Some health conditions, like diabetes, increase risk of severe COVID-19 by suppressing the immune system; others, like asthma, increase risk by weakening the lungs. However, in the early months of the pandemic it was not entirely clear how CVD increased the risk of severe COVID-19. We now have two explanations.
The first is that pre-existing heart conditions, such as damaged heart muscle or blocked heart arteries, weaken the body’s ability to survive the stress of the illness. A person with a vulnerable heart is more likely to succumb to the effects of fever, low oxygen levels, unstable blood pressures, and blood clotting disorders — all possible consequences of COVID-19 — than someone previously healthy.
A second explanation relates to poor underlying metabolic health, which is more common in those with heart disease. Poor metabolic health refers to diseases such as type 2 diabetes or prediabetes and obesity, which themselves cause inflammation and risk of blood clots, compounding the effects of COVID-19 and increasing the likelihood of devastating complications of COVID-19.
How does COVID-19 cause heart damage?
The SARS-CoV-2 virus can damage the heart in several ways. For example, the virus may directly invade or inflame the heart muscle, and it may indirectly harm the heart by disrupting the balance between oxygen supply and demand. Heart injury, which may be measured by elevated levels of the enzyme troponin in the bloodstream, has been detected in about one-quarter of patients hospitalized with severe COVID-19 illness. Of these patients, about one-third has pre-existing CVD.
Inflammation of the heart muscle, called myocarditis, typically occurs only in patients with advanced COVID-19 disease. Myocarditis can result from direct heart invasion by the virus itself, or more commonly by inflammation caused by cytokine storm. When this occurs, the heart may become enlarged and weakened, leading to low blood pressure and fluid in the lungs. While this severe form of myocarditis is rare, recent studies have suggested that a milder form of heart muscle inflammation may be much more common than previously recognized. A recent study showed that asymptomatic heart inflammation was seen on magnetic resonance imaging in up to three-quarters of patients who had recovered from severe COVID-19.
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Finding a silver lining and lowering risk through healthy lifestyle
People with CVD who adopt healthy behaviours can strengthen their defences against COVID-19 while also reducing the long-term risk from cardiovascular disease itself. This means plenty of physical activity and following a healthy diet like the Mediterranean diet. Cook at home when you can, and walk outdoors with friends if your gym is temporarily closed. Purchase an inexpensive and easy-to-use monitor to measure your blood pressure at home. And continue to follow the CDC’s safety guidelines to wear masks, physically distance, and avoid large gatherings.
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