So far, the main focus of Covid-19 has been on the respiratory and lung symptoms, but the coronavirus Sars-CoV-2 apparently also attacks the heart, as several studies from China and Italy suggest. Evidence of this is provided, among other things, by a significantly higher mortality rate of 10.5 percent in Covid patients with cardiovascular diseases and high blood pressure, but also the detection of a molecule released in the damage to cardiac muscle cells in Covid patients with and without such previous diseases. Doctors also report some cases where the viral infection has caused myocarditis in previously healthy patients.
Because the Sars-CoV-2 coronavirus has only recently spread to humans, virologists and medical professionals only learn more about its behavior and the medical consequences of the infection in the course of the current pandemic. It now seems clear, however, that older people and people with pre-existing conditions such as diabetes, high blood pressure, cardiovascular diseases, certain cancers or disorders of the cerebral blood flow have a higher risk of serious courses and also die more often from Covid-19. Most of these patients develop severe pneumonia, which ultimately leads to shortness of breath and death.
Indications of acute heart muscle damage
But there is now also evidence that Covid disease can cause acute damage to the heart muscle. Several studies have shown that in patients with severe courses of coronavirus infection, a biomarker in the blood that was released by destroyed and dying heart muscle cells was often increased. Doctors see this as an indication that the virus infection also attacks the heart – however, it is still unknown in which way. In theory, the virus itself could contribute to this damage, but it is also possible that the inflammatory processes and immune reactions triggered by the infection are responsible for this damage. Viruses that are closely related to the current coronavirus Sars-CoV-2, such as Sars-CoV and Mers-CoV, are also known to have cases in which acute heart damage occurred. In the Sars epidemic in 2003, a study of 75 Sars patients found that two out of five people who died from the disease had an acute heart attack. Cardiac arrhythmia also occurred, as reported by Mohammad Madjid of the University of Texas, author of an overview study in the specialist magazine “JAMA Cardiology” on this topic.
In a study from Italy, researchers led by Riccardo Inciardi from the University of Brescia report the case of a healthy 53-year-old woman who was infected with Sars-CoV-2 and initially developed the classic symptoms of dry cough and fever. About a week after the symptoms started, she developed severe exhaustion with circulatory problems that was so severe that she went to the hospital. There she was tested positive for Covid and transferred to cardiology. Research there revealed that the patients showed clear signs of acute myocarditis – an inflammation of the heart muscle. “This case emphasizes that the heart can be affected by Covid-19 as a complication – even without clear symptoms and without pneumonia,” Inciardi and his colleagues report. Madjid has a similar view: “It is likely that the heart muscle will be affected by the coronavirus and the disease it triggers even in the absence of a previous heart disease.”
“A wake-up call”
This seems to indicate that Covid disease not only causes respiratory symptoms and the inflammatory reactions associated with the infection, but can also attack the heart. Current studies from China show that the patient’s risk of death increases significantly in this case. A team led by Shaobo Shi from the University of Wuhan, based on 416 patients, reports that almost 20 percent of these patients had evidence of myocardial damage. Those affected had a significantly higher risk of dying from Covid-19 – half of them, while only 4.5 percent of those without increased troponin levels and other evidence of cardiac muscle damage died. Another study with 187 patients found similar results: It determined a mortality of 59.6 percent in people with indicators of heart muscle damage, of those with normal troponin levels in the blood died 8.9 percent.
“It is noteworthy that the highest mortality rates were observed in patients who had high troponin levels and previous cardiovascular diseases,” wrote Robert Bonow from Northwestern University in an accompanying editorial in “JAMA Cardiology”. “But the mortality rates were also significant for those who had elevated troponin levels without such pre-existing conditions.” It is still not clear which concrete mechanisms and relationships are behind this effect. “But the wake-up call sounds,” says Bonow.
Sources: Mohammad Madjid et al., JAMA Cardiology, doi: 10.1001 / jamacardio.2020.1286; Riccardo Inciardi et al., doi: 10.1001 / jamacardio.2020.1096; Shaobo Shi et al., doi: 10.1001 / jamacardio.2020.0950; Bonow et al., JAMA Cardiology, doi: 10.1001 / jamacardio.2020.1105