Exercise as it relates to Disease/Myocarditis and exercise

According to the World Health Organization and the Federation of Cardiology; myocarditis has been defined as an inflammatory disease of the heart muscle. Myocarditis can detrimentally affect those in good health; post mortal data has shown that myocarditis has been the cause of sudden death in young adults at rates as high as 12% and can also lead to permanent heart damage and dysfunction.

Aetiology
There have been numerous causes documented for the onset of myocarditis. There are three main causes and they have been categorised into the following:


 * Viral- Accounts for about half of the cases of diagnosed myocarditis. Coxsackie virus being the most common, accounting for over 50% of the cases of viral myocarditis.
 * Fungal- An increasing cause to myocarditis, the major fungal pathogen being Aspergillus fumigatus.
 * Bacterial- Any form bacteria may cause myocarditis with the most common pathogens being meningococcus, streptococcus and Listeria

Other causes include pregnancy, toxins, drug reactions, autoimmune diseases, giant cell myocarditis and sarcoidosis.

Signs and Symptoms
Symptoms of acute myocarditis vary, and depend on the severity of the condition. In most cases, the signs and symptoms mimic those of heart failure or a heart attack; such as chest pain, nausea and arrhythmia of heart beats. As most cases present as a viral infection the immune system is suppressed and symptoms may present as a fever, cold/flu like symptoms, myalgia and headaches. Due to these common and varied signs and symptoms, myocarditis is often difficult to identify and is often misdiagnosed.

Diagnosis
Myocarditis is often difficult to identify and is often misdiagnosed given the broad range of symptoms and degree to which it affects each individual case. The following ways are used to diagnose myocarditis:


 * Electrocardiogram- Identifies nonspecific T-wave changes.
 * Chest X-ray- Identifies chamber dilatation and/or pericardial effusion.
 * Laboratory- In most cases blood tests are performed and blood troponin levels are monitored.
 * Echocardiography- Monitoring heart function and size.
 * Cardiac MRI- Checking for 3 types of cardiac tissue injury; intracellular and interstitial edema, capillary leakage, and necrosis and fibrosis.
 * Endomyocardial biopsy- Examination of the cardiac tissue for any signs of myocarditis.

Treatment
Treatment of myocarditis differs between cases, and depends on the severity of each condition. Depending on the type myocarditis diagnosed dictates which treatment options are issued, however treatment options for each case are very similar. There is a very strong emphasis on pharmacotherapy in the treatment of myocarditis, with beta-blockers, diuretics, anti-inflammatory, angiotensin converting enzyme inhibitors and/or angiotensin-II receptor blockers often prescribed. Withdrawal of physical activity and strenuous activities in the acute stage is also prescribed and once left ventricle function has improved a gradual increase of activity is recommended. Diet and other lifestyle factors that have shown to improve cardiac function is also recommended in not only treating myocarditis, but also preventing it.

Physical Activity and Myocarditis
During acute myocarditis, all aerobic exercise should be avoided as it has been shown to lead to an increased risk of mortality. Athletes that show evidence of myocarditis are to be withdrawn from competition and training for 6 months, and they may commence training again when all ventricle function has returned to normal and when they show no signs of arrhythmia. Numerous studies have shown exercise to have various effects on the immune system and the body’s ability to defend itself against viruses. Exercise at moderate intensities is encouraged as it is thought to release certain stress hormones which play a role in immune-enhancing and anti-inflammatory effects which assist the immune cells in fighting viral infections. However exercise at high intensities is not so beneficial. The effect of Coxsackie virus has been shown to be enhanced by strenuous exercise; with research showing that exercise increases the risk of mortality by 45% with those infected with Coxsackie virus. With this evidence shown, exercise at moderate intensity is highly recommended once the heart muscle has recovered as it will assist in further preventing infection causing myocarditis.

Further Information
Review article on Myocarditis

Video: Diagnosis, treatment and exercise guidelines for Myocarditis