The most emergent form of heart attacks is decreasing nationwide, but this declining incidence could affect emergency departments' quality and timeliness of care.

This is the key finding of a Vanderbilt University study released in the American Journal of Cardiology and presented at the national American Heart Association meeting in Chicago this week.

Using data from the Nationwide Emergency Department Sample, the nation's largest database of information about emergency department visits, the researchers found that approximately 250,000 patients present in emergency departments annually with a specific type of severe heart attack known as a ST-elevation myocardial infarction (STEMI). But, the number of STEMI patients decreased by approximately 30 percent between 2006-2011 in every region of the country and in every age group.

While the nationwide STEMI drop is great news for patients, the authors say this decline makes it difficult for emergency doctors to stay practiced with the most severe and time-sensitive heart attacks.

"If the overall number of severe heart attack patients seen in the emergency department decreases, then health care providers will have less experience caring for these patients, which could lead to delays in recognition for an illness that is highly dependent upon prompt diagnosis and treatment," said lead author Michael Ward, M.D., MBA, assistant professor of Emergency Medicine. "Because of this, it is important that we continue national surveillance on these patients in order to guide health care resource allocation and ensure all of these time-sensitive patients are recognized and treated appropriately."

Senior author Wesley Self, M.D., MPH, assistant professor of Emergency Medicine, added, "Health care has been trying very hard over the last couple of decades to reduce heart attacks, and although more people have cardiovascular disease than ever, the STEMI is declining, which means health care is doing a good job of helping these patients live longer. It looks like heart disease is becoming more of a chronic, lifelong problem instead, with less risk of STEMI and a sudden death, so these patients are going to present in emergency departments differently, perhaps making them more of a 'needle in a haystack' to pick out and treat."