DALLAS -- Two studies released this week provide more evidence that cocaine increases the risk of a heart attack.
"We believe it is a serious problem and definitely underreported," said Dr. Shereif Rezkalla of Marshfield, Wis., co-author of one of the new studies discussed this week in Dallas at the annual meeting of the American College of Cardiology.
The death of 22-year-old University of Maryland basketball star Len Bias in 1986 is the best-known case of a cocaine-related heart attack. A report published two years ago cited at least 58 such cases described in medical journals.
Considering that an estimated 25 million Americans have used cocaine at least once, there probably have been many more such cases, researchers say.
Scientists have theorized several ways that cocaine might increase heart attack risk. In a study published in late 1989, researchers from the University of Texas Southwestern Medical Center at Dallas reported that cocaine triggers spasms in coronary arteries. The drug prevents the body from clearing out adrenaline-like hormones that cause arteries to tighten.
Other research by Texas Southwestern scientists has shown that cocaine increases production of thromboxane -- a substance on blood platelets that can constrict vessels -- in rabbits' aortas.
In the study reported Tuesday, Texas Southwestern researchers compared the hearts of 24 people known to have been cocaine abusers and 14 who had not been abusers. The hearts were removed during autopsies by the Dallas County medical examiner's office.
An equal percentage of each group was found to have fatty deposits in coronary arteries.