Article

Heart transplant (HTx) recipients usually have reduced exercise
capacity, with reported VO2peak levels of 50-70% of predicted values. This study
aimed to evaluate central and peripheral factors predictive of VO2peak. METHODS : Fifty-one clinically stable HTx recipients >18 years old and 1-8
years after HTx, underwent maximal exercise testing on a treadmill. Clinical
laboratory, haemodynamic and echocardiographic data, lung function, and
isokinetic muscle strength and muscular exercise capacity were recorded. The mean
+/- SD age was 52 +/- 16 years, 71% were male, and time from HTx was 4.1 +/- 2.2
years. The patients were assigned to one of two groups: VO2peak 27.3
ml/kg/min, which was the median value, corresponding to 80% of predicted value.
The group with the higher VO2peak had significantly lower body mass index, body
fat, and triglycerides, and significantly higher body water, muscular exercise
capacity, high-density lipoprotein (HDL) cholesterol, lung function, mitral
annular velocity, peak ventilation, O2 pulse, and VE/VCO2 slope. Donor age,
recipient age, sex, medication, ischaemic time, cardiac dimensions, systolic
function, and chronotropic responses during exercise were similar. Multiple
regression analysis showed that muscular exercise capacity and body fat were the
strongest VO2peak predictors. CONCLUSIONS: Chronotropic incompetence is not a
limiting factor for exercise capacity in a population of relatively fit HTx
patients. The most significant predictors, representing only peripheral factors,
are similar to those often determining VO2peak in healthy, non-athletic
individuals. Our findings emphasize the importance of a low percentage of body
fat and high muscular exercise capacity in order to attain a sufficient VO2peak level after HTx.

Langue : ANGLAIS