ATRIAL FLUTTER

ATRIAL FLUTTER - Drew M. Keister, MD
BASICS
DESCRIPTION
• Atrial flutter (A. Flutter) is a cardiac arrhythmia resulting in a narrow-QRS tachycardia with an atrial rate of 250-350 beats per minute.
- "Saw-toothed" P-waves are classic.
 Usually most prominent in lead V1
- Ventricular rate is dependent upon AV node conduction (see Pathophysiology).
• System(s) Affected: Cardiac
EPIDEMIOLOGY
• Predominant age: Most patients >55 years old
• Predominant sex: 2.5:1 Male predominance
Incidence
88 per 100,000 person-years
Prevalence
Range: 0.2% in young adults -0.9% in 65+
RISK FACTORS
• Heart disease (e.g. left ventricular (LV) dysfunction, LV hypertrophy, valvular heart disease (especially rheumatic), coronary artery disease (CAD), acute MI, atrial fibrillation (A Fib), pericarditis, history of congenital heart disease, recent cardiac surgery, atrial scarring)
• Pulmonary disease (e.g. COPD, pulmonary embolism, pneumonia)
• Hypertension (HTN)
• Hyperthyroidism
• Obesity
PATHOPHYSIOLOGY
Most commonly caused by a rapid re-entrant circuit around the tricuspid valve (specifically, the cavotricuspid isthmus)
• AV node conduction is variable
- 2:1 most common; rate usually 150 bpm
- 3:1 possible; rate approx 100 bpm
- 1:1 rare; ventricular rate 200+ bpm
- Irregular conduction can cause irregularly irregular pulse, mimicking A Fib
ETIOLOGY
• Most cases associated with a predisposing factor (see "Risk Factors")
• Lone A. Flutter; no predisposing factor
- 1.7% of patients with atrial flutter
• Digitalis toxicity; rare cause
ASSOCIATED CONDITIONS
• See "Risk Factors"
• Occurs in ~ 30% of patients with A Fib


DIAGNOSIS
SIGNS AND SYMPTOMS
History
• Common
- Palpitations
- Shortness of breath
- Fatigue
- Light-headedness
• Less common
- Chest pain
- Near-syncope
- Insidious onset with fatigue or worsening of a chronic cardiac/pulmonary disease
• Rare
- Syncope
- Symptoms/signs of acute embolic stroke
Physical Exam
• Common: Often fairly normal exam
- Tachycardia
 May be regular or irregularly irregular
- Mild dyspnea
- Evidence of a predisposing factor
• Less common
- Moderate dyspnea
- Congestive heart failure
 More common in elderly or with prior history
• Rarely, hemodynamic compromise occurs
- Hypotension
- Severe dyspnea or respiratory failure
- Hypoxia with cyanosis or pallor
- Decreased level of consciousness
TESTS
Lab
• A serum TSH is indicated to exclude hyperthyroidism.
• When clinically indicated
- CBC if at risk for anemia
- Metabolic panel if renal disease, HTN
- Digoxin level
- PTT/PT/INR if considering anticoagulation
Imaging
• Chest x-ray to exclude lung disease or CHF
• Echocardiogram to assess LV function
Diagnostic Procedures/Surgery
• 12-lead ECG
- Narrow-complex tachycardia with classic saw-toothed P-waves in V1 or inferior leads
- Assess for signs of ischemia/infarction
• When clinically indicated
- Holter monitor: If symptoms are concerning, but rhythm not present at time of evaluation
- Electrophysiologic studies should be considered in patients with recurrent atrial flutter to map the source of the arrhythmia for possible ablation.
DIFFERENTIAL DIAGNOSIS
• A Fib
• Paroxysmal supraventricular tachycardia
• Sinus tachycardia
• Junctional tachycardia
• Multifocal atrial tachycardia
• Wolff-Parkinson-White Syndrome
TREATMENT
PRE-HOSPITAL
• Support ABCs
• Consider immediate cardioversion for hemodynamically unstable patients, if available.
• Initiate O2, IV; monitor throughout transport.
