Heart Failure-Associated Tension Chylothorax: A Rare Presentation of a Common Disease.

Heart failure can present along with pleural effusion, which is usually bilateral and biochemically transudative. This pleural effusion can rarely be chylous, indicating chylothorax. Herein, we describe a case of an 86-year-old male patient with heart failure with reduced ejection fraction who presented with a two-week history of progressive dyspnea and bilateral leg swelling. Physical findings included absent breath sounds in the right mid- and lower lung zones, left basilar crackles, and 3+ pitting edema up to the knees. Chest X-ray and computed tomography of the chest revealed a large right-sided pleural effusion with associated atelectasis. Emergent thoracentesis was performed, yielding 2 L of milky fluid. A pleural fluid triglyceride level of 414 mg/dL confirmed the diagnosis of chylothorax. A CT scan of the chest, abdomen, and pelvis with intravenous contrast and pleural fluid cytology did not show any findings suggestive of malignancy or infection. Blood and pleural fluid cultures were negative. The acid-fast bacilli (AFB) smear, culture, and interferon gamma release assay were unremarkable. Tumor markers, including CA 19-9, CEA, and AFP, were negative. A serum lipid panel was unremarkable. An echocardiogram showed a left ventricular ejection fraction of 40% with diffuse hypokinesis and pulmonary artery systolic pressure of 43 mmHg; the brain natriuretic peptide level was 1290 pg/mL, consistent with decompensated heart failure. The patient was treated with intravenous furosemide, and his symptoms significantly improved during his hospital stay. He was subsequently discharged with instructions for fluid and salt restriction and a low-fat diet with medium-chain triglycerides (MCTs); dietitian counseling was also provided. A pleural fluid triglyceride level of more than 110 mg/dL can establish the diagnosis of chylothorax. In heart failure, the mechanism of chylothorax is likely increased hydrostatic pressure in the lymphatics due to volume overload and high venous pressure. In addition, high venous pressure, increasing the abdominal lymph production, is also implicated. Treatment of underlying heart failure with diuresis along with a low-fat diet with MCT supplementation usually results in improvement.