Does exercise-induced severe ischaemia result in elevation of plasma troponin-T level in patients with chronic coronary artery disease?

Objective - It has been reported that the loss of cell membrane integrity during severe reversible ischaemia results in elevation of plasma troponin T (TnT) in unstable angina. We investigated whether TnT is released into circulation during severe ischaemia (e.g. on treadmill exercise testing) in patients with chronic coronary artery disease (CAD). Methods and results - The study comprised 54 patients who had angiographically documented CAD (22 of them had a prior history of myocardial infarction) and 18 normal subjects., All cases underwent exercise thallium (TI)-201 SPECT myocardial perfusion imaging. Blood samples for TnT analysis were obtained for each patient at pre-exercise, immediately after and 12 hours after exercise. SPECT images were divided into 20 segments. Patients with redistribution defects ! 5 were considered to have severe ischaemia. Sixteen patients had severe ischaemia on SPECT images. The mean TnT levels of the patients with severe ischaemia at pre-exercise, immediately after and 12 hours after exercise were 0.009 +/- 0.008,0.012 +/- 0.009 and 0.010 +/- 0.010 ng/ml, respectively. In normal subjects the mean TnT levels were 0.012 +/- 0.009, 0.010 +/- 0.009, 0.010 +/- 0.010 ng/ml, respectively. There was no significant difference neither between the two groups nor within each group with respect to pre-exercise and post-exercise TnT results. All TnT levels were within normal limits (< 0.1 ng/dl). Additionally, when the patients were grouped according to other SPECT variables (patients with reversible defects vs. fixed defects; patients with increased lung uptake of TI-201 vs. without lung uptake; patients with transient left ventricle dilatation vs. those without) and angiographic findings (patients with. multivessel disease vs. normal subjects), there were no significant differences with respect to pre-exercise and post-exercise TnT results. Conclusion - Severe ischaemia does not result in the elevation of the plasma TnT level in patients with chronic CAD.