While the most severe cases of the new coronavirus typically involve respiratory failure, COVID-19 doesn't always affect only a patient's lungs. The virus sometimes causes infection and swelling in the heart and surrounding muscles, which can be fatal.
New research published Friday in the journal JAMA Cardiology concluded that the COVID-19 virus, much like other respiratory viruses, could affect a patient's cardiac system. The study showed that even healthy people who contract COVID-19 are at risk of heart injury.
"It is likely that even in the absence of previous heart disease, the heart muscle can be affected by coronavirus disease," Dr. Mohammad Madjid, the study's lead author and an assistant professor of cardiology at McGovern Medical School at UTHealth, said in a press release.
"Overall, injury to heart muscle can happen in any patient with or without heart disease, but the risk is higher in those who already have heart disease," he added.
The link between COVID-19 and cardiac problems
After reviewing an array of existing studies about COVID-19, Madjid and his colleagues said patients with preexisting heart disease were among those at the greatest risk for developing severe cases of COVID-19.
The scientists said those patients' risks were twofold: They seem not only more likely to get infected but also more likely to die from the illness, in part because they develop further heart injuries during infection.
The case fatality, or death rate, for COVID-19 patients with heart disease in mainland China was 10.5% between December 30 and February 11, according to research from the Chinese Center for Disease Control and Prevention.
According to another new study in JAMA Cardiology (which echoed Madjid's group's conclusions), that's because patients with underlying heart disease are more prone to experience myocardial, or heart, injury during the course of their COVID-19 infections. These myocardial injuries include an irregular heartbeat or heart failure.
The study, which examined 187 COVID-19 patients at a hospital in Wuhan, China, showed that 28% of patients developed a myocardial injury, which was significantly associated with a higher risk of death. About 70% of patients that had both underlying heart disease and a heart injury from the virus died.
According to Madjid and his coauthors, COVID-19, as well as other respiratory viruses such as the flu and SARS, can exacerbate existing cardiovascular disease and trigger new heart problems in healthy patients.
During most flu epidemics, more patients die of heart problems than respiratory issues like pneumonia, they wrote, adding that they expected similar cardiac issues among severe COVID-19 cases.
One woman with COVID-19 had a heart infection but no respiratory issues
A third study also published Friday in JAMA Cardiology described the case of a 53-year-old healthy woman without any history of cardiovascular disease or underlying health conditions. She came to the emergency room complaining of severe fatigue in March.
The patient told doctors she'd had a fever and dry cough the week before, but she had no difficulty breathing and her chest X-rays were clear. The lining of her heart, however, was inflamed and infected, and she was admitted to the cardiac-care unit for treatment.
Later, because of her prior symptoms, she was given a coronavirus test. It came back positive.
The study authors wrote that this woman's case "provides evidence of cardiac involvement as a possible late phenomenon of the viral respiratory infection."
The researchers offered two explanations about how the COVID-19 virus might affect the heart. The first is that the virus could spread from the lungs through the body via blood or the lymphatic system. They added, however, that no incidences of the coronavirus in the heart had been reported yet.
Alternatively, the coronavirus could trigger inflammation in the body, which may cause heart injury.
