Noninvasive assessment of myocardial composition and function in the hypertrophied heart.

M yocardial hypertrophy is both a useful physiologic adaptive process and an abnormal response to a variety of stimuli.1-4Hypertrophy as an adaptive response to excessive loading conditions is an important compensatory mechanism that tends to minimize abnormalities in myocardial stress related to the inciting load.4However, recent See p 925studies have indicated that hypertrophied muscle differs from normal muscle in many respects, including its structure, mechanical properties, vascularity, biochemistry, and electrophysiology.5-11Current noninvasive imaging methods permit the clinical differentiation of several etiologies of left ventricular hypertrophy, including pressure or vol- ume overload, infiltration, and hypertrophic cardio- myopathy.This differentiation is usually accurately accomplished with echocardiography or other tomo- graphic imaging methods, such as computed tomography or nuclear magnetic resonance imaging.Unfor- tunately, some diagnostic ambiguities occur that may not be easily resolved with current diagnostic methods.For example, amyloid cardiomyopathy presents the picture of concentric left (and right) ventricular hypertrophy.12Although many patients with amyloid heart disease display an unusual, "speckled" myocardial appearance on standard echocardiograms,13 this phenomenon is not always noted, and the amyloid-infiltrated left ventricle may thus be confused with pressure-overload hypertrophy.Hypertrophic cardiomyopathy may resemble infiltrative cardiomyopathy on echocardiograms14; conversely, amyloid cardiomyopathy may be mis- The opinions expressed in this editorial comment are not necessarily those of the editors or of the American Heart Association.