Analysis of serum cardiac biomarkers and treadmill exercise test-electrocardiogram for the diagnosis of coronary heart disease in suspected patients

The serum proteins creatine kinase isoenzyme MB (CKMB) and cardiac troponin T are classic biomarkers of cardiac ischemic damage in clinical practice, which can sensitively detect myocardial necrosis, while other two serum proteins, ischemia-modified albumin and N-terminal pro-B-type natriuretic peptide (NT-proBNP), have been recently identified as novel biomarkers of myocardial ischemia. In this study, the four biomarkers were detected in sera from 44 eligible patients with suspected coronary heart disease (CHD) before and after treadmill exercise test (TET), electrocardiogram (ECG) was measured during TET (TET-ECG) and invasive examination of coronary angiography (CAG), which is the 'gold standard' of CHD diagnosis, was also performed. For CAG, 25 patients were positive and 19 were negative, whereas for TET-ECG the numbers were 19 and 25, respectively. Among these four biomarkers, the NT-proBNP level in CAG positive group was much higher than those in CAG negative group both before and after TET, with statistical significance before TET (P=0.008). Furthermore, according to receiver operating characteristic (ROC) curve, the serum biomarker NTproBNP showed diagnostic effect of CHD and its cutoff value was 67 pg/ml, thus 30 of the patients in this study were NT-proBNP positive and 14 were negative. And it was found that NT-proBNP obviously enhanced the sensitivity of examinations whether analyzed alone or in combination with TET-ECG. More importantly, all the patients who were negative in both NT-proBNP and TET-ECG tests turned out to be CAG negative, which means that the combination of these two non-invasive examinations might take the place of invasive examination of CAG for CHD diagnosis. Further studies with more patients are warranted to validate the findings in this paper.