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Three Part Question

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

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 300mg. 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.

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 8 were relevant to the 3 part question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Kossowsky WA et al, 1989, USA	19 patients presenting with chest pain shortly after intranasal, iv or smoking of cocaine	Prospective cohort study	Coronary angiogram	5 patients: 4 normal coronary arteries 1 proximal stenosis of right coronary artery	Small study Hospitalised patients only
			Incidence of AMI	17 (89%) which demonstrate non-Q wave infarction 2 with Q wave infarction
Amin M et al, 1990, USA	70 patients with cocaine associated chest pain	Retrospective cohort study	Specificity of ECG	60%	Small study Hospitalised patients only
			Incidence of AMI	22/70 (31%)
			Sensitivity of ECG	91%
Zimmerman JL et al, 1991, USA	48 admitted patients with cocaine associated chest pain	Retrospective case note review	Incidence of AMI	3/48 (6%)	Wide distribution of time between use and presentation Not ED patients
			Number of patients with ECG criteria for thrombolysis	18/48 (37%)
Gitter MJ et al, 1991, USA	101 admitted patients with cocaine associated chest pain	Prospective cohort study	Incidence of AMI	No patients had AMI confirmed	Poor gold standard used. CK rises or CKMB fractions
			Number of patients with ECG criteria for thrombolysis	8 (8%)
Hollander JE et al, 1994, USA	246 patients presenting with cocaine associated chest pain in 6 US centres	Prospective cohort study	PPV of ECG for AMI	96%	Gold standard was a 2 fold rise in CKMB Not consecutive enrolment of patients
			Specificity of ECG for AMI	90%
			PPV of ECG for AMI	18%
			Sensitivity of ECG for AMI	36%
			Incidence of AMI	14/246 (6%)
Mittleman MA et al, 1999, USA	Interviewed 3946 patients with AMI (an average of 4 days after infarction onset)	Case cross-over study	38 (1%) reported cocaine use in the prior year. 9 reported cocaine use within the 60 minutes preceding the onset of infarction	The users of cocaine sustained a transient 24-fold increase in risk of MI in the hour immediately after cocaine use and that the elevated risk rapidly decreased thereafter	Data based on patient self-report Small number of exposed cases The absolute risk of MI onset cannot be directly estimated from the data
Weber JE et al, 2000, USA	250 patients presenting with cocaine associated chest pain in 29 US centres AMI diagnosed on WHO criteria	Prospective cohort study	Number without ECG changes who had confirmed infarction	2/67 had confirmed AMI	Wide distribution of time between use and presentation (up to 7 days) 6% had no urinary metabolites Gold standard was a 2 fold rise in CKMB Most (91%) patients used crack cocaine
			Number with ECG changes compatible with infarction	9/250 of which all had confirmed AMI
			Incidence of AMI	15/250 (6%)
			Number with ECG changes compatible with ischaemia	39/250 of which 4 had confirmed AMI
Feldman JA et al, 2000, USA	293 patients with cocaine associated chest pain. Sub study of the Aci-TIPI trial	Prospective cohort study	Incidence of AMI	(0.7%) CI 0.08-2.4% with cocaine	Sub study of another trial. WHO criteria for AMI Wide variation of AMI incidence between hospitals
			Incidence of ACS	1.4% CI 0.37-3.5%

Comment(s)

The incidence of AMI in cocaine associated chest pain is small but significant. The ECG appears to have a higher false positive rate in these patients. A normal ECG reduces but does not exclude myocardial damage. Most AMI 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 following cocaine use would normally be expected. It must be remembered that some of the reported incidence will be co-incidental. Those patients presenting with normal findings, and a normal ECG have a low but not absent AMI 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.

References

1. Kossowsky WA, Lyon AF, Chou SY. Acute non-wave cocaine-related myocardial infarction. Chest 1989;96(3):617-21.
2. Amin M, Gabelman G, Karpel J, et al. Acute myocardial infarction and chest pain syndromes after cocaine use. Am J Cardiol 1990;66(20):1434-7.
3. Zimmerman JL, Dellinger RP, Majid PA. Cocaine-associated chest pain. Ann Emerg Med 1991;20(6):611-5.
4. Gitter MJ, Goldsmith SR, Dunbar DN, et al. Cocaine and chest pain: clinical features and outcome of patients hospitalized to rule out myocardial infarction. Ann Intern Med 1991;115(4):277-82.
5. Hollander JE, Hoffman RS, Gennis P, et al. Prospective multicenter evaluation of cocaine-associated chest pain. Cocaine Associated Chest Pain (COCHPA) Study Group. Acad Emerg Med 1994;1(4):330-9.
6. Mittleman MA, Mintzer D, Maclure M et al. Triggering of myocardial infarction by cocaine. Circulation 2000;99(21):2737-41.
7. Weber JE, Chudnofsky CR, Boczar M, et al. Cocaine-associated chest pain: how common is myocardial infarction? Acad Emerg Med 2000;7(8):873-7.
8. Feldman JA, Fish SS, Beshansky JR, et al. Acute cardiac ischemia in patients with cocaine-associated complaints: results of a multicenter trial. Ann Emerg Med 2000;36(5):469-76.