Heart problems like myocardial infarction and heart failure are among the most concerning complications of SARS-CoV-2, the virus that causes COVID-19. Few follow-up studies have been done to determine the short- and long-term risk of cardiovascular disease in patients during infection and after their recovery. Most of the studies have had a relatively short follow-up period of about three months, a small sample size or were limited to hospitalized patients with severe COVID-19.

Researchers led by a team from the University of Hong Kong followed more than 7,500 patients who tested positive for SARS-CoV-2 for up to 18 months. They found people infected with the virus were 81 times more likely to die in the acute phase of infection (up to 21 days after testing positive for the virus) than those who were uninfected and about five times more likely during the post-acute phase (22 days to 18 months after a positive test).

“COVID-19 patients were more likely to develop numerous cardiovascular conditions compared to the uninfected, which may have increased their risk of death,” researcher Ian C.K. Wong explained. The findings suggest that ongoing monitoring for at least a year after recovery is needed to accurately diagnose the cardiovascular complications that are part of long COVID, he added.

Patients were enrolled in the U.K. Biobank database. Those who were infected were matched with a contemporary control group who tested negative for the virus between mid-March 2020 and August 31, 2021, and an historical control from prior to the pandemic. Each control group had more than 70,000 participants who were demographically similar to the infected group.

Ongoing monitoring for at least a year after recovery is needed to accurately diagnose the cardiovascular complications that are part of long COVID.

“The historical control was included to rule out the effect of routine healthcare services being reduced or cancelled during the pandemic,” when pandemic-related disruptions in healthcare increased morbidity and mortality risk, even in the uninfected, Wong, a professor at the University of Hong Kong, explained.

The infected group was about four times more likely than the uninfected control groups to develop major cardiovascular disease (a composite of stroke, heart failure and coronary heart disease) in the acute phase of infection and about 50 percent more likely in the post-acute phase. Those with severe COVID-19 had a greater risk of major cardiovascular disease and death than those with less severe disease.

During the acute and non-acute phase, those in the infected group had a greater risk of cardiovascular conditions including myocardial infarction, heart failure, coronary heart disease and deep vein thrombosis than the uninfected controls. The risk of certain cardiovascular conditions, such as atrial fibrillation and stroke, was greater in those who were infected during the acute phase, but decreased over time.

The study was done during the first wave of the pandemic, between mid-March 2020 and November 30, 2020. Wong hopes future studies will look at the association between cardiovascular disease risk and SARS-CoV-2 infections during subsequent outbreaks. Since the findings of previous studies suggest that vaccination against SARS-CoV-2 may prevent complications, he believes. “More studies are needed to compare the vaccines’ effectiveness at reducing the risk of cardiovascular disease and death following SARS-CoV-2 infection in the vaccinated and the unvaccinated.”

The study is published in Cardiovascular Research.