Relationship between dobutamine echocardiography and the elevation of cardiac troponin I in patients with acute coronary syndromes.

An elevated cardiac troponin I (cTnI) and a positive dobutamine echocardiography are powerful predictors for future cardiac events in patients with coronary artery disease. Investigating their correlation also should be helpful in understanding their clinical usefulness in evaluating patients with acute coronary syndromes (ACS). Dobutamine echocardiography and a blood sampling for cTnI were performed on 117 patients with ACS 70 +/- 2 hours after arriving at the hospital. CTnI was considered elevated when its value was greater than 2.0 ng/ml. Dobutamine echocardiography was positive in 86 (73.5%) patients, and cTnI was elevated in 37 (31.6%). The occurrence of positive dobutamine echocardiography in patients with elevated cTnI was significantly higher than in those with normal cTnI (86.5% vs. 67.5%, P = 0.042). More patients in the elevated cTnI group developed myocardial ischemia before or at the stage of dobutamine 20 microg/kg/min (43.2% vs. 15%, P = 0.002). When compared with patients with normal cTnI, patients with elevated cTnI had a lower ischemic threshold during dobutamine echocardiography, and more frequently had baseline echocardiographic wall-motion abnormalities, a history of myocardial infarction, and a positive dobutamine echocardiography. Using multivariate analysis, we found that only a lower dobutamine echocardiography ischemic threshold (P = 0.0008) and baseline wall-motion abnormalities (P = 0.0004) were associated independently with the elevation of cTnI. Our results suggest that in patients with ACS, dobutamine echocardiography can offer information regarding wall-motion abnormalities and ischemic threshold, which are suggested to have a clinical value similar to elevated cTnI.