Pericarditis & Myocarditis

Definition

Pericarditis is inflammation of the pericardium, the double-layered sac surrounding the heart. Myocarditis is inflammation of the myocardium, the heart muscle itself. The two frequently coexist (myopericarditis) because they often share the same triggering cause, most commonly a viral illness. The distinction matters clinically: pericarditis is painful but usually benign, whereas myocarditis involves the pump and the electrical system and carries a genuine risk of arrhythmia.¹

Pathophysiology

Pericarditis

Inflammation of the pericardial layers causes friction between them — heard as a pericardial rub — and can lead to fluid accumulating between the layers (a pericardial effusion). If fluid accumulates quickly or in large volume it compresses the heart and impairs filling: cardiac tamponade, a medical emergency. Chronic inflammation can instead leave a thickened, non-compliant pericardium that restricts filling permanently (constrictive pericarditis).

Myocarditis

Inflammatory cells infiltrate and injure heart muscle directly, reducing contractile function and creating areas of electrical instability. In more severe cases this progresses to acute heart failure or, uncommonly, sudden cardiac death. A proportion of patients are left with a dilated cardiomyopathy after the acute inflammation resolves.²

Why exercise matters during the inflamed phase

Exercise during active myocardial inflammation increases myocardial stress and arrhythmic risk. This is the mechanistic basis for the exercise-restriction period, and the reason it applies even to people who feel completely well — the risk relates to the inflamed tissue, not to how the person feels.²

Co-morbidities

Autoimmune and inflammatory conditions (systemic lupus erythematosus, rheumatoid arthritis) predispose to pericarditis, as do prior cardiac surgery or myocardial infarction (post-cardiac injury syndrome) and chronic kidney disease or dialysis (uraemic pericarditis). Myocarditis is more often triggered by recent viral infection, including some cases following COVID-19 or, rarely, as a recognised adverse effect of mRNA vaccines — predominantly in young males after a second dose, typically mild and self-limiting, and at a rate well below the myocarditis risk from SARS-CoV-2 infection itself.³

Prevalence

Acute pericarditis is one of the more common causes of chest pain prompting emergency assessment, though true incidence is underestimated because mild cases go undiagnosed.¹ Myocarditis is less common and harder to quantify, since presentations range from silent to fulminant, but it is increasingly recognised as an important cause of unexplained heart failure, arrhythmia and sudden death in younger people.²

Causes and risk factors

Most cases of both conditions are viral or presumed viral (enteroviruses, influenza, SARS-CoV-2 among others). Other causes include autoimmune and inflammatory disease, uraemia, cardiac surgery or injury (post-cardiac injury syndromes such as Dressler's syndrome after myocardial infarction), certain medications — notably immune checkpoint inhibitors, which cause a rare but severe myocarditis — and, less commonly in high-income settings, tuberculosis or bacterial infection. Idiopathic disease, where no cause is found, is common in pericarditis.¹

Symptoms

Pericarditis

Sharp, pleuritic chest pain that is worse lying flat and eased by sitting forward, sometimes radiating to the shoulder or trapezius ridge, often with low-grade fever. The positional character is the most useful discriminating feature at the bedside.

Myocarditis

Chest pain, breathlessness, palpitations and fatigue, often preceded by a flu-like or gastrointestinal illness days to weeks earlier. Presentation may instead be of new heart failure or arrhythmia, and in athletes an unexplained fall in performance can be the only sign.

Red flags

Diagnosis

Why diagnosis matters

Both conditions mimic myocardial infarction, and both carry management implications that differ completely from it. Getting the diagnosis right determines whether someone receives anti-inflammatory treatment and an exercise-restriction period, or a coronary pathway.

Diagnosing pericarditis

A clinical diagnosis — characteristic positional pain, a pericardial friction rub — supported by widespread ECG ST elevation with PR depression, raised inflammatory markers, and echocardiography to identify effusion. Two of four criteria establish the diagnosis; echocardiography can be normal and does not exclude it.¹

Diagnosing myocarditis

Cardiac troponin is often raised, ECG may show non-specific changes or arrhythmia, and echocardiography assesses ventricular function. Cardiac MRI is the key non-invasive test, visualising oedema and late gadolinium enhancement in a non-ischaemic distribution using standardised criteria; endomyocardial biopsy is reserved for selected severe or unexplained cases.⁴

Distinguishing from myocardial infarction

Both present with chest pain and a raised troponin. Widespread rather than territorial ST elevation, PR depression, positional pain, a preceding viral illness and a non-ischaemic MRI pattern point away from infarction — but coronary disease is excluded rather than assumed absent, particularly with cardiovascular risk factors.

