The prevalence of cocaine use in patients presenting with chest pain

Introduction: Cocaine is the second most commonly used recreational drug in the UK, with 2.3% of those aged 16 to 59 years reporting use in the past year (1). Higher rates of use are seen in urban areas and in those who regularly go to nightclubs. The use of cocaine is associated with a 24-fold increase in the risk of myocardial infarction in the first hour after use (2). The mainstay of management in these patients is benzodiazepines and vasodilators such as nitrates (GTN). Beta-blockers are contra-indicated due to the risk of exacerbating coronary spasm. Studies in the US involving analysis of urine samples have detected cocaine metabolites in up to 25% of all patients with acute coronary syndrome (ACS) (3). Self-reporting of cocaine use in UK patients with chest pain is much lower at 1.9% (4) but clinicians do not routinely ask about cocaine use and so it is not clear how accurate this is (5). No previous studies have looked at the detection of parent cocaine in a cohort of patients presenting to the ED with ACS. In this study we looked at the prevalence of cocaine use as evidenced by the presence of parent cocaine in blood samples of patients presenting with suspected ACS to an urban Emergency Department (ED).

Methods: Patients over 18 years, presenting to the ED of one inner city London hospital from 1-30 September 2014 who had a blood test for troponin T taken, were prospectively identified by the hospital computerised blood result system. Blood samples for these patients were analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the presence of cocaine and its metabolites. Basic demographic data, information on clinical presentation and troponin/creatinine blood results were obtained from the medical records. The study was approved by the National Research Ethics Committee.

Results: A total of 384 patients met the inclusion criteria - 257 males (66.9%) and 127 females with a mean±SD (range) age of 59.2±17.1 (19-98) years. Of these, 6 (1.6%) patients, all male, with a mean age 39.7±11.1 years (p<0.001) had detectable cocaine and/or its metabolites (5 had parent cocaine). In this group, the median (IQR) troponin concentration was 7 (7-25) ng/L (normal range 0-13) and creatinine 80 (73.5-110.5) μmol/L. 3 (50%) volunteered a history of cocaine use prior to the onset of symptoms, In 2 (33.3%) patients there was no documentation regarding whether a history of cocaine use had been taken and in 1 (16.7%) there was no history of recent cocaine use. 4 of those with detectable cocaine were admitted to hospital, 2 were diagnosed with ACS and commenced on ACS treatment. 2 patients who had declared cocaine use also received diazepam and 3 were given GTN as part of their treatment; none received beta-blockers.

Discussion: This study shows that there is a small minority of patients presenting with suspected ACS with evidence of cocaine use prior to the onset of their symptoms. However, only half of those in whom cocaine was detected volunteered this information. Patients with positive samples were younger in keeping with past studies (3, 4). However, there were fewer patients with recent cocaine use detected in this study than in previous studies which looked for cocaine metabolites in urine. Our study is of greater clinical relevance as it is parent cocaine that is most responsible for the coronary vasoconstriction seen with cocaine. Clinicians treating patients presenting with suspected ACS should include a history of cocaine use as part of the medical history.

References:

1. Drug Misuse: Findings from the 2014/15 Crime Survey for England and Wales, https://www.gov.uk

2. Mittleman MA et al. (1999). Circulation 99: 2737-41

3. Hollander JE et al. (1995). Ann Emerg Med 26: 671-6

4. Bishop CR et al. (2010). Eur J Emerg Med 17: 164-6

5. Wood DW et al. (2007). Postgrad Med J 83: 325-8