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Click here for Multimedia Lecture on Heart Attack!
What is a heart attack?
How common is a heart attack?
What are the symptoms of a heart attack?
What should be done if a heart attack is suspected?
What happens when a heart attack patient arrives in the ER?
How does "clot buster" treatment compare with angioplasty?
Why is primary angioplasty and stent not used in every case?
What happens after the patient is admitted to the hospital?
What happens after the first day?
What are the complications of a heart attack?
What medications will be prescribed after discharge?
How does "clot buster" treatment compare with emergency angioplasty and coronary stenting? This is an excellent question for which there is no easy answer. Let us first look at intravenous thrombolytic (clot buster) treatment which became one of the more important advances in the treatment of heart attacks since its introduction. It offers the following advantages (Reference: ACC/AHA Guidelines for Patients with Acute Myocardial Infarction: Executive Summary, Circulation, Nov 1, 1996):
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In comparison with standard medical treatment, thrombolytic therapy reduces the 35-day mortality (death rate) by 21%
This corresponds to an overall reduction of 21 deaths per 1000 patients treated in this manner. -
Time is of essence with the use of thrombolytic treatment. Higher benefits are achieved when it is given within 6 hours of the onset of heart attack symptoms. Best results are observed within two to three hours but continues to be beneficial even if started within 12 hours.
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35 per 1000 lives are saved when it is used within the first hour of symptoms. This drops to 16 lives saved per thousand if treatment is delayed for 7 to 12 hours.
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Thrombolytic therapy benefits the patient regardless of age, sex or presence of risk factors for coronary artery disease.
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Disadvantages include a small risk of a stroke (2%) with a little over half of them (1.1%) being due to bleeding. To place this in the proper perspective, the risk of a stroke due to thrombolytic treatment is far outweighed by the number of lives that are saved
Next, let us examine the advantages of angioplasty performed as a primary procedure in the treatment of a heart attack. According to the recommendations of the American College of Cardiology and the American Heart Association Guidelines (above), primary angioplasty may be performed as an alert native to thrombolytic therapy in the following circumstances:
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It can be accomplished in a timely manner by skilled and experienced staff.
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There is prompt access to coronary bypass graft surgery.
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About half the patients treated with thrombolytic therapy continue to have a significant blockage (since the treatment breaks up blood clots but does nothing for the underlying blockage) and reduced blood flow in the affected artery. In comparison, blood flow is brisk and a mild or no blockage is left behind in over 90% of cases treated with primary angioplasty with or without stenting.
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The mortality or death rate with primary angioplasty is 60% lower (Reference: JAMA 278:2093, 1997) than that achieved with thrombolytic therapy (4.4% compared to 6.5%).
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The risk of stroke is reduced by more than 50%, compared to thrombolytic therapy.
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The probability of having an open artery at 6 months with thrombolytic therapy alone is 59%. The odds improve to 87-91% at 3-6 months with primary angioplasty (References: NEJM: 328, 1993 and Circulation 90:156, 1994).
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In studies where patients were randomized to thrombolytic therapy versus primary angioplasty, those treated with thrombolytic therapy required subsequent PTCA or bypass surgery in 30% of cases. In contrast, only 5% of patients treated with primary angioplasty required a subsequent procedure or surgery during the 3-6 month follow-up (Reference: Circulation 10[Suppl A] 12A, 1998).
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With Primary Stenting in heart attacks, the success rate of the procedure is increased to >95% with less than 1% (0.8%) mortality (death rate) within the hospitalization period (Reference: Cathet Cardiovasc Diag 44, 118, 1998).
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The restenosis rate (chance of blockage returning at same site) is around 25% at 7 months in cases of primary stenting for heart attacks (Reference: J Am Coll Cardiol 31, 23, 1998).
If Primary Angioplasty and Stenting is so good why is it not used in every patient with a heart attack? Excellent question! Since only 18% of hospitals are equipped to perform emergency angioplasty and stenting in patients with heart attacks, this form of treatment is not available in the remaining 82% of hospitals that admit patient's with chest pain. Remember that time is of essence in getting rid of obstructing blood clots and salvaging heart muscle. In most cases, the patient is far better off in receiving a "clot buster" medication in the emergency room if access to a hospital with a cardiac cath lab is not readily available.
The x-ray video on the left shows a normal left ventricle as it fills and empties. The study was obtained during cardiac catheterization. Note how the top (anterior wall) and bottom (inferior wall) move towards each other as the heart pumps blood to the body.
The video on the right shows the same left ventricle after a heart attack involving total blockage of the right coronary artery (RCA). Compared to the video above, please note that the inferior (bottom) wall, which is supplied by the RCA, is now barely moving.
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