Ambulance Diversion Linked To Heart Attack Risk

Heart attack risk increases when ambulances are diverted

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Ambulances are at times diverted to another emergency department when the closest hospitals are at capacity.  But those diversions may be adding an increased risk of death for heart attack patients.

Ambulance diversion happens when emergency departments are forced to temporarily close to ambulance traffic because they are overcrowded or do not have the needed resources. This is especially problematic for serious time-sensitive health conditions such as heart attacks.

New research among Medicare patients suffering from a heart attack in four California counties revealed that diversion of ambulance traffic to the nearest emergency room for 12 hours or more was linked to an increased risk of death for the first year following the cardiac event.

"If you have heart pains, go directly to the closest ER."

Other reports have noted that U.S. emergency departments are being utilized more, yet have less capacity. This trend means longer wait times for patients, overextended staff and disruptions in ambulance service.

Yu-Chu Shen, of the Naval Postgraduate School in California and Dr. Renee Y. Hsia, of the University of California, San Francisco, conducted the research to determine whether heart attack patients are at an increased risk of death when their ambulance is diverted.

They studied 13,860 Medicare heart attack patients within Los Angeles, San Francisco, San Mateo, and Santa Clara counties. All Medicare claims between 2000 and 2005, including those with links to death as late as 2006, were included. Daily ambulance diversion logs were also studied.

Between 2000 and 2006, the average daily diversion duration was 7.9 hours. In the study of patients who were not diverted, 29 percent died within one year of emergency room treatment. Of those who were diverted 31 percent of those who waited for less than six hours died within the first year.

About 30 percent of those diverted for between six and 12 hours died within the first year and 35 percent of heart attack patients whose ambulances were diverted for more than 12 hours died.

The treatment patterns for the two categories also differed. Of those who were not diverted, 49 percent received heart catheterization, while only 42 percent who were delayed for more than 12 hours received that treatment.  The number of patients receiving percutaneous coronary intervention, which includes procedures such as balloon angioplasty or stent placement used to open narrowed coronary arteries, was 24 percent in the category that was diverted for over 12 hours  versus 31 percent in the no diversion category.

The mortality rate was similar for those who were not diverted and those who were diverted within 12 hours. But exposure to 12 or more hours of diversion was associated with higher mortality rates at 30 days  where it was 19 percent instead 15 percent., at 90 days where mortality was 26 percent instead of 22 percent, at nine months, which was 33 percent versus 28 percent and at one year following a heart attack, which indicated a mortality rate of 35 percent instead of 29 percent for those who were not diverted.

Reviewed by: 
Review Date: 
June 13, 2011
Last Updated:
June 14, 2011