Cocaine abuse leaves lingering heart risk.

Cocaine abuse leaves lingering heart risk

For several weeks after giving up cocaine, habitual users experience frequent episodes of reduced blood flow to the heart, new research shows. These temporary and often painless attacks, called myocardial ischemia, may indicate that a cocaine abuser's well-known risk of suffering a sudden, fatal heart attack extends into the first weeks of withdrawal.

A team led by Koonlawee Nademanee and David A. Gorelick at the West Los Angeles Veterans Administration Medical Center in Los Angeles studied 21 male cocaine abusers admitted to a 28-day inpatient drug treatment program. Most of the men reported smoking 1.8 grams of freebase cocaine (a potent form of the drug) every day for two years, but researchers performed frequent urine tests during the study to make sure they remained cocaine-free. For a 24-hour period during the first two weeks of withdrawal and again four weeks later, volunteers wore a device that detects ischemic episodes by recording the heart's electrical activity.

In the first two weeks, eight of the 21 ex-cocaine users experienced frequent episodes of ST elevation, an electrical abnormality indicating ischemia. None of the 42 healthy controls studied showed this abnormality, the scientists report in the Dec. 1 ANNALS OF INTERNAL MEDICINE.

In most cases, the ischemia seen among ex-users cannot be attributed to underlying coronary artery disease, says Gorelick, now working in Baltimore with the Addiction Research Center of the National Institute on Drug Abuse. At the study's beginning and end, the team monitored 20 of the ex-users as they exercised on a treadmill, finding only one whose results suggested arteries clogged with fatty plaques.

The researchers postulate that chronic cocaine use depletes the heart's nerve cells of dopamine, a neurotransmitter that normally signals coronary arteries to dilate. Dopamine deprivation may make coronary arteries prone to spasm, which can cause ischemic attacks and which may persist for several weeks during withdrawal, Gorelick says. Ex-users in the study who stayed off cocaine for six weeks showed no evidence of ischemia, suggesting the attacks subside with time.

Scientists worry that ischemic attacks may damage the ex-users' heart muscles, increasing their risk of heart attack in the long run as well as during withdrawal. But before cardiologists can recommend that ex-users take medication to prevent ischemia, further studies must confirm the elevated heart risk, says Richard A. Lange of the University of Texas Southwestern Medical Center at Dallas.