Atrial Fibrillation with Rapid Ventricular Response (RVR)
Guideline priority: no dedicated Thai CPG rate-control drug protocol identified — 2025 Thai AF Guideline (Heart Association of Thailand, adapted from 2024 ESC) and 2024 ESC AF Guideline used as primary source; 2023 ACC/AHA/ACCP/HRS AF Guideline cross-referenced. Gap flagged where Thai-specific dosing unavailable.
1. Initial Assessment Flowchart
AF with ventricular rate >100–110 bpm → assess hemodynamic stability
Synchronized DC cardioversion 100–200 J biphasic (escalate as needed); procedural sedation; do not delay for anticoagulation status
STABLE
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Check for pre-excitation (WPW) on ECG
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Pre-excited AF (WPW) → AVOID AV-nodal blockers (β-blocker, non-DHP CCB, digoxin, adenosine) — risk of accelerated conduction → VF. Use procainamide or ibutilide, or elective cardioversion if unstable/refractory.
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No pre-excitation → assess LVEF / HF status → select rate-control agent (see Section 2)
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Target: lenient rate control, resting HR <110 bpm (RACE II); tighten to <80 bpm if still symptomatic
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Anticoagulation: calculate CHA₂DS₂-VASc → initiate unless contraindicated. If cardioversion planned and AF >48h/unknown duration: anticoagulate ≥3 wk pre- and 4 wk post-cardioversion, or TEE-guided.
2. First-Line Agents by Clinical Context
LVEF ≥ 40% (no significant HFrEF)
Metoprolol tartrate (Betaloc) first-line
2.5–5 mg IV over 2 min, repeat q5min up to 3 doses; convert to oral metoprolol 25–50 mg q6–12h once controlled.
Critical: hold/use with caution if SBP <100 or active bronchospasm.
LVEF < 40% (HFrEF)
Digoxin (Lanoxin) first-line if hemodynamically borderline
Loading 0.25 mg IV q6h, up to 1.0–1.5 mg total over 24h; maintenance 0.125–0.25 mg/day PO, renally adjusted. Amiodarone (Cordarone) — alternative/adjunct, also provides rhythm control: 150 mg IV over 10 min, then 1 mg/min ×6h, then 0.5 mg/min ×18h.
Critical: avoid non-dihydropyridine CCB (verapamil/diltiazem) — negative inotropy worsens decompensation. Digoxin renal-dose adjust (avoid load in ESRD without levels).
3. Rate-Control Drug Comparison
Drug
Class
IV Dose
Onset
Renal/Hepatic Adj.
Key Caution
Metoprolol (Betaloc)
β1-blocker
2.5–5mg IV q5min ×3
2–5 min
Hepatic dose ↓ in cirrhosis; renal — no adj.
avoid decompensated HF, bronchospasm, bradycardia
Esmolol (Brevibloc)
β1-blocker (ultra-short)
500 mcg/kg load, 50–200 mcg/kg/min infusion
<5 min
No adj. needed (rapid metabolism)
Preferred if hemodynamic uncertainty (short t½)
Diltiazem (Herbesser)
Non-DHP CCB
0.25 mg/kg IV over 2 min, then 0.35 mg/kg; infusion 5–15 mg/hr
2–7 min
Hepatic ↓ dose; renal — mild adj.
avoid in LVEF<40%, decompensated HF
Verapamil (Isoptin)
Non-DHP CCB
0.075–0.15 mg/kg IV over 2 min
3–5 min
Hepatic ↓ dose
avoid HFrEF, pre-excitation
Digoxin (Lanoxin)
Cardiac glycoside
0.25mg IV q6h (max 1.5mg/24h)
Hours (slow)
renal — major adj., avoid load if CrCl<30 without levels
Slow onset — not first-line for acute RVR unless HF/hypotension limits other options; monitor levels/K⁺
Amiodarone (Cordarone)
Class III (rate + rhythm)
150mg IV/10min → 1mg/min×6h → 0.5mg/min×18h
Days for full effect; acute rate effect faster
Hepatic — reduce with impairment; no renal adj.
Preferred if hypotensive HFrEF and other agents contraindicated; thyroid/pulmonary toxicity long-term
Cardioversion of AF >48h or unknown duration without ≥3wk therapeutic anticoagulation or negative TEE carries thromboembolic risk — do not defer emergent cardioversion for hemodynamic instability, but anticoagulate as soon as feasible.
References: 2024 ESC Guidelines for the management of atrial fibrillation, Eur Heart J 2024;45:3314 (developed with EACTS); 2025 Thai Guideline for the Diagnosis and Management of Atrial Fibrillation, Thai Cardiac Electrophysiology Club/Heart Association of Thailand (Ann Behav Med 2025, DOI:10.2478/abm-2025-0028) — adapted largely from 2024 ESC, no independent Thai-specific rate-control drug protocol identified (gap flagged); 2023 ACC/AHA/ACCP/HRS Guideline for Diagnosis and Management of AF, Circulation 2024;149:e1-e156; RACE II trial, NEJM 2010;362:1363-73 (lenient vs strict rate control).