Hemorrhagic events during therapy with recombinant tissue-type plasminogen activator, heparin, and aspirin for acute myocardial infarction: results of the Thrombolysis in Myocardial Infarction (TIMI), Phase II Trial
Article Abstract:
In recent years, several large scale studies have demonstrated marked improvement in survival of patients with heart attacks who are treated with medications that dissolve the blood clots blocking the coronary arteries. One of these drugs is recombinant tissue-type plasminogen activator, or rt-PA, and it was used in the Thrombolysis in Myocardial Infarction, Phase II trial (TIMI II). Drugs like rt-PA not only dissolve existing clots, they prevent new clots from forming; consequently, patients given such drugs are at increased risk of bleeding complications. The rate of bleeding complications in the patients who participated in TIMI II was studied. The earliest participants in the study were given doses of 150 milligrams (mg) of rt-PA, while the later participants received 100 mg of rt-PA. Some patients had cardiac catheterization tests early in the course of their recovery, while others underwent these tests later, if at all (the TIMI II trial showed that there was no benefit to having the test done early). Bleeding complications were seen in approximately four percent of the TIMI II patients, regardless of the rt-PA dose. However, those who had early cardiac catheterization experienced the most frequent and most severe bleeding problems. Other factors associated with higher risk of bleeding complications were female gender, weight less than 70 kilograms (154 pounds), decompensating heart function and low platelet count (platelets are small blood cells necessary for successful blood clotting). A prior history of high blood pressure was associated with a greater risk of bleeding complications. Most of the bleeding complications occurred within three days of treatment. Among the serious bleeding complications noted were stroke, cardiac tamponade (in which blood collects in the sac surrounding the heart, preventing it from pumping effectively), and gastrointestinal bleeding. Some patients had laboratory evidence of blood loss, with decreases in their blood counts, but had no identifiable source of bleeding. To minimize the risk of bleeding, further modification of rt-PA treatment is warranted. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Annals of Internal Medicine
Subject: Health
ISSN: 0003-4819
Year: 1991
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Limitations of the electrocardiogram in estimating infarction size after acute reperfusion therapy for myocardial infarction
Article Abstract:
When a person suffers a myocardial infarction (MI), or heart attack, a portion of his or her heart muscle becomes damaged or ceases to function. The size of the MI correlates with the person's prognosis, in that the greater the size of the MI, the worse the prognosis. The electrocardiogram (ECG), which records the electrical activity of the heart, has been used with success in the past to estimate the size of the MI. Recently, new techniques have been used to reduce the size of an MI by restoring blood flow to the region of the heart muscle that is being damaged. These techniques, known as reperfusion therapies, include the use of thrombolytic (clot-dissolving) agents and coronary angioplasty, the dilatation of the narrowed or blocked coronary artery with a balloon-tipped catheter. To determine if the ECG is a useful tool for estimating the size of an MI in patients who receive reperfusion therapy, it was compared with five other methods of estimating infarct size in 43 patients who had received reperfusion therapy for their MI. The other methods used radionuclide techniques, in which radioactive substances are injected to produce special images of blood flow to particular tissues, including heart muscle. Little correlation was found between the estimations of infarct size indicated by ECG and those determined by the various radionuclide techniques. A significant correlation was found among the estimates made by the different radionuclide techniques. The ECG is thus an unreliable indicator of the size of an MI in patients who receive reperfusion therapy as treatment for their heart attack. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Annals of Internal Medicine
Subject: Health
ISSN: 0003-4819
Year: 1991
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Recent age-related trends in the use of thrombolytic therapy in patients who have had acute myocardial infarction
Article Abstract:
There appears to be a trend towards increased use of clot dissolving, or thrombolytic, drug therapies in older patients following a heart attack. However, younger patients tend to receive these drugs more frequently than older patients. Researchers analyzed the rates of thrombolytic drug therapy use over a 4-year (yr) period in 350,755 patients following a heart attack. Half of the patients younger than 55 yrs received thrombolytic drug therapy while only 7.4% of the patients older than 85 yrs received this treatment. The use of thrombolytic drug therapy increased by 34% over the 4-yr time period among patients 85 yrs and older, particularly among women. The rates of other procedures, including bypass surgery, visualizing blocked blood vessels, and widening of narrowed or blocked blood vessels, was significantly lower in patients older than 85 yrs (1.4%, 3.6%, and 9.8% respectively) as compared to patients younger than 55 yrs (11.1%, 31.2%, and 72.5% respectively).
Publication Name: Annals of Internal Medicine
Subject: Health
ISSN: 0003-4819
Year: 1996
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