In December 2020, a week before cardiologist Stuart Katz was scheduled to receive his first COVID-19 vaccine, he came down with a fever. He spent the next two weeks wracked with a cough, body aches and chills. After months of helping others to weather the pandemic, Katz, who works at New York University, was having his own first-hand experience of COVID-19.
On Christmas Day, Katz’s acute illness finally subsided. But many symptoms lingered, including some related to the organ he’s built his career around: the heart. Walking up two flights of stairs would leave him breathless, with his heart racing at 120 beats per minute. Over the next several months, he began to feel better, and he’s now back to his normal routine of walking and cycling. But reports about COVID-19’s effects on the cardiovascular system have made him concerned about his long-term health. “I say to myself, ‘Well, is it really over?’” Katz says.
In one study1 this year, researchers used records from the US Department of Veterans Affairs (VA) to estimate how often COVID-19 leads to cardiovascular problems. They found that people who had had the disease faced substantially increased risks for 20 cardiovascular conditions — including potentially catastrophic problems such as heart attacks and strokes — in the year after infection with the coronavirus SARS-CoV-2. Researchers say that these complications can happen even in people who seem to have completely recovered from a mild infection.
studies have mirrored these findings, but others find lower rates of complications. With millions or perhaps even billions of people having been infected with SARS-CoV-2, clinicians are wondering whether the pandemic will be followed by a cardiovascular aftershock. Meanwhile, researchers are trying to understand who is most at risk of these heart-related problems, how long the risk persists and what causes these symptoms.
It’s a gaping hole in an important area of public health, says Katz. “We don’t understand if this changes the lifelong trajectory for risk of a heart attack or stroke or other cardiac events — we just don’t know that.” Here, Nature looks at the questions that scientists are asking and the answers they’ve uncovered so far.
How many people are at risk?
Doctors have reported cardiovascular problems related to COVID-19 throughout the pandemic, but concerns over this issue surged after the results of the VA study came out earlier this year. The analysis by Ziyad Al-Aly, an epidemiologist at Washington University in St. Louis, Missouri, and his colleagues is one of the most extensive efforts to characterize what happens to the heart and circulatory system after the acute phase of COVID-19. The researchers compared more than 150,000 veterans who had recovered from acute COVID-19 with their uninfected peers, as well as with a pre-pandemic control group1.
People who had been admitted to intensive care with acute infections had a drastically higher risk of cardiovascular problems during the next year (see ‘Cardiac concerns’). For some conditions, such as swelling of the heart and blood clots in the lungs, the risk shot up at least 20-fold compared with that in uninfected peers. But even people who had not been hospitalized had increased risks of many conditions, ranging from an 8% increase in the rate of heart attacks to a 247% increase in the rate of heart inflammation.