients," said Dr. Robert Carney, a psychiatry professor and the study's principal investigator. "We also found lower heart rate variability was responsible for a sizeable portion of that risk."
Researchers also determined the risk of death increased over time. Depressed heart patients tended to be at greater risk more than 12 months after their heart attacks.
The findings appear in the journal Archives of Internal Medicine.
