Conference News Roundup—American College of Cardiology

Marijuana Increases Risks of Stroke and Heart Failure

Using marijuana increases the risk of stroke and heart failure, even after accounting for demographic factors, other health conditions, and lifestyle risk factors such as smoking and alcohol use, researchers reported. Coming at a time when marijuana, medically known as cannabis, soon may become legal for medical or recreational use in more than half of US states, this study sheds new light on how the drug affects cardiovascular health. While previous marijuana research has focused mostly on pulmonary and psychiatric complications, the new study is one of only a handful to investigate cardiovascular outcomes.

“Like all other drugs, whether they are prescribed or not prescribed, we want to know the effects and side effects of this drug,” said Aditi Kalla, MD, Cardiology Fellow at the Einstein Medical Center in Philadelphia and the study’s lead author. “It is important for physicians to know these effects so we can better educate patients, such as those who are inquiring about the safety of cannabis or even asking for a prescription for cannabis.”

The study drew data from the Nationwide Inpatient Sample, which includes the health records of patients admitted at more than 1,000 hospitals comprising about 20% of US medical centers. Researchers extracted records from young and middle-aged patients—ages 18 to 55—who were discharged from hospitals in 2009 and 2010, when marijuana use was illegal in most states.

Marijuana use was diagnosed in about 1.5% (316,000) of more than 20 million health records included in the analysis. Comparing cardiovascular disease rates in these patients to disease rates in patients not reporting marijuana use, researchers found that marijuana use was associated with a significantly increased risk for stroke, heart failure, coronary artery disease, and sudden cardiac death.

Marijuana use was also linked with various factors known to increase cardiovascular risk, such as obesity, high blood pressure, smoking, and alcohol use. After researchers adjusted the analysis to account for these factors, marijuana use was independently associated with a 26% increase in the risk of stroke and a 10% increase in the risk of developing heart failure.

“Even when we corrected for known risk factors, we still found a higher rate of both stroke and heart failure in these patients, so that leads us to believe that there is something else going on besides just obesity or diet-related cardiovascular side effects,” said Dr. Kalla. “More research will be needed to understand the pathophysiology behind this effect.”

Research in cell cultures shows that heart muscle cells have cannabis receptors relevant to contractility, thus suggesting that those receptors might be one mechanism through which marijuana use could affect the cardiovascular system. It is possible that other compounds could be developed to counteract that mechanism and reduce cardiovascular risk, said Dr. Kalla.

Because the study was based on hospital discharge records, the findings may not reflect the general population. The study was also limited by the researchers’ inability to account for quantity or frequency of marijuana use, purpose of use (ie, recreational or medical), or delivery mechanism (eg, smoking or ingestion).

The growing trend toward legalization of marijuana could mean that patients and doctors will become more comfortable speaking openly about marijuana use, which could allow for better data collection and further insights into the drug’s effects and side effects, said Dr. Kalla.

Study Examines Best Time to Screen for Sleep Apnea After Heart Attack

Conducting a diagnostic sleep test shortly after a heart attack can help doctors rule out sleep apnea in patients, but tests conducted in the immediate aftermath of a heart attack are somewhat unreliable for positively diagnosing sleep apnea, according to results from a single-center study. As a result, it may be best to repeat the test after a few months or to delay initial testing before making a definitive diagnosis and initiating treatment.

“In view of the strong association between sleep disordered breathing and heart attack and the established negative prognostic implications of untreated sleep apnea in these patients, cardiologists are becoming increasingly aware of the importance of screening for sleep disorders in their daily practice,” said Jeanette Ting, MBChB, senior resident at National University Heart Centre in Singapore, the study’s lead author. “Our aim was to determine if the screening should be performed during the acute phase soon after a heart attack or after a period of stabilization.”

Sleep apnea is thought to contribute to cardiovascular disease by increasing stress on the heart and blood vessels, causing inflammation, reducing available oxygen, and affecting hormones. Doctors can use questionnaires to identify patients who might have sleep apnea, but the only definitive test is an overnight sleep study, in which a specialist uses electrodes and sensors to monitor how often the patient stops breathing during sleep and the length of each pause.

For the study, researchers performed an overnight sleep test in 397 patients treated for heart attack at Singapore’s National University Heart Center. This initial test was conducted within five days of hospital admission. A subgroup of 102 patients underwent a second sleep test at home six months later.

In all, 52% of patients tested positive for sleep apnea in the initial test. Forty-two percent had obstructive sleep apnea, the most common form of the disorder. In addition, 10% had central sleep apnea.

About one-quarter of the patients underwent a second sleep study after six months. A majority of the patients initially found to have sleep apnea showed a change of status in the follow-up sleep study. Among those initially diagnosed with obstructive sleep apnea, 46% no longer had sleep apnea at the six-month test. Among those initially diagnosed with central sleep apnea, 83% were found to have obstructive sleep apnea at the six-month test. The vast majority (93%) of those initially found to have no sleep apnea remained apnea-free at six months.

Overall, patients with sleep apnea were older, had a higher BMI, and more often had high blood pressure, compared with those without sleep apnea. Patients showed no significant change in BMI between the first and second sleep tests.