Your chance of getting a critical procedure called angioplasty depends on what your state's healthcare policies are. A new study from the Harvard School of Public Health has found that people living in areas where public reporting is necessary are less likely to get angioplasty than people living in states that don't have such regulations.

Currently, just three states in the U.S. have mandatory public reporting about a patient's health after angioplasty - a procedure where a balloon and stents are inserted to open the arteries in the heart that have narrowed due to cholesterol build up.

However, many states have now chosen to make data regarding the procedures public. The public reporting strategy is aimed at keeping patients informed about hospital performance. However, as nobody likes to see a "bad report card," doctors don't perform this procedure on people who have been admitted at critical stages after a massive heart attack.

"Making performance data available to patients is very important. It helps them choose the best health care. However, the results of our study make us wonder if we're doing public reporting as well as we could be," said Karen Joynt, instructor in the Department of Health Policy and Management at HSPH and a physician at Brigham and Women's Hospital in Boston.

The study included data of people who had suffered heart attacks in Massachusetts, New York and Pennsylvania - the three states where public reporting is mandatory and data of people who've had a heart attack from seven non-reporting states between 2002 and 2010. The data analyzed was of patients who were 65 years or older.

Researchers found that patients from the public reporting states had an 18 percent less chance of getting an angioplasty than patients living in other states.

Shockingly, patients who've had a massive heart attack had a 27 percent lower chance of getting an angioplasty in states that have mandatory public reporting than other states. For people who had cardiac arrest, the chances of getting the procedure were 21 percent lower.

"Improving transparency of the health care system is critical. However, we have to make sure we do it right. Otherwise we risk creating incentives to deny care to the sickest patients," said Ashish Jha, associate professor of health policy and management at HSPH.

Researchers say it is possible that patients were already too ill and the procedure could be a failure, but it's also possible that doctors were reluctant to perform the procedure because a poor patient-outcome would reflect badly on their performance. They say more follow-up research will establish the reason for a decline in the angioplasty procedures.

"It will be important for follow-up work to determine why this is going on, and more importantly, how we can address it," said Joynt.

The study is published in the Journal of the American Medical Association.