What is the initial management for a patient with sustained atrial (A) flutter and tachycardia?

Management of Sustained Atrial Flutter with Heart Rate 160

For a patient with sustained atrial flutter and a ventricular rate of 160 bpm, immediate assessment of hemodynamic stability determines the treatment pathway: if hemodynamically unstable (hypotension, ongoing ischemia, heart failure, or respiratory distress), perform immediate synchronized electrical cardioversion starting at 50-100 J; if hemodynamically stable, initiate intravenous rate control with beta-blockers (esmolol preferred) or diltiazem, followed by consideration of rhythm control strategies. 1, 2

Immediate Assessment and Stabilization

Assess hemodynamic stability first by evaluating for:

• Symptomatic hypotension
• Ongoing chest pain or myocardial ischemia
• Acute heart failure or pulmonary edema
• Altered mental status
• Respiratory distress 3, 1, 2

If Hemodynamically Unstable

Perform immediate synchronized electrical cardioversion without delay 3, 1, 2:

• Start with 50-100 J (atrial flutter requires lower energy than atrial fibrillation) 4, 1
• Increase energy stepwise if initial attempt unsuccessful 2
• Brief general anesthesia or conscious sedation when possible 3
• Anticoagulation considerations are secondary to hemodynamic stability in this emergent scenario 1

If Hemodynamically Stable

Proceed with pharmacologic rate control as the initial strategy 3.

Rate Control Strategy (Stable Patients)

Beta-blockers are the preferred first-line agents for rate control in atrial flutter 3:

• Esmolol is preferred for acute IV rate control due to rapid onset and short half-life 1
• Alternative: Metoprolol 2.5-5 mg IV every 2-5 minutes (maximum 15 mg over 10-15 minutes) 3

Calcium channel blockers are an alternative if beta-blockers are contraindicated 3:

• Diltiazem 20 mg (0.25 mg/kg) IV over 2 minutes, followed by infusion of 10 mg/hour 3, 1
• Verapamil is also effective 3
• Avoid in patients with advanced heart failure, heart block, or sinus node dysfunction without pacemaker 1

Important caveat: Rate control in atrial flutter is paradoxically more difficult than in atrial fibrillation because the slower atrial rate (typically 250-300 bpm) results in less concealed AV nodal conduction, allowing more impulses to conduct to the ventricles 3, 1, 2. Higher doses or combination therapy may be required 3.

Amiodarone can be used for rate control when other options fail or are contraindicated 3:

• Particularly useful in patients with systolic heart failure where beta-blockers are contraindicated 3, 2
• IV amiodarone may also convert atrial flutter to sinus rhythm 3

Digoxin is NOT recommended as monotherapy for acute rate control in active patients 5:

• May be used in combination with other agents 3
• Primarily reserved for elderly, inactive patients or those with severe LV dysfunction 3

Rhythm Control Strategy

Once rate is controlled and the patient is stable, consider rhythm control, especially given the difficulty of maintaining adequate rate control in atrial flutter 3.

Pharmacologic Cardioversion Options

For acute pharmacologic cardioversion in stable patients 4:

• Ibutilide IV (effective in approximately 60% of cases) 4, 1
  • Major warning: Can cause torsades de pointes (1.7% sustained polymorphic VT requiring cardioversion) 6
  • Correct hypokalemia and hypomagnesemia before administration 6
  • Requires continuous ECG monitoring for at least 4 hours after infusion 6
  • Higher risk in patients with CHF (5.4% vs 0.8% sustained polymorphic VT) 6
• Dofetilide oral (first-line for acute cardioversion) 4, 1
• Flecainide or propafenone in patients without structural heart disease 4
  • Critical warning: Can cause 1:1 AV conduction in atrial flutter, paradoxically increasing ventricular rate 5, 7
  • Must be combined with AV nodal blocking agents (beta-blocker or calcium channel blocker) 3, 5

Elective Electrical Cardioversion

Synchronized electrical cardioversion is indicated for stable patients when pursuing rhythm control 4, 1:

• More effective than pharmacologic cardioversion 3
• Requires anticoagulation for 3 weeks before and 4 weeks after if flutter duration ≥48 hours or unknown 4, 1
• Lower energy requirements than atrial fibrillation (50-100 J initial) 3, 4, 1

Definitive Management: Catheter Ablation

Catheter ablation of the cavotricuspid isthmus (CTI) is the most effective long-term treatment and should be strongly considered 3, 4, 1:

• Success rates exceed 90% with low complication rates 4
• Preferred over long-term antiarrhythmic therapy for symptomatic or drug-refractory atrial flutter 3, 4
• Can be considered as first-line therapy before antiarrhythmic drug trials 4

Critical consideration: 22-50% of patients develop atrial fibrillation within 14-30 months after CTI ablation 4, 1, 2. Risk factors include:

• Prior atrial fibrillation
• Depressed left ventricular function
• Structural heart disease
• Increased left atrial size 4, 1

Anticoagulation Management

Anticoagulation recommendations for atrial flutter align with atrial fibrillation guidelines 3, 4, 1:

• Annual stroke risk is approximately 3% in sustained atrial flutter 3, 1
• Use CHA₂DS₂-VASc score to determine need for anticoagulation 3
• For cardioversion: anticoagulate for 3 weeks before and 4 weeks after if duration ≥48 hours or unknown 4, 1

Special Contraindications

Avoid the following in pre-excited atrial flutter (Wolff-Parkinson-White syndrome):

• Beta-blockers, diltiazem, verapamil, digoxin, adenosine, and amiodarone 3
• These agents can accelerate ventricular rates and precipitate ventricular fibrillation 3
• Use immediate cardioversion or IV procainamide/ibutilide instead 3