Pericarditis

Pericarditis is inflammation of the pericardium, the fibroelastic sac surrounding the heart. It is most commonly idiopathic or presumed viral in resource rich settings. It presents acutely with characteristic chest pain.

It carries the potential for serious complications, including pericardial effusion with tamponade and, in a minority of cases, progression to constrictive pericarditis.

Other causes include bacterial infection, tuberculosis, autoimmune disease, malignancy, uraemia and post cardiac injury syndromes.

Aetiology

Idiopathic or presumed viral pericarditis accounts for the large majority of cases in immunocompetent patients in resource rich settings. Specific viral causes (coxsackievirus, echovirus, and others) are rarely confirmed, given the low yield and limited clinical utility of specific viral testing in typical presentations.

Other recognised causes:

• bacterial pericarditis, which is uncommon but carries substantial morbidity and mortality if untreated
• tuberculous pericarditis, which remains an important cause in endemic regions and immunocompromised patients
• autoimmune disease (systemic lupus erythematosus, rheumatoid arthritis)
• malignancy (direct extension or metastatic involvement)
• uraemia in advanced chronic kidney disease
• post cardiac injury syndromes (following myocardial infarction, cardiac surgery, or cardiac intervention)

The classical presenting symptom is sharp, pleuritic chest pain. It is characteristically worse on lying flat and relieved by sitting forward. It often radiates to the trapezius ridge, a relatively specific feature reflecting shared phrenic nerve innervation.

Presentation can be atypical, particularly in tuberculous and malignant pericarditis. A more insidious course with constitutional symptoms may predominate over acute chest pain.

A pericardial friction rub, a scratchy, high pitched sound best heard with the patient leaning forward at end expiration, is a specific though inconsistently present examination finding, and fever, together with symptoms of the underlying cause where relevant, may accompany the chest pain.

Features suggesting a significant pericardial effusion or evolving tamponade, including breathlessness, tachycardia, hypotension, raised jugular venous pressure and pulsus paradoxus, represent a medical emergency requiring immediate assessment and intervention, detailed further under the diagnosis and management sections given the critical importance of prompt recognition.

Diagnosis requires at least two of four established criteria:

• characteristic pleuritic positional chest pain
• a pericardial friction rub on auscultation
• characteristic electrocardiographic changes: widespread concave ST segment elevation and PR segment depression, distinguishing this pattern from the localised, convex ST elevation typical of myocardial infarction
• a new or worsening pericardial effusion on echocardiography

Echocardiography should be performed in every patient with suspected pericarditis, both to confirm and quantify any pericardial effusion and to assess for signs of haemodynamic compromise (tamponade physiology), and is repeated where there is clinical deterioration or a significant effusion identified at initial assessment.

The standard baseline investigation panel comprises:

• full blood count
• inflammatory markers: C reactive protein, which is also useful for monitoring treatment response and guiding duration of anti inflammatory therapy
• renal function, given the relevance of uraemic pericarditis
• troponin, which may be mildly elevated reflecting associated myocarditis; interpret this result with that in mind

Further targeted investigation includes chest radiography, tuberculosis testing, autoimmune serology, and pericardiocentesis with fluid analysis (cell count, protein, glucose, cytology, culture including for tuberculosis). Pericardiocentesis is used where a significant effusion is present or an alternative cause beyond idiopathic or viral disease is suspected.

Investigation is directed by the specific clinical context, risk factors and initial findings. It is not performed routinely in every straightforward, presumed viral presentation.

Nonsteroidal anti inflammatory drugs are first line treatment for idiopathic or viral pericarditis. Options are ibuprofen 600 mg three times daily, or aspirin 750 to 1000 mg three times daily. Aspirin is particularly favoured following recent myocardial infarction, given established safety in this context, where other nonsteroidal anti inflammatory drugs are generally avoided.

Continue until symptom resolution and normalisation of inflammatory markers, typically one to two weeks. Co-prescribe gastroprotection (a proton pump inhibitor).

Add colchicine 500 micrograms twice daily to nonsteroidal anti inflammatory drug therapy from the outset, and continue for three months. Reduce to 500 micrograms once daily in patients under 70 kg or with reduced renal function.

Robust evidence shows this combination substantially reduces both the duration of the initial episode and, critically, the risk of recurrence, compared with nonsteroidal anti inflammatory drug monotherapy alone.

Corticosteroids are reserved for cases with:

• a specific contraindication to nonsteroidal anti inflammatory drugs and colchicine
• autoimmune disease associated pericarditis
• recurrent disease refractory to first line therapy

Early corticosteroid use as initial treatment is associated with a higher rate of subsequent recurrence. Where used, give a low to moderate dose (prednisolone 0.25 to 0.5 mg per kg daily) with a slow taper over weeks to months.

Bacterial pericarditis requires broad spectrum intravenous antibiotic therapy guided by likely or confirmed causative organism. Urgent pericardial drainage is also required, given both its diagnostic and therapeutic benefit and the high mortality of untreated purulent pericarditis.

A typical empirical regimen combines vancomycin (loaded then dosed to a target trough of 15 to 20 mg per litre) with a third generation cephalosporin such as ceftriaxone 2 g intravenously once daily. Narrow once culture results are available.

Tuberculous pericarditis is treated with standard four drug antituberculous therapy: rifampicin, isoniazid, pyrazinamide and ethambutol at standard weight based doses for two months, followed by rifampicin and isoniazid for a further four months.

Consider adjunctive corticosteroid therapy (prednisolone starting at 1 to 2 mg per kg daily with a gradual taper over six to eight weeks). Evidence shows reduced progression to constrictive pericarditis, particularly in HIV negative patients.

Significant pericardial effusion with echocardiographic or clinical evidence of tamponade requires urgent pericardiocentesis. Perform it under echocardiographic or fluoroscopic guidance where time permits, or as an emergency bedside procedure in haemodynamically unstable patients.

Send fluid for diagnostic testing. A drain is frequently left in situ to allow continued drainage and reduce recurrence risk.

Recurrent pericarditis is defined as a further episode following a symptom free interval of at least four to six weeks. It is managed with an extended course of colchicine (typically six months) combined with nonsteroidal anti inflammatory drugs.

Consider interleukin one blockade (anakinra or rilonacept) for colchicine and corticosteroid refractory recurrent disease. Strong evidence of efficacy is emerging in this difficult to treat population.

Constrictive pericarditis is a chronic complication in which the pericardium becomes rigid and non compliant, restricting diastolic filling. It presents with progressive right heart failure symptoms and requires specialist cardiology assessment.

Pericardiectomy is the definitive treatment for established, symptomatic disease not attributable to a reversible or treatable underlying inflammatory process.