Inorganic dietary nitrate lowers contrast-induced acute kidney injury from angiogram
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Key takeaways:
- Inorganic dietary nitrate reduced risk for contrast-induced kidney injury in high-risk patients having an angiogram.
- The intervention was also associated with improved long-term cardiac and renal outcomes.
A short course of inorganic dietary nitrate reduced contrast-induced kidney injury in high-risk patients with non-ST segment elevation ACS referred for invasive coronary angiography, researchers reported.
In addition, inorganic dietary nitrate was associated with improved kidney function at 3 months and reduced cardiac and renal events at 1 year compared with standard care, according to the results of the NITRATE-CIN trial presented at the European Society of Cardiology Congress.
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“In patients presenting with heart attacks at risk of kidney injury from invasive coronary angiography, we found ... that a short course, which was 5 days, of inorganic dietary nitrate led to reduced contrast-induced kidney disease by 70%,” Dan Jones, MBBS, clinical senior lecturer of clinical trials in cardiovascular intervention and honorary consultant in interventional cardiology at Queen Mary University of London, said during a press conference.
The trial included 640 patients with non-ST segment elevation ACS referred for invasive coronary angiography at high risk for contrast-induced kidney injury. High risk was defined as having chronic kidney disease (estimated glomerular filtration rate < 60 mL/min/1.73 m2) or at least two of the following risk factors: diabetes, liver failure, age older than 70 years, exposure to contrast within the past 7 days, HF or concomitant use of renally acting drugs. The mean age of patients was 71 years. Among the cohort, 73% were men, 75% were white and 56% had chronic kidney disease.
Contrast-induced kidney injury from angiography is associated with longer hospital stay, worse long-term kidney function including dialysis, greater risk for recurrent CV events and greater risk for death, Jones said during the press conference.
Patients were randomly assigned to 5 days of potassium nitrate (12 mmol/744 mg nitrate) or a placebo of potassium chloride, with the first dose taken before the procedure.
Why contrast-induced kidney injury happens is not fully understood, but “a common factor that’s seen in preclinical and early-phase studies is a deficiency of nitric oxide,” Jones said. “We know that nitric oxide is essential for normal kidney function and hemostasis. This provides us an opportunity to replace this lost nitric oxide to try to prevent contrast-induced nephropathy. Inorganic nitrate is found in the diet, is produced within the body and is different from organically synthesized nitrate.”
Contrast-induced acute kidney injury occurred in 9.1% of the nitrate group and 30.5% of the control group, for a relative risk reduction of 70% (P < .0001), Jones said during the press conference.
Kidney function in the nitrate group improved by 5.2 mL/min/1.73 m2 at 3 months, for a relative improvement of 10%, he said.
At 1 year, major cardiac events, defined as death, MI or repeat revascularization, occurred in 9.1% of the nitrate group and 18.1% of the placebo group, for a relative reduction of 50% (P < .0001), Jones said.
Kidney events at 1 year occurred in 10.7% of the nitrate group and 28.4% of the placebo group, for a relative reduction of 60% (P < .0001), he said.
“We feel that dietary inorganic nitrate shows huge promise [to prevent contrast-induced acute kidney injury] based on the results of this trial, and these findings could have important implications for reducing the burden of contrast-induced nephropathy on health care systems worldwide,” Jones said during the press conference. “Inorganic dietary nitrate improves the safety of coronary angiography in patients at risk of renal injury following a heart attack. This simple, low-cost intervention should be considered in this patient group.”
Perspective
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Other than hydration, to date, no other strategy has been clearly shown to lower the risk for contrast-induced kidney injury. These results are certainly very interesting and quite provocative. The investigators found a 60% reduction in kidney events and a 50% reduction in cardiac events, both of which were statistically significant. As these results would affect several million patients worldwide, it would be prudent to replicate the study. If the effect sizes seen here are in fact real, such confirmation would not require large trials.
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Jones D, et al. Hot line 8. Presented at: European Society of Cardiology Congress; Aug. 25-28, 2023; Amsterdam (hybrid meeting).
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