Admission troponin T level predicts clinical outcomes, TIMI flow, and myocardial tissue perfusion after primary percutaneous intervention for acute ST-segment elevation myocardial infarction

Background-In ST-segment elevation myocardial infarction, a troponin T grea ter than or equal to0.1 mug/L on admission indicates poorer prognosis despi te early reperfusion. To evaluate the underlying reason, we studied the val ue of cardiac troponin T (cTnT) for prediction of outcomes, epicardial bloo d flow, and myocardial reperfusion after primary percutaneous intervention. Methods and Results-Patients (n = 140) admitted within 12 hours after onset of symptoms were stratified by admission cTnT. Epicardial and myocardial r eperfusion were graded by the TIMI score and by measurement of relative inc reases of myoglobin, cTnT, and creatine kinase (CK)-MB 60 minutes after rec analization, respectively. cTnT was positive in 64 patients (45.7%) and was associated with longer median time intervals to admission (5.5 versus 3.5 hours, P <0.001) and higher mortality rates after 30 days (12.5% versus 3.9 %, P=0.06) and 9 months (14% versus 3.9%, P=0.005). cTnT independently pred icted a 3.2-fold risk for incomplete epicardial reperfusion (P=0.03). In ad dition, cTnT greater than or equal to0.1 mug/L was associated with more sev erely impaired myocardial perfusion despite normal epicardial flow, as indi cated by lower 60-minute ratios of myoglobin (2.6 versus 7.6, P=0.007), cTn T (6.6 versus 29.2, P <0.001), and CK-MB (3.5 versus 21.4, P=0.002) and a t endency for less resolution of ST-segment elevations (54% versus 60%, P=0.0 8). Conclusions-cTnT predicts poorer clinical outcomes, lower rates of postproc edural TIMI 3 flow, and more severely compromised myocardial perfusion desp ite normal epicardial flow. Thus, a cTnT-positive patient may require more aggressive adjunctive therapy when treated by percutaneous coronary interve ntion. The impact of preexisting or evolving microvascular dysfunction and the effect of therapies that target myocardial perfusion require further pr ospective evaluation.