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Very Early Thrombolytic Therapy in Suspected Acute Myocardial Infarction - TEAHAT
Description:
TEAHAT was a randomized, placebo-controlled trial of tissue-type plasminogen activator (t-PA) versus placebo in patients with suspected acute myocardial infarction (AMI). Electrocardiographic criteria were not required.
Hypothesis:
T-PA will be associated with beneficial effects in patients with suspected AMI.
Study Design
Study Design:
Patients Screened: 479
Patients Enrolled: 352
Mean Follow Up: 30 days
Mean Patient Age: <75
Female: 24
Patient Populations:
Age <75 years, time of chest pain <165 minutes but >15 minutes, and pain highly suggestive of AMI
Exclusions:
Inability to give informed consent and contraindication to thrombolytic therapy
Primary Endpoints:
Infarct size determined by serum LDH activity, left ventricular function by radioangiography, and exercise capacity at 30 days
Secondary Endpoints:
Accuracy of diagnosis, mortality, and adverse events
Drug/Procedures Used:
Patients were recruited in Goteborg, Sweden on admission to one of two hospital emergency rooms or at home when an ambulance arrived. A cardiologist accompanied the ambulance to patients' homes when AMI was suspected. Patients suspected of having an AMI were enrolled without using electrocardiographic criteria for eligibility. Patients were randomized to either t-PA (100 mg) or placebo.
Concomitant Medications:
Before start of infusion, all patients received 5000 IU of heparin. Patients with a second episode of chest pain after therapy could receive an additional dose of the study medication. Heparin was transitioned to oral anticoagulation and patients were maintained with an international normalized ratio of 2.24-4.01 for 30 days.
Aspirin was given to all patients in a dose of 125 mg per day and continued for one year. All patients without contraindications received beta blockade with metoprolol 15 mg IV immediately after the start of the trial, and then 200 mg orally for at least one year.
Principal Findings:
A total of 479 patients met inclusion criteria and were evaluated for participation. Of these, 127 were excluded based on physical exam, history, or other criteria. A total of 352 patients were randomized. The groups were well matched at baseline in terms of age, gender, past medical history, clinical status, and time from onset of symptoms. Treatment was initiated at home in 101 patients (29%). The mean difference in time from symptom onset to start of treatment between prehospital and hospital patients was 36 minutes (83 minutes prehospital vs. 119 minutes hospital).
ST-segment elevation was present on the initial ECG in 200 of the randomized patients. In this group, 88% developed a definite AMI during the first three days. Most of the remaining patients in this group were diagnosed as having ischemic heart disease. Of the 152 patients without ST-segment elevation, 21% developed a definite AMI. In this group, most of the patients (53%) were diagnosed as having angina pectoris, and 9% were diagnosed with a noncardiac disorder.
Mean maximum serum lactate dehydrogenase (LDH) concentration was significantly lower in the t-PA arm (9.0 vs. 13.3 ukat/l, p=0.004). This difference was significantly more emphasized in patients with ST-segment elevation at entry (for interaction, p=0.03). Resting global ejection fraction at 30 days was significantly higher among those in the t-PA arm (0.59 vs. 0.55, p<0.05). The difference in left ventricular ejection fraction was only seen among patients with initial ST-segment elevation. At exercise bicycle testing at 30 days, no differences in exercise capacity were detected among the two groups (exact data not reported). Based on the stress testing, criteria for further investigation with angiography was present in 18% of the placebo group and 23% of the t-PA group (p not reported).
There were 18 deaths (10.3%) in the placebo group and 11 deaths (6.2%) in the t-PA group (p=NS) at 30 days. Gastrointestinal bleeding occurred in 19 t-PA patients and five placebo patients. No cerebral hemorrhages occurred and only three patients in the placebo group required blood transfusions.
Interpretation:
Among patients with a strong suspicion of AMI, very early administration of t-PA was associated with a decreased infarct size and an increased ejection fraction compared to placebo without an associated increase in adverse events. The benefit is limited to patients with ST-segment elevation on initial ECG. This study suggests that thrombolysis can be given before hospital admission without additional risks.
References:
Very early thrombolytic therapy in suspected acute myocardial infarction. The Thrombolysis Early in Acute Heart Attack Trial Study Group. Am J Cardiol 1990;65:401-7.
Keywords: Myocardial Infarction, Coronary Disease, Emergency Service, Hospital, Electrocardiography, Blood Transfusion, Chest Pain, Plasminogen Activators, Stroke Volume, Lactate Dehydrogenases, Tissue Plasminogen Activator, Cerebral Hemorrhage, Exercise Test
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