• Consider calcium channel blocker or beta-blocker for rate control, if available.
STABILIZATION
First priority is to determine stability of patient
• Hemodynamically stable
- Continue ABC support.
- Consider calcium channel blocker or beta-blocker for rate control. (1)[C]
• Hemodynamically unstable (see "Physical Exam  hemodynamic compromise"):
- DC cardioversion is best treatment. (1)[C]
- Begin with dose of 50 joules and increase as needed. (1)[C]
- Atrial overdrive pacing is also effective. (1)[C]
GENERAL MEASURES
• Identify and treat underlying causes first.
• A. flutter often self-resolves within days.
- Watchful waiting may be appropriate in hemodynamically stable patients, particularly with a reversible predisposing cause and normal left atrial size.
• Restoration of normal sinus rhythm is generally the goal of therapy. (1)[C]
- Self-limited A. flutter related to an underlying cause rarely requires chronic therapy. (1)[C]
- >50% of patients with chronic or recurrent A. flutter experience recurrence within 1 year of successful cardioversion. (2)
Diet
NPO unless heart rate controlled, hemodynamically stable and no plan to ablate
Activity
Bed rest until heart rate controlled and patient hemodynamically stable
Nursing
Strict I/Os to assess for fluid retention/CHF
SPECIAL THERAPY
IV Fluids
• If hemodynamic unstable, use fluid boluses to maintain blood pressure
• Caution in LV dysfunction: avoid CHF
• If NPO, use appropriate maintenance fluid
MEDICATION (DRUGS)
Embolic Stroke Prevention
• Use anticoagulation (coumadin or heparin) for stroke prevention before cardioversion and when A. flutter persists >48 hours, except in patients 65 with lone A. flutter. (3)[C]
First Line Rate Control Agents
• Rate control agents useful in the initial management, but generally not efficacious in controlling chronic or recurrent arrhythmia. (1)[C]
• Calcium-channel blockers
- Diltiazem (Cardizem)
 Initial dose: 0.25 mg/kg IV  1, may give 0.35 mg/kg IV  1 after 15 min if needed
 Maintenance: 5-15 mg/h IV up to 24 h
 Rate control usually achieved in 30 min (1)
- Verapamil (Isoptin, Calan, Verelan)
 Initial dose: 2.5-5 mg IV over 2 minutes, may repeat 5-10 mg dose after 15-30 minutes to max dose of 20 mg
 Pediatric dose 1 yr: 0.1-0.2 mg/kg IV over 2 min, may repeat  1 in 30 min; 1-15 years: 0.1-0.3 mg/kg (max 5 mg) IV over 2 min; repeat (max 10 mg) in 30 min
 As efficacious as diltiazem; increased hypotension (1)
- Contraindications: Hypotension, documented sensitivity, 2nd or 3rd degree AV block, severe CHF, sick sinus syndrome
- Precautions: Use caution with CHF, LV dysfunction, liver or kidney disease
- Interactions: May increase digoxin levels; with amiodarone or beta-blockers may severely decrease cardiac output
- Adverse reactions: Hypotension, CHF, peripheral edema, AV block
• Beta-blockers
- Rate control usually achieved in 30 min (1)
- Metoprolol (Lopressor)
 Initial: 5 mg IV, repeat q5min; Max: 15 mg
 Maintenance: 5-15 mg IV q3-6h
- Esmolol (Breviblock)
 Initial dose: 500 mcg/kg IV over 1 min, repeat q4min to total of 3 doses if needed
 Maintenance: 50 mcg/kg/min, increased by 50 mcg/kg/min q4min prnmax of 200 mcg/kg/min
 Half-life approx 8 min; good choice for patients at risk for complications
- Contraindications: Hypotension, documented sensitivity, 2nd or 3rd degree AV block, severe CHF, sick sinus syndrome
- Precautions: Use caution with CHF, LV dysfunction, kidney disease, asthma
- Interactions: Bradycardia with digoxin; with amiodarone or beta-blockers may severely decrease cardiac output
- Adverse reactions: Hypotension, CHF, peripheral edema, AV block
