Stiff Left Atrial Syndrome Masquerading as Mitral Stenosis

Background Stiff left atrial syndrome first described in 1988 by Pilote et al. and co in JACC is an uncommon condition that could have similar presentation to congestive heart failure with preserved EF and often missed if not considered as differential diagnosis of patient with heart failure symptoms especially in setting of past history radiofrequency ablation (RFA) for atrial fibrillation (Afib). We present a case of stiff left atrial syndrome that masqueraded as bioprosthetic mitral valve (MV) dysfunction and required multimodality imaging to diagnose this disease (1). Case Description The patient is a 79-year-old female with a past medical history of permanent Afib, paroxysmal atrial flutter, bioprosthetic MVR along with 1 vessel coronary artery bypass graft surgery. 2 years ago, she underwent a pulmonary vein isolation (PVI) radiofrequency ablation (RF) with roof line, posterior inferior line and cavotricuspid isthmus ablation. Recently, she developed progressive dyspnea on exertion (NYHA class III). A transthoracic echocardiogram appeared to show increased mitral valve gradient. She was brought to our institution for left and right heart catheterization followed by transesophageal echocardiogram (TEE).During cardiac catheterization, simultaneous recording of left ventricular pressure and pulmonary capillary wedge pressure (PCWP) demonstrated an elevated transmitral mean gradient of 13.15 mmHg and a calculated effective orifice area of 0.64 cm2. The PCWP was elevated at 25 mmHg, the mean pulmonary artery pressure was elevated at 31 mmHg and the left ventricular end diastolic pressure (LVEDP) and pulmonary vascular resistance were normal. Conversely, a TEE showed a normally functioning MV with no hemodynamically significant stenosis (mean gradient 4 mm Hg). Computed tomography angiography did not show evidence of iatrogenic pulmonary vein stenosis to explain these discordant findings but confirmed an enlarged left atrium (LA). Due to her history of mitral valve replacement and RF ablation, we determined that Stiff Left Atrial Syndrome was the likely cause of the patient’s symptoms. Discussion Stiff left atrium syndrome is a condition that is caused by scarring and fibrosis of the LA leading to decreased compliance. It clinically manifests as pulmonary edema and dyspnea on exertion and is often difficult to discern from diastolic heart failure of other common etiologies. Pulmonary hypertension may develop from this condition as well (1,3). It was initially described in relation to mitral valve replacement surgery and maze procedure, but now being recognized to be caused by radiofrequency ablation for atrial fibrillation. Hemodynamically, there is often elevated pulmonary artery pressures, elevated PCWP and normal LVEDP. A large v wave may be seen in PCWP tracings. In our patient, the elevated PCWP to LVEDP gradient and inaccurate effective orifice area were likely due to elevated LA pressure caused by extensive scarring and noncompliance rather than a problem with the MVR. Pulmonary vein stenosis and mitral valve stenosis must be ruled out, as it was with our patient (1). There are no proven therapies for Stiff Left Atrial Syndrome, but diuretics are primarily used. Creation of an atrial septal defect to relieve LA pressure has been tried experimentally (1,2).