Reduced Cardiovascular Reserve in Chronic Kidney Failure: A Matched Cohort Study

Background Patients with chronic kidney failure (CKF) experience impaired functional cardiovascular reserve with reduced oxygen consumption at peak exercise (Vo 2peak ). No studies have examined whether this is related to impaired cardiovascular compliance as a consequence of loss of adaptive structural alterations, resulting from chronic uremia or hypertension. Study Design Prospective matched-cohort study. Setting & Participants We assessed CKF in parallel with patients with essential hypertension but without cardiovascular disease. Patients with CKF were either scheduled for kidney transplantation or transplant waitlisted. 80 patients with CKF and 80 with essential hypertension matched in age, sex, and body mass index were evaluated. 61 patients with CKF (76.3%) were dialysis dependent. Predictor CKF versus essential hypertension without cardiovascular disease. Measurements & Outcomes Vo 2peak was measured during maximal exercise testing. 2-dimensional echocardiography and arterial applanation tonometry were performed prior to exercise testing. To evaluate for the difference in Vo 2peak between study groups, statistically significant predictors of Vo 2peak in multiple regression models were additionally assessed by fitting models comprising the interaction term of patient group with the predictor variable of interest. Results Vo 2peak was significantly lower in patients with CKF than those with essential hypertension (18.8 vs 24.5mL/min·kg; P 2peak for CKF included left ventricular (LV) filling pressure (E/mean e′; unstandardized regression coefficient: change in Vo 2peak [in mL/min·kg] per 1-unit change of variable = −5.1) and pulse wave velocity (−4.0); in essential hypertension, these were LV mass index (0.2), LV end-diastolic volume index (0.4), peak heart rate (0.2), and pulse wave velocity (−8.8). The interaction effect of Vo 2peak between patient groups with LV mass index ( P P P 2peak . Limitations Skeletal muscle strength was not assessed. Conclusion This study suggests that maladaptive LV changes, as well as blunted chronotropic response, are important mechanistic factors resulting in reduced cardiovascular reserve in patients with CKF, beyond predominantly vascular changes associated with hypertension.