Patients who have trouble paying their medical bills do significantly worse in the year after heart attacks than patients under less financial pressure, a new study finds.

In the study, which appeared last week in The Journal of the American Medical Association, the researchers surveyed almost 2,500 patients when they were hospitalized for heart attacks.

Although most of the patients were insured, the researchers found that almost one in five reported that financial barriers had led them to avoid health care over the previous year. More than one in 10 said they had not been able to afford some medications.

Dr. Harlan M. Krumholz of Yale and his co-authors found that a year after the heart attacks, there were 12 percent more cases of angina among the patients who had reported financial barriers. The rate of rehospitalization for those patients was more than 11 percent higher than for other patients.

The patients who had problems paying for medication did even worse. Their angina rate was 17 percent higher, and they were 50 percent more likely to be rehospitalized than other patients were.

The issue goes beyond the group in this study. The researchers pointed to earlier studies finding that more than 16 million Americans, despite having health insurance, say they avoid medical care because of its cost or have trouble paying for medications. And things seem likely to grow worse, the study said.

“Given the current climate of increased cost sharing,” the authors wrote, “the number of underinsured and uninsured individuals will continue to increase.”