Illicit Drug Use Causes a Third of Sudden Cardiac Deaths

An Australian study found that about one-third of people 50 years or younger who succumbed to sudden cardiac death (SCD) had a positive toxicology test or a history of frequent drug use when they died.

In a study published in Heart Rhythm on June 7, researchers from St. Vincent's Hospital in Melbourne, Australia, examined data from 523 people aged 18 to 50 who experienced an out-of-hospital cardiac arrest and had accompanying toxicology test results. The researchers retrieved the data from events that occurred from April 2019 to April 2021.

After the analysis was complete, the team found that 32.5% of people who experienced cardiac arrest tested positive or reported frequent illegal drug use. Moreover, nearly 14% of these individuals used multiple drugs.

The illicit drugs included amphetamine-type substances, novel psychoactive synthetic substances, cocaine, heroin, and cannabis. However, cannabis was the most commonly used drug identified in the study.

People with SCD and illegal drug use were more likely to be male, smokers, and excessive alcohol drinkers. In addition, individuals who experienced SCD were more apt to have a mental health diagnosis, lower body mass index (BMI), and lower rates of high blood pressure.

Moreover, cardiac fatalities mainly occurred during sleep or while the person was inactive.

According to the study authors, stimulant drugs, such as methamphetamines and cocaine, are known to impact the cardiovascular system. But non-stimulant drugs such as marijuana and heroin may also harm the heart. For example, the researchers point out that reports suggest cannabis can increase the risk of myocardial infarction, cardiac arrhythmias, cardiomyopathy, and SCD.

In addition to the study's primary findings, the authors say that the results also revealed more about the prevalence of illicit drug use.

"Our study's major finding that the prevalence of illicit drug use in young patients with SCD was 50% greater than previous estimates of societal intake. It may reflect the true underreported prevalence of illicit drug use in Australian society, the role of illicit drugs in contributing to SCD, or it may reflect both these hypotheses," the authors wrote.

Still, according to an accompanying editorial, the study period overlapped with the pandemic, and that may have played a role in the frequency of positive toxicology tests identified. Though some people may have had difficulty accessing illegal drugs during the pandemic, those who already had access may have used more to combat social isolation due to lockdowns.