ABSTRACT
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.
Subject(s)
Exercise Test , Heart Transplantation/physiology , Kidney Failure, Chronic/physiopathology , Postoperative Complications/physiopathology , Respiratory Insufficiency/physiopathology , Adult , Age Factors , Aged , Cross-Sectional Studies , Female , Follow-Up Studies , Glomerular Filtration Rate/physiology , Heart Rate/physiology , Hemodynamics/physiology , Humans , Kidney Failure, Chronic/diagnosis , Male , Middle Aged , Oxygen/blood , Postoperative Complications/diagnosis , Prognosis , ROC Curve , Respiratory Insufficiency/diagnosis , Statistics as TopicABSTRACT
BACKGROUND: Recently, a new linear measure of ventilatory response to exercise, the oxygen uptake efficiency slope (OUES), was proposed in the evaluation of heart failure patients. No data are available on the response of the OUES after orthotopic heart transplantation (HTx). METHODS: Thirty patients who underwent HTx between 1999 and 2003 were included in the study. Data from maximal cardiopulmonary exercise test, resting pulmonary function and hemodynamic assessment were collected before the transplant at time of screening and 1 year after HTx. RESULTS: During the first year after HTx, OUES and normalized OUES for body weight (OUES/kg) increased significantly from 15.6 +/- 4.9 to 19.7 +/- 4.8 (p < 0.05). Changes in OUES/kg were significantly correlated with changes in peak VO2, VAT and peak VE, and inversely to changes in peak VD/VT, but not to changes in VE/VCO2 slope (all p < 0.05). Changes in OUES or OUES/kg did not correlate with any changes in measures of resting lung volumes or capacities and measures of central hemodynamic function after HTx. CONCLUSIONS: OUES improved significantly after HTx, but, similar to other exercise parameters, remained considerably impaired. The changes in OUES were highly correlated with the improvements in other exercise variables, but did not correlate with marked improvements in central hemodynamics or resting lung function.
