Since some of the first studies that looked at outcomes in people who developed COVID-19, it has been clear that the viral infection is linked to a higher risk for a number of poor outcomes, including heart attack or stroke. But it wasn’t immediately clear to what degree this higher risk was based on the profile of people who tended to develop COVID-19 or its complications. For example, it’s well known that having diabetes raises the risk of developing severe COVID-19, and diabetes is also linked to an increased risk for heart attack and stroke. So for the latest study, researchers were interested in looking separately at the effect of having COVID-19 to the greatest extent possible.
The researchers set out to look at the independent effect of COVID-19 on cardiovascular events by analyzing all known COVID-19 cases in Sweden between February 1 and September 14, 2020. This ended up being a total of 86,742 people who developed COVID-19, and the study also included a matched group — meaning the participants had broadly similar traits — of 348,481 people who didn’t develop COVID-19. This allowed the researchers to compare heart attack and stroke outcomes between the two groups during the same time period. They also performed an analysis only of people who experienced a heart attack or stroke, looking at how these events lined up with a diagnosis of COVID-19.
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As described in a Healio article on the study, the median age of both groups — those with COVID-19 and the matched group — was 48, and the groups were also evenly matched in the ratio of women to men (57% women) and the balance of where in Sweden people lived.
COVID-19 diagnosis linked to increased risk of heart attack and stroke
In their first analysis, the researchers looked only at people who had a heart attack or stroke. They found that when heart attacks and strokes on the day COVID-19 was identified were excluded — this was done because it appears that many people may have tested positive for COVID-19 because they were hospitalized for a heart attack or stroke — a diagnosis of COVID-19 still increased the risk for heart attack and stroke in the following days and weeks. Heart attack risk was 2.89 times as high during the first week after COVID-19 diagnosis, 2.53 times as high during the second week, and 1.60 times as high during the third and fourth weeks. Ischemic stroke (stroke caused by a blood vessel blockage) risk was 2.97 times as high during the first week, 2.80 times as high during the second week, and 2.10 times as high during the third and fourth weeks.
When comparing people who developed COVID-19 with those in the matched group who didn’t, the results were even more dramatic. People with COVID-19 were 3.41 times as likely to have a heart attack and 3.63 times as likely to have a stroke during the two weeks following their COVID-19 diagnosis, excluding the first day.
The researchers concluded that heart attack and stroke are two clinical outcomes linked to COVID-19, along with all of the other known effects of developing the viral infection. This finding, they wrote, highlights the need for continued and widespread vaccination against COVID-19 to reduce the burden of these serious cardiovascular events.
Want to learn more about coronavirus and diabetes? Read our latest COVID-19 updates.