Chest Imaging Shows Little Long-Term Lung Scarring from COVID-19

How well a patient’s lungs recover post-COVID-19 infection is not necessarily linked with the severity of his or her disease course, but imaging shows that most patients do not experience long-term fibrosis.

To date, little research has focused on lung health post-recovery, and not much is known about whether the lingering effects of the virus, such as fatigue and shortness-of-breath, are directly linked to the patient’s disease course. To answer that question, a group of investigators from Trinity College in Dublin tested more than 150 recovered patients and examined their post-COVID-19 chest X-rays and CT scans.

“We found that fatigue, ill-health, and breathlessness were all common following COVID-19,” said Liam Townsend, M.D., from the infectious disease department at St. James’ Hospital and the Trinity Translational Medicine Institute at Trinity College. “However, these symptoms appeared to be unrelated to the severity of initial infection or any single measurement at the time of an outpatient appointment.”

The team published their findings in the Annals of the American Thoracic Society.

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In order to assess the intensity of the after-effects of the virus, Townsend’s team followed 153 patients for an average of 75 days in an outpatient clinic. They categorized patients into three groups: those who did not require hospitalization, those who did, and those who were placed in the ICU. Of the assessed patients, 74 individuals – 48 percent – had been hospitalized for acute infection.

To evaluate each patient’s condition, the team examined his or her chest images – X-ray and CT for signs of persistent infection or significant fibrosis – as well as their performance on a six-minute walk test – how far a patient was able to walk at a normal pace during the time frame. Patients also self-reported their fatigue levels and whether they felt they had returned to full health. The team also analyzed blood samples for indicators of disease, such as C-reactive protein that appears in high levels in the presence of inflammation in the body.

What the team found, Townsend said, was unanticipated.

“We were surprised by our findings,” he explained. “We expected a greater number of abnormal chest X-rays. We also expected the measures of ongoing ill-health and abnormal findings to be related to severity of initial infection, which was not the case.”

In particular, the found that only 4 percent of patients showed evidence of lung scarring on chest CT scans, suggesting that COVID-19 does not cause significant fibrosis, he said. The results followed X-rays that had indicated earlier abnormalities.

The average distance the patients walked during the six-minute test was 460 meters. Shorter distances were associated with patient frailty and longer hospitalizations, the team explained.

“These results support the need for more in-depth cardiovascular health and fitness assessment of those most severely affected, including cardiac imaging and maximal oxygen uptake assessment,” the team said.

Overall, most patients – 62 percent – said they felt they had not yet rebounded to full health at the time of follow-up, and 47 percent labeled themselves as continuing to experience fatigue.

Ultimately, the team said, their study reveals a need for ongoing support and rehabilitation for the patients who have lingering COVID-19 side effects, including programs that can optimize how they self-manage fatigue and perceive their exertion level in recovery.

“These findings have implications for clinical care in that they demonstrate the importance of following up all patients who were diagnosed with COVID-19, irrespective of severity of initial infection,” Townsend said. “It is not possible to predict who will have ongoing symptoms.”

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