Volume 353, Number 9168

COCAINE USE TRANSIENTLY INCREASES HEART-ATTACK RISK

According to the results of a new study, for 1 hour after its use cocaine
is "associated with a large abrupt and transient increase in the risk of a
myocardial infarction in patients who are otherwise at relatively low
risk". This research, from Murray Mittleman (Harvard Medical School,
Boston, MA, USA) and colleagues, is the first to quantify the myocardial
infarction risk associated with cocaine use.

The researchers interviewed 3946 patients at 64 medical centres who
fulfilled specific criteria identifying them as having had an acute
myocardial infarction. Patients, who were interviewed within a few days of
the event, were asked about time, place, and quality of the myocardial
infarction pain, frequency of exposure to potential triggers, and cocaine
use in the previous year. Those admitting cocaine use were also asked when
they had last used the drug (Circulation 1999; 99: 2737-41 ).

Of the patients interviewed, 38 (1%) reported cocaine use in the 12 months
before the infarction, and nine reported use within 60 minutes before the
onset of symptoms.

The researchers used a case-crossover study design, in which control
information for each patient was based on their own past exposure
experience, to analyse these data. They report that in the first hour after
cocaine use, myocardial infarction risk was 23 (95% CI) times greater than
the baseline risk during periods of non-exposure to cocaine.

Because of the difficulty of getting people to admit to drug use, the risk
increase calculated may even be an underestimate.

"We were doing a large study looking at factors that might trigger the
onset of an acute myocardial infarction", comments Mittleman. "The
interesting thing is that this is one of the most powerful triggers we have
seen."

"At one time cocaine was thought to be a very safe drug", explains Richard
Lange (University of Texas Southwestern, Dallas, TX, USA). But more
recently, cocaine has been implicated as a trigger of acute myocardial
infarction, and some mechanisms have been proposed to explain its effect,
such as its ability to increase heart rate and to cause coronary
vasoconstriction.

"The data [of this study] corroborate what has been shown mechanistically;
what we haven't had before now is an estimate of the risk", adds Lange. Now
that the risk has been quantified, the challenge is to educate cocaine
users, he concludes.