ESC 2023 — NOAH-AFNET 6 is an investigator-initiated randomized trial that was conducted in 18 European countries from February 2016 to December 31, 2022. The trial sought to answer the question of whether patients with atrial high-rate episodes (AHREs) benefit from anticoagulation.

The NOAH-AFNET 6 trial randomized 2,536 patients aged 65 years or older, all of whom had atrial high-rate episodes lasting for a minimum of 6 minutes and presented with at least one additional risk factor for stroke. The mean age of the participants was 78 years with a median CHA2DS2-VASc score of 4. The median duration of AHREs was 2.6 hours, and the episodes generally exhibited atrial rates greater than 200 beats per minute.

Eligible patients were randomly assigned in a 1:1 ratio to receive either anticoagulation or placebo in a double-blind, double-dummy design. Those in the comparator arm received a placebo or, if necessary, aspirin (100 mg/day). Meanwhile, patients in the experimental arm received edoxaban at the recommended dose for stroke prevention in atrial fibrillation.

The primary efficacy outcome was a composite of cardiovascular death, stroke, or systemic embolism. NOAH-AFNET 6 was stopped early at 22 months due to the request of the data and safety monitoring board: A primary efficacy outcome event occurred in 83 of the 1,270 patients in the edoxaban group and in 101 of the 1,266 patients in the placebo group. Patients not treated with anticoagulation had a stroke rate of 1.1%/year. As expected, anticoagulation increased the risk of major bleeding or death with a 30%. Investigator, Dr Kirchhof concluded “anticoagulation increases bleeding as expected but does not prevent cardiovascular events unexpected in patients with atrial heart rate episodes.”

Dr Kirchhof described the findings of the NOAH-AFNET 6 trial, the first randomized trial in this area, as good news for patients with AHREs: “(...) now we know that we can stay calm, and that we don't need to treat these patients until they develop ECG-documented atrial fibrillation.” Dr Kirchhof stressed the importance of research to better understand stroke risk in patients with AHREs.

Sources:

Paulus Kirchhof, 26 August 2023, NOAH-AFNET 6: Oral anticoagulation in patients with atrial high rate episodes, ESC Congress, Amsterdam, The Netherlands.

Kirchhof P, et al. Anticoagulation with Edoxaban in Patients with Atrial High-Rate Episodes et al. N Engl J Med 2023; 389:1167-1179.