ATRIAL FIBRILLATION AND PATENT FORAMEN OVALE: RISK FACTORS FOR STROKE

ATRIAL FIBRILLATION AND STROKE: AN OVERVIEW

More than 2.3 million adults in the U.S. have atrial fibrillation (Afib), which is associated with a 5-fold increased risk of stroke.1 The left atrial appendage (LAA), a remnant structure of the primordial left atrium, is the anatomical site most associated with thrombus formation in the vast majority of patients with Afib, due to the reduced contractility of the LAA. In fact, thrombus formation in the LAA may develop even in patients with Afib who are receiving anticoagulation therapy.2

STATISTICS: PATIENTS AT RISK

The LAA’s role in thrombus formation occurs especially in patients with nonvalvular Afib and, to a lesser extent, patients with mitral valve disease. Thrombi from the LAA account for approximately:

STATISTICS: PATIENTS
AT RISK

The LAA’s role in thrombus formation occurs especially in patients with nonvalvular Afib and, to a lesser extent, patients with mitral valve disease. Thrombi from the LAA account for approximately:

 

 
of atrial thrombi in nonvalvular afib1,3,4
of atrial thrombi in nonvalvular afib1,3,4
 

 

 

of thrombi in patients with rheumatic mitral valve disease (primarily stenosis)1

 

of thrombi in patients with rheumatic mitral valve disease (primarily stenosis)1

An increased number of lobes in the LAA has been associated with the presence of a thrombus, independent of clinical risk and blood stasis (p < 0.001).5

CHALLENGES WITH MEDICAL THERAPY

Warfarin has a narrow therapeutic window, requires frequent monitoring, has significant drug and food interactions, increases the risk of bleeding, and has a high discontinuation rate. Non-vitamin K antagonist oral anticoagulants (NOACs) have been shown to be non-inferior or superior to warfarin but are also associated with increased bleeding risk and costs as well as high discontinuation rates ranging between 17%-25% at 2 years.6

In addition, patients with Afib who also have coronary artery stents present significant challenges, since:6

  • Adding oral anticoagulant (OAC) to dual antiplatelet therapy increases bleeding risk
  • Using antiplatelet therapy alone does not provide effective stroke prevention

NUMBER OF PATIENTS NOT TREATED BY ANTICOAGULANTS

Data reveal that 40% of patients at risk for stroke do not receive any form of oral anticoagulation.7 One reason is therapy cessation: for certain patients serious bleeding and/or intracranial bleeding usually leads to cessation of therapy.

Trial data also reveal that approximately 1 in 5 patients discontinued NOAC therapy. Compliance is another contributing factor.8

Although effective therapies for stroke prevention exist, there is a clear need for other, better methods of stroke prevention.9

SURGICAL OR MECHANICAL LAA OCCLUSION

Because the use of long-term OAC is limited due to bleeding complications, LAA occlusion with surgical ligation or mechanical occlusion is a potential alternative to OAC.4

Surgical exclusion, however, is typically reserved for patients undergoing cardiac surgery for concomitant conditions such as valvular and coronary artery disease. Various surgical techniques include appendectomy, staples, or suture exclusion, and the rates of complete LAA closure among the techniques are reported to be between 0% and 100%.6

ESC INDICATIONS FOR PERCUTANEOUS LAA CLOSURE10

The 2016 European Society of Cardiology (ESC) guidelines recommend that a percutaneous LAA closure device:

  • May be considered in patients with Afib who are at risk of stroke and are contraindicated for long-term anticoagulation (class IIb)
  • Might be an alternative in patients who need to halt OAC due to active bleeding

EHRA/EAPCI CONSENSUS 2014 ON PERCUTANEOUS LAA CLOSURE11

The European Heart Rhythm Association (EHRA) and European Association of Percutaneous Cardiovascular Interventions (EAPCI) published these recommendations related to LAA occlusion:

