The role of Cardiovascular Magnetic Resonance Imaging in assessing silent congenital anomalies in children: atrial appendage aneurysms- the sleeping giants (QF_FR_097)

We present two rare cases of asymptomatic giant congenital atrial appendage aneurysms in two young boys. Case #1 is an 12yo boy diagnosed as an infant with a large congenital aneurysm of the right atrial appendage (RAAA) following the detection of cardiomegaly on a chest X-ray performed pre-operatively for kidney surgery. He is completely asymptomatic under watchful monitoring and was referred for a cardiovascular magnetic resonance scan (CMR) as part of his regular follow-up to assess the dimensions and relative growth of the aneurysm.

Case  #2 is a 16yo teenage boy referred for a CMR scan to further investigate an abnormal echocardiogram performed for post-influenza episodes of palpitations. Echocardiography showed an abnormal mass between the left atrium and left upper pulmonary vein warranting further investigation.

Diagnostic Techniques and Their Most Important Findings:

Both patients underwent echocardiography first and then were referred for a CMR scan.  Case #1 had a gigantic RAAA with maximum volume 199ml. Right atrium (RA) was also dilated with a maximum volume of 125ml (Figure 1). The two compartments were connected via a broad neck. The ratio of max RAA/RA volumes was calculated 1.6. RAA emptying fraction (EF) was rather low (20%) whereas RA EF was 40%. An increase in the size of both RAAA and RA was noted compared to the previous scan dated 2 years ago with maximum volumes of RAAA 141ml and RA volume 125ml (RAA/RA volume ratio 1.8). Tricuspid annulus was hypoplastic (18mm, HLA view in end -diastole) but no active compression of the right ventricle was noted at rest.  Early imaging post gadolinium injection excluded any thrombus in the RAAA or RA.

Case  #2 had a large aneurysm of the left atrial appendage (LAAA) mistaken as a cardiac mass on echocardiogram. LAAA maximum volume was calculated 89ml. Left atrium (LA) was of normal size with a maximum volume of 39ml (Figure 2). The two compartments were connected via a broad neck. The ratio of max LAAA/LA volumes was calculated at 2.3. LAAA EF was 65% whereas LA EF was 69%. Mitral annulus was of normal dimensions. Early imaging post gadolinium injection excluded any thrombus in the LAAA or LA.

Learning Points from this Case:

Giant atrial aneurysms are rare form of congenital heart disease with a wide spectrum of clinical presentation varying from asymptomatic patients to those with refractory atrial arrhythmias or severe airway obstruction. Diagnosis is often confused with other causes of atrial dilation such as Ebstein disease on the right side or cardiac mass on the left side as in our second case. There is no consensus regarding the indications and timing of the surgical intervention, which is generally performed in the presence of symptoms and/or complications. Thromboembolic prophylaxis is essential until surgery is performed. In our cases, first child although asymptomatic has a gigantic RAAA with progressive growth in size and EF decline signs that could serve as a red flag for more aggressive management with surgery. In the second case, size is smaller and mechanical function of the left atrial chambers is preserved. However, there are symptoms (palpitations) that may highlight atrial arrhythmias which serve as a clear-cut indication for surgical exclusion of LAAA.

CMR by providing accurate anatomical and functional data may serve not only as a precision diagnostic tool but also may help to risk stratify this extremely rare population of congenital heart disease especially in the absence of symptoms or complications.