AfibRVR

AF with RVR + new-onset AF · complete reference · all trials · full doses + brand names · Full Card

Symptoms / Associated Sx

• Palpitations (rapid, irregular); dyspnea; fatigue; chest discomfort; lightheadedness; presyncope; polyuria (atrial natriuretic peptide release during AF)

• Irregularly irregular pulse; pulse deficit (apical rate > radial rate — due to variable stroke volume with short diastolic filling times); hypotension if rapid ventricular response depletes cardiac output

• Hemodynamic instability: SBP <90 mmHg + AMS + acute pulmonary edema + active ischemia → synchronized DC cardioversion immediately — do NOT delay for anticoag or rate-control agents

• Signs of precipitant: fever/rigors (infection/sepsis — most common acute trigger); tremor + diaphoresis + exophthalmos + weight loss (thyrotoxicosis); JVD + crackles + S3 + edema (HF decompensation); pleuritic CP + hypoxia + tachycardia (PE); palpitations following ETOH binge (holiday heart)

• Tachycardia-mediated cardiomyopathy: sustained AF-RVR for weeks → dilated CM + ↓EF; fully reversible with rate control (HR <80 for 3–6 months); do NOT implant ICD until EF reassessed after sustained rate control

Neg

• Pt denies regular ventricular rate at exactly ~150 bpm with sawtooth flutter waves negative in II/III/aVF at 300 bpm — argues against atrial flutter (adenosine 6 mg IV transiently increases AV block → flutter waves visible, does NOT terminate flutter; same stroke risk as AF — same anticoag algorithm applies; commonly undertreated for anticoag)

• Pt denies regular narrow tachycardia that terminates abruptly with adenosine 6 mg IV or vagal maneuvers — argues against SVT/AVNRT (retrograde P waves in SVT; P hidden in QRS or just after; terminates completely, does not slow then resume like flutter)

• Pt denies delta wave on ECG (slurred upstroke of QRS) with wide irregular tachycardia at rates >200 bpm — argues against WPW with AF (WPW + AF: NEVER give adenosine/BB/CCB/digoxin [Lanoxin] → AV nodal block → all conduction via accessory pathway → ventricular rates 250–300 bpm → VF → cardiac arrest; procainamide [Pronestyl] 10 mg/kg IV or cardioversion only)

• Pt denies regular rate-appropriate rhythm with upright P waves in I+aVF with P:QRS 1:1 ratio — argues against sinus tachycardia (sinus tachy = physiologic response to underlying cause; never rate-control blindly; treat the cause)

• Pt denies ≥3 distinct P-wave morphologies with irregular rhythm and COPD/hypomagnesemia history — argues against multifocal atrial tachycardia (MAT — no cardioversion; treat underlying COPD + replete Mg2+; verapamil [Calan] or metoprolol [Lopressor] for rate control)

Social History (SHx)

• Prior AF type (paroxysmal <7 days, persistent >7 days, long-standing persistent >1 year, permanent); prior cardioversions (number, success, how long in SR); prior ablation (type, outcome, recurrence); known EF and last echo date (determines rate agent selection)

• Valvular disease (mitral stenosis — anticoag mandatory regardless of CHA2DS2-VASc score; rheumatic AF = highest thromboembolic risk); ETOH (dose, frequency — holiday heart; ETOH cessation ↓AF burden); OSA (untreated OSA significantly ↑AF recurrence — CPAP referral); thyroid history; prior stroke/TIA (CHA2DS2-VASc +2 points)

• Current anticoagulation and CHA2DS2-VASc score; family history of AF or sudden cardiac death; cocaine/stimulant use

Main Etiology

• Cardiac: HF (↑LA pressure → atrial stretch → electrical remodeling); HTN heart disease (most important modifiable risk factor — ↑LA size); valvular disease (MS/MR — LA dilation); CAD; post-cardiac surgery (POAF: peaks Days 2–3; prophylaxis with amiodarone [Pacerone] or BB perioperatively); cardiac tamponade/pericarditis

