A 70-year-old man with a medical history that includes hypertension, COPD, stage 3 chronic kidney disease (CKD), and cardiovascular disease is hospitalized for an elective angiography. Given his underlying kidney disease, you are worried about the risks associated with the use of contrast material during angiography and want to know how you can optimally prepare him for the procedure.
The repercussions of contrast-induced nephropathy (CIN) can range from transient acute renal failure to the need for dialysis or even death. Prehydration with saline is a widely-practiced prevention method for CIN. Some studies suggest that intravenous (IV) sodium bicarbonate and oral acetylcysteine also are beneficial, but results are inconsistent. Further, prior studies have included patients with variable stages of CKD (mild to severe), used different contrast agents, and have been underpowered. Despite having no clear benefit, sodium bicarbonate and acetylcysteine continue to be widely used.
In this week’s NEJM, the well-powered, multicenter, placebo-controlled PRESERVE trial provides convincing evidence that the use of oral acetylcysteine or IV sodium bicarbonate does not prevent CIN or other serious adverse outcomes following administration of contrast in at-risk patients. The trial included 4993 patients who had either an estimated glomerular filtration rate (eGFR) of 15 to 60 mL/min/1.73 m2 (stage 3 or 4) and diabetes mellitus or an eGFR of 15 to 45 mL/min/1.73 m2 (stage 3B or 4) and were scheduled to undergo elective contrast coronary or non-coronary angiography.
Prior to each procedure, patients were randomized in a 2-by-2 factorial design to receive IV 1.26% sodium bicarbonate or 0.9%sodium chloride and 1200 mg oral acetylcysteine or oral placebo. Infusions were begun before angiography and continued for ≥2 hours afterwards in an individualized approach. Serum creatinine levels were assessed before the start of hydration and angiography, 3 to 5 days after angiography, and 90 to 104 days after angiography. The primary endpoint was a composite of death, need for dialysis, or a persistent increase ≥50% in serum creatinine at 90 to 104 days after angiography.
The study was terminated early after a preplanned interim analysis showed no differences in the rates of the primary endpoint between the interventions: 4.4% vs. 4.7% in the sodium bicarbonate and sodium chloride groups, respectively (odds ratio [OR], 0.93, P=0.62) and 4.6% vs. 4.5% in the acetylcysteine and placebo groups, respectively (OR, 1.02; P=0.88). With a sample size of more than two times that of its predecessors, this trial provides convincing evidence that IV bicarbonate and oral acetylcysteine do not prevent CIN or other severe adverse outcomes more effectively than 0.9% saline in patients with moderate-to-severe CKD.
With this information in hand, you feel comfortable prehydrating your patient with 0.9% saline alone to prepare him for his upcoming procedure, which he tolerates well. You continue him on gentle hydration once he is back on your service and he is discharged home 72 hours later without any complications. Prior to discharge, you schedule him for a 2-week follow-up appointment with his PCP for reassessment of his kidney function.
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Balim is a 4th year medical student at University of Massachusetts Medical School and applying for residency in Internal Medicine.