Exercise performance in hypertrophic cardiomyopathies.

Based on bicycle ergometer tests in 50 patients with hypertrophic obstructive cardiomyopathy (HOCM) and 19 patients with hypertrophic non-obstructive cardiomyopathy (HNCM) if clinical (NYHA) class I to IV, the profile of several haemodynamic parameters (heart rate, stroke volume index, cardiac index, pulmonary artery pressure) during exercise was evaluated. The following pattern was found: (1) with increasing degree of clinical symptoms, the mean values of stroke volume decrease and the mean values of pulmonary artery pressure increase; (2) stroke volume does not show the normal increase during exercise in a considerable number of patients (48% of HOCM, 26% of HNCM patients); (3) failing increase in stroke volume is in part compensated by increase in heart rate; (4) pathological increase in mean pulmonary artery pressure correlates with severity of clinical symptoms, but even a considerable number of clinically asymptomatic patients exhibit extremely pathological pressure increase; (5) there is no fundamental difference of the behaviour of the measured haemodynamic parameters between HOCM and HNCM; (6) there is marked overlapping of exercise-induced haemodynamic changes between patients of different NYHA classes of clinical impairment. Therefore, measurements of exercise haemodynamics are necessary to define clearly the degree of functional impairment in the individual patient. Based on identically performed exercise tests in 53 patients with HOCM, the clinical and haemodynamic effects of medical therapy with propranolol (n = 12) or verapamil (n = 25) and of surgical treatment (n = 21) were compared. Maximal exercise capacity was on an average not changed after propranolol but increased after verapamil and, most significantly, after surgery. This could be attributed to corresponding haemodynamic changes, especially concerning cardiac output and pulmonary artery pressure. As a whole, verapamil was clinically and haemodynamically superior to propranolol, but not as effective as surgical treatment.