How should atrial fibrillation be managed, including classification as rate‑controlled or rhythm‑controlled, stroke risk assessment with CHA₂DS₂‑VASc (Congestive heart failure, Hypertension, Age ≥ 75, Diabetes, Stroke/TIA/thromboembolism, Vascular disease, Age 65‑74, Sex category), anticoagulation indications, and first‑line pharmacologic options?

Management of Atrial Fibrillation

For patients with atrial fibrillation, oral anticoagulation with a direct oral anticoagulant (DOAC) is mandated when the CHA₂DS₂-VASc score is ≥2 in men or ≥3 in women, while rate-control or rhythm-control strategies address symptoms separately. 1, 2

Stroke Risk Stratification: CHA₂DS₂-VASc Score

The CHA₂DS₂-VASc system is the standard tool for assessing thromboembolic risk and guides anticoagulation decisions 1:

Score Components

• C – Congestive heart failure: 1 point 1
• H – Hypertension (history or current treatment): 1 point 1
• A₂ – Age ≥75 years: 2 points 1
• D – Diabetes mellitus: 1 point 1
• S₂ – Prior Stroke/TIA/thromboembolism: 2 points 1
• V – Vascular disease (MI, PAD, aortic plaque): 1 point 1
• A – Age 65–74 years: 1 point 1
• Sc – Female sex: 1 point 1

Risk Thresholds and Annual Stroke Rates

• Score 0 (men) or 1 (women, from sex alone): Truly low risk with 0–0.6% annual stroke rate; no anticoagulation recommended 1, 2
• Score 1 (men) or 2 (women): Intermediate risk with 2.2–2.75% annual stroke rate; oral anticoagulation should be considered 1, 3
• Score ≥2 (men) or ≥3 (women): High risk with ≥2.2% annual stroke rate; oral anticoagulation is a Class I indication (strongly recommended) 1, 2, 4

Important Scoring Pitfalls

• Hypertension counts even if controlled: Any history of hypertension or current antihypertensive treatment assigns 1 point, regardless of current blood pressure control 1
• Age scoring differs from older CHADS₂: The CHA₂DS₂-VASc assigns 1 point for age 65–74 and 2 points for age ≥75, whereas CHADS₂ only scored age ≥75; misapplying the old rule underestimates risk 1
• Female sex alone does not mandate treatment: Women with a score of 1 (from sex alone) have stroke risk equivalent to men with score 0 and do not require anticoagulation 1

Anticoagulation Strategy

First-Line Therapy: Direct Oral Anticoagulants (DOACs)

DOACs are preferred over warfarin as first-line therapy for non-valvular atrial fibrillation (Class I, Level A). 2, 4

Available DOACs include 2:

• Apixaban
• Rivaroxaban
• Dabigatran
• Edoxaban

Renal Function Monitoring and Dose Adjustment

Renal function dictates DOAC selection and dosing 2:

• Before initiating any DOAC: Evaluate creatinine clearance (CrCl) 2
• Ongoing monitoring: Reassess renal function at least annually (Class I, Level B); more frequently during acute illness, medication changes, or advancing age 2
• Moderate-to-severe CKD with CHA₂DS₂-VASc ≥2: Dose reduction of DOACs may be considered (Class I, Level B) 2
• End-stage CKD (CrCl <15 mL/min) or dialysis: Dabigatran and rivaroxaban are contraindicated (Class III, Level B); warfarin targeting INR 2.0–3.0 is reasonable (Class IIa, Level B) 2

Warfarin as an Alternative

When DOACs are contraindicated or unavailable 2, 4:

• Target INR: 2.0–3.0 (Class I, Level B) 2
• Monitoring frequency: Check INR weekly during initiation, then monthly once stable 2
• Time in therapeutic range (TTR): Maintain >70% for optimal efficacy 4

Special Populations

Clinical Scenario	Recommendation	Citation
Mechanical heart valves	Warfarin mandatory; dabigatran contraindicated (Class III, Level B)	[2]
Atrial flutter	Manage identically to AF using same CHA₂DS₂-VASc thresholds (Class I, Level C)	[1,2]
Hypertrophic cardiomyopathy or cardiac amyloidosis	Anticoagulate regardless of CHA₂DS₂-VASc score (Class I, Level B)	[2]
Device-detected subclinical AF	DOAC therapy may be considered if elevated thromboembolic risk and not high bleeding risk (Class IIb, Level B)	[2]
Fall risk	Do not withhold anticoagulation solely because of fall risk (Class IIa, Level B)	[2]

Bleeding Risk Assessment: HAS-BLED Score

The HAS-BLED score identifies modifiable bleeding risk factors 2:

• H – Hypertension (systolic >160 mmHg, uncontrolled)
• A – Abnormal renal or liver function
• S – Stroke history
• B – Bleeding history or predisposition
• L – Labile INR (applies only to warfarin patients)
• E – Elderly (>65 years)
• D – Drugs (antiplatelet agents, NSAIDs) or alcohol

A HAS-BLED score ≥3 does NOT contraindicate anticoagulation but prompts more frequent monitoring and correction of modifiable factors (Class IIa, Level B). 2

Rate Control vs. Rhythm Control

This decision addresses symptom management, not stroke prevention 2:

• Rate control: Target resting heart rate <110 bpm for lenient control or <80 bpm for strict control; use beta-blockers, non-dihydropyridine calcium channel blockers (diltiazem, verapamil), or digoxin
• Rhythm control: Consider for symptomatic patients despite rate control; options include antiarrhythmic drugs (amiodarone, flecainide, sotalol) or catheter ablation
• Anticoagulation decisions remain independent of rate vs. rhythm strategy: CHA₂DS₂-VASc score determines anticoagulation regardless of whether sinus rhythm is restored 1

Critical Pitfalls to Avoid

• Never use aspirin for stroke prevention in AF: Aspirin is ineffective for stroke prevention and still carries bleeding risk; it should not be used in patients with CHA₂DS₂-VASc ≥1 2
• Do not withhold anticoagulation based solely on elevated HAS-BLED: Address modifiable bleeding risk factors instead 2
• Avoid dual antiplatelet-anticoagulant therapy without specific indication: Concomitant antiplatelet therapy substantially increases bleeding risk without proportional stroke reduction benefit 4
• Do not misclassify "lone" AF: Even well-controlled hypertension on medication counts as 1 point; subclinical hypertension or occult vascular disease must be excluded before labeling AF as "lone" 1