Early Assessment of Reperfusion Therapy in Acute Myocardial Infarction Using Cardiac Troponin-T

Background

An earlier index of reperfusion is desirable to determine whether additional therapy is necessary for myocardial salvage. Using the washout phenomenon of biochemical markers, many investigator have reported noninvasive methods for detection coronary reperfusion in patients with acute myocardial infarction. Recently cardiac Troponin-T has been developed as a new myocardial specific marker, especially myocardial damage. The object of this study is to investigate the utility of cardiac Troponin-T for early assessment of reperfusion therapy.

Methods

The study group comprised 10 patients with acute myocardial infarction and reperfusion therapy that was initiated within 6 hours after the onset of symptoms. Blood samples were taken before treatment, every 30 min interval for 3 hours and then 6, 24, 72 hours after the onset of reperfusion therapy to measuring Troponin-T, Creatin Kinase(CK), and CK-MB level. Serum concentration of cardiac Troponin-T level was measured with immunoassed using ES-300, Boehringer Mannheim. We compared the real reperfusion that was assessed by coronary angiogram, chest pain disappearence and resolusion of St-segment elevation with an index of coronary reperfusion, the increase in Troponin-T(△ Troponin-T) 60, 90 min after repefusion therapy(Successful Reperfusion Index : Tn-T 60(90)-0>0.3 ng/ml) and the sensitivity, specificity, Positive, and negative predictive value were calculated using this threshold(Successful Reperfusion Index).

Results

1) The studied patients(M/F : 7/3, mean age 54±12 year) were treated within 3 hour with thrombolytic therapy(7 patients, t-PA) or emergency angioplasty(3 patients).

2) The cardiac Troponin-T levels in eight patients with successful reperfusion showed early peak within 24 hours after reperfusion therapy were initiated but in 2 patients without successful reperfusion showed sustained increase without early peak within 24 hours. The CK-MB levels in patients with successful reperfusion also showed early peak within 24 hours but 5 of 8 patients showed no significant increase until 2 hours after reperfusion therapy.

3) The sensivity, specificity, positive and negative predictive value for detecting reperfusion using a threshold value of 0.3 ng/ml of △ Troponin-T 90 min(60 min) after reperfusion therapy was 100%(56%), 50(100%), 89%(100%), and 100%(20%), respectively.

Conclusion

Serial measurements of cardiac Troponin-T, especially reperfusion index(0.3 ng/ml of △ Troponin-T 90 min after reperfusion therapy) are useful for early assessment of reperfusion therapy in acute myocardial infarction.