• Non-cardiac: infection/sepsis (most common acute hospital trigger — inflammatory cytokines + catecholamine surge); hyperthyroidism (TSH <0.1 — increases adrenergic tone; treat thyroid first before cardioversion); ETOH excess/holiday heart (acute binge → ↑vagal tone + catecholamines); PE (↑RA pressure → stretch → AF); hypokalemia/hypomagnesemia; cocaine/stimulants; sleep deprivation

• Idiopathic/lone AF: young patients (<60 years), structurally normal heart, no identifiable risk factors; genetic predisposition (SCN5A, KCNQ1, PITX2 variants)

RF

• Modifiable: HTN (most important — SBP >140 → ↑LA size → AF), obesity (BMI >30 — independent RF; weight loss ≥10% ↓AF burden LEGACY trial), OSA (untreated — repeated hypoxia + catecholamine surges; CPAP ↓AF recurrence), ETOH (>3 drinks/day — dose-dependent; ETOH cessation ↓AF recurrence 50%), hyperthyroidism, DM, physical inactivity

• Non-modifiable: older age (↑fibrosis, ↓conduction velocity), male sex, family history of AF, prior AF episode (50% recurrence at 1 year without antiarrhythmic)

• Additional triggers: post-cardiac surgery (POAF in 20–40% of CABG, 40–50% valve surgery), acute MI, myocarditis, pulmonary disease (COPD, PE), stimulants/cocaine, electrolyte abnormalities (↓K+, ↓Mg2+)

Data

• ECG — immediate, every patient (12-lead required: irregularly irregular, absent P waves, fibrillatory baseline; measure QRS width — narrow = typical AV conduction; wide = WPW vs aberrant conduction vs VT; delta waves — WPW alarm; STEMI trigger pattern; measure QTc before any antiarrhythmic; sawtooth pattern II/III/aVF = flutter, not AF)

• TSH + free T4 (hyperthyroidism: TSH <0.1 — must achieve euthyroid before cardioversion; 50–80% immediate AF recurrence in thyrotoxic patients; PTU [propylthiouracil] + propranolol [Inderal] to control)

• BMP (K+ — target ≥4.0 mEq/L before antiarrhythmic; hypokalemia ↑torsades risk; Mg2+ — target ≥2.0 mEq/L; replete empirically; Cr — affects DOAC dosing; Na+ — hyponatremia in HF decompensation)

• Troponin I/T (ACS as trigger — dynamic rise/fall = ACS; demand ischemia from tachycardia — modest elevation; elevated troponin = worse prognosis in new-onset AF)

• CBC (WBC — infection trigger; leukocytosis with left shift = bacteremia/sepsis; Hgb — anemia as trigger; platelets — anticoag safety threshold)

• Coagulation studies (baseline INR before DOAC initiation; anti-Xa level if on enoxaparin [Lovenox]; PT/PTT if on warfarin [Coumadin])

• Echo (TTE) (EF — critical for rate agent selection: ↓EF = metoprolol [Lopressor]/digoxin [Lanoxin], NOT diltiazem [Cardizem]/verapamil [Calan]; LA diameter/volume — ↑LA = ↑recurrence post-cardioversion; valvular disease — MS/MR; structural heart disease; LV thrombus; IVC size — volume status)

• CXR (pulmonary edema — HF decompensation trigger; PNA infiltrate — infection trigger; cardiomegaly; widened mediastinum — aortic dissection trigger of AF)

• TEE (transesophageal echo) (LAA thrombus: present in 5–15% of AF ≥48h or unknown duration; required before elective cardioversion if adequate anticoag for ≥3 weeks not confirmed; LAA thrombus precluding cardioversion → anticoag 3–6 weeks then repeat TEE)

• Digoxin (Lanoxin) level if on digoxin (goal 0.5–0.9 ng/mL for HFrEF per DIG trial post-hoc; toxic >2.0 ng/mL; amiodarone [Pacerone] doubles digoxin level — halve dose when initiating amiodarone; ↓K+/↓Mg2+/↑Ca2+/renal failure all ↑digoxin toxicity)

