In a group of about 61,000 U.S. residents, researchers writing in the Journal of the American College of Cardiology found that those without any health insurance were between 6 percent and 12 percent less likely than people with either public or private insurance to be prescribed drugs that are considered standard care for heat disease.
"There is some different of treatment. It only applies - interestingly enough - to uninsured patients," said senior author Paul Chan, of Saint Luke's Mid American Heart Institute in Kansas City, Missouri.
In the past, studies have found that uninsured U.S. residents have worse health outcomes compared to the insured. They're also less likely to get screenings and preventive care - possibly because they don't often go to a doctor.
Less is known, though, about uninsured people who do go to doctors and whether they receive worse care than insured people.
For the study, Chan and his colleagues used data from 2009 on 60,814 heart patients at 30 doctors' offices around the United States.
Of those patients, about 9 percent were uninsured, 71 percent had private insurance, and 20 percent had public insurance, such as Medicare or Medicaid.
The researchers looked to see which patients received the recommended medications for their heart conditions and whether the treatment they got was linked to their insurance status.
Overall, patients with public or private insurance received about the same number of prescriptions, but the uninsured patients were less likely to be prescribed drugs, compared to the insured patients.
For example, about 73 percent of uninsured patients were prescribed beta-blockers after a heart attack, compared to about 81 percent of privately insured patients.
About 89 percent of uninsured patients received medication for high cholesterol, compared to about 95 percent of privately insured patients.
"If it's just the lack of insurance, it should not affect the physicians' decisions to sit down and prescribe (a drug)," said Ed Havranek, a cardiologist at the Denver Health Medical Center in Colorado, who wrote a commentary that appeared with the study.
It could be driven by doctors' perceptions of their patients, he added.
Chan said that uninsured people tend to be sicker and their other conditions may take priority over heart problems.
"Truth be told, when many of these patients come in it's not just cardiovascular disease. It's diabetes, obesity and smoking too," he added.
Havranek said the first step to solving the problem is to do what Chan and his colleagues did: by shining a light on it and then finding a practical solution.
"You have to be open to the possibility that you're not doing things accurately or fairly across patient populations," he said.