Ted Bosworth
February 27, 2023
WASHINGTON – Late lumen loss (LLL) after percutaneous interventions (PCI) can be reduced significantly by a daily glass of beet juice, according to a phase 2 randomized trial.
The protection against LLL, attributed to the nitrate contained in beet juice, was accompanied by a trend for a reduced risk of major adverse cardiovascular events (MACE), according to Krishnaraj Rathod, MBBS, BMedSci, PhD, who presented results at the Cardiovascular Research Technologies conference, sponsored by MedStar Heart & Vascular Institute.
The study grew out of relatively recent evidence that ingestion of nitrate-rich foods, such as beets, can trigger noncanonical pathways for nitric oxide generation, sometimes referred to as the nitrate-nitrite-nitric oxide sequence. Dr. Rathod cited experimental evidence associating this pathway with the traditional benefits of NO generation, such as anti-inflammatory and antithrombotic effects.
In this study, 300 patients scheduled for PCI to treat stable angina were randomized to the experimental arm of nitrate-rich beetroot juice or the control arm of nitrate-depleted beetroot juice. Each had a 70-mL glass of juice once daily. Dr. Rathod, a senior interventional cardiology registrar, Barts Heart Centre, London, described this as the equivalent of about four beets.
The primary endpoint of the study was in-stent LLL assessed by quantitative coronary angiography (QCA) at 6 months.
MACE, defined as death, MI, need for revascularization, and in-stent thrombosis, was assessed at 3, 9, 12, and 24 months. In addition, markers of NO activation, platelet reactivity, and inflammation were monitored.
Lumen loss reduced less than 50%
On OCA, the median stent LLL at 6 months was 0.244 mm in the nitrate-depleted beet juice group and 0.117 mm (P = .0165) in the group that received natural beet juice. The mean segment LLL similarly favored the natural beet juice (0.269 vs. 0.050 mm; P = .0011).
The same effect was reflected in the measurement of mean change in minimum lumen diameter at 6 months. From baseline, this in-stent measure was reduced at 6 months by 0.244 mm in the control group, but by only 0.117 mm in the group receiving the dietary nitrate (P = .0154 for two-way analysis of variance).
Over 24 months of follow-up, there were 18 MACE events in the control arm versus 9 in the arm randomized to dietary nitrate (P = .0718). There were no in-stent thromboses observed in either group, but death (two vs. five), MI (one vs. six), and target-vessel revascularization (six vs. seven) were all numerically lower in the group receiving dietary nitrate.
“Once-a-day oral dietary nitrate for 6 months was well tolerated and safe,” Dr. Rathod reported at the meeting.
Asked specifically about the taste of the daily glass of beet juice, Dr. Rathod acknowledged that some patients were not enamored, but many had no objections or even liked the taste.
The patients were reasonably representative of a PCI population. The mean age in both groups was 61 years. There were no significant differences in body mass index (approximately 29 kg/m2) or proportion with diabetes (22%), hypertension, or hypercholesterolemia (about 70% in both groups) and other comorbidities.
More PCI was performed in the left anterior descending artery (36.7% vs. 44.0%) in the control group, while less PCI was performed in the right coronary (27.3% vs. 30.7%). Neither difference was significant. The vast majority (~90%) of patients received drug-eluting stents with a mean of 1.4 implanted. Procedural success was 100% in both groups.
Discharge medications, including antiplatelet and antithrombotic therapies, were similar in the two groups.
Results characterized as highly positive
Based on the 53% reduction in LLL at 6 months and the trend for a MACE reduction, Dr. Rathod concluded that the results were highly positive.
“These results suggest that dietary nitrate may have a therapeutic role in reducing restenosis following PCI for stable angina,” he said.
In the discussion, several panelists pointed out that nearly one-third of patients were not available for evaluation at 6 months (41 of 150 in the experimental group and 51 of 150 in the control group) with further attrition at 1 and 2 years of follow-up. Of these about half were lost to follow-up and the other half withdrew.
The lack of follow-up on such a high proportion of participants is one weakness of this study,” acknowledged Hector M. Garcia-Garcia, MD, PhD, a cardiovascular researcher at MedStar Washington Hospital Center. However, he remains enthusiastic about the premise.
“It was encouraging to see every signal moving in the right direction,” said Dr. Garcia, who consulted with Dr. Rathod’s group on the design of the study. He called these data “promising,” and said they provide support for larger trial for a treatment with potential benefits at low cost.
George Dangas, MD, PhD, professor of medicine at the Icahn School of Medicine at Mount Sinai, New York, was among panelists who seemed surprised by such positive findings from a simple but novel concept. However, he remains open to further evaluations.
“As with any surprising result, further confirmation in a large and multicenter trial should be anticipated,” he said in an interview. If, as this study suggests, dietary changes are capable of providing therapeutic NO at the vascular level, he suggested studies to demonstrate anti-inflammatory effects or other mechanistic benefits would be helpful.
“Other sources of oral nitrate would also be a worthwhile investigation,” he said.
Dr. Rathod reports no potential conflicts of interest. Dr. Garcia-Garcia reports ties to Abbott, Biotronik, Boston Scientific, CorFlow, Medtronic, Neovasc, Phillips, and Shockwave. Dr. Dangas reports financial relationships with Abbott Vascular, AstraZeneca, Boston Scientific, Daiichi-Sankyo, and Medtronic.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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