Relative contributions of a single-admission 12-lead electrocardiogram andearly 24-hour continuous electrocardiographic monitoring for early risk stratification in patients with unstable coronary artery disease

Patients with unstable coronary syndromes are a heterogeneous group with va rying degrees of ischemia and prognosis. The present study compares the pro gnostic value of a standard electrocardiogram (ECG) obtained at admission t o the hospital with the information from 24-hour continuous electrocardiogr aphic monitoring obtained immediately after admission. The admission ECGs a nd 24 hours of vectorcardiographic (VCG) monitoring from 308 patients admit ted with unstable coronary artery disease were analyzed centrally regarding standard electrocardiographic ST-T changes, ST-vector magnitude (ST-VM), a nd ST change vector magnitude episodes. End points were death, acute myocar dial infarction, and refractory angina pectoris within a 30-day follow-up p eriod. ST-VM episodes (greater than or equal to 50 mu V for greater than or equal to 1 minute) during VCG monitoring was the only independent predicto r of death or acute myocardial infarction by multivariate analysis. ST-VM e pisodes during vectorcardiography was associated with a relative risk of 12 .7 for having a cardiac event, hypertension was associated with a relative risk of 1.7, and ST depression on the admission ECG was associated with a r elative risk of 5.7. Patients with ST depression at admission had an event rate (death or acute myocardial infarction) of 17% at 30-day follow-up. Pat ients without ST depression could further be risk stratified by 24 hours of VCG monitoring into a subgroup with ST-VM episodes at similar (8%) risk an d a subgroup without ST-VM episodes at low (1%) risk (p = 0.00005). Continu ous VCG monitoring provides important information for evaluating patients w ith unstable coronary artery disease, It is recommended that patients not i nitially estimated at high risk based on the admission ECG are referred for 24 hours of VCG monitoring for further risk stratification. (C)1999 by Exc erpta Medica, Inc.