Can cardiomegaly cause atrial flutter?

Cardiomegaly as a Cause of Atrial Flutter

Yes, cardiomegaly can cause atrial flutter, particularly when associated with atrial enlargement and structural heart disease. 1

Pathophysiological Relationship

• Cardiomegaly, particularly when involving atrial enlargement, creates an arrhythmogenic substrate that predisposes to atrial flutter and other supraventricular arrhythmias 1
• Atrial flutter can occur in clinical settings similar to those associated with atrial fibrillation, and both arrhythmias commonly coexist in the same patient 1
• Increased left atrial size is a consistent predictor for both atrial flutter and atrial fibrillation 1
• Atrial flutter typically involves a reentrant circuit, which can be facilitated by the structural changes and scarring that occur with cardiac chamber enlargement 1

Specific Mechanisms

• Cardiomegaly creates the anatomical substrate for macroreentrant circuits that characterize atrial flutter 1
• In patients with severe atrial disease (including atrial enlargement from cardiomegaly), the typical atrial rates for flutter may be slower than the usual 250-330 bpm 1
• Non-isthmus-dependent atrial flutters (atypical flutter) can occur in any form of heart disease, including conditions causing cardiomegaly 1
• Risk factors for developing atrial arrhythmias in the setting of cardiomegaly include:
  • Depressed left ventricular function 1
  • Structural heart disease 1, 2
  • Increased left atrial size 1

Clinical Presentations

• Atrial flutter in patients with cardiomegaly may present with:
  • Acute symptoms: palpitations, dyspnea, fatigue, or chest pain 1
  • Insidious symptoms: exercise-induced fatigue or worsening heart failure 1
  • Rapid ventricular rates, typically with 2:1 AV conduction (ventricular rate ~150 bpm) 1
• Patients with impaired cardiac function and cardiomegaly may experience hemodynamic deterioration with the development of atrial flutter, even if the ventricular rate is not excessively rapid 1
• Cardiomegaly with atrial flutter has been reported in various clinical contexts, including:
  • Hypertrophic cardiomyopathy 1, 2
  • Dilated cardiomyopathy 2, 3
  • Congenital heart disease 1, 2
  • Myotonic dystrophy 4

Diagnostic Considerations

• Electrocardiogram findings may show:
  • Typical flutter pattern with negative sawtooth waves in inferior leads and positive P waves in V1 (for typical counterclockwise cavotricuspid isthmus-dependent flutter) 1
  • Atrial rates typically between 250-330 bpm, but may be slower in patients with severe atrial disease 1
• Chest X-ray may show cardiac enlargement (cardiomegaly) 1, 5
• Echocardiography is essential to:
  • Confirm cardiomegaly and chamber-specific enlargement 1
  • Assess ventricular function 1
  • Identify structural abnormalities 1

Management Implications

• Treatment of atrial flutter in patients with cardiomegaly should address both the arrhythmia and the underlying cardiac enlargement 1
• Acute management options include:
  • DC cardioversion for hemodynamically unstable patients 1
  • Rate control with AV nodal blocking agents (beta-blockers, non-dihydropyridine calcium channel blockers) 1
  • Anticoagulation should be considered similar to atrial fibrillation protocols 1
• Long-term management should include:
  • Treatment of the underlying cause of cardiomegaly 5, 3
  • Consideration of catheter ablation, particularly for cavotricuspid isthmus-dependent flutter 1
  • Appropriate anticoagulation based on thromboembolic risk 1

Important Considerations

• Cardiomegaly is a common arrhythmogenic substrate in adults and is strongly associated with obesity 3
• After ablation of atrial flutter in patients with cardiomegaly, there remains a significant risk of developing atrial fibrillation (22-82% of patients) 1
• The risk of thromboembolism in atrial flutter is considered similar to that in atrial fibrillation, necessitating appropriate anticoagulation 1
• Cardiomegaly may be a marker of worse prognosis in patients with atrial flutter 1