• CHA2DS2-VASc score (CHF/LV dysfunction +1; HTN +1; Age ≥75 +2; DM +1; Stroke/TIA/thromboembolism +2; Vascular disease +1; Age 65–74 +1; Sex female +1; score ≥2 M / ≥3 F = Class I anticoag; female sex alone [score = 1] does NOT independently qualify; maximum 9 points)

DDx

Atrial flutter (regular ~150 bpm; sawtooth waves negative in II/III/aVF at 300 bpm; adenosine unmasks NOT terminates; same anticoag algorithm as AF) · SVT/AVNRT (regular; terminates completely with adenosine 6 mg IV or vagal — does not slow then resume; retrograde P waves) · MAT (irregular; ≥3 morphologically distinct P waves; COPD/hypomagnesemia; no cardioversion — treat cause) · WPW + AF (wide irregular + delta waves; rates 250–300 bpm; procainamide [Pronestyl] or cardioversion ONLY; AV nodal blockers → VF) · VT (wide complex; AV dissociation + fusion beats + capture beats; regular; treat as VT until proven otherwise) · Sinus tachycardia (regular P:QRS 1:1; upright P waves in I+aVF; P:QRS ratio <200 bpm; treat underlying cause — NEVER rate-control)

Home Meds

• Continue: anticoagulants (NEVER hold — subtherapeutic anticoag during hospitalization is a common and dangerous error); BB (carvedilol [Coreg]/metoprolol succinate [Toprol-XL]); CCB if prescribed for rate control (diltiazem [Cardizem] — only if EF confirmed ≥50%)

• Check and adjust: digoxin (Lanoxin) level (hold if >2.0 ng/mL or symptomatic bradycardia; amiodarone [Pacerone] doubles digoxin concentration — halve digoxin dose when starting amiodarone); antiarrhythmic doses (renal/hepatic function changes)

• Hold: NSAIDs (ibuprofen [Advil]/naproxen [Aleve] — ↑BP + fluid retention); dronedarone (Multaq) if decompensated HF (ANDROMEDA trial: ↑mortality 2.3× in NYHA III–IV); flecainide (Tambocor)/propafenone (Rythmol) if new structural heart disease or CAD detected

Plan

• Step 1 — Hemodynamic assessment: Stable → proceed with rate control below; Unstable (SBP <90, AMS, APE, active ischemia) → synchronized DC cardioversion 200 J biphasic immediately; if WPW suspected → procainamide (Pronestyl) 10 mg/kg IV over 20–60 min (max 17 mg/kg) or cardioversion; NEVER adenosine/BB/CCB/digoxin in suspected WPW | WPW + AF is the most dangerous arrhythmia mismanagement — AV nodal block → all conduction via accessory pathway → ventricular rates 250–300 bpm → VF → cardiac arrest

• Step 2 — Electrolyte correction (ALL patients before rate or rhythm agents): KCl IV to K+ ≥4.0 mEq/L; MgSO4 2 g IV over 15–30 min (↓ventricular rate ~20 bpm + prevents torsades if antiarrhythmic used); continuous cardiac monitoring

• Step 3 — Rate control:

  • HFrEF (EF <40%): metoprolol tartrate (Lopressor) 2.5–5 mg IV q5 min ×3 (max 15 mg IV total); or metoprolol tartrate (Lopressor) 25–50 mg PO q6–8h; digoxin (Lanoxin) 0.5 mg IV load → 0.125–0.25 mg PO daily (add-on only — blunted at rest; goal 0.5–0.9 ng/mL; NOT monotherapy for acute rate control); amiodarone (Pacerone) 150 mg IV over 10 min → 1 mg/min ×6h → 0.5 mg/min ×18h if refractory; AVOID diltiazem (Cardizem) and verapamil (Calan) — ↓inotropy → cardiogenic shock in EF <40%

