Long-term prognostic value and therapeutic implications of continuous ST-segment monitoring in acute coronary syndrome

Background In patients with acute coronary syndromes (ACS), recurrent ischemia detected by continuous electrocardiographic monitoring portends a poor outcome. We sought to investigate (1) the additional long-term prognostic value of ST-segment monitoring beyond the validated Global Registry of Acute Coronary Events (GRACE) risk score in ACS and (2) whether ST-segment monitoring can identify patients who benefit from early revascularization. Methods We determined the GRACE risk score (a validated predictor of inhospital mortality) in 681 non–ST-elevation ACS patients enrolled in the Integrilin and Enoxaparin Randomized Assessment of Acute Coronary Syndrome Treatment trial. Continuous ST-segment monitoring in the first 48 hours was analyzed by an automated algorithm and reviewed by a blinded cardiologist. Clinical outcomes were centrally adjudicated in a blinded fashion. Results ST-segment shifts were present in 19.1% of 681 patients. After a median follow-up of 30 months, patients with ST-segment shifts had a higher risk of death (17.7% vs 5.8%, log-rank P < .001) and death or myocardial infarction (MI) (24.6% vs 11.1%, log-rank P < .001). In multivariable analysis adjusting for GRACE risk score, the presence of ST-segment shifts remained an independent predictor of death (adjusted hazard ratio = 2.37, 95% CI 1.38-4.09, P = .002) and death/MI (adjusted hazard ratio = 1.93, 95% CI 1.25-3.00, P = .003). Inhospital revascularization was independently associated with a lower risk of death/MI among patients with ST-segment shifts but not among those without (P for interaction = .02). Conclusions Continuous ST-segment monitoring provides incremental prognostic information beyond the validated GRACE risk score determined on presentation and identifies high-risk patients who benefit from early revascularization. This simple and valuable clinical tool may be useful in the routine management of ACS.