Normal saline hydration still best for contrast-induced AKI in PRESERVE substudy

Elvira Manzano
28 May 2018

Neither intravenous (IV) sodium bicarbonate nor oral N-acetylcysteine (NAC) is better than IV saline in reducing 90-day events or contrast-associated acute kidney injury (AKI) in the PRESERVE substudy, suggesting that normal saline hydration is the default therapy for contrast-induced AKI.

Current guidelines by the Society for Cardiovascular Angiography and Interventions (SCAI) endorse the administration of sodium chloride to revert radiocontrast media-induced AKI. The American College of Cardiology/American Heart Association (ACC/AHA) percutaneous coronary intervention (PCI) guidelines are a bit more “wishy-washy,” recommending IV hydration in the same setting but do not specify which fluid to administer, said study investigator Dr Santiago Garcia from the University of Minnesota and Minneapolis VA Healthcare System, Minnesota, US. “The guidelines should probably be more specific about recommending normal saline with the new evidence at hand.”

The original PRESERVE study published in November 2017 showed no benefit for IV sodium bicarbonate or oral NAC vs placebo in the primary outcome of prevention of death, need for dialysis, or increase in serum creatinine (50 percent at 90 days) in patients undergoing PCI. Hence, the trial was prematurely stopped. [N Engl J Med 2018;378:603-614] Experts had described the findings as “practice-changing”, but then some interventional cardiologists challenged the applicability of the results to majority of patients, highlighting that higher amounts of contrast dye were used in patients  undergoing PCI (160 mL vs 75 mL in those not undergoing PCI).  Nearly 5,000 patients from the US, Australia, Malaysia, and New Zealand with chronic kidney disease (CKD) undergoing coronary angiography were included in the study.

Again, in the sub-study, there was no benefit for sodium bicarbonate over saline (2.64 percent vs 4.04 percent; odds ratio [OR], 0.64) or NAC vs placebo (3.84 percent vs 2.84 percent; OR, 1.37) in the primary endpoint.  Similarly, contrast-associated nephropathy was not significantly different between the two groups (OR, 0.93; 95 percent confidence interval [CI], 0.65 –1.34; OR, 0.98; 95 percent CI, 0.69 – 1.41, respectively). [SCAI 2018, abstract 16288)

“We achieved what we wanted to achieve … this was to try to enrich this population with patients who have been exposed to higher amounts of contrast media and who have higher risk of contrast-induced nephropathy, which in the main trial was 8 percent and 11 percent or about 30 percent higher [in this substudy],” Garcia said. “I think we can say that even in this high-risk cohort, this intervention seemed to be effective.”

Session co-moderator Dr H Vernon Anderson of the University of Texas Medical Center, Houston, Texas, US, said standard of care for angiography procedures does require hydration to protect renal function.

“So far, no other agent has been shown to be superior to normal saline,” he said. “The weight of the evidence, including the PRESERVE study, suggests that normal saline is the default hydration agent unless there are other extenuating circumstances.”

Dr George Dangas from the Mount Sinai Medical Center, New York City, US, agreed, saying that routine administration of any IV fluid is not superior to simple normal saline hydration. “However, individualized practices may still apply in high-risk individuals or procedure.” Sodium bicarbonate, for example, may be necessary when specifically indicated, or half dosing of normal saline in patients with significant sodium-dependent hypertension or congestive heart failure, or acetylcysteine for those at high risk for renal failure.

Assessment of left ventricular end-diastolic pressure or pulmonary capillary wedge pressure to guide hydration level during and after coronary heart procedures is also critical in those intolerant of volume overload, and in those whom routine preoperative hydration may be risky, Dangas said.

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