Background: The incidence of pericardial TB has decreased markedly in the developed world, however, it remains a major problem in third world countries, including the Philippines. A common complication of TB is the development of pericardial effusion. Establishing the etiology of pericardial effusion is necessary before instituting medical or surgical intervention. In this study, we will investigate the diagnostic usefulness of 2 D echocardiography, a non-invasive and relatively inexpensive tool in diagnosing tuberculous pericardial effusion and compare it to the gold standard.
Methods: This is a prospective cross-sectional study done among adult patients admitted at Philippine Heart Center with a diagnosis of pericardial effusion. 2D echocardiogram of these patients were assessed for the presence of the following 1.) pericardial thickening 2.) exudative coating/deposits 3.) fibrin strands. The clinical diagnosis of Tb effusion was made by a Tygerberg score of > 6. The diagnostic accuracy in predicting tuberculous pericardial effusion by the following parameters were assessed by computing the sensitivity, specificity, positive predictive value and negative predictive value.
Results: Majority of the patients were female consisting of 64% of the study population with a mean age of 46+15 years old. The presence of fibrin strands (FS) was found to be the most sensitive parameter with a sensitivity of 72% and a positive likelihood ratio of 8. This was followed by pericardial thickening (PT) with a sensitivity of 67%. Exudative coating (EC) on the other hand is the most specific for Tb pericarditis, with specificity of 100% (2/41). Combining two parameters was also found to be specific. The presence of FS+PT and EC+PT both yielded a specificity of 96%. Furthermore, the parameter that has the highest positive predictive value was found to be the presence of EC and the highest negative predictive value is the presence of fibrin strands.
Conclusion: The presence of fibrin strands, thickened pericardium and exudative coating in 2D echocardiogram are accurate diagnostic predictors of tuberculous pericardial effusion. Fibrin strands and thickened pericardium are both sensitive and can be used to rule out the disease. On the other hand, exudative coating is the most specific for tuberculous pericardial effusion and has a potential role in ruling in the disease. Combination of these parameters, FS+PT and EC+PT, yielded a higher specificity which may further strengthen their accuracy.