Investigations for related conditions

Autoimmune screening, renal function, and investigation for tuberculosis where epidemiologically relevant form part of the workup, alongside assessment of ventricular function that will guide the return-to-exercise decision.²

Management

Management and goals

The goals are to control inflammation and pain, prevent recurrence, protect the myocardium during the vulnerable phase, and return the person safely to full activity.¹

Treating pericarditis

NSAIDs or aspirin, plus colchicine. Adding colchicine to conventional anti-inflammatory therapy roughly halved incessant or recurrent pericarditis in randomised trial, and it is now standard rather than optional.⁵ Corticosteroids are reserved for cases that do not respond, or where NSAIDs are contraindicated, because they are associated with a higher recurrence rate. A large or compromising effusion needs drainage.

Recurrent pericarditis

A meaningful minority recur, usually within the first 18 months. Colchicine reduces recurrence when used as first-choice therapy for recurrent disease,⁶ and refractory cases may need interleukin-1 blockade or longer-term immunosuppression under specialist care.

Treating myocarditis

Management is largely supportive: standard therapy for any resulting heart failure or arrhythmia, with intensive care and mechanical circulatory support for fulminant presentations. Specific antiviral or immunosuppressive treatment is used only in selected, biopsy-confirmed cases, and immune checkpoint inhibitor myocarditis is a distinct entity treated with high-dose corticosteroids.²

Identifying deterioration

Rising breathlessness, falling exercise tolerance, syncope, new palpitations or oedema indicate progression. In pericarditis, a rising jugular venous pressure with hypotension and a quiet heart suggests tamponade.

Action plan

1. Observe the restriction in full — at least one month, and in every case until your team confirms remission — even once you feel well. Where the heart muscle was involved, or where you are returning to competitive or high-intensity sport, your cardiologist may set a considerably longer period. This is the instruction most often disregarded and the one that matters most.
2. Take anti-inflammatory and colchicine therapy for the full prescribed course; stopping early is a leading cause of recurrence.
3. Report worsening breathlessness, fainting, palpitations or swelling promptly.
4. Seek emergency care for chest pain at rest, collapse, or rapidly worsening breathlessness.
5. Do not restart sport or heavy training without cardiology clearance, however well you feel.

Medications

Anti-inflammatory therapy

High-dose NSAIDs or aspirin for symptom control, tapered rather than stopped abruptly once symptoms and inflammatory markers settle. Gastric protection is usual, and NSAIDs are avoided where myocarditis with ventricular dysfunction is prominent.⁵

Colchicine

Given for three months in a first episode and six months in recurrence, with dose adjusted for weight and renal function. Diarrhoea is the common reason for discontinuation and often responds to dose reduction rather than stopping.^5,6

Corticosteroids

Effective but associated with higher recurrence, so second-line in pericarditis; they remain first-line in specific settings such as autoimmune or checkpoint-inhibitor disease.¹

Heart failure and arrhythmia therapy

Where myocarditis has impaired ventricular function, standard heart-failure therapy applies and is continued until function recovers, with rhythm monitoring in those who presented with arrhythmia.²

Living with pericarditis and myocarditis

Exercise restriction — personalised, not a fixed ban

Vigorous exercise is restricted, and current guidance sets the end point by remission rather than the calendar. The 2025 European guideline restricts exercise in athletes and non-athletes alike for at least one month and until complete clinical and laboratory remission — symptoms resolved, inflammatory markers and troponin normalised, ventricular function and rhythm satisfactory — with the period set individually rather than by a fixed rule.¹ In pericarditis without myocardial involvement that floor is one month, and three months for competitive athletes. Where there is myocarditis, restriction is commonly longer and cardiology clearance is required before return: the familiar three-to-six-month figure comes from earlier athlete-focused consensus, and is still applied where recovery is slow, scarring is extensive, or arrhythmia was present.^7,8 Both European and American guidance has since moved away from a fixed period and towards an earlier, individually assessed return once the acute phase has resolved — so the honest answer to “how long?” is that remission, not a number, decides it.¹ Inspire Clinic follows this approach. Explaining why — inflamed myocardium, arrhythmic risk, invisible to how you feel — achieves far better adherence than the instruction alone.

