Patients with coronory heart disease who have positive expectations about recovery, expressing beliefs such as "I can still live a long and healthy life," had greater long-term survival, researchers reported.

Among a cohort of almost 3,000 patients undergoing coronory angiography, those with the highest expectations for outcomes actually had the best outcomes, Dr. John C. Barefoot, and colleagues from Duke University Medical Center in Durham, N.C.

"Patients differ widely in terms of their psychological reactions to major illnesses such as coronary heart disease," Barefoot's group explained online in the Archives of Internal Medicine.

To explore the specific potential influence of recovery expectations, rather than overall optimistic personality traits, the investigators enrolled 2,818 patients with clinically significant disease and followed them for about 15 years.

Recovery expectations were assessed on the Expectations for Coping Scale, in which patients agreed or disagreed with statements such as "I doubt that I will ever fully recover from my heart problems" and "My heart condition will have little or no effect on my ability to do work."

Patients were stratified into quartiles according to their expectation scores.

After adjustment for multiple variables, the mortality rate in the highest quartile — the most optimistic group — was 32 per 100 versus 46 per 100, respectively, "illustrating a substantial magnitude of this effect even after taking multiple covariates into account," Barefoot and colleagues observed.

"These observations add to a compelling body of evidence that endorsing optimistic expectation for one's future heart health is associated with clinically important benefits to cardiovascular outcomes," Dr. Robert Gramling and Dr. Ronald Epstein, of the University of Rochester in New York, wrote in a commentary accompanying the study.

"The degrees of evidence observed in these studies suggest that optimism is a powerful 'drug' that compares favorably with highly effective medical therapies," they wrote.

Other experts advised caution, however.

"Like all observational studies, unmeasured patient characteristics may have contributed to the better outcomes," observed Dr. Steven E. Nissen, of the Cleveland Clinic.

"Patients with a 'positive' attitude may simply be healthier than patients with a negative attitude. In fact, their 'attitude' may reflect their health status," Nissen wrote toMedPage Today and ABC News in an e-mail.

Two "plausible" hypotheses can help explain the study findings, according to Barefoot and colleagues.

First, patients who are optimistic may use more effective strategies to cope with recovery from illness, by addressing the problem and reducing risk factors.

Second, patients whose outlook is more negative may experience worse stress that in turn could have harmful cardiac effects.

Limitations of the study, according to the investigators, included the possibility of confounders and selection bias.

"These findings argue for expanded efforts to understand the influence of recovery expectations and the potential benefits of attempts to modify them," Barefoot's group concluded.

However, the potential efficacy of such efforts is uncertain, according to Dr. James Kirkpatrick, of the University of Pennsylvania in Philadelphia.

"Whether a patient's outlook can be changed (or patients can change their outlook) and improve results, and whether there are other factors which might make these patients do better, is unknown. One of those factors might be that cardiovascular providers give better care to patients with a positive outlook — perhaps spending more time with them or being more conscientious," wrote Kirkpatrick in an email to MedPage Today and ABC News.

"Future studies will need to take this possible mechanism into account," wrote Kirkpatrick.

The study was supported by the National Heart, Lung, and Blood Institute and the National Institute on Aging.

One author has a patent pending on an allele as a marker of cardiovascular disease and stress, and is a founder and major stockholder in Williams LifeSkills Inc.

Editorialist Gramling is funded by the National Palliative Care Research Center and the Greenwall Foundation.