Conservative outpatient renoprotective protocol in patients with low GFR undergoing contrast angiography: a case series

BACKGROUND: The correct strategy to prevent radiocontrast-induced nephropathy (CIN) in high-risk patients going for cardiac angiography is widely debated in the literature. It is well known that chronic kidney disease (CKD) patients with lower estimated glomerular filtration rates (eGFRs) at baseline are at the greatest risk for a significant loss in kidney function, or even dialysis after a contrast load. For this reason potentially life-saving procedures such as angiography are sometimes withheld or delayed. METHODS: We describe a case series of 31 well-characterized patients with CKD who underwent cardiac or peripheral vessel angiography, and patients with renal artery stenosis (RAS) who underwent angioplasty and stenting. All were treated with a standardized outpatient protocol of withholding their diuretics and angiotensin-converting enzyme (ACE) inhibitors (ACEs)/angiotensin receptor blockers (ARBs) the day prior to and 2 days after the procedure, restarting the diuretic the day after the procedure and the ACE inhibitor/ARB after 2 days. Calcium channel blockers were prescribed for the 2 days prior to and 2 days after the procedure. Patients had bloodwork on days 2-3 and days 7-10 post-procedure. RESULTS: The patients had a mean baseline creatinine of 214 micromol/l (SD = 123), ranging from 87 to 535 micromol/l. This corresponded to a mean baseline eGFR of 34 ml/min (SD = 15.8), ranging from a minimum of 12-59 ml/min. The mean age was 64 +/- 13.8 years; 48% were male and 11 (35.5%) were diabetic. All patients enrolled had a baseline eGFR of less than 60 ml/min as calculated by the Modification of Diet in Renal Disease (MDRD) formula. Based on pre-procedure CKD stage, 21 (68%) were stage 3 (eGFR 30-60 ml/min), 5 (16%) were stage 4 (eGFR 15-30 ml/min), and 6 (19%) were stage 5 (eGFR < 15 ml/min). No patient required urgent hemodialysis following their angiography. All patients have had a longitudinal follow up of 26 months, and none developed any change in the rate of progression from prior to procedure. CONCLUSIONS: This case series provides data in support of a conservative, outpatient-based approach for high-risk CKD patients going for cardiac angiography. This protocol warrants further study in randomized control trials.