Returning to sport

Return is staged and guided by cardiology review, typically requiring resolution of symptoms, normal ventricular function, normal inflammatory markers and, for athletes, ambulatory rhythm monitoring and exercise testing before clearance.⁸ The minimum one-month restriction applies regardless of how quickly you feel well; remission, not the calendar alone, sets the rest.¹

Recurrent pericarditis and daily life

Recurrence is common enough that people should know it is possible, know its early symptoms, and not interpret it as having done something wrong. Prolonged or repeated courses of colchicine are well tolerated by most.⁶

Work and driving

Sedentary work usually resumes quickly; physically demanding work is treated like sport and staged accordingly. Driving restrictions may apply after arrhythmia or syncope and are set by the treating team against jurisdictional rules.

Anxiety after a cardiac diagnosis

A young, previously well person told to stop exercising for months frequently becomes hypervigilant about chest sensations. Naming this as expected, and providing a graded plan with clear milestones, is part of treatment rather than reassurance around it.

Prognosis

Most pericarditis resolves fully, though roughly one in five to one in three experience a recurrence, usually within 18 months; a small minority develop constrictive pericarditis, which can require pericardiectomy. Myocarditis outcomes are more variable: many recover completely, some are left with reduced ventricular function or dilated cardiomyopathy, and fulminant myocarditis carries a real risk of death or need for mechanical support — though survivors of fulminant disease often recover better in the long term than those with milder-appearing subacute forms.²

Role of the physiotherapist

The physiotherapist's central role is guiding and holding the exercise-restriction period — helping people understand why rest from vigorous activity matters when they feel well, and providing light, symptom-guided activity to limit deconditioning without loading the heart. This is an active clinical task, not a passive prohibition, and it is usually the physiotherapist rather than the cardiologist who has the repeated conversations that make it stick.⁷

Once cardiology clears a graded return, the physiotherapist designs and monitors a structured return-to-activity or return-to-sport programme, watching for chest pain, palpitations, breathlessness and abnormal heart-rate or blood-pressure response, and escalating rather than progressing when any appear.⁸ For those left with impaired ventricular function, care follows heart failure rehabilitation principles.

Physiotherapy red flags — stop and escalate: chest pain during or after activity, palpitations with light-headedness, syncope or near-syncope, disproportionate breathlessness, or a heart-rate response that does not settle normally after exercise.

Part 1 · References

1. Imazio M, Schulz-Menger J, Collini V, et al. 2025 ESC Guidelines for the management of myocarditis and pericarditis. Eur Heart J 2025;46(40):3952. Updates and replaces the 2015 ESC pericardial diseases guideline.
2. Ammirati E, Frigerio M, Adler ED, et al. Management of acute myocarditis and chronic inflammatory cardiomyopathy: an expert consensus document. Circ Heart Fail 2020;13(11):e007405.
3. Oster ME, Shay DK, Su JR, et al. Myocarditis cases reported after mRNA-based COVID-19 vaccination in the US from December 2020 to August 2021. JAMA 2022;327(4):331–340.
4. Ferreira VM, Schulz-Menger J, Holmvang G, et al. Cardiovascular magnetic resonance in nonischemic myocardial inflammation: expert recommendations. J Am Coll Cardiol 2018;72(24):3158–3176.
5. Imazio M, Brucato A, Cemin R, et al. A randomized trial of colchicine for acute pericarditis (ICAP). N Engl J Med 2013;369(16):1522–1528.
6. Imazio M, Bobbio M, Cecchi E, et al. Colchicine as first-choice therapy for recurrent pericarditis: results of the CORE trial. Arch Intern Med 2005;165(17):1987–1991.
7. Pelliccia A, Sharma S, Gati S, et al. 2020 ESC guidelines on sports cardiology and exercise in patients with cardiovascular disease. Eur Heart J 2021;42(1):17–96.
8. Maron BJ, Udelson JE, Bonow RO, et al. Eligibility and disqualification recommendations for competitive athletes with cardiovascular abnormalities: task force 3 — hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy and other cardiomyopathies, and myocarditis. Circulation 2015;132(22):e273–e280.

References are numbered in citation order (Vancouver/BMJ style) and were current at the time of writing. Guidelines are living documents — verify against the latest version before clinical use.