  • HFpEF (EF ≥50%) or no structural disease: diltiazem (Cardizem) 0.25 mg/kg IV over 2 min → repeat 0.35 mg/kg if inadequate response → 5–15 mg/hr infusion → diltiazem ER 120–360 mg PO daily; or verapamil (Calan) 5–10 mg IV over 2 min → repeat 10 mg in 30 min → 240–480 mg PO daily; or metoprolol tartrate (Lopressor) same IV doses above

  • Rate target: HR <110 bpm resting (RACE II 2010: lenient HR <110 = strict HR <80 for composite CV endpoint over 3 years; lenient preferred — fewer side effects); target HR <80 bpm if: symptomatic at HR 80–110, HF exacerbation, tachycardia-mediated CM suspected, LV dysfunction

• Step 4 — Treat precipitant: infection/sepsis → antibiotics ± source control; thyrotoxicosis → PTU (propylthiouracil) 200–300 mg PO TID + propranolol (Inderal) 40–80 mg PO TID for adrenergic control; ETOH → CIWA-Ar protocol + thiamine (vitamin B1) 100 mg IV daily + folate 1 mg PO daily; PE → anticoag ± thrombolytics; ↓K+/↓Mg2+ → IV repletion to targets; HF → ADHF management (see HFrEF/HFpEF card)

• Step 5 — Anticoagulation:

  • New-onset AF <48h without hemodynamic compromise: may cardiovert without prior anticoag (low LAA thrombus risk) → anticoag for ≥4 weeks post-cardioversion mandatory (atrial stunning)

  • AF ≥48h or unknown duration: anticoag ≥3 weeks before cardioversion (warfarin [Coumadin] INR 2–3 ×3 weeks or DOAC ×3 weeks with verified adherence) OR TEE to exclude LAA thrombus → then cardiovert → anticoag ≥4 weeks post-cardioversion regardless

  • Atrial stunning: mechanical LA/LAA dysfunction persists up to 4 weeks post-cardioversion even after return of SR — thrombus can form in SR; anticoag MANDATORY ≥4 weeks post-cardioversion in ALL patients; stopping anticoag after cardioversion = dangerous common error

  • Long-term anticoag: CHA2DS2-VASc ≥2 M / ≥3 F → Class I anticoag; apixaban (Eliquis) preferred (ARISTOTLE 2011: ↓stroke 21%, ↓major bleed 31%, ↓ICH 58% vs warfarin; lowest GI bleed rate among DOACs); rivaroxaban (Xarelto) 20 mg PO daily with evening meal; dabigatran (Pradaxa) 150 mg PO BID; warfarin (Coumadin) INR 2–3 for mechanical valves or moderate-severe MS only

• Step 6 — Rhythm control (when indicated):

  • Indications: persistent symptoms despite rate control; tachycardia-mediated CM; patient preference; first episode new-onset AF; HFrEF + AF (CASTLE-AF: ablation ↓mortality 47%)

  • Pharmacologic cardioversion: flecainide (Tambocor) 200–300 mg PO ×1 ("pill in pocket" — no structural disease, outpatient use) or amiodarone (Pacerone) 400 mg PO TID ×7 days → 200 mg daily for maintenance; ibutilide (Corvert) 1 mg IV over 10 min → repeat ×1 (60–70% conversion rate; QTc monitoring 4–6h; K+ ≥4.0 + Mg2+ ≥2.0 required)

  • DC cardioversion: 200 J biphasic synchronized (higher success than pharmacologic; R-wave synchronization mandatory — unsynchronized → VF); success depends on AF duration (<48h: 90%; >1 year: 40–60%)

  • Antiarrhythmic maintenance: amiodarone (Pacerone) 200 mg PO TID ×4 weeks → 200 mg PO daily (most effective; annual PFTs, TFTs, LFTs, ophthalmology exam); sotalol (Betapace) 80–160 mg PO BID (inpatient initiation — QTc monitoring ×3 days; avoid CrCl <40; avoid QTc >500 ms); dofetilide (Tikosyn) 500 mcg PO BID (inpatient initiation mandatory; CrCl-based dosing); dronedarone (Multaq) 400 mg PO BID (avoid HF EF <35%); flecainide (Tambocor) 100–150 mg PO BID (no structural heart disease only)

