SUNDAY, June 12 (HealthDay News) -- Heart attack patients whose ambulances are diverted from the nearest ER to another one further away are at greater risk of dying -- not just soon after the heart attack, but for up to a year after the intervention, a new study finds.

Researchers examined data from 13,860 Medicare patients who were admitted to emergency departments for heart attack at hospitals in four California counties (Los Angeles, San Francisco, San Mateo and Santa Clara) between 2000 and 2005. Ambulance traffic was diverted from the nearest emergency department to another hospital on an average of 7.9 hours out of 24 hours.

Compared to patients who received care at the nearest hospital, those whose nearest emergency department were diverting ambulances for 12 hours or more had higher death rates after 30 days (19 percent vs. 15 percent), 90 days (26 percent vs. 22 percent), 9 months (33 percent vs. 28 percent), and one year (35 percent vs. 29 percent).

The researchers also found differences in treatment patterns once patients were admitted to the emergency department. Catheterization rates were 49 percent for patients who weren't diverted and 42 percent for those whose nearest emergency department was sending ambulances to a hospital further away for 12 hours or more.

Rates of percutaneous coronary interventions such as balloon angioplasty or stent placement was 31 percent for patients who weren't diverted and 24 percent for patients who were diverted during a 12-hour period or more.

The study appears online and in the June 15 print issue of the Journal of the American Medical Association, and will be presented at an AcademyHealth meeting.

"These findings point to the need for more targeted interventions to appropriately distribute system-level resources in such a way to decrease crowding and diversion, so that patients with time-sensitive conditions such as [heart attack] are not adversely affected," wrote the researchers, Yu-Chu Shen of the Naval Postgraduate School, Monterey, Calif., and National Bureau of Economic Research, Cambridge, Mass., and Dr. Renee Y. Hsia, of the University of California, San Francisco.

"It is important to emphasize that while demand on emergency care is increasing as evidenced by increasing utilization, supply of emergency care is decreasing. If these issues are not addressed on a larger scale, ED conditions will deteriorate, having significant implications for all," they concluded.

Some other experts agreed. Commenting on the study, Dr. Carl Ramsay, chairman of the department of emergency medicine at Lenox Hill Hospital in New York City, said, "While the public sees ambulance diversion as a sign of ED overcrowding, those of us in emergency medicine have known for years that it actually reflects failed processes in the [non-emergency department] areas of the hospital."

"How many people actually know that unbalanced surgical scheduling by stacking up Monday through Thursday {operating room] schedules creates ED overcrowding, which creates ambulance diversion?" Ramsay continued. "This is only one in a chain of many dysfunctional links that leads directly back to the streets that carry patients to hospital emergency departments."

"This study focuses on death as the primary endpoint. The more that optimal disease management is discovered to be time-sensitive -- as in heart attack, stroke and sepsis -- most of the affected patients who do not reach care within the optimal timeframe will not die (thus the mortality figures will not substantially change), but will have permanent alterations that affect their ability to live a quality existence," he said.

"This impacts the person, their family and our society," Ramsay added. "This study reveals the tip of the iceberg."

More information

The American College of Emergency Physicians outlines situations when you need to call an ambulance.