High vs. Standard Dose Rifampicin for Effusive Tuberculous Pericarditis

Inclusion Criteria: 1. Aged \>18 years 2. Suspected PCTB with confirmed pericardial effusion on echocardiography (i.e., echo free space of ≥1 cm anterior to the right ventricle in diastole) 3. Consent to study participation including testing for HIV-1 (if HIV status is unknown) 4. Microbiologically detected Mtb in PCF or diagnosis of probable PCTB. Probable PCTB (in the absence of a positive pericardial fluid culture) will be defined as per Mayosi et al.4: 1. Evidence of pericarditis with microbiologic confirmation of Mtb- infection elsewhere in the body and/or 2. Exudative, lymphocyte predominant effusion with elevated adenosine deaminase (≥35 U/L) 5. Participant will undergo pericardiocentesis (as per clinical indication) 6. Within 5 days of ATT initiation Exclusion Criteria: 1. Glomerular filtration rate \<30ml/min or renal failure requiring dialysis 2. Rifampin-resistant TB 3. Severe concurrent opportunistic infection 4. Contraindication to placement of intra-pericardial catheter 5. Failed pericardiocentesis procedure and/or failure of placement of intra-pericardial catheter 6. Any disease or condition in which the use of the standard anti-TB drugs (or any of their components) are contraindicated. This includes, but is not limited to, allergy to any TB drug or their components. 7. In females: a positive urine pregnancy test result 8. Confirmed autoimmune disorders (e.g. systemic lupus erythematosus) Additional Exclusions for Gadolinium contrasted CMR 1. Any implanted devices that are not MR compatible (e.g. pacemaker, defibrillators, cerebral aneurysm clips, cochlear implants etc.) 2. Claustrophobia 3. Gadolinium allergy 4. Inability to lie on a flat surface for prolonged periods of time (e.g. severe congestive cardiac failure) 5. Breastfeeding