Since early 2020, it was clear that COVID-19 causes a myriad of cardiovascular problems, including blood clots, heart failure, heart inflammation, and more.

A new study assessed the cardiovascular outcomes for recovered COVID-19 patients, one year after their recovery from the initial infection. The study, which analyzed over 11 million US veterans' health records, found that the risk of 20 different cardiovascular problems was "substantial" in those who had COVID-19 one year earlier, compared to those who were not infected with the virus.

The study, published in Nature Medicine earlier this week, also showed that this risk remained constant for every outcome, even for those who were not hospitalized.

"Beyond the first 30 days after infection, individuals with COVID-19 are at increased risk of incident cardiovascular disease spanning several categories, including cerebrovascular disorders, dysrhythmias, ischemic and non-ischemic heart disease, pericarditis, myocarditis, heart failure and thromboembolic disease," the study said.

"These risks and burdens were evident even among individuals who were not hospitalized during the acute phase of the infection and increased in a graded fashion according to the care setting during the acute phase (non-hospitalized, hospitalized and admitted to intensive care). Our results provide evidence that the risk and 1-year burden of cardiovascular disease in survivors of acute COVID-19 are substantial."

The research analyzed electronic health records in the US, at the Department of Veterans Affairs (VA). It included nearly 154,000 people who contracted COVID-19 between March 2020 and January 2021, and who survived at least 30 days after becoming infected. It also included, as control groups, 5,637,647 people who sought VA care during the pandemic but were not diagnosed with COVID-19, and 5,859,411 people who sought VA care in 2017.

To ensure that the results would reflect only COVID-19, and not a vaccine, the study excluded anyone who had received a COVID-19 vaccine.

"The results suggested that COVID-19 was associated with increased risk of myocarditis and pericarditis in both analyses," the authors wrote.

Eric Topol, a cardiologist at Scripps Research, told Science that the results are "stunning" and "worse" than expected.

"All of these are very serious disorders," Science quoted Topol as saying. "If anybody ever thought that COVID was like the flu this should be one of the most powerful data sets to point out it’s not."

He added that the new study "may be the most impressive Long Covid paper we have seen to date."

In an e-mail to Nature, Hossein Ardehali, a cardiologist at Northwestern University in Chicago, Illinois, wrote: "I am actually surprised by these findings that cardiovascular complications of COVID can last so long." He added that because severe disease increased the risk of complications much more than mild disease, "it is important that those who are not vaccinated get their vaccine immediately."

"In the post-COVID era, COVID might become the highest risk factor for cardiovascular outcomes," Larisa Tereshchenko, a cardiologist and biostatistician at the Cleveland Clinic, told Science. Tereshchenko, who recently conducted a similar but smaller analysis, emphasized that the new study will need to be repliacted, and that it was retrospective.

"It looked back. We have to do prospective studies to calculate accurate estimates," she explained.

Senior study author Ziyad Al-Aly, a clinical epidemiologist at Washington University in St. Louis and chief of research at the VA St Louis Health Care system, told Science, "This is clearly evidence of long-term heart and vascular damage. Similar things could be happening in the brain and other organs resulting in symptoms characteristic of Long Covid, including brain fog."

Nature quoted Al-Aly as warning, "We collectively dropped the ball on COVID. And I feel we’re about to drop the ball on long COVID."

Though the study was the largest to date, it included a rather homogenous group of veterans: 90% of patients were men, and 71-76% were white. On average, the patients were in their early 60s, Science added.

But Al-Aly said the study controlled for this bias, emphasizing to Science, "COVID is an equal opportunity offender. We found an increased risk of cardiovascular problems in old people and in young people, in people with diabetes and without diabetes, in people with obesity and people without obesity, in people who smoked and who never smoked."

"What really worries me is that some of these conditions are chronic conditions that will literally scar people for a lifetime. It’s not like you wake up tomorrow and suddenly no longer have heart failure," he added.

Meanwhile, the study's authors warned, "Governments and health systems around the world should be prepared to deal with the likely significant contribution of the COVID-19 pandemic to a rise in the burden of cardiovascular diseases."