Atrial Fibrillation
PATHO
CAD, valvular (↑ in mitral), hyperthyroid, pulmonary disease, CHF, electrolyte abnormalities, HTN, and many more
↑ risk of developing A-fib
Irritable foci ➔ erratic atrial activity ➔ ineffective atrial contraction ➔ ↑ risk of clot
Abnormal electrical activity conducted ➔ irregular HR & tachyarrhythmias
Ventricular rate depends on how many of the atrial impulses make it through the av node
Sympathetic stimulation ➔ ↑ AV conduction
Parasympathetic stimulation ➔ ↓ AV conduction
An accessory pathway ➔ ↑ impulses making it to ventricles
A-fib (new onset) can ➔ paroxysmal (lasting < 1wk) or persistent
Permanent A-fib can ➔ HF
SSX
Presents with tachy associated sx (a-fib with rapid ventricular response)
Thrombotic event ➔ infarct: cerebral, mesenteric, renal, splenic, limb
DX
EKG irregular, fibrillatory waves, no discernible P waves
Halter monitor will catch paroxysmal
If presenting with rapid afib: find out about preexcitation (WPW) hx
Order all the labs to look for reversible causes of A-fib (K, Mg, TSH/fT4)
ECHO indicated for new-onset A-fib to look for structural dz like MS
Trans-esophageal > Trans-thoracic for atrial thrombus
TX
Prevent embolization
CHADS-VASc (for non-valvular A-fib)
> 2 is considered moderate to high risk
All pts with valvular afib are high risk
Rate & rhythm control
Unstable: Synchronized cardioversion
Should get pre-cardioversion anticoagulants ASAP
Continue anticoagulants x4wks even if converted to NS
Stable
Rate controlled first
β-blockers > non-dihydropyridine CCB > digoxin
If decide to cardiovert to NS rhythm
Get ECHO first (look for atrial thrombi)
New afib > 48hrs old ➔ x3weeks of anticoagulants before procedure
Electrical > pharmacological
Pharm cardioversion: flecainide, propafenone
Take into account the risk of bleeding when starting anticoagulation
NondihydroCCB: diltiazem, verapamil. Digoxin is OK if BP soft but levels need to be monitored
AV nodal blocking agents contraindicated in AF with preexcitation (WPW)
CHADS VASc
CHF/SSX of HF +1
HTN +1
Age > 75 +2, 65-74 +1
DM BG > 125, or on DM meds +1
Stroke/TIA/embolism +2
Vascular dz +1
Sex female +1
Anticoagulation
Vitamin K antagonist (common and extrinsic pathway)
Warfarin (cheaper)
Bridged with heparin after event
Monitor PT, INR to therapeutic level: 2-3
For CKD, liver failure pts, valvular a-fib (MS or mechanical valve and Afib)
Can be reversed with FFP (quick), Vit K (slower)
Direct Oral anticoagulants (DOAC) or non vitk antag oral anticoagulants (NOAC)
↓ risk of bleeding and ↑ pt compliance (no monitoring)
Dabigatran ⊣ thrombin (IIA)
Reversal with idarucizumab
Apixaban, rivaroxaban, edoxaban, ⊣ Xa
Reversal with andexanet alfa (no antidote for edoxaban)