Troponin-positive, CK-MB-negative acute myocardial infarction: clinical, electrocardiographic and angiographic characteristics.

Objectives: We assessed the clinical, electrocardiographic (ECG) and angiographic characteristics of patients with acute coronary syndrome, increased troponin I (cTn-I) levels and normal creatine kinase levels.

Background: Cardiac troponins are part of the new definition of acute myocardial infarction by the European Society of Cardiology and the American College of Cardiology. However, there are limited data regarding the angiographic characteristics of these patients.

Methods: Between 1/2002 and 7/2004, a total of 50 consecutive cTn-I-positive, creatine kinase-negative patients were admitted to the intensive coronary care unit of our institution and underwent coronary angiography.

Results: The mean cTn-I level was 10.7 +/- 13.5 mcg/L and the mean creatine kinase was 106 +/- 40 U/L (normal < 180 U/L). Admission ECG showed inverted T-waves in 42% of patients, ST-segment elevation in 36%, ST-segment depression in 20% and a normal ECG in 20%. A total of 168 lesions were analyzed, and 47 (28%) of these were considered to be nonsignificant lesions (< 50% diameter stenosis). Seven patients had normal or nonsignificant coronary artery disease (CAD) and the remainder had at least single-vessel disease. There were 12 patients with stenosis in the left main coronary artery, 6 patients had a visible clot in the artery, 5 of them located in the right coronary artery and 1 in the left circumflex. A total of 37 patients underwent coronary revascularization, the majority (62%) percutaneously, the rest were treated conservatively.

Conclusions: Increased cTn-I levels in the presence of rest pain and normal creatine kinase is not a spurious finding, but may actually be a marker of advanced CAD. However, some of these patients may also have nonsignificant CAD.