Monaz: Hello, I'm Monaz Mehta, editor in the Cochrane Editorial and Methods department. We're producing a series of reviews covering the accumulating evidence on COVID-19, which are not only looking at the diagnosis and treatment of the disease but are also examining its links to other conditions. One of these reviews, on the effects of COVID-19 on cardiovascular health, was published in March 2021. In this podcast, co-author Keng Siang Lee, from the University of Bristol speaks with the first author, Pierpaolo Pellicori from the University of Glasgow in the UK about the findings.

Keng: Hello Pierpaolo, perhaps you could begin by telling us why you wanted to do this review?

Pierpaolo: Hello Keng and thanks for the opportunity to talk about our findings. Our starting point was that although many people with COVID-19 have few or no symptoms, it can make their blood 'sticky' and cause problems with their heart or blood vessels. In some patients, this has led to a heart attack or blood clots in the legs or lungs, which can be fatal.

Keng: So, what did you hope to find out?

Pierpaolo: We set out to answer two main questions: what are the most common pre-existing cardiovascular problems (for example, diabetes, high blood pressure and obesity) in patients with COVID-19, and what are the most common cardiovascular problems that might complicate a COVID-19 infection, such as irregular heart beat, blood clots, heart failure or stroke.

Keng: Those sound like really high priority questions for large numbers of people. Did you find the evidence to answer them?

Pierpaolo: Yes, we actually found a vast amount of evidence, with more than 200 studies published up to July 2020 that reported relevant information.
Bringing these together showed that high blood pressure, diabetes and heart disease are very common in people hospitalised with COVID-19 and are associated with an increased risk of death. For example, more than a third of patients with COVID-19 had a history of high blood pressure and about one in every five had diabetes or obesity. We also found that about one in ten of those hospitalised with COVID-19 had an irregular heart beat or coronary heart disease, about one in twenty had had a stroke and a similar proportion had heart failure.

Keng: What about those without a pre-existing condition? What types of cardiovascular problem did they develop?

Pierpaolo: The most common new cardiovascular complication after a COVID-19 infection was an irregular heartbeat or arrhythmia, especially atrial fibrillation, which developed in more than 8% of hospitalised cases. Blood clots in the legs or lungs, or heart failure, were also common, and developed in more than one in twenty patients admitted to hospital. Heart attacks and strokes were less common, but still affected up to 2% of cases.

Keng: Those are important findings. Are doctors already aware of them?

Pierpaolo: Although we expect that many doctors are aware of the risk of blood clots in patients with COVID-19, this review is particularly important because they may not know about the risk of developing atrial fibrillation or heart failure. Added to this, although heart failure may be difficult to diagnose in a patient with COVID-19, it's important that doctors are aware of the need to look for it so that they don't miss this treatable diagnosis. 

Keng: It's clear that this review will help raise that awareness, but is there still work to do? What are your future plans for the review?

Pierpaolo: The first thing to note is that most of the studies focused on people in hospital who had severe COVID-19, which means that we can't be sure if the results apply to people with milder COVID-19 who were not hospitalized. So, we need more research in those people. We also found that these studies from the first half of 2020 were very different from each other and did not always report their results in a standard way or use the most reliable methods. With that in mind, when we update the review with more recent studies. we'll focus only on the higher-quality evidence to increase the strength of our findings. 

Keng: As you're working on that update, does the review also have implications for the treatment of patients with COVID-19?

Pierpaolo: Yes, one of the take-home messages from the review is that the results suggest a need for trials of additional treatment targets for patients with COVID-19, such as atrial fibrillation and heart failure.

Keng: Thanks again Pierpaolo, and to finish, if people would like to read the review, how they can get hold of a copy?

Pierpaolo: Thanks Keng. The review is available in full online at Cochrane Library dot com. If people go to the website and simply type the two words 'COVID-19' and 'cardiovascular' into the search box, they'll find it.