  • Ablation: pulmonary vein isolation — Class I for paroxysmal AF refractory to/intolerant of antiarrhythmics; Class IIa for persistent AF; Class IIa for HFrEF + AF (CASTLE-AF 2018: catheter ablation ↓all-cause mortality 47%, ↓HF hosp 44%); discuss at every HFrEF + AF admission

• PT/OT eval and treat — ambulate once rate controlled; fall precautions while anticoagulated; assess functional status + ADLs; cardiac rehab if tachycardia-mediated CM

• Trend daily: BMP (K+ ≥4.0 and Mg2+ ≥2.0 to targets; Cr — DOAC dose adjustment); ECG (rate + rhythm; spontaneous conversion to SR?); digoxin (Lanoxin) level 6–8h post-last dose if applicable (goal 0.5–0.9 ng/mL); QTc if on antiarrhythmic (hold if >500 ms); fever curve; HR on telemetry

• Escalation triggers: hemodynamic instability at any time → cardioversion 200 J immediately · WPW confirmed → procainamide (Pronestyl) or cardioversion; ZERO AV nodal blockers · digoxin (Lanoxin) toxicity (level >2.0 + bradycardia + nausea/vomiting + visual halos + junctional rhythm/AV block) → hold digoxin + digoxin immune Fab (Digibind/DigiFab); vials = serum level [ng/mL] × weight [kg] / 100; do NOT cardiovert digoxin-toxic AF (↑VF risk) · thyrotoxicosis + refractory rate control → endocrinology consult + PTU (propylthiouracil) escalation + propranolol (Inderal) · refractory RVR despite BB + CCB + MgSO4 → amiodarone (Pacerone) IV · new focal neuro deficit → stroke code + CT/MRI + neurology

• Discharge: rate control agent at effective dose — metoprolol succinate (Toprol-XL) in HFrEF; diltiazem ER (Cardizem) or metoprolol succinate (Toprol-XL) in HFpEF/no structural disease; DOAC per CHA2DS2-VASc — apixaban (Eliquis) 5 mg PO BID preferred; treat underlying trigger (thyroid, OSA, ETOH); rhythm control discussion (antiarrhythmic vs ablation); cardiology f/u 2–4 weeks; anticoag education (never skip doses); lifestyle counseling: weight loss ≥10% ↓AF burden, CPAP for OSA, ETOH reduction to <7 drinks/week; return precautions: palpitations + dizziness + syncope + stroke symptoms

⚠ Red Flags

• Hemodynamically unstable AF (SBP <90, AMS, APE, active ischemia) → synchronized DC cardioversion 200 J immediately — do NOT attempt pharmacologic rate control; every minute in fast AF with hemodynamic compromise worsens outcome

• WPW + AF (wide irregular tachycardia + delta waves + rates >200 bpm) → procainamide (Pronestyl) 10 mg/kg IV over 20–60 min or cardioversion ONLY; adenosine/BB/CCB/digoxin → AV nodal block → all conduction via accessory pathway → ventricular rates 250–300 bpm → VF → cardiac arrest; most dangerous arrhythmia mismanagement in IM

• Digoxin (Lanoxin) toxicity (level >2.0 ng/mL + bradycardia + nausea + yellow-green visual halos + junctional or AV block rhythm) → hold digoxin; digoxin immune Fab (Digibind/DigiFab); do NOT cardiovert digoxin-toxic patient — ↑VF risk; replete K+ and Mg2+

• Thyrotoxicosis + AF → cardioversion before euthyroid → 50–80% immediate AF recurrence; identify and treat thyroid disease first; endocrinology consult; PTU (propylthiouracil) + propranolol (Inderal) for adrenergic control

• Cardioverting AF of unknown duration without TEE or ≥3 weeks anticoag → LAA thrombus in 5–15% → cardioembolic stroke; always confirm <48h OR TEE negative OR verified ≥3 weeks therapeutic anticoag before elective cardioversion

