Dietary nitrate in the form of beetroot juice reduces restenosis after PCI in stable angina: NITRATE-OCT trial

Findings from the NITRATE-OCT trial, a small, randomized trial out of the U.K., were presented during a Late-Breaking Trial session at Cardiovascular Research Technologies (CRT) 2023 in Washington, D.C., by Krishnaraj Rathod, St. Bartholomew's Hospital, London, on behalf of the investigators of the NITRATE-OCT study.

"The study is the first randomized-controlled trial evaluating the use of dietary nitrate to reduce restenosis rates in patients undergoing PCI for stable angina," the authors noted. "The results will determine the potential of dietary nitrate as adjunctive therapy in stable angina patients."

Stable angina is an area of significant morbidity impacting 14.1 million people in the U.S. and 1.3 million in the U.K. PCI can be an effective treatment for stable angina, complications including stent thrombosis and restenosis remain relatively common. The cost of complications after PCI is estimated to be around $15 billion, leading may look for options to lower the risks of such adverse outcomes after PCI.

The study included 300 participants. 150 were randomized to receive either a nitrate-rich beetroot juice and 150 to a nitrate-depleted beetroot juice, of whom 190 were followed up at two years, 194 were followed up at one years, and 208 were followed up at six months.

At baseline, participants from both the trial's arms were predominantly male and white and had an average age of 61.59. Also, the participants had a similar incidence of diabetes (both 22%), previous myocardial infarction (36.7% vs 37.3%), hypertension (73.3% vs 74%), and comparable body mass index (BMI) scores (28.81 kg/m2 vs 28.95 kg/m2).

The study's primary endpoint was the restenosis assessment, made by measurement of in-stent late-loss evaluated by QCA (quantitative coronary angiography) at six months ± 1 month.

Secondary endpoints were assessments of MACE (major adverse cardiac events) at 24, 12, 9, and 3 months and mechanical information such as inflammation, measuring markers of platelet reactivity, change in flow-mediated dilation, and NO pathways.

The study led to the following findings:

• Once a day, oral dietary nitrate for six months was safe and well tolerated in patients with stable angina undergoing elective PCI with stent implantation.
• Dietary nitrate significantly reduced late lumen loss (LLL) at six months, with approximately a 53% reduction in LLL compared to the nitrate-depleted placebo arm (stent LLL: 0.117 mm vs 0.244 mm; segment LLL: 0.055 mm vs 0.269 mm).
• Alongside a reduction in LLL, a trend toward a reduction in 2-year MACE was noted.

"Our findings indicate that dietary nitrate may have a therapeutic role in restenosis reduction following PCI for stable angina," the researchers wrote. "The findings now warrant further investigation in larger clinical trials."