Danish research shows that most of the people hospitalized with COVID-19 had impaired cardiac function.
A study that included people with COVID-19 hospitalized in Region Zealand and the Capital Region of Denmark found that as many as 80% had impaired heart function, increasing their risk of serious illness and death. The study also found that people had both elevated levels of cardiac biomarkers in the blood and signs of pressure overload in the heart. COVID-19 affects both the right ventricle (RV), which pumps blood to the lungs, and the left ventricle (LV), which pumps blood to the rest of the body.
“COVID-19 negatively affects the entire circulatory system. We know this and currently give blood-thinning medication to people with COVID-19. But maybe we need to use other means to prevent these cardiovascular effects before they occur,” says Tor Biering-Sørensen, physician, Associate Professor and Research Director, Department of Cardiology at Herlev & Gentofte Hospital.
The research has been published in ESC Heart Failure and in JACC: Cardiovascular Imaging.
Impaired heart function
The study recruited 214 people hospitalized with COVID-19 at hospitals in Region Zealand and the Capital Region of Denmark. Their average age was 69 years, and 55% were men. Their heart function was measured by ultrasound scanning (echocardiography) and various heart biomarkers in the blood. Echocardiography can show doctors whether there might be pressure overload in the heart, which can transmit backwards and result in fluid in the lungs. The researchers can also use the echocardiography to determine how the various parts of the heart function in COVID-19. The blood tests measured the levels of a protein secreted from the heart muscle when it is stretched.
“These measurements clearly show whether the heart is under strain,” says Biering-Sørensen.
The results showed that 80% of the 214 people with COVID-19 had signs of impaired heart function. This group had a much higher risk of being admitted to intensive care than those without heart dysfunction. During the 40 days of the study period, 25 of the 214 people died. Impaired heart function was associated with an increased risk of death.
The researchers also compared the hospitalized people with a group of age- and sex-matched controls to confirm that the effects on the heart most likely was a result of COVID-19 and were not just representative of normal effects of the heart with increasing age.
The hospitalized people had more impaired heart function than the control group.
“We could not directly determine whether the 214 patients with COVID-19 already had impaired heart function beforehand, giving them a higher risk of an adverse outcome, or whether COVID-19 affected their hearts, which again gave them a higher risk of an adverse outcome. However, the comparison with matched controls indicates that COVID-19 might directly affect the heart,” explains Biering-Sørensen.
Biering-Sørensen also says that the reason why the researchers were able to start their investigation so quickly was that they had planned to do exactly the same studies on patients hospitalized with influenza, but as the pandemic gained speed, they quickly changed tack. “Infectious diseases are known to increase the risk of developing cardiovascular disease, but very few researchers have studied the mechanisms behind how infections affect the heart. We have now elucidated this, and we will continue to do this in the future, which also means that, as soon as influenza returns, we will also examine these parameters among patients hospitalized with influenza,” says Tor Biering-Sørensen.
COVID-19 affects the whole heart
The researchers also examined how COVID-19 affected the individual parts of the heart. The right ventricle pumps blood to the lungs, where the blood gets oxygenated. The left ventricle pumps oxygenated blood to the rest of the body. COVID-19 affected both the right and left ventricles of the heart, especially among the people who died with COVID-19. According to Tor Biering-Sørensen, this makes sense.
“The right ventricle being affected makes sense because SARS-CoV-2 is a lung disease, and this will be visible on the right ventricle. But surprisingly, the left side was also affected. This indicates that SARS-CoV-2 does not simply attack the lungs. The next step is to determine to what extent COVID-19 is a heart disease, and we might get closer to an answer by taking samples from the heart muscle and finding out whether the virus is present in the heart as well” he says.
After the initial studies, the researchers and doctors invited the 214 participants to attend a follow-up assessment two months later to determine how their heart had recovered from COVID-19. The researchers found that the right ventricle had recovered but that the left ventricle of many of the patients remained compromised. “This may be an early marker for COVID-19 irreversibly impairing heart function, which is quite serious,” says Biering-Sørensen.
Some people with COVID-19 might benefit from being treated with heart medicine
Based on the findings, Tor Biering-Sørensen thinks that there is a basis for considering COVID-19 as affecting not only the lungs but the whole cardiovascular system. Today, physicians understand this, and treatment with blood-thinning medication is therefore standard for people hospitalized with COVID-19 to counteract the risk of developing a blood clot.
However, Tor Biering-Sørensen believes that maybe physicians should use additional treatments to protect the heart against both the acute effects and the long-term effects of COVID-19. The results might be used to identify which patients should be targeted for treatment with, for example, antibodies. Patients with impaired heart functioning are those with an adverse prognosis, and these patients might therefore benefit the most.
“We do not know whether this will work, but we might use an assessment of the heart in patients with COVID-19 to classify them according to their risk of a severe disease trajectory. We can then consider whether treating those at greatest risk aggressively with cardioprotective drugs makes sense. I would think that testing this hypothesis would be the next natural step,” concludes Tor Biering-Sørensen.