Exercise stress test and comparison of ST change with cardiac nucleotide catabolite production in patients with coronary artery disease.

Background: Uridine (Ur) and hypoxanthine (Hx) are the major end products of ischemic nucleotide breakdown in the human heart. Hypoxanthine is further metabolized to uric acid (UA). The aim of the study was the evaluation of whether changes in nucleotide concentrations during exercise correlate with electrocardiography (ECG) changes, and the severity of coronary artery disease (CAD).
Methods: Twenty-nine males with CAD and 11 controls without CAD (mean age 56.1 vs. 51.45) were subjected to treadmill exercise. The test was considered positive if ECG showed more then 1 mm ST segment depression. Venous blood samples taken before and 10 minut after the exercise were analysed by high performance liquid chromatography.
Results: Twenty-two out of 29 patients with CAD and 6 of 11 in the control group had abnormal exercise stress tests according to ECG criteria only. Mean Ur was positive in the CAD group and negative in the control group (0.45 SEM +/- 0.09 microM/L vs. -0.43 SEM +/- 0.21 microM/L, p < 0.0001). UA was positive in the CAD group (15.31 SEM +/- 5.52 microM/L) and negative in the control group (15.31 SEM +/- 5.52 microM/L vs. -48.18 SEM +/- 13,8 microM/L, p < 0.00001); Hx increased in both groups, and the change was not significantly different. Correlations of CAD-index with ST depression, Ur and UA, were: r = 0.43 (p < 0.005), r = 0.62 (p < 0.001), and r = 0.39 (p < 0.01), respectively. Sensitivity of any increase of uridine was superior to 1.5 mm ST depression during exercise.
Conclusions: Blood Ur and UA concentration changes during exercise correlate with severity of CAD. We observed slightly greater accuracy of uridine change in comparison to ST changes, thus being a possible new tool in diagnosis of CAD. (Cardiol J 2007; 14: 573-579).