The 35th Annual Meeting The Royal College of Physicians of Thailand 'Towards better and safer patient care' 25th - 27th April 2019, PEACH Royal Cliff Beach Resort, Pattaya, Chonburi, Thailand Clinical Characteristics of Tuberculous Pericarditis in Adult at Siriraj Hospital Thitiyaporn Boonrubjiraroj1 Rujipas Sirijatuphat1 1Department of Internal Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand Background: Pericarditis is an uncommon manifestation of tuberculosis. Clinical characteristics of adult patients with tuberculous pericarditis in Thailand are not well defined. Objective: To determine the clinical manifestations, diagnosis, complications, treatment, and clinical outcomes of adult patients with tuberculous pericarditis at Siriraj Hospital. Methods: This retrospective study included adult patients diagnosed tuberculous pericarditis at Siriraj Hospital during January 2005 to December 2017. Results: There were 77 patients diagnosed with tuberculous pericarditis, 41 patients with proven tuberculous pericarditis (PTB) and 36 patients with suspected tuberculous pericarditis (STB). Most patients were males (75.6%). Forty-six percent of PTB had no underlying illness, but only 16.7% of STB had no underlying illness. HIV infection was found in 17.1% of patients with PTB and 33.3% of patients with STB. Dyspnea (97.4%), fever (70.0%), and chest pain (51.3%) were the most common clinical manifestations in all patients. Cardiac tamponade occurred in 29.3% in PTB and 27.8% in STB. For pericardial fluid analysis, color varied from serosanguinous to straw color and all were exudative effusion by Light’s criteria. The pericardial fluid with neutrophilic predominate appearance was frequently found in PTB, but lymphocytic predominate appearance was commonly found in STB. ADA level in pericardial effusion was quite high in both PTB (71.2 (29.5-86.0) IU/L) and STB (72.6 (41.0-85.0) IU/L). The confirmed diagnostic methods among patients with PTB were positive AFB stain in pericardial fluid (64.3%), positive mycobacterium culture from pericardial fluid (62.5%), positive PCR for mycobacterium complex from pericardial fluid (40%) and compatible pathologic changes in pericardial tissue i.e. caseous granuloma (59.3%) and positive AFB stain (63%). All patients received anti-tuberculosis drugs. Other interventions among study patients were corticosteroid therapy (56.1% in PTB and 47.2% in STB), surgical treatment with anterior pericardectomy (41.5% in PTB and 5.6% in STB), pleuropericardial window (12.2% in PTB and 22.2% in STB). In-hospital mortality rate was 2.3% in all patients. There were 27.3%, 22.2% in PTB and STB developed constrictive physiology. Conclusion: Tuberculous pericarditis commonly presented with dyspnea, fever and chest pain. Cardiac tamponade was found in nearly 30% of patients. Most patients responded well to anti- tuberculosis drugs, but one-fourth of them developed constrictive physiology after treatment. Keywords: Pericardial effusion, Pericarditis, Tuberculosis, Thailand .