Clinical scenario

A 32 year old man presents to the emergency department with central chest pain suggestive of cardiac ischaemia. He has had pain for 50 minutes after nasal cocaine. He is an occasional cocaine user who has not had chest pain previously. He is previously well. His 12 lead ECG is normal and he is now pain free. You see him in the resuscitation room and prescribe oral aspirin 300 mg. He is cardiovascularly stable. You admit him and do a 12 hour troponin T, which is normal. The next day a colleague suggests that there was no need to admit as he was well, had a normal ECG, had few risk factors, and that as cocaine causes spasm rather than clots he could have gone home. You wonder whether this is good advice.

Three part question

In [patients presenting with cocaine associated chest pain] what [is the incidence] of [acute myocardial infarction]?

Search strategy

Cochrane database and Medline 1966–12/02 using the OVID interface. [exp cocaine OR exp cocaine-related disorders OR exp crack cocaine OR cocaine.mp] AND [exp Myocardial Infarction OR myocardial infarction.mp OR exp Chest Pain OR chest pain.mp] LIMIT to human, English AND abstracts.

Search outcome

No relevant papers found on Cochrane library. Altogether 198 papers were found on Medline of which eight were relevant to the three part question (see table 6).

Comment(s)

The incidence of acute myocardial infarction in cocaine associated chest pain is small but significant. The ECG seems to have a higher false positive rate in these patients. A normal ECG reduces but does not exclude myocardial damage. Most acute myocardial infarction patients will present with ST elevation or an abnormal ECG. Many of the above papers exhibit selection bias as only admitted patients are used, this may account for some of the higher incidences recorded. They also enrol patients who have taken cocaine hours before symptomatology, this contradicts the known pharmacology of cocaine. Early presentation after cocaine use would normally be expected. It must be remembered that some of the reported incidence will be coincidental. Those patients presenting with normal findings, and a normal ECG have a low but not absent acute myocardial infarction risk. They should have myocardial damage excluded.

CLINICAL BOTTOM LINE

Acute myocardial infarction should be excluded using cardiac markers in patients presenting to the emergency department with cocaine related chest pain.