to the editor: We would like to express our concern regarding the statement in the American Family Physician article “Diagnosis of Acute Coronary Syndrome”1 by Dr. Achar and colleagues that patients who use cocaine and subsequently develop chest pain are at a “low risk” for developing an acute cardiovascular event. In their discussion of cocaine-associated chest pain, the authors cite a study that suggests “only” 2 percent of patients with cocaine-associated chest pain had an acute coronary syndrome (ACS) event.2 Unfortunately, this study was not only of patients with cocaine-related chest pain, but a subset of a larger study of patients presenting to emergency departments with any cocaine-related complaints.2 Because this was not a study of only cocaine-related chest pain, we believe the referenced study dilutes the true incidence of ACS associated with cocaine use.
To better determine the rate of ACS associated with cocaine-related chest pain, we cite a prospective study that evaluated 246 patients with cocaine-associated chest pain.3 Results of this study noted that 5.7 percent of these patients sustained a myocardial infarction (95% confidence interval, 2.7 to 8.7).3 A review of this topic concluded that these patients should indeed be evaluated for possible myocardial damage.4
A threefold increase from 2 percent risk of ACS (one in 50 patients) as suggested by Dr. Achar and colleagues to what we believe is a more accurate incidence of nearly 6 percent (one in 18) is not inconsequential and may change physicians’ thoughts as to whether cocaine-associated ACS is truly a low-risk condition.
in reply: Drs. Joslin and Dachs note an important difference in the incidence of acute coronary syndrome (ACS) in patients who have chest pain following cocaine use. In the study they cite by Hollander and colleagues “fourteen of 246 patients (5.7 percent; 95% confidence interval [CI], 2.7 to 8.7) had myocardial infarction, as diagnosed by elevated CK-MB [MB isoenzyme of creatine kinase] isoenzyme levels.”1 Two of the patients, mean age of 33, actually died. Although a relatively high proportion of patients who had myocardial infarction were cigarette smokers (83.3 percent), these results are statistically and clinically significant and should remind physicians to look carefully for signs of ACS in patients who admit to cocaine use and complain of chest pain.
Drs. Joslin and Dachs also reference a study2 by Feldman and colleagues that did not specifically look at cocaine-associated symptoms. Rather, the study was a substudy of all patients who presented to the emergency department with chest pain. Another difference was the inclusion of ‘cocaine-related complaints.” Of these 293 patients, six had a diagnosis of ACS, two had acute myocardial infarctions, and none died. Although admission rates of patients with chest pain with or without cocaine exposure were approximately the same, patients with cocaine-induced chest pain or related symptoms were much less likely to have had confirmed unstable angina (1.4 versus 9.3 percent,P <.001) or acute myocardial infarction (0.7 versus 8.6 percent, P <.001).2
Although these two studies1,2 differ on the degree of risk that cocaine-induced chest pain confers for ACS, decisions about hospitalization and treatment should be made based on the same risk factor analysis, examination, electrocardiogram criteria, cardiac markers, and advanced testing that is included in our article.3