Atrial Fibrillation Detected by Continuous ECG Monitoring
Condition: Atrial Fibrillation; Stroke; Hypertension; Diabetes
MeSH terms: Stroke; Hypertension; Atrial Fibrillation
Study type: Interventional

Summary: 
      The LOOP study aims to determine whether screening for atrial fibrillation (AF) with
      implantable loop recorder and initiation of oral anticoagulation (OAC) if AF is detected will
      reduce the risk of stroke and systemic arterial embolism in patients with risk factors for
      stroke.
    

Detailed description: 
      Background:

      Ischemic stroke is an increasing health problem world-wide (Heidenreich PA, et al.
      Circulation 2011; PMID 21262990). At least 20% of ischemic strokes are attributable to atrial
      fibrillation (AF) (Marini C, et al. Stroke J Cereb Circ 2005; PMID 15879330). Another 30% are
      so-called cryptogenic, possibly related to undiagnosed AF (Brachmann J, et al. Circ Arrhythm
      Electrophysiol 2015; PMID 26763225). In approximately 30% of a general population of
      pacemaker or cardioverter defibrillator patients, previously unknown AF will be detected
      during the first 2-3 years after implantation (Healey JS, et al. N Engl J Med 2012; PMID
      22236222; ASSERT). Although the majority of these AF episodes are short-lasting and
      asymptomatic, the ASSERT study found that such AF is associated with risk of stroke. Since
      this was published, screening for AF has received intensified attention by researchers and
      the industry, although available evidence does not yet support systematic mass screening.

      -

      Aims:

      The LOOP study will determine whether long-term continuous screening and initiation of OAC
      for AF episodes lasting ≥6 minutes will reduce the risk of stroke in patients with stroke
      risk factors.

      -

      Methods:

      Patients from the general population will receive a letter of invitation from one of four
      study centers located in 3 of Denmark's 5 administrative regions.

      Eligible study participants must be ≥70 years old and have ≥1 of the following stroke risk
      factors; hypertension, diabetes, heart failure or previous stroke, while any history of AF or
      existing cardiac implantable electronic device are exclusion criteria.

      A total of 6000 participants will be randomized 3:1 to control (n=4500) or to receive an
      implantable loop recorder with continuous remote monitoring (n=1500) and initiation of OAC if
      AF is detected.

      The primary endpoint is time to first stroke or systemic arterial embolism. The trial is
      event-driven and planned to continue until 279 adjudicated primary events have occurred.

      Sub-studies include AF characterization, health economic analyses, quality-of-life
      assessments, cognitive function assessments, and studies of risk markers from 12-lead ECG,
      genetics, cardiac and brain imaging, biochemistry, and more.
    

Intervention name(s): Implantable loop recorder (Medtronic Reveal LINQ(TM))
Intervention type(s): Device
Intervention description(s): The patients in the experimental arm receive an implantable loop recorder (Medtronic Reveal LINQ(TM)) with continuous monitoring, and are followed by daily automated remote transmissions. New arrhythmia episodes are reviewed daily by an experienced medical doctor. If AF lasting ≥6 minutes is detected and confirmed by at least two senior cardiologists, OAC is initiated. Decision about specific type of OAC, and possible further clinical work-up or treatment, is left to the treating physician and the patient. The remote monitoring continues until end of service of the device, patient withdrawal or other end-of-study.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: atrial fibrillation; cardiac arrhythmia; stroke; implantable loop recorder; bleeding; anticoagulation; hypertension; diabetes; heart failure; mortality