Cardiovascular medication use after coronary bypass surgery in patients with renal dysfunction: A National Veterans Administration study

Background. Chronic kidney disease is now recognized as an independent risk factor for cardiovascular events. We sought to determine if cardiovascular medications were utilized less in patients with renal dysfunction following coronary artery bypass grafting (CABG) and if the association of decreased medication use was independent of comorbid conditions. We also examined associations between cardiovascular medication use and mortality at 6 months. Methods. Data from the National Veterans Adminstration (VA) Continuous Improvement in Cardiac Surgery Program were merged with the national VA pharmacy database. Prescription rates within 6 months of discharge for CABG were obtained for four classes of medicines: beta blockers, lipid-lowering agents, antiplatelet agents, and angiotensin antagonists. Utilization of medications in patients with estimated glomerular filtration rate (GFR) 60 to 90, 30 to 60, and <30 were compared with the reference group of GFR >90. Results. In a retrospective analysis of 19,411 patients, the frequency of nonprescription increased with declining GFR. Decreased utilization for patients with GFR 30 to 60 and <30 remained highly significant after adjustment for age, race, hypertension, diabetes, and prior myocardial infarction. In patients with more advanced renal dysfunction (GFR <60), cardiovascular medication use for all medication classes was associated with survival at 6 months after adjusting for demographic and clinical variables. Cumulative protection was seen with use of medication from each additional class. Conclusion. In a large VA population undergoing CABG, renal disease is associated with highly significant decreases in utilization of cardiovascular medications. Nonprescription of medications was associated with adverse outcomes in those with renal dysfunction.