ST-elevation myocardial infarction

What is a STEMI ? ST-Elevation Myocardial Infarction (STEMI) is a very serious type of heart attack during which one of the heart’s major arteries (one of the arteries that supplies oxygen and nutrient-rich blood to the heart muscle) is blocked. ST-segment elevation is an abnormality detected on the 12-lead ECG.

It is a profoundly life-threatening medical emergency and usually associated with a disease process called atherosclerosis (coronary artery disease). You can find a useful video about heart disease and heart attacks at the Khan Academy.

Patients experiencing acute STEMI are at risk for developing life-threatening arrhythmias like ventricular fibrillation which causes sudden cardiac arrest, sometimes referred to as a “massive heart attack”. These patients require cardiopulmonary resuscitation (CPR) and defibrillation — a “shock” to restore a normal heart rhythm.

Signs and symptoms of a STEMI include:

Chest pain or discomfort Shortness of breath Dizziness or light-headedness Nausea or vomiting Diaphoresis (sweatiness) unexplained by ambient temperature Palpitations (uncomfortable awareness of the heartbeat) Anxiety or a feeling of impending doom Some patients experience denial and dismiss their symptoms as heartburn or indigestion. When this happens they may delay seeking care for hours.

STEMI can be treated with “clot-busting” drugs called thrombolytics (also called fibrinolytics ) or with a primary percutaneous coronary intervention (PCI) in a cardiac catheterization lab. This procedure is also referred to as angioplasty or stenting.

There is a direct relationship between the amount of time a heart artery is blocked and the severity of the heart attack and odds of survival. Cardiologists have a mantra that “time is muscle” to express the importance of early treatment.

One of the quality measures for STEMI care is the “door-to-balloon” (D2B) time or the amount of time it takes to successfully re-open the occluded artery. The clock starts when the patient arrives at the hospital and stops when the balloon is inflated in the cardiac cath lab (which is part of the procedure).

In recent years the American Heart Association has encouraged a new quality measure called “first medical contact-to-balloon”. The goal is to have the procedure completed within 90 minutes of EMS arriving at the patient’s side. Some argue that the clock should start with the 9-1-1 call.