• Stopping anticoag after successful cardioversion → atrial stunning persists ≤4 weeks; mandatory anticoag ≥4 weeks post-cardioversion in ALL patients regardless of apparent SR maintenance — most dangerous anticoag error in AF management

• Diltiazem (Cardizem) or verapamil (Calan) in HFrEF (EF <40%) → significant negative inotropy → acute hemodynamic deterioration → cardiogenic shock; always confirm EF before CCB; if unknown → use metoprolol (Lopressor)

• Rate control <80 bpm with QTc >500 ms on antiarrhythmic → torsades de pointes risk → hold antiarrhythmic + replete K+/Mg2+ + EP consult

Senior IM Resident Pearls

• RACE II (2010, NEJM): lenient rate control (HR <110 bpm) = strict (HR <80 bpm) for composite CV outcome over 3 years; use HR <110 as initial admission target; downgrade to <80 bpm if symptomatic at 80–110, tachycardia-mediated CM, or HF exacerbation; lenient strategy associated with fewer drug-related adverse effects

• WPW + AF — most dangerous arrhythmia mismanagement in IM: giving adenosine/BB/CCB/digoxin (Lanoxin) to WPW + AF blocks the AV node → all conduction via the accessory pathway → ventricular rate 250–300 bpm → VF → cardiac arrest; risk is increased in fast pre-excited rates (>200 bpm); procainamide (Pronestyl) is safe in BOTH regular AF and WPW-AF; treat ANY wide complex irregular tachycardia with rates >200 bpm as WPW until proven otherwise

• Digoxin (Lanoxin) therapeutic window: DIG trial post-hoc analysis showed ↑mortality at serum levels >0.9 ng/mL in HFrEF; goal 0.5–0.9 ng/mL; toxicity enhanced by hypokalemia, hypomagnesemia, hypercalcemia, renal failure, amiodarone (doubles level), quinidine; classic toxicity: GI (nausea/vomiting), visual (yellow-green halos, blurry vision), cardiac (AV block, junctional tachycardia, bidirectional VT)

• ARISTOTLE (2011, NEJM): apixaban (Eliquis) vs warfarin (Coumadin) → ↓stroke/systemic embolism 21%, ↓major bleeding 31%, ↓ICH 58%, ↓all-cause mortality 11%; apixaban has lowest GI bleed rate of all DOACs; dose reduce to 2.5 mg BID if ≥2 of: age ≥80, weight ≤60 kg, Cr ≥1.5; female sex alone (CHA2DS2-VASc score = 1) does NOT independently qualify for anticoag — need ≥1 additional risk factor

• EAST-AFNET 4 (2020, NEJM): early rhythm control (within 1 year of AF diagnosis + ≥1 CV risk factor) → ↓composite CV death/stroke/HF hosp/MI 21%; stopped early for benefit; Class IIa 2023 ACC/AHA AF guideline; does not mean ALL AF needs cardioversion — applies to symptomatic patients within 1 year of diagnosis with CV risk factors

• CASTLE-AF (2018, NEJM): catheter ablation vs antiarrhythmic drugs in HFrEF + AF → ↓all-cause mortality 47%, ↓HF hosp 44%; Class IIa for ablation in HFrEF + symptomatic AF; discuss catheter ablation referral at every HFrEF + AF admission — it is the most effective rhythm control strategy in this population

• Atrial stunning — the post-cardioversion anticoag trap: LA/LAA mechanical function remains impaired for up to 4 weeks after cardioversion regardless of rhythm; thrombus can form even in SR; mandatory anticoag ≥4 weeks post-cardioversion in ALL patients; cardioversion from flutter carries same risk as AF; the most common dangerous error in AF management

• Common mistake — rate control agent selection: giving diltiazem (Cardizem) to a patient with unknown or reduced EF (HFrEF) → significant negative inotropy → acute hemodynamic deterioration → cardiogenic shock; ALWAYS confirm EF before choosing rate control agent; if EF unknown → default to metoprolol (Lopressor) — safe across all EF ranges; CCBs cause hemodynamic collapse in EF <40%