1 Novel Biomarkers of Cardiovascular Disease: Applications in Clinical 2 Practice 3 Magnus Nakrem Lyngbakken MD, PhDa*; Peder Langeland Myhre MD, PhDa; 4 Helge Røsjø MD, PhDa; Torbjørn Omland MD, PhD, MPHa 5 a 6 Heart Failure Research, University of Oslo, Oslo, Norway 7 * corresponding author Division of Medicine, Akershus University Hospital, Lørenskog, Norway and Center for 8 9 10 11 12 13 14 15 16 17 18 19 20 Key words: biomarker; cardiovascular disease; prognosis; diagnosis 21 Word count: 8943 22 Corresponding author: 23 Magnus Nakrem Lyngbakken, MD PhD 24 Division of Medicine, Akershus University Hospital, Postboks 1000, 1478 Lørenskog, Norway 25 Institute of Clinical Medicine, University of Oslo, Oslo, Norway 26 Tel: +47 93 40 88 37, Fax: +47 67 96 88 60, Email: [email protected] Text tables: 2 Figures: 1 1 1 2 1 Abbreviations 2 ACC, American College of Cardiology 3 ACS, acute coronary syndrome 4 AHA, American Heart Association 5 AMI, acute myocardial infarction 6 ANP, A-type natriuretic peptide 7 BNP, B-type natriuretic peptide 8 CAD, coronary artery disease 9 CgA, chromogranin A 10 CgB, chromogranin B 11 c-MyC, cardiac myosin binding protein-C 12 CRP, C-reactive protein 13 cTnI, cardiac troponin I 14 cTnT, cardiac troponin T 15 GDF-15, growth differentiation factor 15 16 HDL, high-density lipoprotein 17 HF, heart failure 18 hFABP, heart-type fatty acid-binding protein 19 IDI, integrated discrimination improvement 20 IL-6, interleukin 6 21 LDL, low-density lipoprotein 22 Lp-PLA2, lipoprotein-associated phospholipase A2 23 MMP-9, matrix metalloproteinase-9 24 MR-proADM, mid-regional pro-adrenomedullin 25 MR-proANP, mid-regional proANP 26 NRI, net reclassification improvement 27 ROC AUC, receiver operating characteristic area under the curve 28 sCD40L, soluble CD40 ligand 29 SgII, secretogranin II 30 ST2, suppressor of tumorigenicity 2 1 2 2 1 Abstract 2 Measurement of biomarkers has revolutionized the work-up of patients with suspected cardiovascular 3 disease. The most widely used contemporary cardiovascular biomarkers are the natriuretic peptides in 4 the diagnosis and prognosis of heart failure, and cardiac troponins in the diagnosis of acute myocardial 5 infarction. Numerous other biomarkers pertaining to diagnosis, prognosis and risk prediction have 6 been identified, but few have made their way to clinical practice. 7 In this review, we will initially describe the fundamental approach to evaluate a novel 8 biomarker. Before implementation of a biomarker into clinical practice, several stringent criteria 9 related to its clinical usability are required. Essential statistical metrics such as discrimination, 10 calibration, and reclassification are required to properly evaluate prediction models. We will then 11 discuss the biomarkers according to main groups of cardiovascular pathology: 12 13 14 15 16 17 (1) myocardial injury (cardiac troponins, heart-type fatty acid-binding protein, cardiac myosin binding protein-C) (2) myocardial stress (A-type and B-type natriuretic peptides, mid-regional pro-adrenomedullin, copeptin) (3) inflammation (C-reactive protein, interleukin 6, growth differentiation factor 15, soluble suppressor of tumorigenicity 2, galectin-3) 18 (4) platelet activation (soluble CD40 ligand, P-selectin) 19 (5) plaque instability (lipoprotein-associated phospholipase A2, matrix metalloproteinase-9) 20 (6) systemic stress (catecholamines, granin proteins) 21 (7) calcium homeostasis (secretoneurin) 22 23 Finally, we will discuss novel applications of cardiovascular biomarkers, more specifically prediction of ventricular arrhythmias, and the use of biomarkers in composite risk prediction models. 1 3 2 1 Introduction 2 Cardiovascular disease is the primary cause of death worldwide, in both industrial and developing 3 countries, and includes atherosclerotic (e.g. coronary artery disease [CAD], cerebrovascular disease, 4 peripheral artery disease) and non-atherosclerotic disease (e.g. valvular disease, rheumatic heart 5 disease, congenital heart disease and venous thromboembolism) [1]. The prevalence of cardiovascular 6 disease increases with age, and several modifiable risk factors, such as tobacco use, obesity, physical 7 inactivity and alcohol abuse, are associated with development and progression of cardiovascular 8 disease [2]. 9 In