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 (Tl)-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 > or = 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 Tl-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.