• Digoxin (Lanoxin)
- Initial dose: 0.75 mg-1.25 mg PO or 0.5-1 mg IV divided 50% initially, then 25%  2q6-12h
- Maintenance: 0.125-0.5 mg PO per day or 0.1-0.4 mg IV per day
- Therapeutic level: 0.8-2 ng/mL
- Contraindications: Documented sensitivity, sick sinus syndrome, IHSS
- Precautions: Use caution with electrolyte abnormalities (especially hypokalemia, hypercalcemia), impaired renal function, thyroid disease, acute MI, AV block
- Interactions: Unpredictable effects with many anti-arrhythmics; additive bradycardia with calcium-channel blockers, beta-blockers
- Adverse reactions: AV block, bradycardia, mental disturbances, nausea
- Rate control usually achieved in 4 hours (1)
Second Line Anti-Arrhythmics
• Pure Class III Anti-arrhythmics
- Ibutilide (Corvert)
 Initial dose: 60 kg: 0.01 mg/kg over 10 minutes; 60 kg: 1 mg over 10 minutes; may repeat in 10 minutes prn
- Dofetilide (Tykosyn)
 Dosing: Dependent on QTc interval and creatinine clearance, see package insert
 Oral medication
- Contraindications: Documented sensitivity, QTc > 440 ms, use of a class I or III anti-arrhythmic within 4 hours, structural heart disease, sinus node disease
- Precautions: Correct hypokalemia and hypomagnesium prior to use; use caution in AV block, CHF, QT prolongation, renal/hepatic disease, elderly patients
- Interactions: Many anti-arrhythmics have unpredictable effects with digoxin; additive bradycardia with calcium-channel blockers, beta-blockers
- Adverse reactions: Polymorphic VT/torsades de pointes (1.5-3%), AV block, QT prolongation, CHF, renal failure, allergy, hypotension, hypertension, headache (4%)
- Efficacy = 38-76% (1)
• Class 1a and 1c anti-arrhythmics, sotalol, beta-blockers, calcium channel blockers, and amiodarone have limited utility in converting A. flutter to sinus rhythm. (1)
SURGERY
Catheter ablation is the treatment of choice for patients with recurrent or chronic A. flutter. (1)[A]
• 80% remain in sinus rhythm at 21 months compared to 36% with anti-arrhythmics. (1)
• To prevent rehospitalization with ablation compared to anti-arrhythmics, NNT is 2.2. (1)
• Catheter ablation results in improved symptoms and improved quality of life. (1)
FOLLOW-UP
DISPOSITION
Admission Criteria
• Most patients with first diagnosis of persistent A. flutter require admission for cardiac monitoring.
• All patients who cannot be rate controlled in the outpatient setting should be admitted.
• Patients with hemodynamic compromise may require ICU admission.
Discharge Criteria
Hemodynamically stable patients with normal heart rates may be discharged in A. flutter, but most patients admitted until sinus rhythm restored
Issues for Referral
Cardiology consult suggested for refractory cases and for patients with multiple comorbidities
PROGNOSIS
Incidence of embolization with A. flutter is similar to A. fib, 1.7-7%. (1)
COMPLICATIONS
• Acute stroke/other embolic events
• Congestive heart failure
• Acute cardiopulmonary failure
PATIENT MONITORING
Patients with chronic atrial flutter require monitoring of anticoagulation and LV function.
REFERENCES
1. Blonstrom-Lundqvist C, Schienman MM, et al. ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias-executive summary. J Am Coll Cardiol. 2003;42(8):1493-1531.
2. Crijns HJ, Van Gelder IC, Tieleman RG, et al. Long-term outcome of electrical cardioversion in patients with chronic atrial flutter. Heart. 1997;77(1):56-61.
3. Scholten MF, Thornton AS, Mekel JM, et al. Anticoagulation in atrial fibrillation and flutter. Europace. 2005;7(5):492-499.
MISCELLANEOUS
See also: Atrial Fibrillation