Can marijuana use affect heart rhythm?

Marijuana's Effects on Heart Rhythm

Marijuana use can significantly affect heart rhythm, causing various arrhythmias including tachycardia, atrial fibrillation, ventricular tachycardia, and bradycardia, with potentially serious cardiovascular consequences. 1, 2

Cardiovascular Effects of Marijuana

• Acute marijuana use causes immediate cardiovascular effects including increased heart rate, elevated blood pressure, and increased myocardial oxygen demand through sympathetic nervous system stimulation 1, 3
• Cannabis smoking has been associated with tachycardia during acute use, with heart rate increases of up to 20 minutes after consumption in healthy individuals 4
• After initial tachycardia, heart rate may decline below baseline levels within 4 hours following use, with this effect being blunted in individuals with ischemic heart disease 4
• Marijuana can cause orthostatic hypotension with chronic use, potentially leading to syncope 1

Specific Arrhythmias Associated with Marijuana Use

• The most common arrhythmias associated with marijuana use include:
  • Supraventricular tachycardia (SVT) - more common in healthy individuals 4
  • Nonsustained ventricular tachycardia (NSVT) - significantly more prevalent in those with ischemic heart disease 4
  • Atrial fibrillation and atrial flutter 2
  • Atrioventricular block, including complete heart block 2, 5
  • Ventricular fibrillation - reported in 21% of case reports 2
  • Bradycardia and asystole in some cases 2, 5

Mechanisms of Marijuana-Induced Arrhythmias

• Marijuana affects heart rhythm through multiple mechanisms:
  • Blocks reuptake of catecholamines at presynaptic terminals, causing sympathetic stimulation 6
  • Increases heart rate and blood pressure in a dose-dependent fashion 6
  • Causes coronary vasoconstriction, which may be more pronounced in patients with preexisting coronary artery disease 6
  • Increases levels of endothelin-1 (a vasoconstrictor) and decreases nitric oxide (a vasodilator) 6
  • Promotes a prothrombotic state through increased platelet activation and aggregation 6

Risk Factors and High-Risk Populations

• Individuals with preexisting ischemic heart disease are at particularly high risk for marijuana-induced arrhythmias 4
• Older adults who use cannabis have increased risk for cannabis-related emergency department visits with potential for sedation, obtundation, and myocardial ischemia or infarction 1
• Combined use of marijuana with tobacco smoking results in greater increases in heart rate and vasoconstriction than either substance alone 6
• Higher potency cannabis products (THC concentration increased from 9% in 2008 to 17% in 2017, with concentrates reaching up to 70% THC) may intensify cardiovascular risks 1

Clinical Implications

• Marijuana use increases the risk of myocardial infarction onset by 4.8 times within the 60 minutes after consumption 3
• Annual risk of myocardial infarction in daily cannabis users may increase from 1.5% to 3% 3
• Cannabis-induced arrhythmias can be life-threatening, with case reports documenting cardiac arrest and death 2
• Electrocardiographic changes associated with marijuana use include ST segment elevation, Brugada pattern in leads V1 and V2, and right bundle branch block 2

Recommendations

• Healthcare providers should inquire about acute and chronic cannabis use in patients presenting with tachycardia, bradycardia, dysrhythmia, chest pain, or unexplained syncope 2
• Patients with a history of coronary artery disease or arrhythmias should be strongly advised against recreational marijuana use 3
• Patients who use marijuana should be educated about its potential cardiovascular effects, especially those with underlying cardiac disease or risk factors 2
• Monitoring for arrhythmias may be warranted in regular marijuana users with cardiovascular risk factors 1, 4