Cannabis as a precipitant of cardiovascular emergencies.

Cannabis smoking is on the increase both in the United Kingdom and in the United States. For over three decades it has been known that cannabis has pathophysiological effects on the cardiovascular system, and previously an association with an increased risk of myocardial infarction has been reported. However, it is not yet known whether cannabis contributes directly to coronary artery disease. We describe two distinct cases; in the first cannabis use precipitated a malignant arrhythmia in a patient with critical ischaemia from longstanding coronary artery disease. In the second, a young patient presented with an acute myocardial infarction that had started whilst smoking marijuana; subsequently diffuse coronary artery disease was found at angiography despite the patient's low risk factor status. Patients who are known cannabis smokers and who have cardiovascular disease should be warned that it is likely to aggravate coronary ischaemia, and may even trigger myocardial infarction.