Aetiology
The most common causes of pericardial effusion include malignancy (25% to 32%), infection (7% to 24%), and iatrogenic (15% to 21%). In addition, a substantial proportion of pericardial effusions is considered idiopathic (16% to 26%).[8][9][10]
Aetiology varies between populations and is affected by factors such as demographic characteristics, clinical settings, or geographical distribution. For example, tuberculosis is one of the leading causes of pericardial effusion in endemic regions, and especially in areas where co-infection with HIV is common, but is a rare cause of pericardial effusion in developed countries.[11]
Malignancy
Malignant effusions
Malignant pericardial effusion is a common and serious manifestation of cancer.[12]
Most malignant pericardial effusions are caused by solid tumours, including lung cancer and breast cancer, or haematological malignancies such as lymphoma or leukaemia. Lung cancer is the most common malignancy involving the pericardium, in both men and women.[13]
The effusion may result from direct local tumour extension to the pericardium, haematogenous or lymphangitic tumour spread, or mediastinal lymphatic drainage obstruction.[13]
In patients with malignancy, pericardial effusion is most likely to be malignant. Occasionally, pericardial effusion is the first manifestation of malignancy. Therefore, malignancy should be excluded in patients with pericardial effusion with cardiac tamponade at presentation, with rapidly accumulating pericardial effusion, and/or with a persistent or recurrent course.[12]
Accumulation of pericardial fluid may be gradual, or rapid if erosion into the pericardial blood vessels occurs.
Effusion associated with antineoplastic therapies
Infectious
Viral
Viral pericarditis rarely produces effusions large enough to cause tamponade, but it can be associated with constrictive physiology.
Causes of viral pericarditis include Coxsackie virus, echovirus, Epstein-Barr virus (EBV), cytomegalovirus (CMV), and parvovirus-B19.[16]
In 259 patients with moderate to large pericardial effusions, polymerase chain reaction detected viral genomes (including parvovirus-B19, EBV, human herpes virus [HHV]-6, CMV, hepatitis C, and influenza) in 51 (19.7%) of patients.[17]
The clinical course of pericardial effusion associated with viral pericarditis is usually self-limiting and benign.
Bacterial
Bacterial pericarditis is a life-threatening condition that presents as an acute febrile illness and is commonly complicated by cardiac tamponade.
Purulent pericarditis is the most serious manifestation of bacterial pericarditis, with purulent fluid, ranging from a thin layer to large quantities of gross pus, accumulating in the pericardial space.[18]
The most likely causes of bacterial pericarditis include Staphylococcus aureus (typically haematogenous spread) and Streptococcus pneumoniae (often direct extension from an adjacent pneumonia).[19]
Patients at higher risk for bacterial pericarditis include those on dialysis, immunosuppressed people, people dependent on alcohol, and people who have recently had cardiac surgery.
Tuberculous
Tuberculous pericarditis is responsible for less than 5% of cases in developed countries, but is one of the leading causes of pericarditis in developing countries, especially in areas where HIV infection is common.[20]
Tuberculosis (TB) is the most common cause of pericardial diseases in Africa. Patients with tuberculous pericarditis present with effusive pericarditis (approximately 80%) or effusive-constrictive pericarditis (15%); up to 20% of patients with tuberculous pericarditis present with cardiac tamponade.[21]
An increased level of adenosine deaminase (ADA) >40 units/L in pericardial effusion is 93% sensitive and 90% to 97% specific for TB.[22][23]
Fungal
Fungal pericarditis is rare, but cases of pericardial effusion or tamponade associated with fungal infection have been reported.[24]
Fungal pericarditis in immune-competent individuals has been documented in endemic areas for Histoplasma capsulatum and Coccidioides immitis. In patients with immune deficiency, candidiasis, aspergillosis, and blastomyces infections are the major fungal pathogens.[25][26]
Parasitic
Chagas disease caused by Trypanosoma cruzi, which is endemic in Latin America, is the most common parasitic infection that involves the heart.
Chagas myocarditis is rare, but pericardial effusion is common (42%) when it occurs.[27]
Iatrogenic
Post cardiac surgery
Post-surgery pericardial effusion has been reported in up to three-quarters of patients undergoing cardiac surgery.[28][29]
The effusion tends to reach its maximum size around day 10 postoperatively, after which it usually resolves without intervention. However, post-cardiac surgery effusions can also persist or progress and ultimately lead to cardiac tamponade (approximately 4% of patients).[30]
Post-cardiac surgery pericardial effusion is more likely to be loculated (50% of posterior effusions) compared with pericardial effusion of other aetiologies, and therefore less accessible for pericardiocentesis.[31]
Early postoperative cardiac tamponade is caused by bleeding, while late cardiac tamponade is commonly related to post-pericardiotomy syndrome (an inflammatory response of the pericardium to the surgical procedure). However, postoperative infection must always be considered.
Pericardial constriction post surgery is rare, and the underlying mechanisms are not well understood. Although reported data are not entirely consistent, evidence suggests a relationship with prior post-pericardiotomy syndrome.[32]
Post cardiac intervention
The incidence of percutaneous cardiac intervention (PCI)-related effusions has increased significantly in recent decades, consistent with the increase in the frequency of coronary intervention, and newer interventional techniques such as atrial fibrillation ablation, left atrial appendage closure, and trans-catheter valve replacement.
