The structural integrity of the heart is dependent on an extensive network of fibrillar collagens. First recognised in skeletal muscle by Holmgren in 1907, 1 these collagen fibres are grouped in weaves that surround myocytes, struts that interconnect adjacent myocytes, small fibrils that attach the plasma membrane to the encircling basal lamina, long tendon-like bundles that link adjacent weaves, and collagen struts that connect the myocytes to adjacent capillaries. 2 This complex scaffolding facilitates the transmission of force between neighbouring myocytes, maintains capillary patency during ventricular contractions, maintains lateral cell-to-cell alignment, and precludes cell slippage and ventricular-cavity dilatation during diastole. 3 In addition, collagen cross-linking is an important determinant of systolic and diastolic performance. In the cardiac extracellular matrix, collagens are produced by fibroblasts, the most common collagen subtypes in the myocardium being types I and III. 3 Type I, which predominates in the heart, has a higher tensile strength than type III, which provides greater distensibility. To what extent is research into their metabolism contributing to the development of therapies for heart failure?