COVID-19 and the heart: What have we learned? – . Health Blog

At the beginning of the pandemic, epidemiologists made a remarkable observation. Compared to the general population, people with cardiovascular disease (CVD) were more than twice as likely to develop severe forms of COVID-19. Over the past six months, death rates from COVID-19 have decreased significantly, but CVD remains an important predictor of poor outcome. What did we learn about heart disease and COVID-19 during this time?

Pre-existing heart disease and poor metabolic health increase the risk of severe COVID-19

As I described in a blog post in April, some health conditions like diabetes increase the risk of severe COVID-19 by suppressing the immune system. others, like asthma, increase the risk by weakening the lungs. However, in the early months of the pandemic, it wasn't 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 disease. A person with a vulnerable heart is more likely to succumb to the effects of fever, low oxygen levels, unstable blood pressure, and bleeding disorders – all possible consequences of COVID-19 – than a previously healthy person.

A second explanation relates to poor underlying metabolic health, which is more common in people with heart disease. Poor metabolic health refers to diseases like type 2 diabetes or prediabetes and obesity, which in themselves cause inflammation and the risk of blood clots, increase the effects of COVID-19, and increase the likelihood of devastating complications from COVID-19.

How does COVID-19 cause heart damage?

The SARS-CoV-2 virus can damage the heart in a number of ways. For example, the virus can invade the heart muscle directly or inflame it, and it can indirectly damage the heart by disrupting the balance between supply and demand for oxygen. Heart injury, which can be measured by increased levels of the enzyme troponin in the bloodstream, has been identified in about a quarter of patients with severe COVID-19 illness. About a third of these patients already have CVD.

Inflammation of the heart muscle

The majority of people with COVID-19 have mild symptoms and make a full recovery. However, about 20% will develop pneumonia and about 5% will develop serious illness. In the severe form of COVID-19, the body's immune system reacts excessively to the infection and releases inflammatory molecules called cytokines into the bloodstream. This so-called "cytokine storm" can damage several organs, including the heart.

Inflammation of the heart muscle known as myocarditis typically only occurs in patients with advanced COVID-19 disease. Myocarditis can be caused by direct cardiac invasion by the virus itself, or more commonly, inflammation caused by a cytokine storm. When this happens, the heart can become enlarged and weakened, resulting in low blood pressure and fluid in the lungs. While this severe form of myocarditis is rare, recent studies have shown that a milder form of myocarditis is much more common than previously thought. 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.

Increased oxygen demand and decreased oxygen supply lead to heart damage

Fever and infection make heart rate faster and increase heart work in COVID-19 patients who develop pneumonia. Blood pressure can go down or up, adding further stress to the heart, and the resulting increase in oxygen demand can cause heart damage, especially if the heart arteries or muscles were initially unhealthy.

Heart damage is most commonly caused by heart attacks, which result from the formation of a blood clot in a compromised heart artery and blocking the supply of oxygen to the heart muscle. Inflammation caused by COVID-19 increases the risk of this type of heart attack by activating the body's clotting system and disrupting the lining of blood vessels. When inflamed, this lining loses its ability to resist clot formation. These blood clots in the large and small arteries of the heart interrupt the supply of oxygen. The increased tendency to clot can also lead to blood clots in the lungs, which can lead to a drop in blood oxygen levels. Severe pneumonia further lowers blood oxygen. If the demand for oxygen exceeds the supply, the heart muscle is damaged.

Finding a silver lining through a healthy lifestyle and reducing the risk

People with CVD who behave healthily can strengthen their defenses against COVID-19 and at the same time reduce the long-term risk of cardiovascular disease themselves. This means lots of physical activity and a healthy diet like the Mediterranean diet. Cook at home when you can and go for a walk with friends outside when your gym is temporarily closed. Buy an affordable and easy-to-use monitor to measure your blood pressure at home. Continue to follow CDC safety guidelines to wear masks, keep your distance, and avoid large gatherings.