Paul Chan is hopeful that the Affordable Care Act, aka Obamacare, will improve the treatment of people who lack health insurance.

That would come as welcome relief if his research is any indication of what’s happening to the uninsured right now.

Chan is a heart specialist at St. Luke’s Hospital and part of a group of superstar researchers there who have been mining national data on heart patients and coming up with findings that have major implications about poverty, race and health care.

Chan’s previous work has found that uninsured patients are more likely to delay going to the hospital when they have urgent heart attack symptoms such as chest pains, and that people in cardiac arrest are less likely to get CPR from a bystander in neighborhoods that are predominantly poor or black.

A new study by Chan and his colleagues looks at how health insurance coverage affects the quality of care that doctors provide to patients with coronary artery disease. They combed data on 61,000 patients from 30 medical practices nationwide and came up with some alarming findings.

Uninsured heart patients were 6 to 12 percent less likely than insured patients to be prescribed the medications considered essential to their care. That may not seem surprising by itself. But the researchers dug deeper, looking at the kinds of medical practices patients went to.

Uninsured heart patients received the poorest care in practices that saw relatively large numbers of other uninsured patients. The lower quality seemed to vanish when they went to practices that saw few other uninsured patients.

Chan suggested several reasons why this may be happening.

Uninsured patients frequently go to crowded safety net clinics where doctors have less time to spend on each case. Uninsured patients also tend to have multiple health problems — a doctor may be able to address only the most urgent issues.

“There’s less face time opportunity,” Chan said. “It’s a lot harder to get to all the things needed to be done.”

Doctors also may not bother writing prescriptions for uninsured patients, assuming they won’t fill them. Another possibility Chan is reluctant to endorse is that “the quality of physicians may be different.”

Chan expects that as people gain insurance through Obamacare, safety net clinics will see more paying patients and have the revenue to hire more staff.

“I suspect those practices won’t have as many crammed patient slots,” he said.

If these clinics don’t improve, Obamacare will let market forces come into play, Chan said.

“If a practice is underperforming, now (newly insured) patients will have more options,” he said. “Patients may not know what medications they need, but they do know if they’ve been short-shrifted with face time.”