Some of these procedures require intraprocedural anticoagulation and/or trans-septal puncture, which increase the risk of pericardial effusion and cardiac tamponade.
The incidence of pericardial complications has been reported as <0.5% after PCI, <1.5% after atrial fibrillation ablation, and 1% to 5% for pacemaker insertion.[33]
Idiopathic
A pericardial effusion is considered idiopathic once thorough evaluation does not result in a diagnosis.
It is generally assumed that most cases are due to viral infection, either acute or chronic.
As in viral pericarditis, patients generally present with features typical of acute pericarditis and experience a self-limiting, benign course.
However, idiopathic effusions may persist, recur, and, when large, progress to tamponade.[34]
Cardiac
Congestive heart failure
Transudative pericardial effusion is not uncommon in congestive heart failure; however, cardiac tamponade is not a recognised complication.[35]
In a small study of patients with heart failure requiring diuresis, 20% had a small or moderate pericardial effusion. More than 90% of these patients were found to also have pleural effusion.[35]
In patients with pulmonary arterial hypertension, the presence of pericardial effusion is an indicator of right heart failure. Its persistence despite vasoactive therapy is associated with poor prognosis.[36]
Aortic dissection
Pericardial effusion is a common complication of acute type A aortic dissection.
The dissected aorta can rupture directly into the pericardial space, resulting in cardiac tamponade.
Cardiac tamponade is diagnosed in <20% of patients presenting with acute type A aortic dissection, and is associated with an approximately two- to three-fold increase in in-hospital mortality in this patient population.[37][38][39][40] Presence of cardiac tamponade mandates urgent aortic repair.[38]
Post-myocardial infarction syndrome
Also known as Dressler's phenomenon, this condition is caused by the development of antibodies to heart antigens following myocardial infarction (MI). Patients develop fever and chest discomfort in the weeks or months following an infarct.[41]
The occurrence of pericardial effusion after MI has been declining in the era of primary percutaneous coronary intervention (PCI).
A study of 1732 patients with ST-segment elevation MI treated with primary PCI demonstrated a 14.2% occurrence rate of pericardial effusion assessed by echocardiography.[42]
Pericardial effusion in the setting of acute MI may represent contained left ventricular free wall rupture that can progress to cardiac tamponade and sudden cardiac death.[43]
Traumatic
Direct penetrating injuries of the heart are usually the result of stab wounds or gunshots and have a high pre-hospital mortality.
For patients who reach a hospital, emergency department echocardiography is 96% accurate in the diagnosis of traumatic effusion.[44]
Renal
Pericardial effusion in renal disease can occur due to uraemic pericarditis or dialysis pericarditis. The latter may be associated with inadequate dialysis and/or fluid overload.
In a study of 44 patients with uraemic pericardial effusion, echocardiography showed small, moderate, and large effusions in 38%, 32%, and 30% of patients, respectively. Tamponade signs were observed in 16% of patients.[45]
Radiation-related
In the course of radiotherapy for thoracic malignancies such as Hodgkin's lymphoma, breast cancer, or lung cancer, the heart and pericardium may be exposed to high doses of radiation.
Advances in radiation oncology, including better shielding strategies, have resulted in a decreasing occurrence of radiation-associated pericarditis and pericardial effusion.[46]
Pericarditis related to radiation may be acute or delayed. Chronic pericardial effusion is one of the delayed complications after radiotherapy.[47]
In a study of patients with non-small cell lung cancer undergoing radiotherapy, the cumulative incidence rates of pericardial effusion were 31% at 1 year and 45% at 2 years, with a median time to pericardial effusion of 9 months.[48]
The underlying mechanisms are thought to be impaired ability of the venous and lymphatic system of the heart to drain fluid, resulting in a pericardial effusion of either haemorrhagic or serous composition with a fibrin-rich exudate.[47]
Amyloidosis
Pericardial effusion was reported in approximately 50% of patients with cardiac amyloidosis (including acquired monoclonal light-chain, hereditary transthyretin, and senile amyloidosis).[49]
In all but a few cases, the size of the effusion is small or moderate and cardiac tamponade is rare.
Systemic inflammatory diseases
Pericardial disease is common in many connective tissue diseases, but especially in systemic lupus erythematosus (SLE).
Pericardial effusion is the most common echocardiographic finding in SLE. Pericardial effusion occurs in >50% of patients and it is usually asymptomatic.[50] Large effusion or cardiac tamponade is rare.
Pericardial effusion and pericarditis have been reported in patients with IgG4-related disease.[51][52]
Endocrine
Hypothyroidism
Pericardial effusions are most commonly found in states of severe hypothyroidism. Most are asymptomatic, even if large (up to 30% of cases).[53]
Typically, effusions resolve within weeks to months following institution of hormone replacement therapy.
Ovarian hyperstimulation
Drug-induced
Hydralazine, procainamide, and isoniazid are the most common drugs associated with drug-induced lupus erythematosus, causing pericarditis and pericardial effusion.[56]
Antineoplastic drugs can also be associated with pericardial effusion.[14]
Typically, the disease and its manifestations resolve following cessation of the offending agent and cardiac tamponade is extremely rare.
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