TUESDAY, Dec. 13 (HealthDay News) -- Chewing the green leaves of the khat plant for its amphetamine-like effect appears to raise the risk for both stroke and death among heart patients, according to a large new study from the Middle East.

The finding, however, could have relevance far beyond that region, as emigration has increasingly brought khat-chewing to the shores of both Europe and North America.

Consumed by an estimated 10 to 20 million people worldwide, for centuries the naturally grown Catha edulis shrub has been widely available (and most popular) across East Africa and the southern Arabian Peninsula, where some people munch on khat in pursuit of a euphoric or aroused state of mind.

"We need to be careful about the risk of using 'herbs' and 'natural substances,' and khat is an example, although it is leaves, which appear 'harmless'," said study co-author Dr. Jassim Al Suwaidi, senior consultant cardiologist at Hamad General Hospital in Doha, Qatar.

"It has chemical constituents that are similar to harmful drugs," Suwaidi noted, "such as cocaine and amphetamine, and may cause heart attack as well as increase the risk of death and stroke from heart attack."

Suwaidi and his colleagues report their findings in the Dec. 12 issue of Circulation.

The principal active ingredients in khat are cathine and cathinone. According to the U.S. National Institute on Drug Abuse (NIDA), these chemicals are similar in structure to amphetamine and have similar (although weaker) stimulant effects.

The NIDA notes that the euphoria, elation, alertness and arousal from chewing khat typically last anywhere from 1.5 to three hours, but can endure for a full day. Blood pressure and heart rates may rise during that time, followed by the short-term onset of depression, irritability and sleep problems.

Long-term chewing of khat can lead to tooth decay and gastrointestinal problems, in addition to cardiovascular issues such as coronary artery spasm.

Because cathinone is a Schedule I narcotic under U.S. federal law, khat is illegal and as with drugs such as heroin or mescaline, cannot be used for medical or other purposes.

Although banned in Germany, France and the Netherlands, khat is currently legal in the United Kingdom.

Khat is legal and in widespread use throughout Yemen and Ethiopia, and is currently permitted for sale in Israel.

To explore how khat might boost health risks among individuals with a history of heart disease, between 2008 and 2009 the authors focused on roughly 7,400 men and women who were part of the 2nd Gulf Registry of Acute Coronary Events (Gulf RACE-2) Study.

All were being treated for acute coronary syndrome in one of 65 hospitals across Saudi Arabia, Bahrain, Yemen, Qatar, United Arab Emirates and Oman.

Of these participants, about 20 percent were deemed to be regular khat chewers, almost all (96 percent) from Yemen. They more likely to be older and male (14 percent were women), but less likely to have heart health risk factors than non-Khat chewers.

While still being treated in hospital, khat heart patients had about double the death rate due to cardiovascular illness compared to non-khat heart patients (7.5 percent death rate vs. 3.8 percent).

One month out, the risk spread was even greater: a 15.5 percent death rate among khat users vs. 6.4 percent among non-users. And at one year, the death rate was nearly 19 percent among khat users, compared with just under 11 percent among non-users.

Overall, Suwaidi and associates determined that independent of other contributing factors, khat-using heart patients were more likely to experience arrhythmia, heart failure, heart attack or a stroke than non-khat-using heart patients, in addition to facing a higher risk for death, regardless of gender.

"The ease and rapidity of travel [make khat] available in distant places," Suwaidi said. "And hence it is important to be aware of these practices," he noted, adding that prior research suggests that the elevated risk attributed to khat use among heart patients is very likely to also apply to otherwise healthy patients.

Dr. Kirk Garratt, clinical director of interventional cardiovascular research at Lenox Hill Hospital in New York City, commented on the study.

"We know very well that when you have cardiovascular disease any exposure to any meaningful stimulant would be expected to increase heart risk, by changing the vascular dynamic of the blood vessels that control the blood flow through the brain and heart," he said. "We also know that these drugs can facilitate or trigger irregular heart rhythms, which can be very problematic.

"Cocaine, for example, can have a negative impact on people both with and without heart disease," Garratt added. "And those with heart disease face an especially elevated risk. So these findings are not really surprising."

More information

Visit the U.S. National Institute of Drug abuse for more on khat.