Transesophageal Echocardiography: Not for Everyone?
To the Editor:
We read with interest the article by de Bruijn et al comparing transesophageal and transthoracic echocardiography (TEE versus TEE) for the evaluation of TIA or stroke.1 We congratulate the investigators on this important study. TEE proved superior to TTE for identification of a cardiac embolic source in patients with TIA or stroke without a definite cause and without a preexisting indication or contraindication for anticoagulation. We are perplexed by their findings of a remarkably high prevalence of thrombus in the left atrial (LA) appendage (38/231, 16%) and a relatively low prevalence of patent foramen ovale (12/231, 5%). They refer to a previous study by Leung et al where TEE was performed on 236 consecutive stroke patients with normal TTE without atrial fibrillation.2 Not one thrombus was identified in the LA appendage. Even in patients with abnormal TTE, the prevalence of thrombus in the LA appendage was only 8% (49/588). In this study, PFO was identified in 13% of patients. A population-based study using TEE found PFO in 20% of people.3 Does some difference in technique, definitions, or population explain these discrepancies? For instance, older TEE probes (monoplane and biplane) were used in nearly half of the cases from the previously quoted study,2 whereas de Brujin et al used exclusively multiplane.1 If this difference in technique is the explanation, why was the prevalence of PFO so low? The investigators’ answer will influence how their results can be generalized to other settings. Indeed, a major conclusion from this study could be that most, if not all, patients with new stroke or TIA should undergo transesophageal echocardiography.
de Bruijn, SFTM, Agema WRP, Lammers GJ, van der Wall EE, Wolterbeek R, Holman ER, Bollen ELEM, Bax JJ. Transesophageal echocardiography is superior to transthoracic echocardiography in management of patients of any age with transient ischemic attack or stroke. Stroke. 2006; 37: 2531–2534.
Leung DY, Black IW, Cranney GB, Walsh WF, Grimm RA, Stewart WJ, Thomas JD. Selection of patients for transesophageal echocardiography after stroke and systemic embolic events. Role of transthoracic echocardiography. Stroke. 1995; 26: 1820–2824.