Non-vitamin K Antagonist Oral Anticoagulants in Patients With Atrial High Rate Episodes

NOAH is an investigator-initiated, prospective, parallel-group, double-blind, randomised, multi-centre trial. The objective of the trial is to demonstrate that oral anticoagulation using the NOAC edoxaban is superior to current therapy to pre-vent stroke, systemic embolism, or cardiovascular death in patients with AHRE and at least two stroke risk factors but without AF. The trial will be conducted in several European countries.

Atrial fibrillation (AF) is a common cause of stroke, especially ischemic stroke. So far, all available data that demonstrate a beneficial effect of oral anticoagulation for stroke prevention have been collected in populations with AF documented by conventional ECG recordings. It is well established that a large proportion of AF episodes remain undiagnosed ("silent AF"), and many of these patients present with a stroke as the first clinical sign of AF. Earlier initiation of anticoagulation could prevent such events. Continuous monitoring of atrial rhythm by implanted devices could close this diagnostic gap. Pacemakers, defibrillators, and cardiac resynchronisation devices already provide automated algorithms alerting to the occurrence of highly organised atrial tachyarrhythmia episodes, also called "subclinical atrial fibrillation" or, more commonly, "atrial high rate episodes" (AHRE). Data from large prospectively followed patient cohorts demonstrated that stroke rate is increased in patients with AHRE. A sizeable portion of these patients develops clinically detected AF over time. In these patients, AHRE can be considered as an early manifestation of paroxysmal AF. A few AHRE patients do not develop clinically overt AF, and the absolute stroke rates are lower in patients with AHRE when compared to stroke rates in patients with clinically diagnosed AF. In light of the bleeding complications associated with oral anticoagulant therapy, there is thus uncertainty about the optimal antithrombotic therapy in patients with AHREs.

The Non-vitamin K antagonist Oral anticoagulants (NOACs) provide similar or slightly better stroke prevention, and appear slightly safer compared to vitamin K antagonists (VKAs). In addition, no individual therapy adjustment of NOACs has to be performed. Edoxaban, a newly introduced NOAC, at a dose regime of 60 mg once daily (OD) has a favourable profile compared to dose-adjusted VKA therapy: In the ENGAGE-TIMI 48 trial, edoxaban prevented strokes at least as effectively as VKA therapy but caused less major bleeding events than VKA therapy.

Eligibility Criteria:
Inclusion Criteria:

* Pacemaker, defibrillator or insertable cardiac monitor implanted for any reason with feature of detection of AHRE, implanted at least 2 months prior to randomisation
* AHRE detection feature activated for adequate detection of AHRE (refer to Appendix XIII)
* AHRE (≥ 170 bpm atrial rate and ≥ 6 min duration) documented by the implanted device via its atrial lead and stored digitally. Any AHRE episode recorded is potentially eligible, but AHRE episodes detected in the first 2 months after implantation of a new device involving placement or repositioning of atrial electrodes are not eligible. AHRE episodes recorded in the first two months after a simple "box change" operation, i.e. exchange of a pacemaker or defibrillator device without exchange or repositioning of atrial electrodes, are eligible
* Provision of signed informed consent
* Age ≥ 65 years

In addition, at least one of the following cardiovascular conditions leading to a modified CHA2DS2VASc score of 2 or more:

* Age ≥ 75 years
* Heart failure (clinically overt or LVEF \< 45%)
* Arterial hypertension (chronic treatment for hypertension, estimated need for continuous antihyper-tensive therapy or resting blood pressure \> 145/90 mmHg)
* Diabetes mellitus
* Prior stroke or transient ischemic attack (TIA)
* Vascular disease (previous myocardial infarction, peripheral, carotid/cerebral, or aortic plaques on transesophageal echocardiogram \[TEE\])
* Provision of signed informed consent

Exclusion Criteria:

* Any disease that limits life expectancy to less than 1 year
* Participation in another controlled clinical trial, either within the past two months or still ongoing
* Previous participation in the present trial NOAH - AFNET 6
* Drug abuse or clinically manifest alcohol abuse
* Any history of overt AF or atrial flutter
* Indication for oral anticoagulation (e.g. deep venous thrombosis)
* Contraindication for oral anticoagulation in general
* Contraindication for edoxaban as stated in the current SmPC
* Indication for long-term antiplatelet therapy other than acetylsalicylic acid or a need for treatment with any antiplatelet agent in addition to edoxaban, especially dual antiplatelet therapy (DAPT). Patients with a transient requirement for DAPT (e.g. after receiving a stent) will be eligible when the need for DAPT is no longer present
* Acute coronary syndrome, coronary revascularisation (PCI or bypass surgery), or overt stroke within 30 days prior to randomisation
* End stage renal disease (creatinine clearance (CrCl) \< 15 ml/min as calculated by the Cockcroft-Gault method)
* All persons exempt from participation in a clinical trial by law