Analysis of ST/HR hysteresis improves long-term prognostic value of exercise ECG test

BackgroundST/HR hysteresis is one of the better diagnostic exercise ECG variables for coronary artery disease. This study evaluates the long-term prognostic value of ST/HR hysteresis in predicting acute myocardial infarction (AMI) and all-cause mortality in men and women.MethodsThe study population consisted of 8317 patients who had undergone routine exercise test on bicycle ergometer at one Swedish centre. Information on AMI and all-cause mortality was obtained from national Swedish registers covering a mean follow-up period of 9.5 years.ResultsThe adjusted hazard ratio for AMI at a diagnostic cut point of ≤ − 20 µV for ST/HR hysteresis was 1.88 (95% CI, 1.62–2.17) in men and 2.31 (95% CI, 1.83–2.91) in women. For all-cause death the adjusted hazard ratio was 1.72 (95% CI, 1.52–1.96) in men and 1.90 (95% CI, 1.57–2.29) in women. The corresponding hazard ratios for ST-segment depression with horizontal or down-sloping ST-segment, ST-segment depression, ST/HR index, and ST/HR slope were lower. For comparison, the adjusted hazard ratio for AMI using maximal workload in percent of predicted was 2.02 (95% CI, 1.77–2.32) in men and 2.14 (95% CI, 1.71–2.67) in women. Area under the ROC curves for prediction of AMI was significantly larger using ST/HR hysteresis than using any of three other evaluated ECG indicators.ConclusionsST/HR hysteresis appears to improve the prognostic ability of an exercise ECG test for AMI and all-cause mortality in a long-term perspective compared to conventional ST-segment and ST/HR indicators in both genders and clearly more markedly in women.