Left Appendage Occlusion Device Therapy in Atrial Fibrillation

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Atrial Fibrillation

Atrial Fibrillation (AF) is one of supraventricular tachyarrhythmia characterized by uncoordinated atrial activation with consequent deterioration of atrial mechanical function disturbance. AF is the most common arrhythmia in clinical practice, accounting for approximately one-third of hospitalization caused by heart rhythm disturbance.(1) Epidemiology research held in Denmark from 1983 to 2003 showed for the past 20 years, there had been 66% increase in hospital admission for AF.(2)

AF affects more than 2.5 million people in US and is thought to be responsible for 17% of all stroke cases, which are primarily due to the thrombus formation and embolization in left atrial.  The rate of ischemic stroke in patient with non-valvular AF averages 5% per year, two to seven times higher than people without AF. Around one of every 6 strokes occurs in patient with AF. Additionally when transient ischemic attack (TIA) and clinically “silent” stroke detected by brain imaging are considered, the rate of brain ischemia accompanying non-valvular AF exceeds 7% per years.(1)

The risk for stroke and thromboembolism is higher in patients with AF and valvular disturbance. Specifically, mitral valve stenosis, showed a risk for stroke and thromboembolism in  9-20% of patients, 75% of them is cerebral emboli.(1) One research in French observed the characteristics of patient with AF and found 18.5% patient with AF have underlying  valvular heart disease.(4)

Before 1990, antithrombotic therapy for prevention of ischemic systemic embolism in patient with AF was limited mainly to those with rheumatic heart disease or prosthetic heart valves.(1) In 1993, meta-analysis according to the principle of intention to treat showed that adjusted-dose oral anticoagulant is highly efficacious for prevention of all stroke with risk reduction of 64% versus placebo. The absolute risk reduction for primary prevention was 2.7% per year and 8.4% per year for secondary prevention.(5)

Antithrombotic therapy to prevent thromboembolism is recommended for all patients with AF unless contraindicated. The election of the antithrombotic agent should be based upon the absolute risk of stroke and bleeding and the relative risk and benefit for a given patient. For patient without  mechanical heart valves at high risk of stroke, chronic oral anticoagulant with vitamin K antagonist is recommended  in all dose adjusted to achieve the target intensity INR of 2.0 to 3.0 unless contraindicated.(1)

Using CHA2DS2-Vasc score, risk of stroke can be predicted based in risks inclunding, history of congestive heart failure  or left ventricle systolic dysfunction, hypertension, age ≥75 years, diabetes mellitus, history of prior thromboembolism (stroke/TIA), vascular diseases( peripheral arthery disease, myocard infarct, aortic plague), age between 65-74 years, and gender (female). (6) INR has to be adjusted every week in therapy initiation and every moth when anticoagulation is stable.(1)

Treatment with warfarin in effective for stroke prevention in AF but many physicians hesitate to prescribe it to elderly patients. This reluctance may be ascribed to the associated risk for bleeding complications, inconvenience for the patient and low estimated compliance from the elderly.(7) To assess bleeding risk in warfarin consumed patient, some score had been proposed  such Outpatient Bleeding Risk Index (OBRI)(8), HEMORR2HAGES(9), Anticoagulation and Risk Factor in Atrial Fibrillation (ATRIA)(10) and HAS-BLED.(12) Until now, none of the scoring systems has perfect accuracy.  Until now, HAS-BLED still the most commonly used scoring system, for it has the best bleeding-risk predictive score, simple to use, and is able to show predictive performance for intracranial bleeding.(12)

Observational research held in 2010 found the rate of fatal and non-fatal bleeding risk of 3.9% per patient each year for warfarin monotherapy. This bleeding risk increased in proportion to the number of antithrombotic agent used.  Most of the bleeding cases are documented in a short time after the initiation of anticoagulation therapy. A study in elderly with AF who began warfarin therapy showed rate of major bleeding of 7% in the first year.(13)

 

Left Atrial Appendages

Based on study review of TEE and operative autopsy, 90% of thrombotic material related to non –valvular AF and 54% in valvular AF, was formed in Left Atrial Appendage (LAA)(14) which can’t be routinely examined with precordial (transthoracal) echocardiogram. To be able to access LAA function and thrombus formation, Doppler Transesophageal Echocardiography Examination (TEE) is a more specific and sensitive method (see image 1). Although clinical management based in assumption that thrombus formed in 48 hours, it is often identified by TEE in less than 48 hour.(15)
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About the author

Alexander Randy Angianto

Board Certification: Medical Doctor, Faculty of Medicine, Universitas Gadjah Mada Internal Medicine Resident, Faculty of Medicine, Universitas Indonesia

Posted: November 7, 2013 at 10:59 pm, Last Updated: January 19, 2016 at 10:53 am

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