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Treatment of an Acute Heart Attack

The First Few Hours Are Critical


Updated June 10, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

An acute heart attack (also called a myocardial infarction, or MI) is a medical emergency. Having an MI means that one of your coronary arteries has become suddenly blocked, and the heart muscle supplied by that artery is beginning to die. Early and aggressive medical therapy is necessary to stabilize your cardiovascular system, and to prevent or mitigate long-term complications from the heart attack.

Acute Heart Attack Treatment: The Immediate Priorities

The first priorities after you arrive in the hospital with a possible MI are:
  • to make sure your vital signs (pulse and blood pressure) are stable
  • to prepare to deal with life-threatening conditions that may appear (such as ventricular fibrillation)
  • to decide whether or not you're actually having an MI

Diagnosing the most severe form of heart attack -- the ST-segment elevation myocardial infarction (STEMI) -- is usually pretty easy for the doctors to do. It is done by looking for characteristic changes on an ECG.

If you are having the less severe form of MI, the non-STEMI (which generally means that the artery is not quite completely blocked), the diagnosis may require more testing -- especially the measurement of elevations in cardiac enzymes, proteins released into the bloodstream by damaged cardiac muscle cells.

If it turns out that you are having a STEMI, immediate steps must be taken to relieve the blockage and to get the blood flowing through the coronary artery once again.

(Treating a non-STEMI heart attack is done differently.)

How Is the Blockage Treated?

There are two general methods for opening a blocked coronary artery: thrombolytic therapy and angioplasty with stenting.

Thrombolytic therapy consists of giving drugs (the so-called "clot-busters," such as Activase (t-PA), streptokinase, urokinase, or anistreplase), which act rapidly to dissolve the blood clot that has blocked the artery. Studies have shown that approximately 50% of occluded arteries can be opened by giving these drugs early in the course of a heart attack, and that patients whose arteries are opened end up with significantly less heart damage and a significantly better chance of long-term survival.

In every study, the earlier the drug is given, the better the chances of success. The best results are obtained within the first three hours; relatively satisfactory results are seen between three to six hours; and some benefit is seen up to 12 hours, with little or no benefit after that.

The major side effect of thrombolytic therapy is bleeding, and this form of therapy should not be used in patients who are at relatively high risk of bleeding (for instance, if you had recent surgery, have a history of stroke due to brain hemorrhage, or have very high blood pressure).

Using angioplasty and stenting instead of thrombolytic drugs is now generally felt to be more effective in successfully opening a blocked coronary artery during an acute MI. Rapid angioplasty and stenting is successful in opening the blocked artery about 80% of the time. The disadvantages of this approach are that it is an invasive procedure, and unless the hospital is geared up to perform emergency angioplasty rapidly and efficiently, the opening of the blood vessel may be accomplished more quickly with thrombolytic therapy.

The main point, no matter which method is used, is to open up the occluded vessel as rapidly as possible. This being the case, choosing between thrombolytic therapy and angioplasty should generally be based on circumstances.

Most cardiologists will opt for angioplasty if their catheterization lab can be rapidly mobilized, and experienced personnel are readily available. This invasive approach would also be chosen if there is a good reason to avoid thrombolytic therapy in your case.

On the other hand, if there is likely to be a substantial delay in performing angioplasty, or if there is a good reason to avoid performing an invasive procedure, then thrombolytic therapy would be the better choice.

Both methods can be highly effective if given rapidly enough. The most important thing is not which method is used, but to act quickly. Time is of the essence, and the method chosen should usually be whichever method is likely to open the artery more rapidly.

In addition to getting the blocked artery opened up as quickly as possible, there are several other treatments that need to be given during an acute MI.

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