Ebstein Anomaly Associated With Left Ventricular Noncompaction
A 56-year-old woman with gradually progressing exertional dyspnea was referred to our hospital. She had a known diagnosis of Ebstein anomaly and patent foramen ovale since childhood. One year previously, she had presented with a transient ischemic attack that was thought to be secondary to a paradoxal embolism through the patent foramen ovale, so an Amplatzer occluder had been implanted.
Clinical examination revealed a normal sinus rhythm at 56 bpm and a New York Heart Association class II dyspnea without cyanosis. ECG (Figure 1) showed a first- degree atrioventricular block with a pattern of complete right bundle-branch block. Chest radiography (Figure 2) demonstrated mild cardiomegaly and clear lung fields. Two-dimensional echocardiography showed malposition of the anterior and septal tricuspid valve leaflets with grade 2 tricuspid regurgitation. The atrial septal occluder was in correct position without residual shunt. In addition, echocardiography revealed a small left ventricle with a noncompacted apical wall appearance that had not been depicted before.
In order to provide precise morphological and functional characteristics of this noncompacted left ventricle, the patient underwent cardiovascular magnetic resonance (CMR) imaging. Four-chamber (Figure 3 and online-only Data Supplement Movie I), apical short-axis (Figure 4 and online-only Data Supplement Movie II), and long-axis (Figure 5 and online-only Data Supplement Movie III) cine images were obtained using steady-state free precession (SSFP) cine sequences. Four-chamber and short-axis views confirmed downward displacement of the hinge points of the leaflets of the tricuspid valve and subsequent “atrialization” of the right ventricle with normal function (ejection fraction, 57%). CMR also demonstrated left ventricular apical noncompaction. On 4-chamber, apical short-axis, and long-axis views, the diastolic noncompacted to compacted (NC/C) ratios were 3.3, 3.4, and 3.5, respectively. However, left ventricular function was not significantly impaired (ejection fraction, 60%).
Previously known as “spongy left ventricular myocardium” or left ventricular hypertrabeculation, left ventricular noncompaction (LVNC) is a congenital cardiomyopathy thought to be caused by an arrest in normal embryogenesis. It is characterized by prominent myocardial trabeculations and deep intertrabecular recesses that lie in continuity with the left ventricular cavity.1 According to magnetic resonance imaging criteria,2 a NC/C ratio >2.3 in diastole distinguishes pathological noncompaction with a sensitivity of 86% and a specificity of 99%.
The natural history of LVNC is variable, ranging from asymptomatic left ventricular dysfunction to severe congestive heart failure with complications such as arrhythmias and embolic events. LVNC may be an isolated finding or may be associated with other congenital cardiopathies such as complex cyanotic heart diseases and especially Ebstein anomaly.
The pathology of the LV myocardium is observed in 39% of patients with Ebstein anomaly, and within that subgroup, LVNC might occur in 18% of patients.3 The pathophysiological mechanism that might explain this association remains unknown. However, it is expected that the genetic change that is responsible for Ebstein anomaly might play a role in the differentiation of the LV myocardium.
Identification of LVNC in Ebstein anomaly has prognostic implications because it may be associated with LV systolic dysfunction. CMR appears to be the imaging technique of choice to precisely define structural and functional abnormalities of these 2 rare conditions, as well as to indicate the best follow-up care. Three-dimensional echocardiography might also offer new insights into the morphology and function of both diseases.4
The online-only Data Supplement can be found with this article at http://circ.ahajournals.org/cgi/content/full/118/16/e•••/DC1.
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Vettukattil JJ, Bharucha T, Anderson RH. Defining Ebstein’s malformation using three-dimensional echocardiography. Interact Cardiovasc Thorac Surg. 2007; 6: 685–690.