How Should a Patient with Cocaine-Associated Chest Pain be Treated?

^{click for large version}

Cocaine is the second-most-commonly used illicit drug in the U.S. and represents 31% of all ED visits related to substance abuse.

Case

A 38-year-old man with a history of tobacco use presents to the emergency department complaining of constant substernal chest pain for three hours. His temperature is 37.7°C, his heart rate is 110 beats per minute, and his blood pressure is 155/95 mmHg. He appears anxious and diaphoretic but examination is otherwise unremarkable. He admits to cocaine use one hour before the onset of symptoms. What are the appropriate treatments for his condition?

Overview

Cocaine is the second-most-commonly used illicit drug in the U.S. and represents 31% of all ED visits related to substance abuse.^1,2 According to recent survey results, 2.1 million people report recent cocaine use, and 1.6 million engage in cocaine abuse or dependence.² Acute cardiopulmonary complaints are common in individuals who present to the ED after cocaine use, with chest pain being the most frequently reported symptom in 40%.³

Numerous etiologies for cocaine-associated chest pain (CACP) have been discovered, including musculoskeletal pain, pulmonary hypertension, cardiomyopathy, arrhythmias, and endocarditis.⁴ Only 0.5% of patients with aortic dissection over a four-year period had a recent history of cocaine use, making cocaine a rare cause of a rare condition.⁵ Cardiac chest pain remains the most frequent underlying etiology, resulting in the most common complication of myocardial infarction (MI) in up to 6% of patients.^6,7

The ways in which cocaine use can cause myocardial ischemia and MI are multifactorial. A vigorous central sympathomimetic effect, coronary artery vasoconstriction, stimulation of platelets, and enhanced atherosclerosis all lead to a myocardial oxygen supply-demand imbalance.⁸ Other key interactions in the cardiovascular system are displayed in Figure 1. Understanding the role of these mechanisms in CACP is crucial to patient care.

Clinician goals in the management of CACP are to rapidly and accurately exclude life-threatening etiologies; assess the need for urgent acute coronary syndrome (ACS) evaluation; risk-stratify patients and ensure appropriate disposition; normalize the toxic effects of cocaine; treat resultant organ damage; and prevent long-term complications. An algorithm detailing this approach is provided in Figure 2.

^{click for large version}

Figure 1. Cocaine’s pathophysiologic effects on the cardiovascular system8

^{click for large version}

Figure 2. Diagnostic and therapeutic approach to patients with cocaine-associated chest pain18

Review of the Data

Diagnostic evaluation. Given potential differences in treatment regimens, it is imperative to differentiate patients who present with CACP from those whose chest pain is not associated with cocaine either by direct questioning or by screening of urine for cocaine metabolites. Once the presence of cocaine has been confirmed, guideline-based evaluation for potential ACS with serial electrocardiograms (ECG), cardiac biomarkers, and close monitoring of cardiac rhythms and hemodynamics is largely similar to standard management of all patients presenting with chest pain, with a few caveats.

Interpretation of the ECG can be challenging in the setting of cocaine. Studies have shown “abnormal” ECGs in 56% to 84% of patients, with many representing early repolarization or left ventricular hypertrophy.^9,10 Likewise, patients with MI are as likely to present with normal or nonspecific ECG findings as with ischemic findings.^7,11 ECG interpretation to diagnose ischemia or infarction in patients with CACP yields a sensitivity of 36% and specificity of 90%.⁷