Marijuana may be harmful to heart patients, but improves some risk factors, studies show


According to two new studies recently presented in scientific sessions of the American Heart Association, there is more evidence that smoking marijuana can be dangerous for people with heart disease. But in an unexpected twist, people using cannabis were less likely to experience sudden kidney failure, the researchers found.

Patients who smoked marijuana and underwent angioplasty to clean blocked arteries were more likely to experience stroke and bleeding after the abortive procedure than those who did not use the pot, a study found . The second study concluded that patients who survived a heart attack and used marijuana were more likely than those who did not use cannabis to have a subsequent heart attack. Both studies were released Monday.

“Marijuana is becoming more accessible, and patients should be aware of the subsequent increased risk [angioplasty], “Said the study’s lead author, Dr. Internal Medicine resident at the University of Michigan. Song Yu “While these risks should be known, they should not prevent patients from achieving this life process.”

In fact, four more states legalized recreational marijuana during the 2020 election, bringing a total of 15 to the District of Columbia. In addition, 34 states, plus DC, have made medical marijuana legal.

The new findings are another example of why we need more studies into the effects of cannabis on the heart and the rest of the body, Yu said, noting that its classification as a Schedule 1 drug by the federal government has led to scientific Has hindered research. .

The research is particularly relevant to older Americans. Heart disease is the No. 1 killer in the US and the Centers for Disease Control and Prevention estimates that approximately 805,000 Americans suffer heart attacks each year. The majority, or 605,000, are heart attacks for the first time. According to the American Heart Association, coronary angioplasty occurs in hundreds of patients in the US each year – a procedure for blocked arteries that improves blood flow to the heart. Many of those patients also receive stents, a small, wire mesh tube that helps keep the artery open.

To take a closer look at the effects of marijuana on the results of angioplasty, UO and his colleagues examined data from 113,477 Michigan patients, of whom 3,970 identified themselves as marijuana users. After matching 3,903 users with 3,903 nonusers, researchers found that more pot smokers experienced bleeding (5.2 percent vs. 3.4 percent) and stroke (0.3 percent vs. 0.1 percent).

A deeper finding that the authors could not explain was that marijuana users were less likely to experience sudden kidney failure.

Is it THC or Smoke?

In another study, which analyzed information from a national database, the researchers found that patients who had an arterial-clearing procedure after a heart attack had higher rates of heart failure later than those who used marijuana. The rate of seizures was higher for those who do not use cannabis, or 7.2 percent vs. 4.5 percent. The study also had an intriguing finding: the risk factors for heart attack — including high blood pressure, diabetes, and high cholesterol — were significantly lower in cannabis users.

Experts contacted by NBC News had mixed reactions to the new reports.

“I have studied the effects of marijuana and THC over the last 25 years [the psychoactive component in cannabis], And I think the Yo study raises some important questions, especially since we have seen more and more reports of cardiac events occurring in the context of marijuana, “said Dr. Deepak Cyril D’Souza, a psychology professor at Yale University . Medicine School. “This is an interesting paper.”

One question cannot answer whether the increased risks come from marijuana, from THC in marijuana or from the smoke that comes from burning a plant-based product, D’Souza said.

“In our study on THC, we found a significant increase in heart rate and a significant effect on blood pressure, which can be quite profound,” said D’Souza. “Our study generally included people who were healthy and young. Getting out of someone who is older and has heart problems or other medical problems can be problematic if they use marijuana. “

Looking at the totality of the two studies, they incorporate some contradictory findings, with a cannabis expert Dr. Said Peter Grinspoon, Harvard Medical School instructor and member of the board of doctors for cannabis regulation. On one hand, Grinspoon said, researchers are reporting an increase in stroke, bleeding and other heart attacks among those using cannabis, but on the other hand, they have improved cardiovascular risk factors such as high blood pressure, high cholesterol and diabetes Are reporting.

In the study, Grinspoon was particularly struck by the low rate of kidney failure among those using marijuana.

“By their measures, they have actually shown that cannabis reduces kidney damage, which in itself should be a big limitation,” he said.

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