Atrial Fibrillation and Cor Triatriatum Sinister: A Case Report

Hoa Jeannie Tran, MD; Robert Gordon, MD; Thomas Alloggiamento, MD, MS;
Sukhvinder Kaur Nagi, MD, PhD; Ashok Krishnaswami, MD, MAS

Perm J 2015 Spring; 19(2):e105-e106 [Full Citation]


A 29-year-old man presented with palpitations, shortness of breath, and orthopnea. After being admitted, he progressed to cardiogenic shock and respiratory failure, which required ventilator support and cardioversion. Subsequent evaluation revealed a fibromuscular membrane across the left artrium, requiring urgent corrective surgery. This case report highlights the importance of identifying and treating the relatively rare cor triatriatum.

Case Report

A 29-year-old man presented to the ambulatory clinic after 4 days of palpitations, shortness of breath, and orthopnea. Electrocardiography revealed atrial fibrillation with a rate of 181 beats per minute and a chest x-ray consistent with pulmonary edema. The patient was transferred to the Emergency Department and became progressively dyspneic. The initial attempt at controlling his heart rate by using a standard regimen of intravenous beta-blockers and calcium-channel blockers was ineffective. His condition subsequently deteriorated and progressed to cardiogenic shock with acute hypoxemic respiratory failure, which required ventilator support and emergent synchronized cardioversion at 200 Joules to restore normal sinus rhythm. A transthoracic echocardiogram was performed to assess whether left ventricular dysfunction or valvular abnormalities could be implicated in the patient's clinical deterioration. The echocardiogram revealed the presence of a linear density across the left atrium, which was consistent with cor triatriatum sinister (CTS) (Figures 1A and 1B). Echocardiographic Doppler measurements revealed an elevated peak and mean gradient of 27 mm Hg and 10 mm Hg, respectively, across the fibromuscular membrane (Figure 1C) with associated moderate-to-severe eccentric mitral regurgitation and an intact interatrial septum. The left ventricular ejection fraction was mildly reduced at 50% (normal for this patient would be > 55%).

The patient underwent urgent corrective cardiac surgery with resection of the fibromuscular septum to address the CTS, placement of a Number 30 Carpentier-Edwards Physio annuloplasty ring (Carpentier-Edwards, Irvine, CA) to address the dilatation of the mitral annulus, and a CryoMaze procedure to address the atrial fibrillation (Figures 2 and 3). The patient was postoperatively prescribed oral warfarin. A follow-up transthoracic echocardiogram 1 year after surgery demonstrated normal left ventricular systolic function and appropriate functioning of the mitral valve. Eighteen months after surgery, the patient remained asymptomatic and in normal sinus rhythm and was able to stop taking oral anticoagulant therapy.





Cor triatriatum is a rare congenital cardiac anomaly represented by the development of a thick fibromuscular membrane that divides the left atrium (sinister) or the right atrium (dexter) into 2 chambers.1,2 CTS is much more common and occurs in approximately 0.1% to 0.4% of patients with congenital heart disease, whereas cor triatriatum dexter occurs in less than 8% of all cor triatriatum patients. CTS has a higher prevalence in males with a 1.5:1 male-to-female ratio. CTS is usually diagnosed in childhood; however, some cases, such the one reported here, may present in adulthood.3-5

According to a simple classification by Loeffler6 in 1949, there are three groupings of CTS. These are based on the size and number of fenestrations in the fibromuscular membrane. Group 1 has no fenestration, Group 2 has one or a few tiny fenestrations, and Group 3 has a single wide opening.6 Adults usually present as Group 3 because the other two groups become symptomatic early in life and are associated with a high early mortality.7

When CTS is diagnosed in adulthood, the patient may be asymptomatic with diagnosis made incidentally, or the patient may present with dyspnea, orthopnea, or hemoptysis.1,3,8 It is thought that patients become symptomatic owing to gradual fibrosis of the fenestrations in the fibromuscular membrane as well as development of valvular insufficiency and atrial arrhythmias.4 Classically, CTS is found in isolation; however, atypical CTS is associated with other anomalies, including secundum-type atrial septal defect, anomalous partial pulmonary venous connection, or mitral regurgitation, as in our patient's case.1,9


The clinical features of CTS mimic mitral stenosis because of flow obstruction across the membrane, leading to an increase in pulmonary pressures and subsequently causing arrhythmias such as the atrial fibrillation found in our patient.10 On auscultation of the heart, one might appreciate a diastolic murmur similar to the diastolic murmur of mitral stenosis. However, the lack of an opening snap or a loud first heart sound distinguishes CTS from mitral stenosis. Surgical intervention involving removal of the fibromuscular membrane is usually reserved for cases with severe obstruction and has been shown to provide significant symptomatic relief as well as mortality benefit.9,11

Disclosure Statement

The author(s) have no conflicts of interest to disclose.

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