USEFULNESS OF HOLTER MONITORING FOR DETECTING MYOCARDIAL-ISCHEMIA IN PATIENTS WITH NONDIAGNOSTIC EXERCISE TREADMILL TEST

To determine if Hotter monitoring can predict cardiac risk in patients when the exercise test is nondiagnostic, a total of 90 eligible patie nts were monitored for 24 hours after their exercise test without alte rations in baseline medications. Prospective follow-up was obtained an d event were confirmed by investigators unaware of subjects' clinical data. Nineteen patients (21%) had a total of 71 episodes of ST depress ion, all of which were asymptomatic. During a mean follow-up of 719 da ys, there were 10 patients with adverse events: 3 with cardiac deaths, 3 with nonfatal myocardial infarctions, and 4 with admissions for uns table angina. Of the 10 adverse events, 9 occurred in the group of 19 with ST depression detected by Holter (relative risk 34, 95% confidenc e interval 10 to 114). The sensitivity of ST depression was the specif icity 88%, the predictive positive value 47%, and the predictive negat ive value 99%. In a multivariate Cox proportional-hazards model that c ontrolled for prior history of coronary artery disease, hypercholester olemia, and all exercise test variables, the presence of ST depression detected by Holter was the only independent predictor of outcome. In patients with nondiagnostic exercise tests, ST depression detected by Hotter monitoring identified those with an increased risk of adverse c ardiac events. The absence of ST depression detected by Holter was a u seful predictor of low risk.