EXERCISE-INDUCED ST-SEGMENT VARIABILITY MAY DISCRIMINATE FALSE-POSITIVE TESTS

The clinical value of exercise-induced variations in ST-segment depres sion and R wave amplitude in consecutive sinus beats was studied in 16 0 patients who had a positive treadmill exercise test with the Bruce p rotocol. The patients, all of whom underwent cardiac catheterization, included 100 with coronary artery disease (CAD) (group with tree posit ive test) and 60 with normal coronary arteries (group with false posit ive rest), Minimal or no exercise-induced variations in the magnitude of ST-segment depression despite variations in R wave amplitude were o bserved in 84 of the 100 patients with CAD and in only 9 of the 60 pat ients with normal coronary arteries (P <.0001). Significant exercise-i nduced variations in ST-segment depression were observed in only 16 of 100 patients with CAD and in 51 of 60 patients with normal coronary a rteries (P <.0001). The coefficient of variation of R wave amplitude w as similar in both groups (no statistical significance), while the coe fficient of variation of ST-segment depression was much greater in the patients with normal corollary arteries than in those with CAD (P <.0 001). It is concluded that variability of ST-segment depression at pea k exercise may discriminate false positive from the true positive exer cise tests, improving the diagnostic ability of the method.