Study procedures: cardiac biomarkers
Troponin-I was determined using the Abbott/Architect stat hsTnI assay ARCHITECT i2000SR Diagnostic System (Abbott) and measured by chemiluminescent microparticle immunoassay (CMIA). The limit of detection ranged from 1.1 to 1.9 ng/L, and the coefficients of variation below 10% was 4.7 ng/L. For patients with hsTnI level below 2.0 ng/L, we defined the level as 1.9 ng/L and used this number for analysis. The gender-specific 99th percentile for female was 15.6 ng/L. NT-proBNP was evaluated with electrochemiluminescence immunoassay by using the Cobas e601 system (Roche Diagnostics). The analytical measurement range of NT-proBNP was 5–35,000 pg/mL. The NT-proBNP level more than 125 ng/L indicated an elevation in cardiac filling pressure