Atrial Fibrillation

Question 1

Different phenotypes of Afib

Answer 1

Paroxysmal, persistent, longstanding persistent

Have their own associated independent electrical phenotypes as well

Question 2

Epidemiology of Afib

Answer 2

Most common arrhythmia treated in clinical medicine. 33% of arrhythmia-related hospitalizations. Risks include: age, male sex, CHF, aortic and mitral valve disease, left atrial enlargement, HTN, obesity, obstructive sleep apnea, psoriasis.

Question 3

Two major mechanisms of Afib

Answer 3

1. One or more automatic, triggered, or microreentrant foci, so-called drivers, which fire at rapid rates and cause fibrillation-like activity
2. Multiple reentrant circuits meandering throughout the atria, annihilating and reforming wavelets that perpetuate the fibrillation

Question 4

Most common trigger of Afib

Answer 4

Rapid discharges from the pulmonary veins

Question 5

The majority of people with atrial fibrillation have ___.

Answer 5

The majority of people with atrial fibrillation have hypertension or pre-existing structural heart disease.

Question 6

Epicardial fat in Afib

Answer 6

Increased epicardial fat, as seen in obesity, predisposes to afib.

Most likely mechanisms include slow or anisotropic conduction caused by adipocyte infiltration into atrial muscle, atrial fibrosis caused by adipokines secreted by epicardial fat, and the local secretion of proinflammatory factors (e.g., IL-6, IL-8, TNF-α).

Sustained weight loss can reduce AF burden in these patients.

Question 7

Reversible causes of afib

Answer 7

• Excessive alcohol intake
• Hyperthyroidism
• Open heart thoracic surgery
• Myocardial infarction
• Pericarditis
• Myocarditis
• Pulmonary embolism

Question 8

Afib secondary to tachycardia

Answer 8

Patients with tachycardia-induced AF most often have AV nodal reentrant tachycardia or a tachycardia related to WPW syndrome that degenerates into AF

AF in a patient with a history of rapid and regular palpitations before the onset of irregular palpitations or with a WPW electrocardiographic pattern should suggest tachycardia-induced AF.

Treatment of the tachycardia in these cases also treats AF.

Question 9

Clinical features of AF

Answer 9

• Range from asymptomatic (25% of patients) to severe and life-threatening
• Palpitations, fatigue, diarrhea, effort intolerance, lightheadedness
• Polyuria due to excessive atrial natriuretic peptide
• Syncopy
• Thromboembolism
• Irregularly irregular pulse

Question 10

Strongest predictors of thromboembolism in Afib

Answer 10

History of stroke or transient ischemic episode and mitral stenosis

Question 11

Preventing thromboembolism in Afib

Answer 11

Aspirin is useless here. You need something more heavy-duty: Warfarin or newer oral anticoagulants. The oral anticoagulants have outperformed warfarin for this use in several studies.

Question 12

CHADS ₂

Answer 12

cardiac failure, hypertension, age (>75 high risk, 65-75 intermediate risk), diabetes, stroke

Estimates risk for atrial fibrillation

The first our are 1 point each, the last is 2

Being female also increases risk

Question 13

Rate control for atrial fibrillation

Answer 13

• Beta blockers
• Non-dihydropyridine CCBs
• Digoxin

Won’t get you out of afib, but will slow down your ventricular rate

Question 14

Rhythm control in atrial fibrillation

Answer 14

• Electrical cardioersion
• Chemical cardioversion

Question 15

Coagulability control in atrial fibrillation

Answer 15

• Warfarin
• oral anticoagulants (Xa inhibitors)