Marijuana May Muddle a Chest Pain Diagnosis, CTA Study Hints

GRAPEVINE, TX—Among patients presenting to a single institution with chest pain and undergoing coronary CTA, those who said they’ve used marijuana were less likely to ultimately have coronary artery disease than those who did not, according to new research.

To date, studies of marijuana and cardiovascular risk and outcomes have been “very limited,” said Ali M. Agha, MD (The McGovern Medical School at UT Houston, TX), who presented the findings in a poster session Friday at the Society of Cardiovascular Computed Tomography (SCCT) annual scientific meeting. Recent data have indicated that marijuana users might be at an increased risk of mortality, yet specific details about the drug’s effects on the cardiovascular system remain unclear.

“Marijuana is one of the most popular drugs of abuse in the United States,” Agha told TCTMD. “Especially with it becoming decriminalized in some states and becoming [more] popular, it's more important than ever that we understand what some of the effects of marijuana are on our health.”

For the study, Agha and colleagues looked at 1,420 men (< 50 years) and women (< 40 years) who received coronary CTA for the evaluation of chest pain at their center in 2016. About 10% of the population indicated present or former marijuana use; this cohort was younger, had a lower prevalence of diabetes and hypertension, and was more likely to smoke cigarettes.

After multivariate analysis, the researchers found a negative association between marijuana use and CAD diagnosis (P = 0.048). Not surprisingly, older age, diabetes, and tobacco use were positively associated with CAD.

Agha acknowledged that this study is not enough to confirm that marijuana is protective against heart disease. In this case, however, it’s possible that since “marijuana can activate the sympathetic nervous system and cause an increase in blood pressure, heart rate, and cause vasospasm, which may present as chest pain, . . . I think what may have happened is you have young patients presenting with unstable vital signs, high heart rate, high blood pressure, and very anxious and they thought maybe there was a heart attack,” he explained.

‘Nobody's Truly Paying Attention’

But Shereif H. Rezkalla, MD (Marshfield Clinic, Marshfield, WI), commenting on the study for TCTMD, called its conclusions “very misleading.” Because of the vast differences in baseline patient characteristics, the researchers “compared presence or absence of coronary artery disease between apples and oranges, not the same group of people,” he said. “To have a good comparison, you should get all patients who present with chest pain, with similar risk factors, of similar age, and find out if the cannabis or marijuana users have more or less coronary artery disease.”

Additionally, he pointed out that there is selection bias present in the study given that not all patients with chest pain go for coronary CTA, with some receiving stress tests instead. “Patients with no insurance will never get a CTA,” Rezkalla noted. Also, “many insurance carriers in the United States. . . still don't approve CTA. In fact, they still call it after all these years an ‘experimental procedure.’”

Agha agrees that the study has limitations, especially since marijuana use was all self-reported and some patients might not be willing to share this information. Additionally, there are many methods by which someone can use marijuana, and each one might be associated with a different cardiovascular response, he said.

Still, Rezkalla said he does agree with Agha and colleagues that “we need definitely more research in this topic before we will start telling our communities through legalization in many states: ‘Use marijuana. It is safe.’”

The optimal design of a future trial should include an all-comers population of patients who present to the emergency department with chest pain who undergo either CTA, stress testing, or invasive angiogram, to observe both “the percentage of patients who used marijuana either by smoking or by any other means and the time from marijuana consumption to the time of development of the cardiac event,” Rezkalla suggested. “Then you can do all kinds of statistical analysis at that point in time, including a multivariate analysis,” as was conducted in the present study.

But unless the US National Institutes of Health (NIH) “will sponsor such a study, it's not going to happen,” he said. “There are strong forces and good financial interest from legalizing marijuana in any state. . . . The states want it to get more money. The people want it because they feel good. And nobody's truly paying attention to the medical aspect of the whole entire issue.”

Agha also encouraged clinicians that “it's really important that however you feel about marijuana use, to acknowledge that it's very frequently used and a very popular drug. One way or another we have to accept that and we have to learn more about it.” Without NIH funding for further research, “we're going to end up spending a lot of money on maybe reducing some of the comorbidities caused by marijuana use, or by creating and identifying really expensive pharmacologic drugs. Perhaps this natural substance could benefit us in a lot of ways,” he concluded.