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Effect of early intravenous rt-PA on infarct size estimated from serum enzyme activity: results from the TEAHAT Study
M Risenfors1, M Hartford, M Dellborg
1Department of Medicine I, Sahlgrenska Hospital, Göteborg, Sweden.
Insights
Early administration of recombinant tissue plasminogen activator (rt-PA) significantly reduced infarct size in acute myocardial infarction patients. This effect was most notable in those with ST-elevation on their electrocardiogram.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Acute myocardial infarction (AMI) is a leading cause of mortality.
- Early reperfusion therapy is crucial for limiting infarct size and improving outcomes.
- Assessing infarct size indirectly through biomarkers aids in treatment evaluation.
Purpose of the Study:
- To evaluate the effect of early intravenous recombinant tissue plasminogen activator (rt-PA) compared to placebo on infarct size in patients with suspected AMI.
- To identify patient subgroups that benefit most from early rt-PA treatment.
Main Methods:
- A double-blind, placebo-controlled trial involving 319 patients with suspected AMI.
- Treatment with rt-PA or placebo initiated within 3 hours of symptom onset.
- Infarct size assessed by measuring serum lactate dehydrogenase isoenzyme 1 (LD 1) activity.
Main Results:
- Maximum LD 1 activity was reduced by 32% in the rt-PA group (9.0 mu kat l-1) compared to placebo (13.3 mu kat l-1) (P = 0.001).
- The reduction in LD 1 activity was significant only in patients with ST-elevation on their initial electrocardiogram.
- Benefits were more pronounced in patients with prior ischemic heart disease, above median age, and shorter treatment delay.
Conclusions:
- Very early intravenous rt-PA treatment effectively limits indirect signs of infarct size in acute myocardial infarction.
- The therapeutic benefit of rt-PA for infarct size reduction is primarily observed in patients with ST-segment elevation myocardial infarction.
Abstract:
In 319 patients who participated in a double-blind trial to evaluate the effect of early rt-PA administration compared to placebo in suspected acute myocardial infarction, infarct size was assessed from analyses of serum activity of lactate dehydrogenase isoenzyme 1 (LD 1). Treatment was always started less than 3 h after the onset of symptoms, with one-third of the patients' treatment being initiated outside the hospital. The maximum activity of LD 1 was reduced by 32%, from 13.3 mu kat l-1 in placebo to 9.0 mu kat l-1 in rt-PA treated patients (P = 0.001). A reduction in LD-1 activity after rt-PA treatment was restricted to patients with ST-elevation in the initial electrocardiogram, and was more pronounced in patients with previous ischaemic heart disease, above median age, and in those with a shorter delay in initiation of treatment. We conclude that very early intravenous treatment with rt-PA limits indirect signs of infarct size. The effect appears to be restricted to patients with ST-segment elevation in their initial electrocardiogram.