EARLY CONTINUOUS ST SEGMENT MONITORING IN UNSTABLE ANGINA - PROGNOSTIC VALUE ADDITIONAL TO THE CLINICAL CHARACTERISTICS AND THE ADMISSION ELECTROCARDIOGRAM

Background and objective-In unstable angina, clinical characteristics, resting electrocardiography, and early continuous ST segment monitori ng have been individually reported to identify subgroups at increased risk of adverse outcome. It is not known, however, whether continuous ST monitoring provides additional prognostic information in such a set ting. Design-Observational study of 212 patients with unstable angina without evidence of acute myocardial infarction admitted to district g eneral hospitals, who had participated in a randomised study comparing heparin and aspirin treatment versus aspirin alone. Methods-Clinical variables and a 12 lead electrocardiogram (ECG) were recorded at admis sion, and treatment was standardised to include aspirin, atenolol, dil tiazem, and intravenous glyceryl in addition to intravenous (randomise d treatment). Continuous ST segment monitoring was performed for 48 h and all inhospital adverse events were recorded. Results-The admission ECG was normal in 61 patients (29%), showed ST depression in 59 (28%) (17 greater than or equal to 0.1 mV), and T wave changes in a further 69 (33%). The remaining 23 had Q waves (18), right bundle branch bloc k (four), or ST elevation (one). During 8963 h of continuous ST segmen t monitoring (mean 42.3 h/patient), 132 episodes of transient myocardi al ischaemia (104 silent) were recorded in 32 patients (15%). Forty pa tients (19%) had an adverse event (cardiac deaths (n = 3), non-fatal m yocardial infarction (n = 6) and, emergency revascularisation (n = 31) ). Both admission ECG ST depression (P = 0.02), and transient ischaemi a (P < 0.001) predicted an increased risk of non-fatal myocardial infa rction or death, while no patients with a normal ECG died or had a myo cardial infarction. Adverse outcome was predicted by admission ECG ST depression (regardless of severity) (odds ratio (OR) 3.41) (P < 0.001) , and maintenance beta blocker treatment (OR 2.95) (P < 0.01). A norma l ECG predicted a favourable outcome (OR 0.38) (P = 0.04), while T wav e or other ECG changes were not predictive of outcome. Transient ischa emia was the strongest predictor of adverse prognosis (OR 4.61) (P < 0 .001), retaining independent predictive value in multivariate analysis (OR 2.94) (P = 0.03), as maintenance beta blocker treatment 2.85) (P = 0.01) and admission ECG ST depression, which showed a trend towards independent predictive value (OR 2.11) (P = 0.076). Conclusions-Patien ts with unstable angina and a normal admission ECG have a good prognos is, while ST segment depression predicts an adverse outcome. Transient myocardial ischaemia detected by continuous ST segment monitoring in such patients receiving optimal medical treatment provides prognostic information additional to that gleaned from the clinical characteristi cs or the admission ECG.