Researchers in Minnesota say that cocaine users may be putting themselves at risk of coronary aneurysms, a ballooning of the walls of coronary arteries, which is potentially fatal.
The newly discovered risk increases the chance of heart attacks, even years after the drug is no longer used. The researchers found that the risk of developing an aneurysm was four times as high among cocaine users in their mid-40's than among nonusers in the same age group.
Aneurysms occurred in 30.4 percent of cocaine users in the study compared with 7.6 percent of non-users.
Dr. Timothy D. Henry, a co-author of the study says the precise amount of cocaine needed to produce the aneurysms is not known, but the frequency of use was clearly linked to the development of aneurysms.
Henry, who directs research at the Minneapolis Heart Institute Foundation at Abbott Northwestern Hospital says the risk was definitely more common in people who used cocaine at least once a week. He says aneurysms can be prevented by avoiding cocaine, but no specific treatment is available once they develop.
According to the Substance Abuse and Mental Health Services Administration in 2003, 34.9 million Americans ages 12 and older reported having used cocaine at least once during their lifetimes and about 2.3 million reported having used the drug in the previous month.
Cocaine is known to increase the risk of heart attacks within hours of its use but because coronary aneurysms are uncommon and generally take years to form, a link to cocaine had not been suspected.
Dr. Henry cited the case of a prominent businessman who asked for a second opinion about coronary angiograms, X-rays taken when the man suffered a heart attack at 38. The angiograms showed multiple aneurysms of the coronary arteries that nourish the heart.
As the man did not have atherosclerosis, which accounts for about half of coronary aneurysms, or any of the rarer conditions associated with aneurysms, like syphilis, trauma and lupus and other connective tissue disorders, Henry asked if the man had ever used cocaine.
The man responded by asking Henry how he knew, as he had in fact used cocaine for two years when he was in his 20's, but not since.
Dr. Henry says he started a systematic search to determine how often the aneurysms occurred among the users five years ago when he saw aneurysms in angiograms of three heavy cocaine users.
The records of 191 men and women whose average age was in the early 40's were examined, including 112 cocaine users who had angiography for known or suspected heart problems during a 10-year period and 79 nonusers of similar age who also had the procedure.
Three cardiologists examined the angiogram of each patient in the study to determine the presence or absence of coronary artery aneurysms. If all three doctors agreed that a coronary aneurysm was present, they classified it as definite. If two doctors concurred, they considered the aneurysm probable. In the cocaine user group, 24 patients had definite coronary artery aneurysms and 10 had probable ones.
Using information that the patients had previously told their doctors, the researchers calculated the frequency of cocaine use in 61 of the drug users and found that 66 percent reported using the drug at least once a week.
Aneurysms can occur in any artery. They are particularly frequent in the brain and in the aorta, the main artery that carries blood from the heart to the rest of the body, often ripping open to cause strokes and sudden death.
Aneurysms in the coronary arteries rarely burst and pose a less direct risk of death than do brain aneurysms or aortic aneurysms. But the study showed that coronary artery aneurysms might kill by setting up cocaine users for a heart attack.
Dr. Henry's team theorized that cocaine might weaken the artery wall and lead to an aneurysm by causing sharp spikes in blood pressure and damaging cells in the inner walls of the heart's arteries. Once an aneurysm forms, blood may flow through it in a way that makes it easier for blood clots to form. Those, in turn, can then stop the flow of blood and cause a heart attack.
Dr. Henry said he hoped to collaborate with other cardiologists to further confirm the findings by conducting similar studies and using non-invasive techniques like echocardiography and rapid CT scans to determine when and how often the aneurysms form.
Meanwhile, a number of other doctors who have learned of the Minnesota team's findings have told Dr. Henry that they have found coronary aneurysms among cocaine users.
The study is published in the current journal Circulation, which is published by the American Heart Association.