CHICAGO • St. Bernard Hospital has received a five-star rating for its congestive heart failure program — yet soon may face substantial financial penalties because of its high patient readmission rates.

Medicare's new penalty system, which takes effect next fall, is designed to prod hospitals to make sure patients get the care they need after discharge and to reduce the number of potentially avoidable readmissions, which by one estimate cost the government $12 billion a year.

But critics of the policy say that what happens off the hospital campus can have a huge impact on patient outcomes. Heart failure patients who seek treatment at St. Bernard, in one of Chicago's poorest neighborhoods, typically suffer from multiple health problems and often can't afford their medications, factors that can lead to repeat hospital visits.

"When some of our patients get home, their lights and gas are shut off," said Roland Abellera, the hospital's vice president of quality and corporate compliance. "So what ends up happening is that the ambulance brings them back to us and we have to house them until our staff can help them get the utilities turned on."

Data from the Centers for Medicare & Medicaid Services show that the new policy is likely to have a disproportionate effect on hospitals that treat the most low-income patients, according to a Kaiser Health News analysis.

Hospitals with the highest proportion of poor Medicare patients were nearly three times as likely as others to have substantially high readmission rates for patients with heart failure who had stayed in the hospital at least one night, the analysis found.

These hospitals already operate on tight margins. St. Bernard officials estimate that the Medicare penalty could amount to about $600,000 a year.

Heart failure, a condition in which fluid builds up when the heart pumps poorly, is the most common condition sending Medicare patients back to the hospital. But much of the recovery depends on what happens to patients after they leave the hospital.

Health experts say low-income people often can't afford their medications or the healthier foods they are advised to eat. Many have trouble getting to follow-up medical appointments, and they can be confused about instructions given for managing their conditions.

Within 30 days of discharge, one in four Medicare patients with heart failure is readmitted.

The Affordable Care Act passed by Congress in 2010 mandated that, starting in October, Medicare will penalize hospitals whose patients with heart attacks, heart failure or pneumonia return frequently. By 2014, hospitals with high readmission rates stand to lose up to 3 percent of their regular Medicare reimbursements.

Medicare has set aside money to help hospitals better plan patients' post-discharge care, and the program's chief medical officer, Patrick Conway, said some of that will be targeted to hospitals treating large numbers of poor people. "We especially are concerned about safety-net hospitals that take care of a high portion of patients in poverty and racial and ethnic minorities," he said.

Some hospital administrators worry the new policy will be overly punitive. "In essence, they are penalizing those hospitals and areas that need the most help and the most money to address these issues because we have the sickest, most noncompliant and vulnerable patient population," said Guy Alton, chief financial officer at St. Bernard.