BOSS: Sodium Bicarbonate May Protect Heart After Coronary Angiography

San Francisco, CA—In a study originally designed to address the efficacy of using bicarbonate for the prevention of acute kidney injury in patients undergoing angiography, data presented at TCT 2013 show that intervention with sodium bicarbonate may protect the heart and reduce cardiac death following the procedure.

“The reduction in mortality among patients who received bicarbonate occurred without evidence of a decrease in acute kidney injury, suggesting a non-renal mechanism for cardioprotection,” Richard J. Solomon, MD, of the University of Vermont, said.

For the randomized BOSS trial, 376 patients who underwent either coronary (n=299) or peripheral angiogram (n=77) were assigned to receive either a bicarbonate solution (n= 151 in coronary group; n=35 in peripheral group) or sodium chloride (n=148 in coronary group; n=42 in peripheral group). Primary endpoints included renal replacement therapy, death, and sustained loss of eGFR >20% over 6 months of follow-up. Secondary endpoints consisted of death, length of stay and contrast-induced nephropathy.

Isotonic sodium bicarbonate or saline was given 5 mL/Kg bolus over the first hour prior to angiography, followed by 1.5 mL/Kg/Hr throughout the angiogram and for 4 hours following the procedure, consisting of a total dose of 12 to 13 mL/Kg. 

According to the study results, there was no significant difference in the primary composite endpoint of death or dialysis, and sustained 20% loss of eGFR between the bicarbonate group and the saline group – this difference remained unchanged between the coronary and peripheral angiogram groups. In addition, the difference in the component endpoints of death or dialysis was not significant, and the sustained loss of eGFR was not significantly different between treatment groups. 

“However, there is a difference in the death rate for all the angiograms that, importantly, was only evident for those who underwent a coronary angiogram,”  Solomon said. “The death rate was nearly two-thirds lower in patients who received bicarbonate compared with saline.” (see Figure) 

To determine whether the saline group exhibited increased mortality that affected the results found in the bicarbonate group, the researchers compared the mortality rates with other predictors in the literature. Based on the Mehran scoring, the saline group exhibited a 10.8% death rate at 6 months; the Mehran risk score modeling in this group would have predicted 13.3%. “In addition, we found that there was no difference in the incidence of acute kidney injury, which is important because many have argued that the mortality difference in trials to prevent acute injury actually results from protecting the kidney,” 

Solomon said. “In our data, there is a clear dissociation between the effects on the kidney and mortality. However, those patients who did have acute kidney injury were likely to progress at 6 months to loose more than 20% of their eGFR.”

Disclosures:

Solomon reports conflicts of interest with several device and pharmaceutical manufacturers.