SAN FRANCISCO –Patients with stable angina need to be explicitly told that percutaneous coronary intervention will not prevent heart attacks, survey results of 1,678 people suggest.

Even if patients are informed that percutaneous coronary intervention (PCI) does not reduce myocardial infarction (MI) risk, there’s still a good chance that roughly a third of patients may leave an office thinking that it does, Dr. Mohammad A. Kashef and his associates reported at the annual meeting of the American College of Cardiology.

"In the absence of information to the contrary, most patients assume that PCI prevents MI in stable angina and are biased towards choosing PCI, " said Dr. Mohammad A. Kashef.

During a hypothetical visit with a cardiologist, 69% of patients who were uninformed that PCI doesn’t reduce MI risk said that they would choose to undergo PCI to treat stable angina, compared with 49%, 46%, and 44% of patients in three groups who were informed that PCI has no effect on MI risk but would still choose to undergo the procedure, said Dr. Kashef, an internal medicine resident at Baystate Medical Center, Springfield, Mass.

"In the absence of information to the contrary, most patients assume that PCI prevents MI in stable angina and are biased towards choosing PCI," he said. "Explicit information can partially overcome that bias and influence decision making." The most effective way to overcome bias toward PCI is to explain why PCI doesn’t prevent MI, the the survey results suggest.

Participants in the Web-based surveys were aged 50 years or older and had never undergone PCI. All were asked to imagine that they had experienced occasional chest pain "like someone is pressing down on your chest, when you climb up four flights of stairs or exercise vigorously," said Dr. Kashef. They were to imagine that the feeling is uncomfortable but does not interfere with their normal activities, and that they are visiting a cardiologist for management of stable angina with a positive stress test.

All were told, by the hypothetical cardiologist, the options for treating with medication or with medication plus PCI, about the potential complications of PCI and the role of PCI in reducing angina, and about the risks and benefits of medication. In other ways, though, the scenarios diverged.

In the first scenario, the hypothetical cardiologist did not mention whether PCI does or does not affect MI risk. In the second scenario, participants specifically were told that PCI does not reduce the risk of MI. In the third scenario, patients were told why PCI does not reduce MI risk, with a description of how the "clogged-pipe model" of angina is flawed. In the fourth scenario, patients were informed that PCI does not reduce MI risk, and coronary artery disease was described as inflammation of the arteries, not as artery blockage.

A questionnaire followed, asking patients if they would undergo PCI and take medicine, and how effective they believed PCI or medical therapy to be for prevention of MI.

The proportions that said they believed PCI prevented MI were 71% in scenario one, 39% in scenario two, 31% in scenario three, and 39% in scenario four.

Patients who heard no mention of PCI’s effects on MI risk were less likely to say they would take medication (83%), compared with patients in scenarios two (87%), three (92%), and four (90%).

When asked which they thought to be more effective in preventing MI – medication or PCI – patients in group one favored PCI, while those in the other three groups favored medication.

Fully, 52% of patients in the first group falsely remembered that the doctor said PCI prevents MI, when asked if they were told this. In contrast, 19% in the other three groups reported this false memory.

Previous data have shown that PCI can relieve symptoms but does not reduce the risks for MI or death, yet 71%-88% of patients believe that PCI benefits MI and mortality risks.

The hypothetical nature of the current study’s scenarios, and the fact that the patients did not actually have stable angina, limited the significance of the findings, but the percentages of patients who chose PCI were similar to percentages in previous studies that surveyed real patients, Dr. Kashef said.

Participants had a mean age of 60 years, 51% were female, and 79% were white. Thirty-four percent had an associate’s or bachelor’s college degree, and 12% had higher degrees. Patients who completed the survey were rewarded by being entered in a lottery sponsored by the survey company

Dr. Kashef reported having no financial disclosures.

*This article was updated 3/19/13.

sboschert@frontlinemedcom.com <[lb]>

Straight talk partially counters bias towards PCI