Purpose: Chronic kidney disease (CKD) is common after heart transplantation (HTx). This study assessed the influence of CKD on exercise capacity and ventilatory efficiency after HTx.
Methods: This cross-sectional study included 79 HTx patients (age 64 +/- 10 years, 66 men) at 8.1 +/- 4.3 years post-HTx who underwent maximal exercise testing, cardiac function assessment, and blood analysis. According to estimated glomerular filtration rate (eGFR, ml/min/1.73 m(2)), patients were categorized as having severe (Group 1, GFR < or = 30; n = 15), moderate (Group 2, GFR 30-60; n = 40), and mild (Group 3, GFR > 60; n = 24) renal impairment.
Results: Patients in Group 1 were older, had lower peakVO(2) and impaired ventilatory efficiency compared with Groups 2 and 3 (all p < 0.05) Peak Watts, peak ventilation, and peak heart rate were lower in Group 1 compared with Group 3 (all p < 0.05). Exercise-derived variables did not differ significantly between Groups 2 and 3. GFR correlated with peakVO(2)/kg (r = 0.47; p < 0.01) and peak Watts (r = 0.34, p < 0.01). GFR (adjusted r(2) = 0.34), mean arterial pulmonary pressure, and age were the strongest independent predictors of peakVO(2). The proposed model explained 48% of variability in peakVO(2). By receiver operator characteristic analysis, eGFR was superior in distinguishing patients with impaired from those with preserved exercise capacity (peakVO(2) < 18 vs > 18 ml/kg/min).
Conclusion: Chronic KD after HTx is associated with impaired maximal exercise capacity and decreased ventilatory efficiency. GFR is a strong independent non-exercise-derived predictor of peak VO(2) in these patients.