What is the diagnosis of pericardial effusion when a pericardial fat pad is present and occluding the view?

From the Guidelines

Diagnosing pericardial effusion when a pericardial fat pad is present requires a comprehensive approach, and I strongly recommend starting with a transthoracic echocardiogram (TTE) using multiple acoustic windows, as it is the first-line imaging test for suspected pericardial disease 1. When a fat pad obscures the view, using different acoustic windows can help differentiate between fat and fluid.

• Start with a comprehensive TTE using subcostal, apical, and parasternal views, as fat pads typically appear more echogenic than fluid collections.
• If TTE results are inconclusive, proceed to transesophageal echocardiography for better posterior visualization.
• CT imaging with contrast can definitively distinguish fat (which has negative Hounsfield units) from fluid collections, as suggested by the 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR guideline 1.
• Cardiac MRI offers excellent tissue characterization without radiation exposure and can clearly differentiate fat from fluid based on signal characteristics, with a sensitivity of 94% to 100% in detecting inflammation of the pericardium 1. When performing echocardiography, look for key signs of effusion including right ventricular diastolic collapse, right atrial collapse, and respiratory variation in mitral inflow velocities, which would not be present with just a fat pad. Pericardial fat typically appears as an echogenic structure adherent to the pericardium, while effusions appear as echo-free spaces. The clinical context, including symptoms of tamponade or inflammatory markers, should always be considered alongside imaging findings for accurate diagnosis, as recommended by the 2015 ESC guidelines for the diagnosis and management of pericardial diseases 1 and the 2017 ACR Appropriateness Criteria for dyspnea-suspected cardiac origin 1.

From the Research

Diagnosis of Pericardial Effusion

• The diagnosis of pericardial effusion can be challenging when a pericardial fat pad is present and occluding the view 2, 3.
• Echocardiography is essential to define the location and size of an effusion, and it provides insight into the pathophysiologic alterations 2.
• Transthoracic echocardiography is the most important tool for diagnosis, grading, the pericardiocentesis procedure, and follow up of pericardial effusion 4.
• Other imaging techniques such as computed tomography scan, cardiac magnetic resonance imaging, and pericardiocentesis can also be utilized to evaluate pericardial effusion 5, 6.

Challenges in Diagnosis

• The presence of a pericardial fat pad can occlude the view and make it difficult to diagnose pericardial effusion 2, 3.
• The diagnosis of pericardial effusion requires a combination of clinical findings, imaging techniques, and laboratory tests 3, 6.
• The size of the effusion and the presence or absence of tamponade can also affect the diagnosis and treatment of pericardial effusion 2, 3.

Treatment Options

• Pericardiocentesis is a common treatment option for pericardial effusion, especially in cases of cardiac tamponade or large pericardial effusion 2, 3, 4.
• Other treatment options include pericardial window, sclerosing therapies, and medical treatment depending on the underlying cause of the effusion 3, 6.
• The selection of the treatment option depends on the etiology of the effusion, the size of the effusion, and the presence or absence of tamponade 2, 3.