The Interstitium in the Hypertrophied Heart

Pathological left ventricular hypertrophy is a common feature of many cardiac diseases. It results from both myocyte hypertrophy and interstitial expansion. Interstitial expansion is most commonly secondary to the accumulation of mature cross-linked collagen fibers due to dysregulated metabolism, known as interstitial fibrosis. This occurs secondary to a variety of stimuli including ischemic, toxic, metabolic, infective, genetic, and hemodynamic factors. Less commonly, interstitial expansion may occur because of the accumulation of misfolded amyloid protein or interstitial edema. It is now well recognized that the presence and extent of interstitial disease are associated with adverse outcomes. There is therefore interest in the development of novel therapies that target the pathways that drive these disease processes. With the emergence of such therapies, it is becoming increasingly important to be able to characterize the type and extent of interstitial disease to enable the use of such targeted therapies in a personalized manner. (C) 2019 by the American College of Cardiology Foundation.