Evidence of substance abuse found in 10% of young myocardial infarction patients

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Ron Blankstein

Data from the YOUNG-MI registry indicate that 10% of young myocardial infarction patients (≤50 years) have cocaine and/or marijuana in their system. These findings also show that patients with substance abuse have significantly higher rates of cardiac mortlaity and all-cause mortality after myocardial infarction even though they have lower rates of traditional risk factors.

Ersilia M DeFilippis (Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, USA) and others report in the Journal of the American College of Cardiology that substance abuse—including cocaine and marijuana—is on the increase in the USA and its “potential cardiovascular consequences are not fully understood”. They add while American College of Cardiology (ACC) guidelines advise that urine toxicology screening be considered when substance abuse is suspected in myocardial infarction patients (particularly those (≤50 years), data for the true prevalence of substance abuse in young myocardial infarction patients are limited.

Furthermore, according to DeFilippis et al, cocaine is a “well-established” strong risk factor for myocardial infarction and injury but there is insufficient evidence for the effect of marijuana use on cardiovascular outcomes. They report: “The recent increase in substance abuse among young adults and the legalisation of marijuana in multiple sites has led to a significant public health debate with an urgent need to understand their health effects.”

Therefore, the authors reviewed data from the YOUNG-MI Registry to determine the incidence of substance abuse and its association with cardiovascular outcomes in young individuals with their first myocardial infarction at or below the age of 50. They write: “The outcomes of interest were cardiovascular and all-cause mortality.”

Of 2,097 patients aged ≤50 years with a type 1 myocardial infarction, 224 (10.7%) had evidence of cocaine and/or marijuana. Of these, 99 (4.7%) had evidence of cocaine and 125 (6%) had evidence of marijuana. DeFilippis et al report that patients with substance abuse tended to be younger than those without substance abuse but there was not a significant difference in race. They add: “There was a significantly higher proportion of ST-segment elevation myocardial infarction [STEMI] in the substance abuse group (64.7% vs. 80.1%; p=0.03). When compared with patients without substance abuse, patients with substance abuse significantly lower rates of prevalent diabetes and hyperlipidaemia. Notably, rates of tobacco use were significantly higher in the substance abuse group.”

When substance abuse was analysed by drug type, cocaine users had similar rates of diabetes and hypertension but significantly lower rates of hyperlipidaemia compared with those without substance abuse while marijuana users had lower rates of diabetes, hypertension, and hyperlipidaemia (compared with patients without substance abuse). DeFilippis et al comment: “The lower burden of traditional risk factors among substance users suggest that their substance abuse provided sufficient risk to overcome their otherwise lower risk profiles from their non drug-user counterparts.” They add their data support other findings that “substance abuse is an important risk factor for developing premature myocardial infarction”.

Additionally, substance abuse was associated with a significantly higher incidence of out-of-hospital cardiac arrest: 8% vs. 3.5% (p=0.003). This increased incidence was largely driven by the marijuana group as there was no significant differences in out-of-hospital cardiac arrest between cocaine users and those without substance abuse.

The authors also compared outcomes after myocardial infarction in substance abusers with those of patients without substance abuse. After adjusting for baseline risk factors, they found that patients with substance abuse had a significantly higher risk of both cardiac death and non-cardiac death after myocardial infarction.

Concluding their findings, DeFilippis et al say: “These findings reinforce current recommendations for screening for substance abuse among adults who experience a myocardial infarction at a young age, and highlight the need for implementation of therapies and counselling that could prevent future adverse events.”

Study investigator Ron Blankstein (preventive cardiologist and associate professor of Medicine and Radiology, Harvard Medical School, Boston, USA) told Cardiovascular News: “Given our findings, individuals who have experienced a myocardial infarction and are users of either cocaine or marijuana should be advised regarding the increased risk associated with these substances and the importance of cessation. Additionally, given the increased risk of these patients, careful attention is needed for identifying and treating all other modifiable risk factors.

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