Occasional Cocaine Use Can Do Acute and Chronic Damage

Reed Miller

November 08, 2012

LOS ANGELES — Regular cocaine use by otherwise-healthy people can increase systolic blood pressure, aortic vascular stiffness, and left ventricular mass, a new Australian study shows [1].

Dr Rebecca Kozor (Royal North Shore Hospital, Sydney, Australia) and colleagues used cardiac MRI to investigate whether cocaine caused cardiovascular abnormalities in regular "social" cocaine users who are otherwise healthy. Dr Gemma Figtree (Royal North Shore Hospital) presented results of the group's 40-patient controlled study at the American Heart Association (AHA) 2012 Scientific Sessions.

Cocaine is known to cause MI by increasing thrombotic risk, blood pressure, and sympathetic drive, while often causing vasospasm. "We've had a spate of young males with large heart attacks related to cocaine use [at our center]," Figtree told heartwire . "People seem to be very ill-informed about this risk, [so] we were interested to know the background incidence of cardiovascular abnormalities in people who consider themselves social or recreational cocaine users. These guys were using cocaine usually once or twice a week, usually related to work, but considered it to be just a social thing. They were quite shocked to learn that it could cause a potentially fatal heart attack."

The trial enrolled 40 asymptomatic volunteers: 20 regular cocaine users and 20 nonusers. The two groups had similar age, gender, self-reported history of dyslipidemia, diabetes, and hypertension, but the cocaine users had an average higher body-surface area and were more likely to smoke, drink alcohol, or use other recreational drugs. The MRIs of the study subjects were taken at least 72 hours after they had last used the drug.

Figtree pointed out that finding volunteers who would reveal their drug use for the study was "tricky, but we had an 'in' when a lot of the patients who came in who didn't know about cocaine-induced heart attacks and suffered large heart attacks had a lot of friends who were very keen to know more about it. So when we were educating them, through word of mouth, we enrolled a large number of people."

Figtree said that cocaine users are often unaware of the cardiovascular risks associated with the drug and often wait a while to seek medical attention for chest pain, "because they think it's just chest pain related to a 'party drug.' But they need to be educated that if they do get chest pain while taking cocaine, they should come straight for medical attention." Also, clinicians should consider the possibility of cocaine-related cardiovascular damage when presented with a relatively young patient with chest pain.

Long-Term Damage on Top of the Acute Risk

The cocaine users in the study had a higher average systolic blood pressure (134 mm Hg vs 126 mm Hg, p=0.036), independent of age, size, or smoking status, and cocaine use was the most significant predictor of systolic blood pressure, but there were no differences in diastolic blood pressure and heart rate between cocaine users and nonusers in the study. Cardiovascular MRIs showed that the cocaine users' proximal descending aortas were, on average, significantly less compliant, with a higher stiffness index than that of the nonusers. Age was also a significant predictor of arterial stiffness.

The cocaine users in the study had an 18% greater left ventricular mass than control subjects (p=0.007). The difference remained significant (p=0.038) even after researchers controlled for body-surface area, and cocaine use was the most significant predictor of left ventricular mass independent of body-surface area and other covariates. "It was more than 72 hours after their last use, so it seems to be having a chronic effect," Figtree said. "Obviously, it's a small study, but that's one of the powerful things about MRI; because of the precision of the measurement, you can get these statistically significant and relevant results.

"What this says is that [cocaine] has the acute effect of causing a heart attack at any time--it could cause a heart attack the first time you ever use it . . . but also what is new in this study is that [cocaine] does seem to be associated with more chronic abnormalities in the cardiovascular system many hours after [the last ingestion]," she said. "Although we know you're taking a gamble every time you take cocaine as to whether you're going to have a heart attack, on top of that you've got these longer-term side effects."

However, despite the known risk of MI associated with cocaine, there was no evidence of silent MI, as determined by late gadolinium enhancement, or segmental wall-motion abnormalities in any of the study patients. This finding is in contrast to that of a recent study by Dr Giovanni Donato Aquaro (Fondazione G. Monasterio Regione Toscana, Italy), in which cardiac MRI at least 48 hours after drug withdrawal found myocardial structural damage in 83% of asymptomatic cocaine addicts [2].

The difference in the studies' results may be related to how the drug was mixed or administered or a difference in the underlying propensity of the study subjects, Figtree said, adding that the cohort in the Italian study included heavier users of cocaine than the group in the Australian study.

She said that her group is currently working with hematologists to better understand the interaction between thrombophilic conditions and susceptibility to cocaine-induced thrombosis as well as long-term effects of cocaine on vascular smooth muscle.

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