Risk stratification of emergency department patients with acute coronary syndromes using P-Selectin

OBJECTIVES We compared the predictive properties of P-selectin to creatine kinase, MB fraction (CK-MB) for detecting acute myocardial infarction (AMI), acute coronary syndromes (ACS) and serious cardiac events upon emergency department (ED) arrival. BACKGROUND Practioners detecting early diagnosis of ACS have focused on cardiac markers of myocardial injury. Plaque rupture/platelet aggregation precedes myocardial ischemia. Therefore, markers of platelet aggregation may detect ACS earlier than cardiac markers. METHODS Consecutive patients with potential ACS presenting to an urban university ED were identified by research assistants who screened all ED patients between November 12, 1997 and January 31, 1998. Whole blood was drawn at presentation and 1 h later and rapidly stained and fixed for membrane P-selectin assay and plasm was separated for soluble P-selectin assay. Creatine kinase, MB fraction values were determined using standard immunoassay techniques. Clinical history and hospital course were followed daily. Outcomes were AMI, ACS (AMI and unstable angina) and serious cardiac events. Receiver operator characteristic curves were derived for CK-MB, and soluble and membrane-bound P-selectin to determine the optimal cutoff values. Predictive properties were calculated with 95% confidence intervals. RESULTS total of 263 patients were enrolled. They had mean age of 56.5 ± 14 years; 52% were male. There were 22 patients with AMI; 87 patients with ACS and 54 patients with serious cardiac events. Creatine kinase, MB fraction had higher specificity for detection of AMI, ACS and serious cardiac events than both soluble and membrane-bound P-selectin. At the time of ED presentation, the specificity of CK-MB, and soluble and membrane-bound P-selectin for AMI was 91% versus 76% versus 71%; for ACS, 95% versus 79% versus 71%, and for serious cardiac events, 91% versus 76% versus 72% (p < 0.05). The sensitivities for AMI were 50% versus 45% versus 32%; for ACS, 26% versus 35% versus 30%, and for serious cardiac events, 29% versus 35% versus 36%. CONCLUSIONS Although theoretically attractive, the use of soluble and membrane-bound P-selectin for risk stratification of chest pain patients at the time of ED presentation does not appear to have any advantages over the use of CK-MB.