Atrial Fibrillation

Symptoms of afib may develop from RVR or slow ventricular rhythm, CHF, variable R-R intervals (perceived irregularity), cardiac ischemia
Causes include thyroid disease, etoh, pulmonary embolism, cardiac surgery, myocarditis, pericarditis

Patients with new atrial fibrillation should receive-
careful H&P including assessment of symptoms, frequency, triggers (drug use)
ECG to evaluate pre-excitation, ischemia, LVH, atrial enlargement
CXR to evaluate pulmonary processes ie) pneumonia
Echo to evaluate atrial size, ventricular function, effusions, valvular abnormalities; not sensitive for L atrial thrombus
TEE should be used to look for LA thrombus if pt is cardioversion candidate (unless unstable afib where you cardiovert regardless)
TSH and FT4 should be measured as subclinical hyperthyroidism is a precipitant in up to 5% of new onset afib
renal and liver function should be measured to dose medications
hemoccult is recommended prior to initiating anticoagulation

Indications for EMERGENT cardioversion of afib
Class I evidence for afib with RVR with ischemia (ACS), hemodynamic
instability, unacceptable symptoms (CHF)

What are the indications for anticoagulation pre and post cardioversion in afib?
NOTE: These recommendations are for cardioversion and do not reflect guidelines for chronic afib managment (ie. CHADS2, CHA2DS2VASc)

If Afib> 48 hrs, coumadin for 3 wks before and 4 wks after successful
cardioversion
If Afib>48 hrs + negative TEE for emboli,coumadin/hep/lovenox for 5 days before and 4 wks after successful cardioversion. If emboli seen, must receive 3 wks coumadin and negative TEE before cardioversion
If Afib<48 hrs, start heparin and lovenox and then cardiovert
If emergent cardioversion, start heparin gtts immediately after
cardioversion and cont coumadin for at least 4 wks

Stroke Risk: CHADS2 vs CHA2DS2VASc for nonvalvular afib
The European Society of Cardiology (ESC) released an afib update in 2010 including the CHA2DS2VASc score in order to further stratify those deemed "intermediate" risk patients by CHADS2. With the new scoring system, only 15% are intermediate risk whereas 61% are intermediate based on the CHADS2 score.

Bleed risk on coumadin
The ESC also outlined the HAS-BLED prediction tool to assess for bleeding
The following increase bleed risk: Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized ratio, Elderly (> 65 years), Drugs/alcohol concomitantly
Our pt had a score of >/= 3 or "high risk" for bleed, which should also be taken into account when considering anticoagulation
For more details on HAS-BLED, see the Chest study

Rate vs Rhythm Control
The AF-CHF study observed no difference in CV mortality between rate and rhythm control in patients with EF<35% and with symptoms of HF and AF
AFFIRM and RACE studies support this finding
Most recommend rhythm control for those with symptoms such as palpitations, dyspnea
One must also take into account likelihood of maintaining sinus rhythm on cardioversion
Risk of recurrent afib after successful cardioversion increases with hypertension, an enlarged left atrium (LA), AF for more than one year, or heart failure or any direct trigger such as mediastinal metastasis

Ref:
ACC/AHA/ESC guidelines for the management of patients with atrial
fibrillation. A report of the American College of Cardiology/American
Heart Association Task Force on Practice Guidelines and the European
Society of Cardiology Committee for Practice Guidelines (Writing
committee to revise the 2001 guidelines for the management of patients
with atrial fibrillation). J Am Coll Cardiol 2006; 48:e149.
http://www.uptodate.com/online/content/image.do?imageKey=CARD%2F1643
Circ J. 2010 Nov 25;74(12):2534-7. Epub 2010 Nov 2.
The 2010 update of the ESC guidelines for the management of atrial fibrillation.
CHEST. 2010 Nov;138(5):1093-100. Epub 2010 Mar 18.A Novel User-Friendly Score (HAS-BLED) To Assess 1-Year Risk of Major Bleeding in Patients With Atrial Fibrillation
The Euro Heart Survey

(Ellen Eaton MD, 4/8/11)