[Exercise studies in patients with cardiomyopathy (author's transl)].

Exercise tests were performed on 50 patients with hypertrophic obstructive cardiomyopathy (HOCM) and 19 patients with hypertrophic nonobstructive cardiomyopathy (HNCM) of NYHA classes I to IV, and on 16 patients with congestive cardiomyopathy (CCM) of NYHA classes III and IV as well as, for detection of latent cardiomyopathy (LCM), i.e. functional impairment during exercise with normal findings at rest, on 102 patients with typical or atypical angina pectoris and ECG abnormalities of unknown etiology (left bundle branch block or ST segment depression) but normal coronary arteries and normal left and right ventriculogram. Measurements included heart rate, stroke volume, cardiac output, pulmonary artery pressure and minimal cardiac transit times of Indium-113m. Furthermore, in a large number of patients with latent cardiomyopathy, thallium-201 myocardial imaging and measurements of myocardial lactate extraction during high-rate atrial pacing were performed. The findings suggest that 1. the functional classification based on the patients' complaints often differs from the grade of hemodynamic impairment detected by exercise testing, 2. therapeutic effects (propranolol or surgery in HOCM, prazosin in CCM) are more pronounced under exercise as compared with resting conditions. Latent cardiomyopathy can be diagnosed only by detection of impaired function during exercise (increased pulmonary artery pressure, impaired myocardial lactate extraction during high-rate stimulation), since ventricular function and hemodynamics are normal at rest.