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

studies have indicated that hypertrophied muscle differs from normal muscle in many respects, including its structure, mechanical properties, vascularity, biochemistry, and electrophysiology.5-11 Current noninvasive imaging methods permit the clinical differentiation of several etiologies of left ventricular hypertrophy, including pressure or volume overload, infiltration, and hypertrophic cardiomyopathy. This differentiation is usually accurately accomplished with echocardiography or other tomographic imaging methods, such as computed tomography or nuclear magnetic resonance imaging. Unfortunately, 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.12 Although 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-