Study Reveals Blood Thinners’ Limited Efficacy in Preventing Stroke!

Anticoagulants Pose Bleeding Risk Without Stroke Prevention in AHRE

Attention India
4 Min Read
  • AHRE Patients Face Bleeding, Not Stroke Prevention
  • NOAH-AFNET 6 Trial Uncovers Anticoagulant Ineffectiveness
  • Call for ECG Confirmation Prior to Anticoagulation Initiation

30th August 2023, Mumbai: Anticoagulants, commonly known as blood thinners, have long been prescribed to prevent strokes in individuals with atrial fibrillation. However, a recent study presented at ESC Congress 2023 reveals that these medications might be causing bleeding without effectively preventing stroke in individuals with atrial high-rate episodes (AHRE) who lack electrocardiogram (ECG)-diagnosed atrial fibrillation.

The Ineffectiveness in Non-AF Cases

While anticoagulants serve as vital stroke preventatives for individuals with atrial fibrillation, they appear to lack efficacy in those without this condition, such as individuals with heart failure. The study indicates that people with AHRE, a less common form of atrial arrhythmia detectable by implanted devices, show increased bleeding risk when prescribed anticoagulants without a corresponding reduction in stroke incidence.

Understanding AHRE and Risk Factors

Atrial high-rate episodes (AHRE) are short and infrequent atrial arrhythmias, resembling atrial fibrillation, often detected by pacemakers, defibrillators, and loop recorders implanted within patients. Approximately 10% to 30% of individuals with implanted devices experience AHRE. Although AHRE sufferers exhibit a heightened risk of stroke, this risk remains lower than that seen in individuals with full-blown atrial fibrillation.

The NOAH-AFNET 6 Trial: Investigating Anticoagulation

The NOAH-AFNET 6 trial serves as a groundbreaking investigation into the efficacy and safety of oral anticoagulation in patients experiencing AHRE but lacking ECG-confirmed atrial fibrillation. The randomized, double-blind, double-dummy trial compared the anticoagulant edoxaban to a placebo in patients aged 65 and older, who had AHRE episodes lasting over 6 minutes, detected by implanted devices. These patients also possessed at least one additional stroke risk factor, such as heart failure, hypertension, diabetes, prior stroke, transient ischemic attack, vascular disease, or age exceeding 75 years. Notably, this patient population lay outside the approved use of edoxaban.

Study Design and Allocation

The trial enrolled patients across 206 sites in 18 European countries, assigning them randomly in a 1:1 ratio to either receive anticoagulation or not. Anticoagulation involved the use of edoxaban, administered at the dose approved for atrial fibrillation stroke prevention. The trial also included a no anticoagulation group that received either placebo or aspirin based on indications for antiplatelet therapy. The primary outcome measured a composite of stroke, systemic embolism, or cardiovascular death, while the safety outcome considered a combination of major bleeding and all-cause death.

Results and Implications

The study involved 2,536 patients with a median age of 78 and a median CHA2DS2-VASc score of 4.5. The trial was halted prematurely due to safety concerns and a trend toward ineffectiveness after enrolling all intended participants. The primary efficacy outcome occurred in 3.2% per year of patients in the anticoagulation group and 4.0% per year in the no anticoagulation group. Interestingly, the stroke rates were low in both groups, highlighting the unexpected nature of these results. Safety outcomes exhibited a notable difference, largely driven by an anticipated rise in major bleeding among those on anticoagulation therapy.

 Future Directions

Principal investigator Paulus Kirchhof emphasizes that the NOAH-AFNET 6 trial demonstrates increased bleeding risk and no reduction in stroke, systemic embolism, or cardiovascular death when administering oral anticoagulation to patients with AHRE. The study underscores the importance of ECG confirmation of atrial fibrillation before initiating anticoagulation therapy. Further research is imperative to better comprehend stroke risks in patients with infrequent and short atrial arrhythmias. As medical understanding evolves, personalized decisions will continue to shape treatment strategies for these patients.

-by Kashvi Gala

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