STEMI or ST Segment Elevation Myocardial Infarction 
STEMI or ST Segment Elevation Myocardial Infarction

More than one million Americans have a heart attack annually. Approximately half of them die, and many have permanent heart damage or die because they did not get help right away1a. Most heart attacks, or myocardial infarctions, occur when a blood clot blocks one of the coronary arteries, preventing blood and oxygen from reaching the heart. When this happens, heart muscle dies or is permanently damaged.

There are two kinds of heart attacks. The STEMI, or ST segment elevation myocardial infarction, is the more severe type that is identified by an electrocardiogram (ECG) test. During a STEMI, the coronary artery is completely blocked by a blood clot and essentially all the heart muscle being supplied by the artery begins to die. A STEMI causes an elevation in the ST segment of an ECG that indicates there is a large amount of heart muscle damage. The milder form of a heart attack is called the NSTEMI, or non-ST segment myocardial infarction. In this type of heart attack, the coronary artery is only partially blocked and causes only a portion of the affected heart muscle to die.

A heart attack is an emergency that requires immediate medical treatment. Indications of a heart attack include chest pain or discomfort, shortness of breath, nausea, vomiting, palpitations, dizziness, sweating or indigestion. If these symptoms occur, call 9-1-1 immediately. Do not delay or try to drive yourself to the hospital.

The preferred treatment for opening blocked arteries caused by a STEMI is angioplasty, also known as percutaneous coronary intervention. The procedure should be performed within 90 minutes of arriving at the hospital and no longer than 12 hours after the heart attack. An angioplasty involves threading a thin catheter with a balloon on the end into the blocked artery. The balloon is then expanded to restore blood flow. A stent, which is a small, metal mesh tube, may be placed in the artery to help open it and prevent it from closing again.

A nationwide program initiated by the American College of Cardiology and 38 partner organizations has helped to decrease the time between arriving at the hospital and lifesaving angioplasty. The campaign involved having ambulance attendants call the hospital to notify them that a heart attack victim would be arriving soon, preparing the cardiac catheterization laboratory where the angioplasty would be performed prior to patient arrival, and transporting the patient to the cath lab as quickly as possible.

Several studies have shown that a reduced door-to-balloon time is associated with improved patient survival. In 2005, approximately 50 percent of STEMI patients were treated within the recommended 90-minute deadline for door-to-balloon time. By the first half of 2009, more than 80 percent of patients received treatment within the accepted time frame. The average time for starting an angioplasty decreased from 121 minutes in 2005 to 80 minutes in 2009.

Patient outcome after a STEMI will depend on the amount and location of damaged heart tissue. Follow-up care will be required to reduce the chance of having another heart attack. For more information about STEMIs, talk with your doctor or call 561-625-5070 for a free referral to a cardiologist near you.