From the Guidelines
Late pleural effusions after Coronary Artery Bypass Grafting (CABG) are primarily caused by immune-mediated responses, with the biochemical characteristics of these effusions suggesting an inflammatory reaction to surgical trauma or cardiac antigens 1. The causes of late pleural effusion after CABG can be multifactorial, including:
- Immune-mediated responses to surgical trauma or cardiac antigens
- Lymphatic disruption or damage to the thoracic duct, leading to chylothorax
- Postoperative infection
- Post-cardiac injury syndrome (Dressler's syndrome) These effusions typically develop beyond 30 days after surgery and are characterized by a lymphocytic predominance and lower LDH levels compared to early effusions 1.
Key Characteristics of Late Pleural Effusions
- Exudative nature with lymphocyte predominance
- Lower LDH levels compared to early effusions
- Often associated with immune-mediated responses or inflammatory reactions
- May be asymptomatic or symptomatic, requiring intervention
Management of Late Pleural Effusions
- Observation for small, asymptomatic effusions
- Thoracentesis for diagnosis and symptom relief in larger or symptomatic effusions
- NSAIDs or prednisone for treatment of post-cardiac injury syndrome (Dressler's syndrome)
- Dietary modification and possible surgical intervention for chylothorax Regular follow-up with chest imaging is essential to monitor resolution and detect complications 1.
From the Research
Causes of Late Pleural Effusion after CABG
The causes of late pleural effusion after Coronary Artery Bypass Grafting (CABG) can be attributed to several factors, including:
- Postcardiac injury syndrome, which can occur after any type of cardiac injury and is thought to be due to anti-myocardial antibodies 2
- Trapped lung, which often requires decortication 3, 4
- Pleural thickening characterized by dense fibrous tissues with associated mononuclear cell infiltration 4
- Follicular lymphoid hyperplasia involving the pleural serosa and a non-necrotizing granulomatous reaction with a mild inflammatory infiltrate 5
- Unknown causes, as the mechanism of pleural effusion remains unclear in some cases 5, 6
Characteristics of Late Pleural Effusion
Late pleural effusions after CABG can be characterized by:
- Lymphocytosis, with pleural fluid showing a high percentage of lymphocytes 4, 5
- Exudative or transudative fluid, with some cases showing bloody effusions and others showing non-bloody effusions 5, 6
- Large effusions, occupying more than 25% of the hemithorax, which can be predominantly left-sided 6
- Dyspnea as the primary symptom, with chest pain and fever being uncommon 2
Management of Late Pleural Effusion
The management of late pleural effusion after CABG can include:
- Therapeutic thoracentesis, which can be repeated one to three times 6, 2
- Anti-inflammatory agents, such as nonsteroidal anti-inflammatory agents or corticosteroids 3, 2
- Tube thoracostomy or intrapleural injection of sclerosing agents, which can be used to manage non-bloody effusions 6
- Video-assisted thoracic surgery (VATS) with talc pleurodesis, which can lead to symptomatic and radiologic improvement 5