Reduced exercise capacity in genetic haemochromatosis.
BACKGROUND
Many patients with genetic haemochromatosis complain about fatigue and reduced physical capacity. Exercise capacity, however, has not been evaluated in larger series of haemochromatosis patients treated with repeated phlebotomy.


METHODS
We performed exercise echocardiography in 152 treated haemochromatosis patients (48+/-13 years, 26% women) and 50 healthy blood donors (49+/-13 years, 30% women), who served as controls. Echocardiography was performed at rest and during exercise in a semiupright position on a chair bicycle, starting from 20 W, increasing by 20 W/min. Transmitral early and atrial velocity and isovolumic relaxation time were measured at each step. Ventilatory gas exchange was measured by the breath-to-breath-technique.


RESULTS
Compared with healthy controls, haemochromatosis patients were more obese and less trained. More of them smoked, and 17% had a history of cardiovascular or pulmonary disease. Adjusted for training, the left ventricular function and dimensions at rest did not differ between the groups. During exercise the haemochromatosis patients obtained a significantly lower peak oxygen (O2) uptake (28.1 vs. 34.4 ml/kg per min, P<0.001). In a multiple regression analysis haemochromatosis predicted lower peak O2 uptake independently of significant contributions of sex, age, and height, as well as of systolic blood pressure and log-transformed isovolumic relaxation time at peak exercise, whereas no independent association was found with weight or physical activity (multiple R=0.74, P<0.001). Adding genotype, s-ferritin, prevalence of smoking, or history of cardiopulmonary disease among the covariates in subsequent models did not change the results.


CONCLUSIONS
Genetic haemochromatosis, even when treated with regular phlebotomy, is associated with lower exercise capacity independently of other covariates of exercise capacity.
Davidsen
Einar Skulstad
ES
Department of Heart Disease, Haukeland University Hospital, University of Bergen, Norway. einar.davidsen@helse-bergen.no
Liseth
Knut
K
Omvik
Per
P
Hervig
Tor
T
Gerdts
Eva
E
D000328:Adult; D016022:Case-Control Studies; D017079:Exercise Tolerance; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006432:Hemochromatosis / Q000000981:diagnostic imaging / Q000235:genetics / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000503:physiopathology; D010101:Oxygen Consumption; D018962:Phlebotomy; D012107:Research Design; D014463:Ultrasonography; D016276:Ventricular Function