What are the acute cardiovascular effects of cannabis?

Cannabis produces significant acute cardiovascular effects, primarily mediated by THC. Tachycardia: THC causes dose-dependent heart rate increases of 20–100% above baseline, peaking at 10–30 minutes and lasting 2–3 hours. Mechanism: sympathetic activation and vagal inhibition via CB1 receptors. Blood pressure: biphasic response — initial increase followed by orthostatic hypotension (particularly with standing). Cardiac output increases acutely. Clinical risks: In healthy young adults, these effects are generally well-tolerated. In patients with coronary artery disease, the increased cardiac workload (heart rate × blood pressure) can precipitate angina or myocardial infarction. A 2001 study (Mittleman et al.) found cannabis use increased MI risk 4.8-fold in the hour after use. Arrhythmias: case reports of atrial fibrillation, ventricular tachycardia, and Takotsubo cardiomyopathy associated with acute cannabis use. Risk is substantially higher in older adults and those with pre-existing cardiac disease.