What type of echocardiogram (echo) should be ordered for a new diagnosis of atrial flutter?

Echocardiographic Evaluation for New Atrial Flutter

For a new diagnosis of atrial flutter, a transthoracic echocardiogram (TTE) should be ordered as the initial imaging test, with transesophageal echocardiogram (TEE) reserved for patients requiring cardioversion who have not been adequately anticoagulated. 1

Initial Evaluation with Transthoracic Echocardiography (TTE)

TTE is the first-line imaging modality for patients with newly diagnosed atrial flutter for several important reasons:

• Provides essential assessment of cardiac structure and function that guides management decisions and helps determine the underlying cause 1
• Evaluates left atrial and right atrial size, which are important predictors of arrhythmia recurrence 1
• Assesses left ventricular size and function, which influence treatment decisions and prognosis 1
• Identifies valvular heart disease that may be contributing to or resulting from the arrhythmia 1
• Detects structural heart disease that may increase thromboembolic risk 1
• Screens for conditions that may contraindicate certain treatments 1

When to Consider Transesophageal Echocardiography (TEE)

TEE should be considered in specific clinical scenarios:

• Prior to cardioversion in patients with atrial flutter lasting >48 hours who have not been adequately anticoagulated 1, 2
• When TTE images are suboptimal or non-diagnostic 1
• To exclude left atrial appendage thrombus before cardioversion 2, 3
• When there is suspicion of intracardiac thrombi not visualized on TTE 4
• In patients with congenital heart disease and atrial flutter, who have a higher risk of atrial thrombi 5

Key Components of Echocardiographic Assessment

The echocardiographic evaluation should include:

• Left atrial size and volume assessment 1
• Left ventricular size, wall thickness, and systolic function 1
• Right ventricular size and function 1
• Valvular structure and function (stenosis or regurgitation) 1
• Assessment for structural heart disease that may contribute to atrial flutter 1
• Estimation of pulmonary artery pressure 1
• Evaluation for intracardiac thrombi (though TTE has limited sensitivity) 1

Important Considerations and Pitfalls

• TTE has limited sensitivity for detecting left atrial appendage thrombi compared to TEE 4
• A normal TTE in a patient with sinus rhythm has a high negative predictive value for left atrial appendage thrombi 4
• TEE-guided cardioversion without prior anticoagulation is not recommended despite the ability to exclude thrombi, as post-cardioversion thrombus formation remains a risk 3, 6
• In patients with congenital heart disease and atrial flutter, TEE may be necessary even with non-fibrillation atrial arrhythmias due to higher thrombus risk 5
• Contrast echocardiography may be useful in cases with poor endocardial definition 1

Summary of Approach

1. Order a standard transthoracic echocardiogram as the initial imaging test for all patients with newly diagnosed atrial flutter 1
2. If cardioversion is planned and the patient has not been adequately anticoagulated for at least 3 weeks, order a TEE to exclude thrombus 1, 2
3. Consider TEE if the TTE is technically limited or if there are specific concerns about thrombus that cannot be adequately assessed by TTE 1