Abstract & Commentary
Source: Weber JE, et al. Validation of a brief observation period for patients with cocaine-associated chest pain. N Engl J Med 2003;348:510.
Cocaine use can cause both acute and chronic cardiovascular disease and complications, including acute coronary syndromes such as acute myocardial infarction (AMI) and unstable angina. In fact, nearly one-quarter of all AMIs in patients age 18-45 years are associated with cocaine use. In 2000, cocaine-related complaints accounted for 175,000 emergency department (ED) visits in the United States, 40% of which involved the complaint of chest discomfort. Yet prior studies indicate that patients who present to the ED with cocaine-associated chest pain generally are at low risk for AMI.1
In this prospective study, investigators evaluated the safety of a nine- to 12-hour observation period for patients with cocaine-associated chest pain who were at low-to-intermediate risk of cardiovascular events. During a two-year period, 344 ED patients with the chief complaint of chest discomfort were evaluated; each had either a history of cocaine use within the week prior to presenting or positive cocaine metabolites on urine screening. Of these, 42 high-risk patients immediately were admitted to the hospital because of ischemic electrocardiogram (ECG) changes, positive initial cardiac markers, recurrent ischemic chest pain, or hemodyamic instability.
The remaining 302 patients were admitted to a chest pain center for a nine- to 12-hour observation period. Patients with no ischemic changes on continuous ST-segment monitoring and normal troponin-I levels at 0, 3, 6, and 9 hours underwent a functional test (either exercise or pharmacologic stress test) at the discretion of a cardiology consultant prior to discharge.
The primary outcome was death from cardiovascular disease within 30 days. Follow-up was obtained by contacting the patient, relative, friend, or primary physician (300 patients), accessing the National Death Index (two patients), and review of medical records at one year. No cardiovascular deaths occurred within 30 days (there was one death due to trauma and one due to heroin overdose). Four patients (1.6% of 256 patients with detailed follow-up information) did suffer a nonfatal AMI within 30 days.
In all four cases, patients had continued to use cocaine and all had two or more cardiac risk factors. Based on their findings, the investigators believe a nine- to 12-hour observation period for patients with cocaine-associated chest discomfort and low-to-intermediate risk for cardiovascular disease is safe in terms of short-term risk for acute coronary syndromes and death.
Commentary by Theodore C. Chan, MD, FACEP
The chronic effects of cocaine include accelerated atherosclerosis, cardiomyopathy, and myocarditis. Acutely, cocaine use can increase myocardial oxygen demand by increasing heart rate and blood pressure, as well as decrease myocardial oxygen delivery by causing coronary vasospasm. Despite these effects, the incidence of AMI in ED patients presenting with cocaine-associated chest discomfort has been reported to be approximately 6%.2 Determining which patients are at risk and which patients can be safely discharged home is paramount in terms of patient care, medicolegal risk, and efficient use of resources. This study prospectively validated the utility and safety of a nine- to 12-hour observation period for patients who have low risk for significant cardiovascular disease.
A number of points should be kept in mind regarding this study. First, the observation period took place in a dedicated chest pain observation unit in which patients had continuous ECG monitoring, as well as troponin-I levels drawn every three hours. Such care, including prolonged monitoring capabilities, may not be feasible in all EDs. Second, all patients had a cardiology consultation; more than half (158) underwent stress testing, and of those, four underwent subsequent cardiac catheterization prior to discharge. The course of these patients more likely reflects that of a routine chest pain hospitalization as opposed to an observation period. Finally, the importance of substance abuse education and possible referral for these patients cannot be under-emphasized. As the investigators point out, all four cases of nonfatal AMIs occurred in patients who continued to use cocaine. Moreover, one death occurred as a result of an illicit (albeit not cocaine) drug overdose.
Dr. Chan, Associate Clinical Professor of Medicine, Emergency Medicine, University of California, San Diego, is on the Editorial Board of Emergency Medicine Alert.
References
1. Kushman SO, et al. Cocaine-associated chest pain in a chest pain center. Am J Cardiol 2000;85:394.
2. Hollander EJ, et al. Prospective multicenter evaluation of cocaine-associated chest pain. Acad Emerg Med 1994;1:330.
In this prospective study, investigators evaluated the safety of a nine- to 12-hour observation period for patients with cocaine-associated chest pain who were at low-to-intermediate risk of cardiovascular events.
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