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Patients taking prescription medications for heart disease should tell their doctors about any alternative medicines they might be popping because certain combinations could be dangerous, cardiologists say.

"You have to be careful and you have to talk to your doctor and your pharmacist about all complementary or alternative therapies, including vitamins," said Dr. Beth Abramson, a heart specialist at St. Michael's Hospital in Toronto. "Anything we ingest can potentially interact with heart pills.

"It's not as benign as patients might think."

For instance, Hawthorne berries — believed to lower blood pressure — can be dangerous to patients taking heart drugs, said Abramson. St. John's wort, a plant-based remedy used to alleviate depression, can interfere with prescribed drugs like digoxin and the blood-thinner warfarin.

Even vitamin E can throw off carefully calculated levels of warfarin (sold under the brand name Coumadin), a common drug used to help prevent the formation of harmful blood clots. Because of vitamin E's anticoagulant properties, the combination could thin blood too much, leading to hemmorhage in the brain or elsewhere. The herbs gingko biloba and ginseng have a similar blood-thinning effect.

"When we're dealing with medications that need careful adjustment in the first place, to add another issue may harm patients in the long run," she said.

Yet a study led by Abramson shows the use of "natural" supplements among heart patients is more common than expected.

In a survey of 308 patients — 207 men and 101 women — who were seeing a cardiologist for already diagnosed heart disease or evaluation for suspected cardiac problems, researchers at the inner-city hospital found that about 45 per cent were taking complementary medicines.

Among those taking the supplements, just over half said their specialist was aware they were taking natural remedies. Few said their doctors had asked about complementary products: 8.4 per cent said their specialists had asked, while 12.7 per cent said their family doctor had inquired.

Still, many respondents said they did not plan to discuss the issue with their physicians, and less than 40 per cent believed it was important for their doctors to know about what other remedies they were taking.

"We were surprised at the use of CAM (complementary and alternative medicine) therapies in our cardiac patients," Abramson said Tuesday from Dallas, where she was presenting her findings to the annual meeting of the American Heart Association.

"Even if they're not taking it for heart-related reasons, you need to discuss anything you ingest with your physician and pharmacist."

Also unexpected was the profile of alternative medicine products users, she said. Men and women were equally likely to take herbal, vitamin and other preparations, but use was more common among older, higher-income and well-educated patients.

"We looked at predictors of CAM use and the number of (prescribed) pills a person was on for their heart did not predict CAM use, nor did ethnic background in a very multiculturally diverse group of patients."

Abramson, a spokeswoman for the Heart and Stroke Foundation of Canada, said better communication is needed to avoid adverse reactions from combining powerful prescription drugs with complementary medicines.

Patients need "to be proactive and talk to their doctors," she said. "Physicians need to try to close the communication gap, as well."

New Brunswick pharmacist Jeannie Collins Beaudin said druggists can play an important role in helping patients avoid risky medicinal interactions by checking patients' use of complementary health products as they fill prescriptions.

"I'm really glad to see this type of study being done because it points out the lack of communication we can have and what the dangers can be," Beaudin, a member of the Canadian Pharmacists Association, said from Keswick, N.B.

"I think all of us should be doing it, and patients as well — supplying the information, whether they're asked or not. But all health professionals, doctors and pharmacists both, should be asking about supplements and herbal medications people are taking."