Based on reports from China, we know that most COVID-19 patients (about 80%) will develop mild flulike symptoms, including fever, dry cough, and body aches that can be managed at home. 20% will develop more serious symptoms, such as pneumonia requiring hospitalization, with about a quarter of these requiring ICU-level care.
Initial reports focused on the respiratory effects of COVID-19, such as pneumonia and difficulty breathing. But more recent literature has described serious cardiovascular complications occurring in about 10% to 20% of hospitalized patients.
Someone with pre-existing heart disease who becomes ill with COVID-19 may suffer a heart attack or develop congestive heart failure. This rapid worsening of cardiovascular health is likely due to a combination of the severe viral illness and its increased demands on the heart (fever causes rapid heart rate, for example), compounded by low oxygen levels due to pneumonia and increased propensity for blood clot formation. In addition to the increase in these heart problems, a more unusual condition called myocarditis has also been observed in COVID-19 patients.
COVID-19 triggers inflammation of the heart muscle
Some COVID-19 patients who appear to be having a heart attack are instead suffering from marked inflammation of the heart muscle, called myocarditis. The electrocardiograms in these patients show changes suggestive of a major heart attack, and blood tests reveal elevated levels of troponin, a cardiac enzyme that is released when heart muscle is damaged. The heart muscle becomes weak, and dangerous heart rhythms may develop. Severe injury to the heart muscle, as measured by troponin levels, has been strongly associated with increased risk of death in people with COVID-19, according to a review published in JAMA Cardiology.
It is not clear whether myocarditis is due to a direct effect of the virus on the heart muscle, or whether it is due to an overactive immune response to the virus, so doctors do not yet know how best to treat these patients.
Increased risk of severe illness and death in heart patients with COVID-19
About 10% of patients with pre-existing cardiovascular disease (CVD) who contract COVID-19 will die, compared with only 1% of patients who are otherwise healthy. Increased risk has also been seen in people with high blood pressure (hypertension) and coronary artery disease (CAD), though it is not clear why. Some experts have suggested that the missing link may be the use of certain blood pressure medications called angiotensin converting enzyme (ACE) inhibitors and angi