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A relatively recent advance in the treatment of acute myocardial infarction (MI, heart attack) is the use of thrombolytic drugs to dissolve the clot blocking the coronary artery. One thrombolytic agent is tissue plasminogen activator (tPA). While tPA is effective at dissolving the clot in 70 to 89 percent of patients, it can induce hemorrhage as a side effect. Clinical studies of tPA have noted bleeding in 15 to 33 percent of patients, with a serious form of bleeding, intracranial (brain) hemorrhage, occurring in 0.6 to 1.6 percent. The cases of six patients who were treated with tPA after an MI and developed intracranial hemorrhage are discussed. Hemorrhage began between two and 14 hours after the infusion of tPA was finished; all patients also received heparin, an anticoagulant drug. Four of the patients died from massive intracranial hemorrhage, and it was concluded that several factors may have contributed to this response. The medication tPA, or the combination of tPA and heparin, was considered a potential cause, as was a possible vascular abnormality at the site of the bleeding. Hypertension was not implicated as a contributing factor. In theory, tPA should be less likely to cause unintended bleeding than other thrombolytic agents due to its effects on blood components, yet these cases suggest that the risk may not be as small as expected. Continued reporting of intracranial hemorrhage in patients receiving tPA is needed so that the mechanism, and potential patient risk factors, can be identified. Use of heparin in combination with tPA may not be warranted if no benefit can be demonstrated and the risk for bleeding is shown to be enhanced. (Consumer Summary produced by Reliance Medical Information, Inc.)

One of the major causes of myocardial infarction (damage to the heart muscle from lack of blood supply), is a blood clot caught in one of the heart's arteries. Recently, drugs known as thrombolytic agents have become available that rely upon the action of enzymes to dissolve clots, and these are being used with success in the management of myocardial infarction. However, hemorrhage can be a side effect of treatment for clots, and the effects can be severe, as in the case of cerebral hemorrhage, which occurs in 0.2 percent to 0.6 percent of the cases. A review of thrombolytic therapies for myocardial infarction reveals that careful selection of patients and the avoidance of unnecessary procedures can reduce the risk of hemorrhage. Patients with bleeding ulcers, previous stroke or intracranial lesions, and other conditions predisposing towards bleeding should not be treated with thrombolytics. Since more than 70 percent of reported bleeding episodes occur at puncture sites, care should be taken when drawing blood or inserting catheters, and it is recommended that jugular or subclavian sites be avoided. If puncture is unavoidable, extended pressure, at least 15 minutes, should be applied to the site. In addition, other medications being taken should be checked for their effects on clotting. Careful attention to detail can reduce risk, but the internist opting for thrombolytic therapy must be prepared to make quick life-saving decisions when faced with bleeding complications in the myocardial infarct patient. (Consumer Summary produced by Reliance Medical Information, Inc.)