Inorganic nitrate reduced contrast-induced nephropathy in patients at risk for renal injury undergoing coronary angiography for acute coronary syndrome.

Dietary inorganic nitrate significantly reduced contrast-induced nephropathy (CIN) in patients at risk for renal injury undergoing coronary angiography for acute coronary syndrome (ACS). Moreover, long-term renal and cardiovascular outcomes in the NITRATE-CIN trial were in favor of patients treated with inorganic nitrate compared with placebo.

“Older patients with heart failure, chronic kidney disease, or diabetes undergoing angiography for ACS have an increased risk for CIN, a condition that potentially has severe consequences,” said Dan Jones, MBBS. The double-blind, single-center phase 2 NITRATE-CIN trial enrolled 640 participants undergoing invasive coronary angiography for non-ST elevated ACS who were at risk for CIN. They were randomly assigned 1:1 to a 5-day intervention with potassium nitrate (12 mmol/744 mg nitrate) or a placebo. The primary endpoint was the incidence of CIN as defined by KDIGO criteria.

After a median follow-up of 12 months, CIN was observed in 30.5% of the participants in the placebo arm and 9.1% in the inorganic-nitrate arm (P<0.0001). These results were consistent across troponin levels, Mehran risk scores, and diabetes status. However, participants who received prior organic nitrate (n=72) appeared to benefit less from the intervention than those who had not received prior organic nitrate (n=484; OR, 0.65 vs 0.17; P_interaction=0.04).

Procedural myocardial infarction, a secondary endpoint, occurred in 12.5% and 4.1% of the patients in the placebo arm and inorganic-nitrate arm, respectively (P=0.003). Furthermore, Dr. Jones said that renal outcomes at 3 months, major adverse cardiovascular events (MACE) at 1 year, and major adverse kidney events (MAKE) at 1 year all favored participants in the inorganic-nitrate arm over those in the placebo arm.

“These results could have important implications for the reduction of the burden of CIN worldwide,” said Dr. Jones. “However, studies powered for MACE and MAKE outcomes should be conducted to confirm these findings.”

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