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Cannabis and Myocardial Infarction
It has been
noted that there is a five-fold increase risk of Myocardial Infarctions (MI) in
the first hour after cannabis use. Traditional risk factors for MI include
diabetes, hypertension and dyslipidemia. The rising use of cannabis may have
ushered in an additional MI risk factor to be added to the list; that is
cannabis. In this review, we discuss the growing use of cannabis and potential
link with MI, highlighting the common pathogenic hypotheses linking these risk
factors. While Metabolic and Inflammatory effects accrue over time with
cannabis use, cardiovascular effects from cannabis use can precipitate to a MI
much more acutely. Myocardial effects result from alterations in coronary blood
flow and heart rate promoting myocardial ischemia and potential infarction.
Several studies have reported that acute THC use may be involved in reducing
coronary blood flow.
Additionally,
intravascular ultrasoundson patients experiencing THC associated
myocardialinfarction usually findno evidence of atherosclerotic CAD. Coronary angiography usually confirms
coronary vasospasm and platelet thrombus formation without underlying atherosclerosis.
Moreover, myocardial oxygen supply is further restricted by an increased concentration
of carboxyhemoglobin leading to a reduction in oxygen carrying capacity of red
blood cells. Further exacerbating the myocardial oxygen supply are elevations in
both heart rate and blood pressure, resulting in reductionof diastolic coronary
filling and elevated diastolic coronary pressures.
Therefore,
the reduction in coronary blood flow in combination with reduced oxygen
carrying capacity and potential systemic and coronary vasoconstriction lead to
an increase in myocardial oxygen supply-demand mismatch, resulting in ischemia.
Patients suffering from preexisting cardiac conditions such as stable angina
are especially prone to develop symptoms. Decreased exercise time to angina was
reported in volunteers who use THC. Other studies have proposed that the
hemodynamicmresponse caused by THC interrupts perfusion in susceptible atherosclerotic
plaques. The role of beta blockers in reducing the myocardial oxygen
supply-demand mismatch in cannabis users warrants further investigation.
The above Article originally got
published at SciFed Journal of Cardiology in 2017, to have a glance please
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