Segment Elevation Myocardial Infarction (STEMI)

 Segment Elevation Myocardial Infarctions (STEMIs) are caused by the sudden occlusion of a major coronary artery. For 25 years, clinical research has focused on ways to quickly open these blocked arteries, which reduces the chance of dying from a STEMI.

This was accomplished first by clot dissolving “thrombolytic” drugs, which unfortunately are ineffective 33% of the time and can cause life-threatening bleeding. Re-occlusion causing a repeat heart attack often occurs following their use. Restoring blood supply to the effected heart muscle using immediate or “direct” coronary angioplasty and stenting has been demonstrated to be an option markedly superior to thrombolytic therapy for treatment of STEMIs.

In order to provide emergent STEMI care, a medical center must have 24/7 interventional cardiology facilities and personnel as well as cardiac surgery backup. For Tennesseans living within 30 minutes of one of the 43 medical centers capable of providing this care, angioplasty within 90 minutes should be achieved most of the time. Eighty-nine percent of patients presenting to The University of Tennessee Medical Center in 2009 achieved the 90-minute door-to-balloon benchmark, compared to a state average of 82% and a national average of 79%.

Controversy still surrounds the best treatment of STEMI patients who do not have easy access to medical centers capable of providing coronary angioplasty. Data suggests that every 10-minute delay in treatment can result in a 1% higher chance of dying from an acute myocardial infarction. Across the country, programs are underway to improve the access of these patients to interventional care by creating regional STEMI centers. In Tennessee, the Cardiac System of Care Task Force is identifying factors necessary to develop STEMI networks. The Heart Lung Vascular Institute has been functioning as a regional STEMI referral center for more than a decade.

The medical center’s system of care for STEMI patients in rural East Tennessee began in 1999 with a “rapid transport protocol,” allowing patients with STEMIs in rural emergency departments to be transferred directly to The University of Tennessee Medical Center. The UT LIFESTAR dispatch center became the communication hub for coordinating STEMI care by calling in the catheterization lab team at the moment a STEMI patient was identified, further reducing door-to-balloon time.

The UT LIFESTAR team went a step further beginning in 2005 with a program to train local EMS providers to recognize the EKG of STEMI patients in the field and to call for aeromedical transport directly from the patient’s location to an interventional center. This has been an enormous step forward in improving time to treatment.