Cardiac MyBP-C may be more useful than the gold standard biomarker cardiac Troponin I. Blood levels of the current gold standard cardiac biomarkers are very low during the initial stages of myocardial infarction (MI), making early diagnosis difficult. Plasma levels of MyBPC3 are significantly elevated in MI patients. MyBPC3 levels increase from baseline at 3 hours after MI and peak at 6 hours. This is faster than for Cardiac Troponin I which is normally detected 6-12 hours after the onset of MI. Cardiac MyBPC (cMyBP-C, MyBPC3) is a 140 kDa structural protein that is present only in the heart. It is phosphorylated by several kinases. Phosphorylation of MyBPC3 regulates myocardial function and confers resistance to proteolysis, preserving cardiac function post-myocardial infarction. Dephosphorylation at Ser-273 and Ser-282 facilitates MyBPC3 degradation and release of a 40 kDa N-terminal fragment (C0C1f). This C0C1f fragment is pathogenic within cardiac tissue and it is released into the circulation. It was later established in vivo that the C0C1f fragment could cause cardiac dysfunction and heart failure. Importantly, it was shown that plasma MyBPC3 levels are significantly raised in humans with hypertrophic cardiomyopathy undergoing trans-coronary ablation of septal hypertrophy. The assay is validated for human serum and citrate plasma and shows excellent sensitivity (LOD 1.74 pg/ml).