#2246 Cardiovascular changes and outcomes across the early CKD spectrum: a UK Biobank cardiovascular MRI substudy
Authors: Stoumpos Sokratis , Gillon Jodie , Lang Ninian , Patel Raj , Mark Patrick , Lees Jennifer 
Published: May 2024

Abstract

Background and Aims
Chronic kidney disease (CKD) patients are at a significant risk of accelerated cardiovascular (CV) disease (CVD), which increases as glomerular filtration rate (GFR) declines. The prevalence of CVD in early CKD is high but there is lack of data on early myocardial changes in this group of patients. We investigated the associations of early CKD with alterations in cardiac structure and function and adverse CV outcomes using cardiovascular magnetic resonance (CMR) imaging.

Method
We used measures of CMR analysis from participants in the UK Biobank CMR imaging substudy to extract information on morphology and function of the four heart chambers. Early CKD was defined as an estimated GFR with cystatin (eGFRcys) between 60 and 90 ml/min. Patients with left ventricular ejection fraction &lt;50%, history of CVD, eGFRcys &lt; 60 ml/min, uACR &gt; 3 mg/mmol, and those on renal replacement therapy were excluded. The association between early CKD and CMR parameters was analysed in 5 linear regression models: unadjusted, age adjusted, sociodemographic adjusted, sociodemographic and lifestyle adjusted, and a fully adjusted model also including clinical characteristics. Cox regression analyses were used to determine association between mildly decreased eGFR and adverse CV outcomes (myocardial infarction, stroke, CV death, and a composite CV outcome).

Results
A total of 33 124 individuals [17 825 (53.8%) women, age 64 (11) years] who received CMR imaging between 2014 and 2019 and fulfilled the inclusion criteria were identified: 19,919 with no CKD and 13,205 with early CKD. Participants with early CKD were more likely to be older, males and smokers. In the fully adjusted model, early CKD was associated with structural changes in the left ventricle (LV) [mass −1.04 g (−1.75 to −0.33), end-diastolic volume −2.69 mL (−4.01 to −1.38), end-systolic volume −0.95 mL (−1.30 to −0.60)], right ventricle (RV) [end-diastolic volume −3.24 mL (−4.67 to −1.82), end-systolic volume −1.73 mL (−2.55 to −0.91)], right atrium (maximum volume −2.81 mL (−4.09 to −1.53), minimal volume −1.46 mL (−2.30 to −0.62)]. Early CKD was also associated with a change in LV global circumference strain [-0.16 (−0.31 to −0.01)] but it was not associated with changes in the left atrium parameters or functional parameters [LV ejection fraction 0.21 (−0.05 to 0.48), RV ejection fraction 0.21 (−0.07 to 0.49)]. These changes were not associated with adverse CV outcomes on multivariable analyses (HR for MI 1.35, 95% CI 0.94-1.94; HR for stroke 0.98, 95% CI 0.63-1.50).

Conclusion
In a low-risk general population (without known CVD and with preserved LV ejection fraction) mildly reduced kidney function, as measured with eGFRcys, was associated with smaller LV and RV volumes, larger LV mass, and impaired LV global circumference strain. This early cardiac remodelling was not associated with adverse CV outcomes, but the event rate was very small during follow up. These findings suggest that cardiomyopathy associated with early CKD is not a regional condition of the left ventricle but affects the heart globally.