Coronary Artery Calcification, Cardiovascular Events, and Death: A Prospective Cohort Study of Incident Patients on Hemodialysis

Abstract

Background: Coronary calcification in patients with end-stage renal disease (ESRD) is associated with an increased risk of cardiovascular outcomes and death from all causes. Previous evidence has been limited by short follow-up periods and inclusion of a heterogeneous cluster of events in the primary analyses. Objective: To describe coronary calcification in patients incident to ESRD, and to identify whether calcification predicts vascular events or death. Design: Prospective substudy of an inception cohort. Setting: Tertiary care haemodialysis centre in Ontario (St Joseph's Healthcare Hamilton). Participants: Patients starting haemodialysis who were new to ESRD. Measurements: At baseline, clinical characterization and spiral computed tomography (CT) to score coronary calcification by the Agatston-Janowitz 130 scoring method. A primary outcome composite of adjudicated stroke, myocardial infarction, or death. Methods: We followed patients prospectively to identify the relationship between cardiac calcification and subsequent stroke, myocardial infarction, or death, using Cox regression. Results: We recruited 248 patients in 3 centres to our main study, which required only biochemical markers. Of these 164 were at St Joseph's healthcare, and eligible to participate in the substudy; of these, 51 completed CT scanning (31 %). Median follow up was 26 months (Q1, Q3: 14, 34). The primary outcome occurred in 16 patients; 11 in the group above the median and 5 in the group below ( p = 0.086). There were 26 primary outcomes in 16 patients; 20 (77 %) events in the group above the coronary calcification median and 6 (23 %) in the group below ( p = 0.006). There were 10 deaths; 8 in the group above the median compared with 2 in the group below ( p = 0.04). The hazard ratios for coronary calcification above, compared with below the median, for the primary outcome composite were 2.5 (95 % CI 0.87, 7.3; p = 0.09) and 1.7 (95 % CI 0.55, 5.4; p = 0.4), unadjusted and adjusted for age, respectively. For death, the hazard ratios were 4.6 (95 % CI 0.98, 21.96; p = 0.054) and 2.4 (95 % CI 0.45, 12.97; p = 0.3) respectively. Limitations: We were limited by a small sample size and a small number of events. Conclusions: Respondent burden is high for additional testing around the initiation of dialysis. High coronary calcification in patients new to ESRD has a tendency to predict cardiovascular outcomes and death, though effects are attenuated when adjusted for age.