Approximately 10-15% of patients with COVID-19 will develop myocarditis as a complication. The myocarditis normally presents approximately 10-days into the infection, and it can be difficult to diagnose myocarditis if that patient is also experiencing Acute Respiratory Distress Syndrome.

The clinical features which might suggest a superadded myocarditis include:

• Dramatic decline in the patient’s overall condition
• Increased need for oxygenation
• ECG changes, including sinus tachycardia, diffuse T wave changes, heart block, prolongation of the QT interval
• Chest x-ray findings of pulmonary oedema, although these are difficult to differentiate from ARDS caused by COVID-19
• Biomarkers including troponin T and BNP are often elevated in myocarditis
• Echocardiography findings of impaired LV function, although this test may not be available due to risk of cross infection

Patients with myocarditis can also present with arrhythmias.