Coronary Artery Calcification as a Marker for Coronary Artery Stenosis: Comparing Kidney Failure to the General Population

Abstract Rationale and objective The presence of calcified plaques in the coronary arteries is associated with cardiovascular mortality and is a hallmark of chronic kidney failure, but it is unclear whether this is associated with the same degree of coronary artery stenosis as in patients without kidney disease. We compared the relationship of coronary artery calcification and stenosis between dialysis patients and patients without chronic kidney disease (non-CKD). Study design Observational cohort study. Setting and participants: 127 dialysis patients and 447 non-CKD patients with cardiovascular risk factors underwent cardiac computed tomography (CT), consisting of non-contrast enhanced CT and CT angiography (CTA). Coronary artery calcification (CAC) score and degree of coronary artery stenosis were assessed by independent readers. Predictor Dialysis treatment. Outcome Association between calcification and stenosis. Analytical approach Logistic regression to determine the association between CAC score and presence of stenosis in a matched cohort and, in the full cohort testing, for interaction of dialysis status with this relationship. Results There were 112 patients matched from each cohort, totaling 224 patients, using propensity scores for dialysis, balancing numerous cardiovascular risk factors. Median CAC-score was 210 (IQR 19-859) in dialysis and 58 (0-254) in non-CKD patients; 35% of dialysis and 36% of non-CKD patients had coronary artery stenosis of ≥50%. Per each 100 units higher CAC score, the matched dialysis cohort had significantly lower odds ratios for stenosis than the non-CKD cohort, 0.67 (95% CI 0.52-0.83) for stenosis ≥50% and 0.75 (95% CI 0.62-0.90) for stenosis ≥70%. Limitations No comparison with the gold standard fractional flow reserve. Conclusions Dialysis patients have a higher risk of coronary artery stenosis with higher CAC scores, but this risk is comparatively lower than in non-CKD patients with similar CAC scores. In dialysis patients a high CAC score can easily be found without significant stenosis. Our data enable ‘translation' of degree of calcification to probability of coronary stenosis in dialysis patients.