USE OF CARDIAC TROPONIN-I AS A MARKER OF PERIOPERATIVE MYOCARDIAL-ISCHEMIA

Troponin I is a contractile protein comprising three isoforms, two rel ated to the skeletal muscle and one to the cardiac fibers. Cardiac tro ponin I (CTn I) is specific, without any cross-reactivity with the oth er two. Several studies have demonstrated its release after acute myoc ardial infarction. In contrast, CTn I never has been found in a health y population, marathon runners, people with skeletal disease, or patie nts undergoing non-cardiac operations. Thus, CTn I is a more specific marker of cardiac damage than common serum enzymes. It is also more se nsitive, allowing diagnosis of perioperative microinfarction and detec tion of acute myocardial infarction much earlier after the onset of is chemia (4 hours). Using a rapid one-step assay, we measured the releas e of CTn I in two groups of patients after operation: 20 with calcifie d aortic stenosis and normal coronary arteries (aortic valve replaceme nt group and control group) and 20 undergoing coronary artery bypass g rafting. In the overall population CTn I peaked at hour 6 and practica lly disappeared after day 5. Mean values were higher in the coronary a rtery bypass grafting group. In the aortic valve replacement group, a positive correlation was found between aortic cross-clamping time and CTn I, which is a reliable marker of cardiac ischemia during heart ope rations and can be used to evaluate cardioprotective procedures.