  • LAA occlusion has been shown to be equivalent to oral vitamin K antagonists in reducing thromboembolic events
  • The main indication for LAA occlusion is a relative or absolute contraindication to (N)OACs in patients with Afib and a CHADS2  score of ≥ 1 or CHA2DS2VASc score ≥ 2*
  • Patients who refuse (N)OACs after a thorough discussion of current data may be considered for LAA occlusion
  • Some patients who are not well characterized by the HAS-BLED score† (eg, patients with cancer or chronic inflammatory bowel disease) but have a high risk of bleeding with OAC may also be considered for LAA occlusion if NOACs are also thought to carry an unacceptable bleeding risk

With increasing thromboembolic risk, the use of LAA occlusion becomes a more attractive option.

*CHADS2 score: congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke (double weight) CHA2 DS2 -VASc score: congestive heart failure, hypertension,
age (> 65 = 1 point, ≥ 75 = 2 points), diabetes, prior stroke/transient ischemic attack (2 points), vascular disease (peripheral arterial disease, previous myocardial infarction, aortic plaque), sex (female)
HAS-BLED: hypertension, abnormal renal and liver function (1 point each), stroke, bleeding, labile INRs, elderly, drugs or alcohol (1 point each)

MORE LAA CLOSURE STUDIES UNDERWAY

Because of the lack of prospective trials on LAA occluder therapy, there are a number of ongoing occluder trials. Among them are 4 trials with the Amplatzer Amulet LAA Occluder.

Treatment for left atrial appendage

Abbott offers effective treatment to prevent thrombus embolization from the LAA.
 

Amplatzer Amulet LAA Occluder


The information provided is not intended for medical diagnosis or treatment as a substitute for professional advice.  Consult with a physician or qualified healthcare provider for appropriate medical advices.

AP2947067-WBO Rev. A

References
  1. Chanda A, et al. Left atrial appendage occlusion for stroke prevention. Prog Cardiovasc Dis. 2017;59(6):626-635. doi.org/10.1016/j.pcad.2017.04.003.
  2. Beigel R, et al. The left atrial appendage: anatomy, function, and noninvasive evaluation. JACC Cardiovasc Imaging. 2014;7(12):1251-1265. doi.org/10.1016 /j.jcmg.2014.08.009.
  3. Al-Saady NM, et al. Left atrial appendage: structure, function, and role in thromboembolism. Heart. 1999;82:547–555.
  4. Bajwa RJ, et al. Left atrial appendage occlusion for stroke prevention in patients with atrial fibrillation. Clin Cardiol. 2017;40:825-831. doi: 10.1002/clc.22764.
  5. Yamamoto M, et al. Complex left atrial appendage morphology and left atrial appendage thrombus formation in patients with atrial fibrillation. Circ Cardiovasc Imaging. 2014;7(2):337-343. doi: 10.1161/CIRCIMAGING.113.001317.
  6. Suradi HS, et al. Left atrial appendage closure: outcomes and challenges. Neth Heart J. 2017;25:143-151. doi: 10.1007/s12471-016-0929-0.
  7. Kakkar AK, et al. Risk profiles and antithrombotic treatment of patients newly diagnosed with atrial fibrillation at risk of stroke: perspectives from the international, observational, prospective GARFIELD registry. PLOS ONE. 8(5):e63479. doi.org/10.1371/journal.pone.0063479.
  8. Baman JR, et al. Percutaneous left atrial appendage occlusion in the prevention of stroke in atrial fibrillation: a systematic review. Heart Failure Rev. 2018;23:191–208. doi.org/10.1007/s10741-018-9681-4.
  9. Piccini JP, et al. Left atrial appendage occlusion: rationale, evidence, devices, and patient selection. Eur Heart J. 2017;38:869–876. doi:10.1093/eurheartj/ehw330.
  10. Kirchhof P, et al. 2016 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. Europace. 2016;18:1609–1678. doi:10.1093/europace/euw295.
  11. Meier B, et al. EHRA/EAPCI expert consensus statement on catheter-based left atrial appendage occlusion. EP Europace. 2014;16(10):1397–1416.
     

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