Introduction:
Cardiac troponins are the preferred biomarkers of myocardial injury. More sensitive assays led to the detection of circulating troponins not only in myocardial infarction, but also in apparently healthy subjects after prolonged exercise.
Hypothesis:
In the era of highly sensitive troponin T (hs-TnT) tests we assesed the hypothesis that brief but intense exercise during diagnostic tests might cause elevated troponin levels in patients with stable coronary artery disease (CAD).
Methods:
Seventy-two patients (71% male, age 64±10 years) with documented CAD, LVEF >45%, normal renal function and normal baseline hs-TnT levels (<14 ng/l) underwent myocardial perfusion imaging (MPI, Tc-99m sestamibi) using bicycle stress test (n=19) or adenosine stimulation (n=55). Hs-TnT levels were detected immediately before and immediately after stress, and again after 4 hours and 24 hours. The extent of stress-induced myocardial ischemia was estimated from perfusion scores derived from single-photon emission computed tomography (SPECT) post stress and rest images. Significant reversible myocardial ischemia was prospectively defined as regional perfusion abnormality ≥10% of the left ventricular myocardium.
Results:
Transient elevations of hs-TnT levels above the normal limit occurred in 5/72 patients (7%) after diagnostic stress testing with a peak level at 4 hours after stress. Hs-TnT elevations were more common in patients with stress-induced myocardial ischemia (3/12, 25%) compared to patients without ischemia (2/60, 3%; p=0.038). However, no relation between peak hs-TnT levels and the extent of reversible myocardial ischemia was found (r=-0.16, n=72, p=NS). Furthermore, peak hs-TnT levels were similar with both types of stress (bicycle 6.6 [4.0 – 10.5] pg/l versus adenosine 5.1 [3.1 – 8.6] pg/l, median [IQR]).
Conclusions:
Transient hs-TnT elevations are quite common after diagnostic stress testing and occur more frequently in patients with documented reversible ischemia. No relation between peak hs-TnT levels and the extent of reversible myocardial ischemia at MPI was obtained. In conclusion this suggests that hs-TNT elevation during stress testing depends on other factors then those leading to SPECT-detected myocardial ischemia.
Highly sensitive troponin I assay in the diagnosis of coronary artery disease in patients with suspected stable angina
