Increase in the ΔSTΔheart rate (HR) index: A new predictor of restenosis after successful percutaneous transluminal coronary angioplasty

after percutaneous transluminal coronary angioplasty (PTCA), we evaluated the usefulness of the ΔSTΔheart rate (HR) index derived from serial exercise treadmill tests. Exercise treadmill tests were performed by 125 patients with single-vessel coronary artery disease before and several days after PTCA, and just before followup angiography 3 to 12 months later. Simple HR-adjusted indexes of ST-segment depression during exercise (ΔSTΔHR index) were derived. We compared the usefulness of the increase in ΔSTΔHR index at follow-up over the value obtained several days after PTCA for prediction of restenosis with that of a positive exercise treadmill test and a positive thallium scintigram at follow-up. At follow-up, 47 of the 125 patients showed restenosis. The ΔSTΔHR index increased in 43 of 47 patients in the restenosis group and in 18 of 78 patients without restenosis (p < 0.0001). Separate analysis of each criterion revealed the following respective values for sensitivity, specificity, and positive and negative predictive values for prediction of restenosis: increased ΔSTΔHR index at follow-up: 91%, 77%, 70%, and 94%; positive exercise treadmill test: 83%, 65%, 59%, and 86%; and positive thallium scintigram: 79%, 78%, 69%, and 86%. The increased ΔSTΔHR index had a significantly (p < 0.05) higher sensitivity than the positive thallium scintigram and a significantly (p < 0.01) higher specificity than the positive exercise treadmill test. An increased ΔSTΔHR index at follow-up identifies subgroups of patients who are at high risk for restenosis after PTCA.