COVID-19 and its cardiovascular effects: a systematic review of prevalence studies

Drawing of a human torso with a beating heart with an image overlay of covid virus particle

In this short interview, Prof. John GF Cleland, senior author of this recently published Cochrane review, tells us about what this review found regarding the type of heart and blood vessel problems that complicate COVID-19 infections.

Tell us about this review.

This review first  focuses on cardiovascular problems pre-existing the development of COVID, usually in cases that were severe enough to require hospitalization. We know that older people are more likely to have cardiovascular disease and to be admitted with severe COVID. We are only looking at associations. It is unclear whether cardiovascular disease or age was the key driving factor, because the two problems are so interconnected. It is possible that after adjusting for age, cardiovascular problems are similarly common in people with and without COVID.

The review then goes on to assess the risk of cardiovascular complications, highlighting which are the most common (unexpectedly, this was atrial fibrillation). The review does not investigate which treatments might effectively reduce the risk of cardiovascular complications.

What bought brought you to this topic?

The Cochrane Team put out a request to the British Heart Foundation Clinical Research Collaboration for help with reviewing the risk factors associated with developing or being hospitalized with COVID, and the consequences of hospitalization. We answered that call. We knew that many people infected by COVID-19 have few or no symptoms. However, COVID-19 can make the blood ‘sticky’, clogging up both small blood vessels (capillaries) and large ones, which may cause heart attacks, strokes or blood clots in the legs or lungs. These can be fatal. We wanted to find out, in cases of confirmed or suspected COVID-19:

  • what are the most common pre-existing heart and blood vessel (cardiovascular) problems (for example, diabetes, high blood pressure and obesity); and
  • what are the most common complications affecting the heart and blood vessels (for example, irregular heartbeat, blood clots, heart failure and stroke)  in different setting (in the community, care homes or in hospital).

What can the evidence tell us?

We found 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. More than one-third of patients with COVID-19 had a history of high blood pressure and about one in every five had diabetes or were obese. Many had all three of these problems. Many people also had more advanced disease including an irregular heart beat or coronary heart disease (both about one in ten), stroke or heart failure (both about one in twenty). 

The most common new complication (in addition to pre-existing problems) after being hospitalized with COVID-19 is an irregular heartbeat (atrial fibrillation; 8.5%). Blood clots in the legs (6.1%) or lungs (4.3%), and heart failure (6.8%) were also common, but the reported rates may be underestimated because the studies did not always carry out appropriate investigations. Heart attacks (1.7%) and strokes (1.2%) were reported less often. Blood tests also often suggested heart damage or stress.

These results show what the clinical teams looking after patients with COVID should watch out for. Clinical teams are already aware of the risk of blood clots but may be less aware of the risk of developing atrial fibrillation or heart failure. Also, heart failure may be difficult to diagnose in a patient with COVID, so great care and attention is required not to miss this treatable diagnosis. 

What’s next?

The studies focused on people in hospital, with severe COVID-19, so the results do not apply to people who had milder COVID-19 who were not hospitalized. The studies were very different from each other and did not always report the results in the same way or use the most reliable methods. Older patients are at greater risk of having pre-existing problems, being hospitalized with COVID and having severe complications. This needs to be taken into account when assessing the risks. Accordingly, some uncertainty exists about how to apply our results to new patients with COVID. Analysis including more high-quality studies will increase the precision of risk-estimates overall, for specific subgroups (eg: older patients) and specific settings (eg: severe COVID managed in hospital compared to milder cases managed in the community). Our results also suggest additional potential therapeutic targets, such as atrial fibrillation and heart failure, that have not been the focus of trials so far.

We plan to update this review. However, in future, we will focus only on higher-quality evidence to increase the strength of our findings.  

We also plan to compare the risk of cardiovascular complications with COVID-19 with that observed in large series of other severe respiratory infections in hospitalised patients.

Thursday, March 11, 2021