BACKGROUND: Using the exercise ECG for diagnosing coronary artery disease (CAD) is hampered by the occurrence of false-positive (FP) ST-segment depression. Because it is known that the recovery ST-T time-course in CAD differs from that in FP subjects, the ST slope may help discriminate FP from true-positive (TP) results. METHODS AND RESULTS: Treadmill digitized ECG from patients with significant ST-segment depressions and normal resting ECG were analyzed in 134 patients with CAD on angiography (>50% narrowing) and reversible perfusion defects (TP group), and 64 subjects with normal perfusion (FP group) on exercise single photon emission computed tomography. The ST slope between the J-point and J(80) was measured every minute up to 6-min postexercise. The ST slope was significantly higher in FP than in TP at peak exercise, and at postexercise 1-, 2- and 3-min (p<0.01, all). Thereafter, it gradually increased in TP, while monotonically decreasing in FP. Its decrease from 3- to 6-min could correctly diagnose 88% of FP subjects, whereas it was found in only 19% of TP patients (total accuracy 83%). CONCLUSIONS: The ST slope change from early to late recovery is a simple yet reliable marker for discriminating FP from TP ST-segment responses in subjects with a normal resting ECG.
BACKGROUND: Using the exercise ECG for diagnosing coronary artery disease (CAD) is hampered by the occurrence of false-positive (FP) ST-segment depression. Because it is known that the recovery ST-T time-course in CAD differs from that in FP subjects, the ST slope may help discriminate FP from true-positive (TP) results. METHODS AND RESULTS: Treadmill digitized ECG from patients with significant ST-segment depressions and normal resting ECG were analyzed in 134 patients with CAD on angiography (>50% narrowing) and reversible perfusion defects (TP group), and 64 subjects with normal perfusion (FP group) on exercise single photon emission computed tomography. The ST slope between the J-point and J(80) was measured every minute up to 6-min postexercise. The ST slope was significantly higher in FP than in TP at peak exercise, and at postexercise 1-, 2- and 3-min (p<0.01, all). Thereafter, it gradually increased in TP, while monotonically decreasing in FP. Its decrease from 3- to 6-min could correctly diagnose 88% of FP subjects, whereas it was found in only 19% of TPpatients (total accuracy 83%). CONCLUSIONS: The ST slope change from early to late recovery is a simple yet reliable marker for discriminating FP from TP ST-segment responses in subjects with a normal resting ECG.
Authors: Mitalee P Christman; Marcio Sommer Bittencourt; Edward Hulten; Ekta Saksena; Jon Hainer; Hicham Skali; Raymond Y Kwong; Daniel E Forman; Sharmila Dorbala; Patrick T O'Gara; Marcelo F Di Carli; Ron Blankstein Journal: J Am Coll Cardiol Date: 2014-02-05 Impact factor: 24.094