Impact of glomerular filtration rate estimation on cardiovascular events in elderly patients undergoing coronary angiography

Background Estimation of kidney function by glomerular filtration rate (eGFR) is affected by age and is important for decision making regarding treatment and prognosis of patients with cardiovascular disease. We investigated the impact of eGFR on long-term cardiovascular outcomes in an elderly population undergoing coronary angiography for evaluation or treatment of coronary artery disease. Methods GFR was estimated according to Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation in 3690 elderly patients (aged 70-100 years) undergoing coronary angiography. Patients receiving maintenance dialysis were excluded. The association between eGFR and major adverse cardiovascular events (MACE) including myocardial infarction, ischemic stroke or death, was investigated. GFR was further calculated according to modification of diet in renal disease (MDRD) and the Cockcroft-Gault equations, and compatibility between estimations was analyzed. Results Cardiovascular comorbidities were more prevalent with the reduction in kidney function as was the proportion of patients presenting with acute coronary syndromes. The adjusted hazard ratio (95% confidence interval) for MACE during a mean follow-up of 5 years was 0.95 (0.77-1.16), 1.04 (0.84-1.29), 1.56 (1.16-1.84), 2.22 (1.65-2.97) and 3.74 (2.20-6.38) in patients with eGFR 60-89, 45-59, 30-44, 15-29 and <15 ml/min/1.73m(2), respectively, compared to >90 ml/min/1.73m(2). Reclassification of eGFR stages by MDRD (upward 23.8%, downward 0.4%) and Cockcroft-Gault (upward 4.3%, downward 28.1%) compared to CKD-EPI estimation, was noted. However, the association between eGFR stages and MACE was similar between equations. Conclusions Kidney function, as manifested by eGFR, has a graded inverse association with the burden of cardiovascular comorbidities and long-term adverse events in elderly patients undergoing coronary angiography.