Why is the Right Heart Big?
A 63-year-old woman with a history of atrial arrhythmia requiring ablation 10 years ago presented with diverticulitis. During her surgical evaluation, physical exam was significant for a fixed split-second heart sound and a grade III/VI systolic ejection murmur at the left upper sternal border. Room air oxygen saturations were 99%. An echocardiogram revealed a structurally normal heart, with severe right atrial dilation and moderate right ventricular dilation (Figure 1). No significant atrial level shunting was noted. Given the unusual findings, a magnetic resonance imaging (MRI) was performed (Figures 2A-C). At the time of initial diagnosis, she was asymptomatic and active, able to walk or bike approximately 2 miles/three times a week, and surgical intervention was declined. Over the course of a few years, she developed increased fatigability with progressive exercise intolerance, and returned for management. She denied palpitations, chest pain nor syncope. Her electrocardiogram (ECG) is shown (Figure 3).
Figure 1: Echocardiogram
Figure 2A: Video of axial stack through the chest
Figure 2B: Video of coronal stack through the chest
Figure 2C: 3D reconstruction
Figure 3: ECG
What is the most likely cause for her right heart dilation?