Atrial Fibrillation

Atrial fibrillation – an irregular, usually rapid supraventricular rhythm caused by simultaneous discharge and reentry at multiple atrial fociCAUSES

Serious cardiopulmonary causes	Other causes
Acute myocardial infarction or acute coronary syndrome	Hyperthyroidism
Pulmonary embolism	Ethanol use (“holiday heart”)
Cardiomyopathy	Hypothermia
Restrictive heart disease	Drugs: sympathomimetics, cocaine, amphetamine derivatives, ephedra
Chronic obstructive pulmonary disease	Metabolic causes: hypokalemia
Sleep apnea	Idiopathic: lone AF
Hypertension
Valvular heart disease
Left ventricular hypertrophy
Left ventricular diastolic dysfunction
Congestive heart disease
Sick sinus syndrome
Pericarditis
Post-cardiac surgery

 

History

HPI

• Onset, duration (< or > 48 hours) and frequency
• Symptoms: palpitations, fatigue, dyspnea
• chest pain?
• fevers/ constitutional symptoms assoc’d with sepsis
• EtOH ingestion, drug use

PMHx

• CAD, MI, valve disease, CHF, other cardiac abnormalities
• thyroid disease
• COPD

Physical

• Vitals – irregularly irregular pulse +/- tachycardia
• CV – murmurs, S3 gallop, increased JVP, pedal edema
• Respiratory – crackles
• Neuro – assess for embolic complications

Investigations

• ECG – no organized P waves, chaotic baseline, irregularly irregular ventricular response, narrow QRS
• Initial labs – CBC/diff, elytes (hypokalemia can cause Afib), glucose, TSH, free T4, CXR
• Trop/ CK – if ACS suspected
• CT chest – possible PE
• ABG – CO poisoning, hypercarbia, shock, acidemia
• Echo – not usually used in acute assessment
• Holter monitor – used in some patients with paroxysmal Afib

Management
Dependent upon several factors: acuity of onset, associated symptoms, hemodynamic status, and the duration of the dysrhythmia (<48 h or >48 h).

Options:

• RATE CONTROL
  • B-blockers, diltiazem, verapamil
  • if CHF, use amiodarone or digoxin
  • initial management in hemodynamically stable patients
    Note: carotid massage may slow ventricular rate
• THROMBOEMBOLISM PROPHYLAXIS
  • Acute: heparin
  • Chronic: use CHADS2 score (see below) to determine appropriate Rx
    • 0 stroke risk factors – ASA 81 – 325 mg daily
    • 1 mod RF – ASA or warfarin
    • > 1 mod RF or any high risk factor – warfarin (goal INR 2.0 – 3.0)
• RESTORE SINUS RHYTHM
  • New onset
    • Self-limited episode – no antiarrhythmic drugs necessary if serious symptoms absent
    • if high stroke risk, anticoagulation beneficial
  • Persistent
    • rate control + anticoagulation OR
    • cardioversion
      • • Chemical – amiodarone, sotalol, diltiazem, Class I anti-arrhythmic agent
        • Electrical – synchronized DC cardioversion
      • if duration <48 h, can cardiovert without anticoagulation
      • if duration>48h, MUST anticoag 3 wks prior/ 4 wks following cardioversion
      • use CHADS2 score to assess need for longterm anticoagulation
  • Recurrent/ Permanent
    • Brief episodes or minimal symptoms- rate control + anticoag
    • Prolonged or bothersome symptoms – antiarrhythmic drugs
    • Permanent Afib – rate control + anticoag (use CHADS2 score)

Risk Factor	Points
> 75 years	1
diabetes	1
hypertension	1
congestive heart failure	1
Prior stroke/TIA	2

CHADS 2 score	Yearly risk of stroke (%)	Anticoagulation
0-1	1.9-2.8	aspirin 81-325 mg
2-3	4.0-5.9	coumadin
4-6	8.5-18.2	coumadin