A recent review examines the relationship between coronaviruses and the cardiovascular system. Although information about SARS-CoV-2, specifically, is scant, the authors believe that research into other coronaviruses might provide insight.

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A new review investigates coronaviruses and heart health.

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A type of coronavirus called SARS-CoV-2 causes COVID-19, an illness infamous for its effects on the lungs and airways.

However, as the authors of the latest review — which features in the journal JAMA Cardiology — explain, acute respiratory infections “are well-recognized triggers for cardiovascular diseases.”

For instance, scientists have shown that influenza, respiratory syncytial virus, and bacterial pneumonia can affect cardiovascular health and increase the severity of the condition. In fact, the authors explain, “during most influenza epidemics, more patients die of cardiovascular causes than pneumonia-influenza causes.”

As our understanding of COVID-19 is still evolving, the authors reference earlier research on similar coronavirus outbreaks, including studies investigating severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).

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Like SARS-CoV-2, scientists believe that the virus that causes SARS also originated in bats. In 2003, 8,096 people in 29 countries developed SARS. As the authors explain, the sparsity of evidence makes it difficult to draw conclusions about the impact of SARS on cardiovascular health.

The largest study that the authors outline included just 121 people with a SARS diagnosis.

The authors of the 2006 study concluded: “In patients with SARS, cardiovascular complications, including hypotension and tachycardia [an abnormally fast heartbeat], were common but usually self-limiting. […] However, only tachycardia persisted even when corticosteroid therapy was withdrawn.”

As the authors of the latest review explain, most of the evidence of cardiovascular complications associated with SARS is either anecdotal or from small-scale studies.

MERS results from another coronavirus, again, apparently originating in bats. The epidemic began in Saudi Arabia in June 2012. According to the World Health Organization (WHO), by 2019, there had been almost 2,500 confirmed cases and more than 850 deaths in 27 countries.

Evidence of cardiovascular factors for MERS appears to be even more difficult to find than it is for SARS. However, one analysis of 637 individuals with a diagnosis of MERS did offer some insight.

The researchers found that cardiac diseases were present in 30% of the people who took part in the trial.

Of course, this does not necessarily mean that MERS causes cardiovascular issues. Instead, it might indicate that people with these existing conditions were more likely to develop symptoms of MERS or less able to fight off the infection.

It seems that people with poor cardiovascular health are more likely to experience worse symptoms of COVID-19. For instance, in a study involving 44,672 people with COVID-19 in China, 4.2% had cardiovascular disease.

However, these individuals accounted for 22.7% of all fatal cases, giving a case fatality rate of 10.5%.

In this context, the case fatality rate describes the proportion of people with COVID-19 who died in this particular group of people. As a comparison, the case fatality rate for people with diabetes was 7.3%, and for those with a chronic respiratory condition, it was 6.3%.

A smaller study, also in China, included 99 people with COVID-19. The researchers found that 40% of these people had existing cardiovascular or cerebrovascular disease.

In another small, retrospective study of 150 people with COVID-19, cardiovascular health appeared to influence mortality rates. The findings showed that none of the 82 people who survived had cardiovascular disease, but 13 of the 68 who died did have cardiovascular disease.

The myocardium is the muscular tissue of the heart. Myocarditis is an inflammation of this tissue, and it can cause a rapid or abnormal heart rhythm.

According to the authors of the review, there is some evidence that SARS-CoV-2 can cause myocarditis.

They explain that autopsy reports suggest that interstitial mononuclear inflammatory cells invade the myocardium — this is a hallmark of inflammation.

Other case studies document individuals who have developed myocarditis alongside COVID-19. This is, perhaps, not entirely surprising. As the authors of one case study explain, “Virus infection has been widely described as one of the most common causes of myocarditis.”

Overall, it is still too early to judge the impact of COVID-19 on heart health. However, the review outlines some fairly strong evidence that existing cardiovascular disease might increase the chance of developing COVID-19, the mortality risk, or both. The authors conclude:

“Lessons from the previous coronavirus and influenza epidemics suggest that viral infections can trigger acute coronary syndromes, arrhythmias, and development of exacerbation of heart failure.”

They continue, “[COVID-19] may either induce new cardiac pathologies and/or exacerbate underlying cardiovascular diseases. The severity, extent, and short-term vs. long-term cardiovascular effects of COVID-19, along with the effect of specific treatments, are not yet known and are subject to close scrutiny and investigation.”

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