Discussion

Right atrial appendage aneurysm is an uncommon condition which can be either congenital or acquired. ^{Reference Aryal, Hakim and Giri1} In our review of 44 documented cases, males were affected way more often than females. ^{Reference Aryal, Hakim and Giri1,Reference Mercuro, Bassareo, Mariucci, Deidda, Zedda and Bonvicini47} Although right atrial appendage aneurysm has been observed across all age groups, it is most commonly diagnosed in individuals in their 30s. It has also been identified in newborns and even during prenatal development.

The congenital form of right atrial appendage aneurysm is thought to result from abnormal development of the right atrial muscular wall. ^{Reference Ishii, Inamura and Kayatani30} The exact cause of the acquired form remains unclear, but it is suspected to be associated with prolonged elevation of right atrial pressure and increased atrial volume due to underlying conditions such as pulmonary hypertension, congenital heart defects like atrial septal defect, or heart failure. ^{Reference Aryal, Hakim and Giri1}

The coexistence of left atrial appendage aneurysm and patients with right atrial appendage aneurysm is anecdotal. ^{Reference Sevimli, Gundogdu, Aksakal, Arslan, Gurlertop and Senocak40} Histological examination often reveals endocardial fibrosis, and in some cases, lipomatous degeneration of the aneurysm is observed without signs of inflammation. ^{Reference Guaricci, Tarantini and Basso19,Reference Corti, Sciuchetti, Ferro, Porta, Redaelli and Paolini44}

The most frequent symptom of right atrial appendage aneurysm was palpitation caused by atrial tachyarrhythmias, such as atrial fibrillation/flutter, atrial tachycardia, or supraventricular tachycardia. Some individuals with right atrial appendage aneurysm exhibited no symptoms, with the condition being discovered incidentally during cardiac imaging, autopsy, or surgeries conducted for unrelated reasons. ^{Reference Kurata, Shishido-Hara and Hosaki45} Others presented with thromboembolic complications. ^{Reference Tejero-Hernández, Espejo-Pérez and Suárez-de-Lezo-Cruz-Conde29} Dyspnoea, often linked to underlying cardiovascular issues such as heart failure and pulmonary hypertension, can also be a symptom. In our review, some patients had pulmonary hypertension with or without Eisenmenger’s syndrome or had left ventricular dysfunction. ^{Reference Sevimli, Gundogdu, Aksakal, Arslan, Gurlertop and Senocak40–Reference Mizui, Mori and Kuroda42}

Cardiomegaly, indicative of underlying heart disease, was observed on chest X-rays in 45.5% of patients with right atrial appendage aneurysm. Transthoracic echocardiography served as the initial imaging modality for right atrial appendage aneurysm diagnosis. In cases where transthoracic images were inconclusive, transoesophageal echocardiography with or without contrast enhancement was employed. ^{Reference Fang, Zeng, Chen and Cui13,Reference Guaricci, Tarantini and Basso19} Advanced imaging techniques such as CT and MRI were valuable adjuncts, offering high sensitivity and specificity. These modalities were particularly useful for confirming the connection of the aneurysm to the right atrial appendage and assessing its relationship to adjacent structures. ^{Reference Sondhi, Wardhan, Pandit and Nath16}

Surgical resection is recommended for symptomatic patients and those with enlarging right atrial appendage aneurysms to reduce the risk of arrhythmias and thromboembolic events. Concomitant procedures, such as bi-atrial aneurysm resections, the Maze procedure, and CHD repair, can be performed simultaneously to address associated cardiac conditions. ^{Reference Contreras, Courtis, Brenna, Amuchastegui and Amuchastegui18,Reference Guaricci, Tarantini and Basso19,Reference Sevimli, Gundogdu, Aksakal, Arslan, Gurlertop and Senocak40,Reference Mizui, Mori and Kuroda42} Currently, there is no information available regarding the use of device direct closure for right atrial appendage aneurysm. While device-based closures are commonly employed for left atrial appendage management to reduce stroke risk in atrial fibrillation patients, ^{Reference Lorenzoni, Merella, Pischedda and Casu48} their application in right atrial appendage aneurysm cases is not documented yet. One patient experienced right atrial appendage aneurysm reduction in size after atrial septal defect device closure. ^{Reference Duan, Li and Sun28} Surgical resection remains the standard treatment for symptomatic or enlarging right atrial appendage aneurysms to mitigate risks such as arrhythmias and thromboembolic events. ^{Reference Aryal, Hakim and Giri1}

Less than half of right atrial appendage aneurysm patients were managed conservatively without reported complications. A conservative approach is typically recommended for asymptomatic individuals. ^{Reference Aryal, Hakim and Giri1} However, factors such as large right atrial appendage aneurysm size, enlarged right atrium, and associated congenital heart defects have been linked to increased risks of thromboembolic events and arrhythmias. ^{Reference Contreras, Courtis, Brenna, Amuchastegui and Amuchastegui18,Reference Guaricci, Tarantini and Basso19,Reference Sevimli, Gundogdu, Aksakal, Arslan, Gurlertop and Senocak40,Reference Mizui, Mori and Kuroda42} Regular monitoring of asymptomatic patients using CT imaging or cardiac magnetic resonance to detect right atrial appendage aneurysm enlargement has proven useful in identifying candidates who may benefit from early surgical intervention. ^{Reference Gulati, Gheta and Chan32}

Asymptomatic right atrial appendage aneurysm patients undergoing conservative management should receive anticoagulation therapy to prevent thrombus formation. Antiarrhythmic medications are used to manage atrial tachyarrhythmias. The prognosis for these patients is generally favourable, but they require close monitoring. ^{Reference Cianciulli, Rubinetti, Saccheri, Dethinne and Prezioso17}

A large or progressively enlarging right atrial appendage aneurysm has been identified as a risk factor for thromboembolic complications and atrial arrhythmias. Although there is limited long-term data supporting routine repeat imaging, some experts suggest follow-up cardiac MRI every two years. ^{Reference Gulati, Gheta and Chan32}

Patients with evidence of aneurysm enlargement should be considered for surgical excision due to their heightened risk of arrhythmias and thromboembolic events. Those with a patent foramen ovale or atrial septal defect should be carefully monitored for systemic thromboembolism, and these defects should be closed during right atrial appendage aneurysm surgical treatment. ^{Reference Ishii, Inamura and Kayatani30,Reference Leonard, Marras, Calcaterra and Bassareo49}

Potential complications of right atrial appendage aneurysm include pulmonary embolism, rupture of the aneurysmal right atrial appendage, and sudden death. ^{Reference Cianciulli, Rubinetti, Saccheri, Dethinne and Prezioso17}

In conclusion, right atrial appendage aneurysm can lead to significant health issues. Surgical removal is advised for symptomatic individuals and those with large aneurysms. Asymptomatic patients may be managed conservatively, focusing on preventing thromboembolic events and atrial tachyarrhythmias. Regular follow-up imaging, such as echocardiography and cardiac magnetic resonance, can be considered to monitor aneurysm size and progression (see Figures 2, 3, 4).

Figure 2.

Axial four chamber view on cardiac MRI showing a massive right atrial dilatation in a 10-month-old patient (unpublished case). Acronyms: RA = Right Atrium; RV = Right Ventricle; LA = Left Atrium; LV = Left Ventricle.

Figure 3.

Cardiac MRI (short axis view) displaying the presence of a right atrial appendage aneurysm in the same baby who has subsequently undergone surgery for aneurysm plication. Acronyms: RAAA = Right Atrial Appendage Aneurysm; RA = Right Atrium; AO = Aorta; LA = Left Atrium.

Figure 4.

Prisma flow diagram.