Sodium Bicarb a Washout for CIN Prevention in Angiography


NEW ORLEANS — Periprocedural intravenous hydration with sodium bicarbonate is no more effective than normal saline for prevention of contrast-induced nephropathy in patients undergoing coronary angiography, Dr. Somjot S. Brar reported at a conference sponsored by the American College of Cardiology.

He presented a single-center randomized trial in 353 patients undergoing coronary angiography, all with at least moderate kidney dysfunction, defined as a baseline glomerular filtration rate (GFR) of 60 mL/min per 1.73 m

The primary end point—contrast-induced nephropathy (CIN) as defined by a 25% or greater decline in GFR within 4 days—occurred in 13.6% of the sodium bicarbonate group and 13.5% on normal saline, the most commonly used hydration fluid in clinical practice, said Dr. Brar of Kaiser Permanente Medical Center, Los Angeles.

The secondary end point—at least a 25% increase in creatinine—occurred in 16.3% on sodium bicarbonate and 15.4% on 0.9% sodium chloride. No patient subgroup fared significantly better on sodium bicarbonatein in the trial, sponsored by Kaiser Permanente. Half of patients in each study arm received Mucomyst (acetylcysteine); their outcomes were similar to those who didn't.

The incidence of CIN ranged from less than 1% in patients with only one CIN risk factor to 37% in those with six or more. The known CIN risk factors are a low GFR, age greater than 75, diabetes, hypertension, a history of heart failure, anemia, inpatient status, a contrast volume in excess of 150 mL, and female gender, he added.

Fully 47% of patients who developed CIN had persistent kidney dysfunction, compared with baseline at 2–8 weeks post procedure. Thirty-day all-cause mortality was 2.0% in the sodium bicarbonate group and 1.3% with sodium chloride. One patient in the saline arm went on dialysis within 30 days.

“One of the fundamental problems we have in treating CIN is while we can identify patients at risk for it we obviously don't have any effective way to reduce their risk. Having rates of CIN of up to 37% is clearly unacceptable and something needs to be done for these patients,” Dr. Brar said at the conference, also sponsored by the Society for Cardiovascular Angiography and Interventions.

Ultrafiltration has been proposed as a possible solution. However, it's quite expensive and not widely available. “Perhaps the answer will be intraarterial administration of a pharmacologic agent, where infusion directly into the kidneys might be more effective. I think there are still some possibilities to test,” he said.

For now, the best evidence for prevention of CIN remains “hydration, hydration, hydration—and the best fluid we have evidence for is normal saline,” according to Dr. Brar.

The theory behind using sodium bicarbonate was it would address both mechanisms involved in CIN. The sodium would attenuate contrast-induced renal vasoconstriction, while the bicarbonate would reduce oxidative stress by raising tubular pH.

One prior randomized trial in which sodium bicarbonate outperformed normal saline in preventing CIN. But that study included patients undergoing a variety of procedures, while the Kaiser study involved a single uniform intervention.

It's also possible that other investigators didn't follow patients long enough to pick up all cases of CIN.

“We had 10 patients in the sodium bicarbonate group who didn't meet criteria for CIN on day 1 or 2 but did on day 3 or 4. This raises the possibility in my mind that with sodium bicarbonate we may delay onset of CIN as opposed to preventing it,” he said.

'Having rates of CIN of up to 37% is clearly unacceptable and something needs to be done for these patients.' DR. BRAR

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