Abstract 4865: Detection of Basal and Transient Myocardial Ischemia-Induced Cardiac Troponin Release Into Coronary Circulation by Highly Sensitive Assay
Background: Cardiac troponin is well established as a specific biomarker for cardiomyocyte necrosis in acute coronary syndromes but not in angina pectoris. However, troponin release from coronary circulation during transient ischemic attack by angina remains to be determined because of lower sensitivity of traditional troponin assay. We assessed the basal and angina-induced occurrence of troponin release using highly sensitive troponin T (TnT) assay before and after acetylcholine-induced coronary spasm.
Methods and Results: Serum cardiac TnT levels sampled from peripheral vein (PV), aortic root (Ao), and coronary sinus (CS) were measured by highly sensitive assay in 108 consecutive patients (57% men, 67±10 years) suspected of stable coronary artery disease (CAD). TnT in PV was detectable in 91.4% of the patients [9.8 (7.1, 14.7) pg/mL for median (25th, 75th percentile)]. At the baseline condition, there was significant increase in TnT levels from Ao [9.6 (6.9, 14.3) pg/mL] to CS [10.9 (7.9, 17.3) pg/mL, p<0.001] in 92.5% of patients and the difference was 1.2 (0.6, 2.5) pg/mL, which reflects basal transcardiac release of TnT. The cardiac release of TnT positively correlated with PV levels (r=0.21, p<0.05). In univariate logistic regression analysis, male gender (odds ratio [OR]; 3.65, 95% confidence interval [CI]; 1.58 – 8.47, p<0.01), presence of heart failure (OR; 3.18, 95% CI; 1.11–9.15, p<0.05), and presence of organic CAD (OR; 2.40, 95% CI; 1.05–5.47, p<0.05) were significantly correlated with elevated transcardiac TnT release (above median). Furthermore, there was significant increase in transcardiac TnT release after acetyocholine provocation test in patients with positive result of coronary spasm [7.2 (−1.8, 11.5) pg/mL, p<0.05] but not in 19 patients with negative result [0.0 (−0.5, 0.5) pg/mL, p=0.95].
Conclusions: Basal TnT release in coronary circulation was observed in most of patients suspected of CAD and the transcardiac TnT values were significantly correlated with the peripheral levels. Presence of heart failure or CAD significantly contributed to the elevated TnT release in stable states. This sensitive assay detected angina like transient myocardial ischemia-induced significant increase in transcardiac troponin release.