The heart and COVID-19

Reports from China, Italy and the U.S. suggest that some people with underlying cardiovascular disease are at heightened risk for severe illness associated with COVID-19. There are also reports of increased risk for cardiovascular complications in some people with COVID-19.

Cardiologists at Zonghan Hospital in Wuhan, China, have been studying cardiovascular complications in people with COVID-19. Their study focused on proteins in the blood associated with heart injury. In some severe cases of COVID-19 with cardiovascular complications, levels of these proteins in the blood were elevated.

Study details

The cardiologists reviewed data collected from 187 people who were hospitalized and diagnosed with COVID-19 in January and February 2020. A total of 144 people survived and were able to leave the hospital, while 43 people died. The doctors collected information about signs, symptoms, lab tests and other assessments.

Two lab tests were a particular focus of their research:

  • TnT (cardiac-specific troponin) – this protein is released from dying or dead heart cells
  • NT-proBNP (N-terminal pro B-type natriuretic peptide) – this is a small molecule produced by the heart that is released into circulation when heart failure occurs

When participants were first admitted to the hospital and evaluated, the doctors stated that there was no evidence of the following:

  • heart attack
  • chronic liver disease
  • problems with excessive clotting of blood
  • rheumatism


The cardiologists found that more deaths occurred in people with elevated levels of TnT (60%) than in people with normal TnT levels (9%).

Furthermore, the doctors found that people with elevated TnT levels were more likely to have underlying health issues, such as the following:

Higher-than-normal blood pressure

  • with elevated TnT – 64%
  • with normal TnT – 21%

Coronary heart disease

  • with elevated TnT – 32%
  • with normal TnT – 3%

Enlarged heart

  • with elevated TnT – 15%
  • with normal TnT – 0%


  • with elevated TnT – 31%
  • with normal TnT – 9%

Chronic Obstructive Pulmonary Disease (COPD)

  • with elevated TnT – 8%
  • with normal TnT – 0%

Rates of smoking and cancer were not different between people with elevated TnT and those with normal TnT.

As reported in other studies of COVID-19, lab tests revealed elevated levels of proteins associated with inflammation, such as high-sensitivity C-reactive protein (hsCRP). Such markers were higher in people who had elevated levels of TnT.

People with elevated levels of TnT in the present study tended to have less-than-normal levels of oxygen in their blood. During the course of hospitalization, doctors found that people with elevated TnT levels developed “more frequent complications,” including the following:

  • severe lung injury
  • abnormal heart rhythms that became life threatening
  • excessive formation of blood clots
  • acute kidney injury

Although liver injury occurred in some of the people in the cardiology study (this was found by detection of elevated liver enzymes in blood samples), there was no connection to TnT levels.


As data were captured during an evolving approach to the management of COVID-19, patients received a wide variety of treatments, including the following:

  • antiviral drugs such as oseltamivir and ribavirin
  • antibiotics such as moxifloxacin for respiratory infections
  • steroids such as methylprednisolone

Also, some patients required invasive mechanical ventilation because of severe lung injury. More people with elevated TnT required this intervention.

Risk of dying

The doctors found that the risk of death was distributed as follows:

  • normal TnT and no underlying cardiovascular disease – 8%
  • normal TnT and underlying cardiovascular disease – 13%
  • elevated TnT and no underlying cardiovascular disease – 38%
  • elevated TnT and underlying cardiovascular disease – 69%


Over the course of hospitalization, levels of TnT and NT-proBNP successively rose in people who subsequently died. However, among people who survived, there was no increase in levels of these markers.

Bear in mind

Some studies in the pre-COVID-19 era suggest that viral respiratory infections are associated with an increased risk for cardiovascular events—heart attack, stroke and so on.

In 2002-03 when SARS occurred, doctors were able to conduct autopsies of some of the deceased from this complication. They found that 35% of tissue samples taken from hearts of people who died had the virus (SARS-CoV) that caused SARS. Laboratory-based studies done in the past three months suggest that SARS-CoV-2, the cause of COVID-19, can infect heart cells. Therefore, it is at least plausible that some of the cardiovascular problems found in the present study were caused in some way by SARS-CoV-2.

It is also plausible that multiple mechanisms triggered by SARS-CoV-2 infection contributed to the increased risk for cardiovascular problems that have been reported in some people with COVID-19. These other mechanisms could include the following:

  • intense levels of inflammation
  • changes to expression of a protein called ACE2 found on the surface of some cells (further information about ACE2 is found earlier in this issue of TreatmentUpdate)
  • less-than-normal levels of oxygen in the blood – this can occur in severe respiratory infections when the lungs become injured
  • injury to the lining of blood vessels – this could decrease the flow of blood to organs and also contribute to an increased risk for blood clots

The cardiologists suggested that doctors presently caring for people hospitalized with COVID-19 could screen them for underlying cardiovascular injury with blood tests of key markers (TnT, NT-proBNP) and cardiograms.

The present study was retrospective in design and cannot provide definitive conclusions. However, it provides a foundation for more intensive investigation into the risk for severe cardiovascular events in people with COVID-19. Such investigation can lead to the development of interventions to help people who are ill with COVID-19.

—Sean R. Hosein


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