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Disease and treatment

The heart is key to finding COVID patients at greatest risk

COVID-19 has been called an insidious virus, in part because it affects people in vastly different ways. Some have no symptoms, but others end up requiring a ventilator in intensive care. Researchers are therefore working at full speed to understand who has the greatest risk. A new study performing ultrasound scanning of COVID patients’ hearts appears to identify those at greatest risk. Whether COVID attacks the heart or these patients already have heart problems is unknown, but the new knowledge can be useful now in identifying the patients at highest risk.

The COVID-19 pandemic has resulted in hundreds of thousands of people dying globally, and many more will die. Acute respiratory failure seems to be the immediate cause of death, but new studies suggest that COVID-19 also causes complications involving the heart. A new study therefore examined whether patients hospitalized with COVID-19 who have myocardial impairment comprise a specific high-risk group.

“We tried to find a simple method to screen the people hospitalized with COVID-19 and thereby identify those who get the most serious complications. Our preliminary results show that we can do this with a simple ultrasound scan of the heart combined with blood tests. Surprisingly, most of those affected have not had heart problems previously, so the heart function could be impaired because COVID-19 attacks the heart and the combination of weak lungs and a weak heart is the reason why so many people die,” explains Tor Biering-Sørensen, Department of Cardiology, Herlev & Gentofte Hospital and Associate Professor, Department of Biomedical Sciences, University of Copenhagen.

A small but important reduction

To investigate how COVID-19 patients’ hearts function, the researchers commuted between the hospitals in Region Zealand with a portable ultrasound scanner. All newly admitted COVID-19 patients were offered an echocardiogram with the scanner and blood tests for the level of the heart proteins troponin and BNP (B-type natriuretic peptide). Although only 174 patients were scanned, the results are compelling.

“We found that almost four fifths of the patients had myocardial impairment, determined by ultrasound scanning or elevated cardiac biomarkers in blood. Patients who had both high infection biomarkers and impaired heart function at admission had more than 70% risk of requiring hyperbaric oxygen therapy or ventilator therapy later. However, people had less risk if they had neither high infection biomarkers nor impaired heart function at admission,” says Tor Biering-Sørensen.

The researchers especially noticed the change in the volume of blood the heart pumps at each beat among COVID-19 patients. A normal heart fills up, expands and then contracts and pumps 60% of the blood out again, but this drops to about 50% for the COVID-19 patients weakened by the infection: a small but important reduction.

“The idea of scanning COVID-19 patients’ hearts did not suddenly materialize, because for several years we have found that infection and heart function are very closely linked. For example, like the lungs, infections affect the heart by increasing pressure, causing the blood vessels to leak, which results in oedema, filling the lungs with fluid when the heart’s pumping function is impaired,” says Tor Biering-Sørensen.

Two organs fail simultaneously

Previous studies have shown that influenza can increase the risk of blood clots in the brain seven-fold, and Tor Biering-Sørensen’s research team has previously shown that influenza vaccination of people with high blood pressure and people with diabetes is associated with an 18% lower risk of death during the flu season. Similarly, Tor Biering-Sørensen believes that a specific focus on myocardial impairment may help to determine who will need intensive care during hospitalization for COVID-19.

“Surprisingly, patients having heart disease before getting COVID-19 is not clearly linked with developing heart problems when they get COVID-19. The myocardial impairment among people without any history of known heart disease is just as strong as that among people with known heart disease. This again suggests that, in severe cases, the virus may weaken heart function and that these cases become really serious because the two crucial organs, the heart and lungs, fail simultaneously,” explains Tor Biering-Sørensen.

The new study opens up obvious therapeutic applications and, according to Tor Biering-Sørensen, ultrasound scanning may potentially be an important supplement to other tests when COVID-19 patients are hospitalized because this knowledge can be used to assess who should be monitored and prescribe medicine to the patients who really need it. However, the research raises several unanswered questions.

“We will try to compare our data with, for example, the Copenhagen City Heart Study, which focuses on cardiovascular diseases and their risk factors, so that we can accurately determine whether these patients become severely ill because they have a latent heart condition or because the virus weakens their heart,” says Tor Biering-Sørensen.

If the researchers’ theory of the virus attacking the heart is validated, the next step will be to understand the mechanism of how the virus attacks the heart.

“There are plenty of unanswered questions in addition to how this happens, whether some people are more susceptible than others and, naturally, whether anything can be done to prevent the virus from attacking the heart. In addition, we hope we can follow up the COVID-19 patients to determine whether they have lasting effects on the heart or whether the symptoms diminish over time,” says Tor Biering-Sørensen.

Two medical students at the University of Copenhagen, Kristoffer Grundtvig Skaarup and Mats Højbjerg Lassen have performed ultrasound scans of coronary patients' hearts and lungs and are the main authors of a scientific article "Myocardial impairment and acute respiratory failure in hospitalized COVID-19 Study: the ECHOVID-19 Study", which has been submitted for publication. The Novo Nordisk Foundation recently awarded DKK 1.8 million to Tor Biering-Sørensen under its emergency coronavirus programme to mitigate the adverse health effects of the COVID-19 pandemic in Denmark. In 2018, the Foundation awarded Tor Biering-Sørensen a grant for the project Influenza Vaccination in Cardiovascular Disease: a Nationwide Epidemiological Study. Europcar sponsored the COVID-19 project by providing free courtesy cars for the researchers to commute between the participating hospitals with their portable ultrasound scanner. GE Healthcare sponsored the project by providing a portable ultrasound scanner.

Tor Biering-Sørensen
MD, Ph.d.
The research takes place from ’bench to bedside’ and from ’bedside to bench’, and the projects cover everything from basic molecular and cell biologic projects to studies of intact animals and humans in both normal and pathophysiological stages.