NIH Protocols 01-H-0066, Double Blind Placebo Controlled Study of Pirfenidone A Novel Anti-Fibrotic Drug in Symptomatic patients with Hypertrophic Cardiomyopathy (HCM) Associated with left Ventricular Diastolic Dysfunction and 96-H-0144, Double Blind Placebo-Controlled Study of Long-Term Effects of Angiotensin Converting Enzyme Inhibition (Enalapril) and Angiotensin II Receptor Blockade (Losartan) On Genetically-Induced Left Ventricular Diastolic Dysfunction were undertaken to assess the effect of therapeutic interventions on left ventricular (LV) diastolic function. The relationship between baseline measures of diastolic function as assessed by noninvasive modalities such as Doppler echocardiography and radionuclide angiography, and qualitative and objective measures of functional capacity in patients without LV outflow tract obstruction has not been reported. In this protocol we will look at measures of LV geometry, relaxation and novel indices of ventricular compliance as they may influence measures of exercise capacity. In all cases, we will use pre-existing baseline data obtained with informed consent as part of the above protocols.