Prior studies based on echocardiography have suggested that the prevalence of pulmonary hypertension in patients with chronic kidney disease on dialysis varies widely from 17% to as high as 50%. probably reflecting the multiple variables associated in assessment of these patients including whether dialysis has been initiated in the context of chronic kidney disease (CKD), mode of dialysis, day of the echocardiogram vs. day of dialysis, presence or absence of an AV fistula, and efficacy of dialysis (ability to be maintained at dry weight). Echocardiography is a common non-invasive test that is obtained in almost all patients with chronic kidney disease. The numbers surrounding prevalence of pulmonary hypertension in CKD can be confusing because different studies can vary how pulmonary hypertension is defined and the setting in which it is measured. The diagnostic test of choice for pulmonary hypertension is a right heart catheterization as it can help define pulmonary hypertension as a mean PA pressure > 25 mm Hg and further refine whether the elevation in pulmonary pressure is “precapillary” (possibly intrinsic to the lungs) or “postcapillary” (lungs are passive conduit transmitting elevated pressures from the left side).

Pulmonary hypertension was a predictor of mortality in both the CKD and non-CKD group with a higher prevalence in the CKD group. Interestingly, there was no significant difference in mortality between those with precapillary vs. postcapillary hemodynamics – although it is noted that treatment advances have occurred over the time of this study that may have offered greater treatment options to the precapillary group. Patients with CKD are at increased risk for venous thromboembolism with prior studies reporting a 1.3–2.0-fold increase with mild-moderate kidney disease and 2.3-fold increase with end-stage kidney disease as compared to the general population. Therefore, patients with CKD are at increased risk for chronic thromboembolic pulmonary hypertension (CTEPH), which is WHO group 4. Although randomized trials in CKD patients are lacking, pulmonary hypertension WHO groups 1–4 have established diagnostic criteria and treatment pathways which should optimize patient outcomes. Further work is needed in WHO group 5 as the mechanism, prognosis, and treatments are less well defined.

Regards

Calvin Parker
Editorial Assistant
Journal of Nephrology and Urology