(CNN) As the Covid-19 pandemic enters its third year, scientists are finding that the coronavirus has far-reaching effects on health beyond the acute phase of illness. One recent study has found that people with Covid-19 are at an increased risk for cardiovascular diseases for at least a year after recovery.
The study, published this month in the journal Nature Medicine, used data from US Department of Veterans Affairs national health care databases to follow over 153,000 veterans with a history of Covid-19 infection for up to a year after their recovery.
Compared with those who were never infected, people who had a coronavirus infection were more likely to have symptoms including inflammatory heart disease, heart failure, dysrhythmia, heart attacks, strokes and clotting in the long term. People with prior Covid-19 infections were more than 60% more likely to develop any cardiac issue. Many of these conditions, such as pulmonary embolisms, are life-threatening.
"One thing that was sobering was that the risk was evident even in people who had very mild disease or did not need hospitalization," said lead researcher Dr. Ziyad Al-Aly, chief of research and development at the VA St. Louis Health Care System.
As disease severity increased, so did the risk of cardiovascular complications in the long run. People who had been treated in an ICU had the highest risk for cardiovascular disease after recovery. For example, people who weren't hospitalized were twice as likely to have a pulmonary embolism than people who had not had Covid-19, and those treated in the ICU were more than 21 times more likely to have one.
This risk for problems was also found across all ages, sexes, races and cardiac risk factors such as smoking, high blood pressure and obesity.
People with a history of Covid-19 infection were more than five times more likely to develop myocarditis -- inflammation of the heart muscle -- a year later. Although studies have shown that myocarditis may be a rare reaction to an mRNA vaccine, this research found that risk of myocarditis from Covid-19 infection was evident regardless of vaccination status.
Although the study had a robust sample size, most of the people in the research were White men. In addition, because the study enrollment period ended on January 15, 2021, before Covid-19 vaccinations were widely available, almost none of the participants was vaccinated before infection.
According to Al-Aly, dysrhythmias, such as atrial fibrillation, were the most common cardiac issues after infection.
"In my own practice, I was more likely to see people who had more of the arrhythmias or report a rapid heartbeat after the Covid infection. Many times, over several months, the heart rate came down and improved," Dr. Nieca Goldberg, an NYU Langone cardiologist and the medical director of Atria New York City, told CNN. She was not involved in the new study.
According to Goldberg, people who've had Covid-19 and other viral infections can develop a condition called postural orthostatic tachycardia syndrome, or POTS, in which someone's heart rate spikes when they stand up. With proper hydration, these symptoms will usually improve on their own. Some people who continued to have symptoms required treatment with medications, Goldberg said.
Still, "those viral infections didn't have the magnitude of disease that we're seeing in Covid-19," she added.
Goldberg also said that although cardiac complications from Covid-19 would be expected in people who have certain risk factors, she is surprised that the study demonstrated long-term complications even in people with no history of cardiac disease.
"I think this issue of these people being otherwise at low risk, except that they had Covid-19, is an area that should really be explored," she said.
Al-Aly says the findings should change the way we think about Covid-19 and heart health.
"Physicians need to understand that Covid-19 is now a cardiovascular risk factor, like we talk about diabetes and high blood pressure and cholesterol as a risk factor for heart problems," he said.
It is still unclear why Covid-19, a respiratory virus, can have such crucial effects on the cardiovascular system. According to Al-Aly, one theory involves how the receptor the virus uses to enter cells is also commonly found in cells in the heart. The Covid-19 spike protein thus acts as a "key to people's heart" and can lead to damage, he said.
The findings add to a growing list of potential lingering consequences from Covid-19 infection, called long Covid.
"The numbers that our study suggests is that there are likely to be millions of people in the US who now have heart problems or will have heart problems in the near future. ... And I think, as a nation, we are not paying enough attention to the aftermath of the Covid-19 pandemic," Al-Aly said. "We decided to bury our head in the sand and forget that this Covid-19 pandemic and Covid-19 itself can have long-term lasting effects," especially as the national conversation has shifted toward lifting mask mandates and other preventive measures.
Coronavirus infections themselves are already testing the limits of the US health care system, and there is concern for how prepared the nation is to treat the long-term disease burden.
"Our health care system, in many ways, was already overburdened prior to the pandemic -- in particular with regard to care for those people who are the most vulnerable and who face the greatest barriers to care. I would hate to see these inequities perpetuated when it comes to treatment of long-term consequences, too," said Dr. Leana Wen, a CNN medical analyst and a professor of health policy and management at the George Washington University Milken Institute School of Public Health.
As physicians and patients alike grapple with the unknowns of long Covid, there is one clear preventative measure to address the issue: vaccines.
"Simply saying that you don't want to get Covid because you might become severely ill in the short term is not the full answer," said Wen, who is also an emergency physician. "Because there may be people who don't become severely ill enough to be hospitalized immediately but may have multiple consequences. Again, that underscores the need for vaccination in order to reduce the chance of acquiring Covid in the first place."
Experts advise anyone who's had a Covid-19 infection to take any unexplained cardiovascular symptoms seriously and seek help right away.
Though this study focuses on the impact of Covid-19 to the cardiovascular system, other organ systems are probably affected as well. The researchers are planning to look into the effects this virus can have on diabetes and the nervous system.