The treatment depends on the cause of acute pericarditis, the person's strength and the presence of pericardial effusion, myocarditis or circulatory failure. In an 1866 answer, rest, relief of pain and repeated assessment of the heart are more defensible starting points than an indiscriminate attempt to suppress every sign of inflammation by depletion.
The bedside assessment would include the history of rheumatic illness, chest pain, a pericardial friction rub, the character of the pulse, breathing, the extent of cardiac dullness on percussion and changes in the heart sounds. Serial examination matters: disappearance of a pericardial friction rub need not mean recovery if fluid is separating the inflamed surfaces. Increasing oppression of breathing, weakness or a failing pulse would require reconsidering both the disease and the treatment. Auscultation with a stethoscope and careful repeated percussion supplied information that modern imaging now refines.
Period practice included local bloodletting with medicinal leeches, counterirritation with a blistering agent, opium for pain and rest, and disputed Mercury treatment intended to alter inflammatory exudation. A robust adult early in an apparently vigorous inflammatory attack was treated differently by depletion advocates from an exhausted person with anaemia, previous blood loss or advanced kidney disease. Even in that framework, a rapid weak pulse was not a command to remove more blood. Nor was Mercury an uncontested standard: a medical address published in December 1866 specifically listed its use in pericarditis among unresolved therapeutic questions.[ref]
Introductory Address at the Public Opening of the Medical Session, 1866–67 by William Tennant Gairdner. p. 294, therapeutic uncertainties concerning mercury in pericarditis and diuretics in Bright's disease
Modern correction: establish the diagnosis, identify complications and use cause-directed treatment rather than bloodletting or mercurialization. Electrocardiography, inflammatory markers, troponin where myocardial injury is suspected and echocardiography help distinguish uncomplicated pericarditis from important associated disease. A typical uncomplicated inflammatory episode is treated with aspirin or a suitable nonsteroidal anti-inflammatory drug, usually with colchicine and appropriate gastroprotection. Renal impairment, gastrointestinal bleeding, interactions and a specific infectious or systemic cause can modify this plan. Corticosteroids have selected indications and are not the routine first choice. Activity is restricted during active disease and return to exertion follows reassessment.[ref]
2025 ESC Guidelines for the management of myocarditis and pericarditis. Diagnostic assessment; section 6.2.2, pharmacological therapy for pericarditis
A large pericardial effusion requires attention to its haemodynamic effect, not merely its size. Cardiac tamponade requires urgent specialist drainage and stabilization. Purulent disease requires treatment of the infection and drainage; associated myocarditis or a systemic cause changes management further.[ref]
2025 ESC Guidelines for the management of myocarditis and pericarditis. Pericardial effusion and cardiac tamponade management pathways
These distinctions explain why treatment cannot be fixed solely by the label “acute”.