Pericardial cardiac troponin I release after coronary artery bypass grafting

Pericardial fluid can reflect the composition of cardiac interstitium in my ocardial ischemia. This study investigated the hypothesis that pericardial cardiac troponin I (CTnI) measurements could be a more accurate marker of p erioperative myocardial infarction (MI) than serum CTnI after coronary arte ry bypass grafting (CABG). Postoperative arterial and pericardial blood sam ples were taken in 102 subjects undergoing elective CABG allocated to one o f three groups according to the 12-lead electrocardiogram (ECG) abnormaliti es observed during the first postoperative 24 h: Group 1 = normal EGG; Grou p 2 = nonspecific ECG abnormalities; and Group 3 = perioperative Q-wave MI. Peak pericardial CTnI concentrations were much higher than peak serum conc entrations in all subjects and significantly greater in Group 3 than in Gro ups 1 and 2 (1,318 +/- 1,810 ng/mL vs 367 +/- 339 ng/mL and 558 +/- 608 ng/ mL, respectively; P < 0.01). However, no significant difference between gro ups occurred at any time for pericardial/serum CTnI ratios, indicating that time courses of CTnI were not different in pericardial fluid and serum. A significant correlation was found between serum and pericardial CTnI: conce ntrations (R = 0.70, P < 0.001). Pericardial CTnI was not more accurate tha n serum CTnI in predicting Q-wave MI as shown by the low value of the area under the receiver-operator characteristic curve (=0.71). Peak and early pe ricardial CTnI were also not accurate in predicting an increase of serum CT nI greater than a cutoff value of 19 ng/mL. Thus, pericardial CTnI measurem ents were less useful than serum CTnI measurements in the diagnosis of peri operative MI after CABG. Implications: Although cardiac troponin I concentr ations were much higher in pericardial fluid than in serum and significantl y increased in subjects who experienced perioperative Q-wave myocardial inf arction, pericardial cardiac troponin I measurements were of less value tha n serum cardiac troponin I measurements for the diagnosis of perioperative myocardial infarction after coronary artery bypass grafting and cannot be r ecommended in routine clinical practice.