Abstract
BACKGROUND: The early diagnosis of acute myocardial infarction (AMI) remains challenging, especially for institutions without the high-sensitive cardiac troponin (hs-cTn) assay. Herein, we aim to assess the value of creatine kinase-myocardial band isoenzyme (CK-MB) combined with different cardiac troponin (cTn) assays in AMI diagnosis. METHODS: This multicenter, observational study included 3,706 patients with acute chest pain from September 1, 2015, to September 30, 2017. We classified the participants into three groups according to the cTn assays: the point-of-care cTn (POC-cTn) group, the contemporary cTn (c-cTn) group, and hs-cTn group. The diagnostic value was quantified using sensitivity and the area under the curve (AUC). RESULTS: Compared to the single POC-cTn/c-cTn assays, combining CK-MB and POC-cTn/c-cTn increased the diagnostic sensitivity of AMI (56.1% vs. 63.9%, P<0.001; 82.7% vs. 84.3%, P=0.025). In contrast, combining CK-MB and hs-cTn did not change the sensitivity compared with hs-cTn alone (95.0% vs. 95.0%, P>0.999). In the subgroup analysis, the sensitivity of combining CK-MB and c-cTn increased with time from symptom onset <6 h compared with c-cTn alone (72.8% vs. 75.0%, P=0.046), while the sensitivity did not increase with time from symptom onset >6 h (97.5% vs. 98.3%, P=0.317). The AUC of the combination of CK-MB and POC-cTn significantly increased compared to the single POC-cTn assay (0.776 vs. 0.750, P=0.002). The AUC of the combined CK-MB and c-cTn/hs-cTn assays did not significantly decrease compared with that of the single c-cTn/hs-cTn assays within 6 h. CONCLUSIONS: The combination of CK-MB and POC-cTn or c-cTn may be valuable for the early diagnosis of AMI, especially when hs-cTn is not available.