Treatment of Atrial Flutter with Variable AV Block
For atrial flutter with variable AV block, the first-line treatments in hemodynamically stable patients are beta blockers, diltiazem, or verapamil to control ventricular rate. 1
Acute Management Based on Hemodynamic Status
Hemodynamically Unstable Patients
- Emergent DC-synchronized cardioversion is indicated for patients presenting with hemodynamic collapse or congestive heart failure 2, 1
- Lower energy requirements (typically <50 joules with monophasic shocks, and even less with biphasic shocks) are usually sufficient for atrial flutter conversion 2
Hemodynamically Stable Patients
- Intravenous rate control agents are the initial therapy of choice 2, 1
- Beta blockers (propranolol, atenolol, metoprolol, or esmolol) are effective for acute rate control and particularly useful in states of high adrenergic tone 2, 3
- Non-dihydropyridine calcium channel blockers (diltiazem, verapamil) are equally effective alternatives for acute rate control 1, 3
- Target heart rate should be <100 beats per minute at rest 4
Special Considerations
Wolff-Parkinson-White Syndrome
- AVOID beta blockers, digitalis, adenosine, and non-dihydropyridine calcium channel blockers in patients with WPW syndrome and atrial flutter 2
- These agents can facilitate antegrade conduction along the accessory pathway, potentially resulting in acceleration of ventricular rate, hypotension, or ventricular fibrillation 2
- For hemodynamically stable patients with pre-excitation, type I antiarrhythmic agents or amiodarone may be administered intravenously 2, 1
Heart Failure Patients
- Beta blockers are generally preferred in patients with heart failure 1
- Avoid non-dihydropyridine calcium channel blockers in patients with advanced heart failure due to their negative inotropic effects 2, 1
- Amiodarone may be considered for rate control when conventional measures are ineffective 2, 1
Medication-Induced Complications
- Class Ic antiarrhythmic drugs (like propafenone, flecainide) can slow the flutter rate and paradoxically increase ventricular response due to decreased concealed conduction into the AV node 2
- When these agents are given for prophylaxis against recurrent paroxysmal atrial flutter, AV nodal blocking drugs should be routinely co-administered 2, 5
- Propafenone should not be used to control ventricular rate during atrial flutter 5
Long-Term Management Options
Pharmacological Options
- Long-term rate control can be achieved with oral beta blockers, diltiazem, or verapamil 1, 4
- Digoxin is not recommended as monotherapy for rate control in active patients but may be used in combination with other agents 1, 4
- For patients with infrequent episodes, intermittent "pill-in-the-pocket" antiarrhythmic therapy may be considered 4
Interventional Options
- Catheter ablation of the cavotricuspid isthmus is highly effective (>90% success rate) for typical atrial flutter and should be considered in patients with symptomatic or drug-refractory atrial flutter 1, 6
- AV nodal ablation with permanent pacemaker implantation provides effective control of heart rate and improves symptoms in selected patients with atrial flutter that cannot be controlled adequately with medications 2
- Catheter ablation of inferior atrial inputs to the AV node can slow ventricular rate without pacemaker implantation but has limitations including risk of complete AV block 2
Anticoagulation
- For atrial flutter lasting more than 48 hours or of unknown duration, anticoagulation is recommended for at least 3 weeks before and 4 weeks after cardioversion 1
- Antithrombotic therapy should follow the same risk profile used for atrial fibrillation 1
Pitfalls and Caveats
- Digitalis toxicity is a common cause of atrial tachycardia with AV block and should be considered in the differential diagnosis 1
- Atrial flutter with 1:1 AV conduction can occur during treatment with class Ic antiarrhythmic drugs, leading to dangerous acceleration of ventricular rate 7
- Patients treated with AV nodal blocking drugs who are well-controlled during atrial fibrillation may experience a rise or fall in rate if they develop atrial flutter 2
- Always consider underlying causes of atrial flutter with variable AV block, including structural heart disease, atrial enlargement, and medication effects 1