Solving the Link Between COVID-19 and Cardiac Impact

From Wuhan, the initial epicenter of the coronavirus pandemic, a strong association was reported between preexisting heart ailments and how well patients fared when infected by COVID-19. Indeed, half of those who died had a cardiovascular condition, with hypertension (high blood pressure) being the most common finding (30%).[1]

As the epidemic left China and began to cross the globe, the reasons for this association were rapidly investigated yielding some interesting preliminary results. It seems not only do patients with a cardiovascular condition fare worse but they may be more susceptible to infection by COVID-19.[2, 3] Furthermore, there is stronger evidence that, after passing through the lungs, the virus ends up directly attacking the heart.[4-6]

In addition to research as to how the virus damages the heart, clinical trials have also started to evaluate possible therapeutic answers. One example of this is the use of hydroxychloroquine or chloroquine administered in high doses with azithromycin. On Friday (April 24th, 2020), the FDA issued a caution against use of these for COVID-19 “outside of the hospital setting or a clinical trial due to risk of heart rhythm problems. Close supervision is strongly recommended.”

GE Healthcare Insights sat down with Paul A. Friedman, M.D., chair of Cardiovascular Medicine at Mayo Clinic, to gain a better understanding of these findings.


Q: How can a clinician gain insight into a COVID-19 patient’s health based on their symptoms?

Paul A. Friedman, M.D.: Most people who get COVID-19 will present with respiratory symptoms, such as a cough or shortness of breath, but there are a minority that will present with symptoms that may mimic a heart attack.

So, if a person presents with symptoms involving the heart, the clinician would likely order an ECG, or a recording of the heart’s electrical activity, because an ECG is fairly easy to do, quick and doesn’t require highly specialized training, yet it reveals a lot of information about the heart. It can tell us if the person is having a heart attack, if there’s a blocked artery or if there’s a heart rhythm disorder. 

There is also another reason to take the ECG and that is to record the QT interval.


Q: What is the QT interval and why is it important?

Paul A. Friedman, M.D.: The QT interval is a feature of the ECG related to how long it takes for the heart to recharge.  In other words, it measures how long it takes for the heart to get electrically ready for the next discharge and contraction. As the QT interval gets longer - let’s say in excess of a half a second - it sets up an environment where the heart can become electrically unstable. This can lead to the heart no longer contracting properly.  Instead, the heart quivers. This can lead to sudden death, cardiac arrest.


Q: Why is the QT interval important in COVID-19 patients?

Paul A. Friedman, M.D.:  There are two reasons for this. Some of the drugs we may use for helping COVID-19 patients can prolong the QT interval. It has also been found that COVID-19 patients tend to have a longer QT than those who don’t have the disease.


Q: Which drugs used to treat COVID-19 patients can potentially impact the heart?

Paul A. Friedman, M.D.:  A small population could be harmed by specific medications used in the treatment of COVID-19, including hydroxychloroquine and Zithromax – or azithromycin -- because those drugs have shown to  prolong the QT interval. These medicines have been used effectively to fight other viruses, but there are still a number of clinical trials being performed to determine which medicines are the best for COVID-19.

So, ECG can play a highly valuable role in identifying a small group of people at risk for serious problems. In the majority of people, these drugs are likely safe to use.


Q: Recently the FDA issued a caution about the use of these drugs.  How is that going to change things at the Mayo Clinic?

Paul A. Friedman, M.D.:  For Mayo, it changes nothing. We have always used the ECG to check the QT interval before using drugs known to prolong the QT and cause Torsade de Pointes, an arrhythmia that can kill.

Look. The FDA didn’t say don’t use these drugs. It said be smart about it. Measure the QT interval before using them and after they are administered to see if there is a significant change. Also, due to the risk of arrhythmias, the FDA recommended the use of this therapy in a hospital setting or a clinical trial.



  1. Zhou, F., et al., Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet, 2020. 395(10229): p. 1054-1062.
  2. Fang, L., G. Karakiulakis, and M. Roth, Are patients with hypertension and diabetes mellitus at increased risk for COVID-19 infection? The Lancet Respiratory Medicine, 2020. 8(4): p. e21.
  3. Driggin, E., et al., Cardiovascular Considerations for Patients, Health Care Workers, and Health Systems During the Coronavirus Disease 2019 (COVID-19) Pandemic. Journal of the American College of Cardiology, 2020: p. 27204.
  4. Shi, S., et al., Association of Cardiac Injury With Mortality in Hospitalized Patients With COVID-19 in Wuhan, China. JAMA Cardiology, 2020.
  5. Fox, S.E., et al., Pulmonary and Cardiac Pathology in Covid-19: The First Autopsy Series from New Orleans. medRxiv, 2020: p. 2020.04.06.20050575.
  6. Bansal, M., Cardiovascular disease and COVID-19. Diabetes Metab Syndr, 2020. 14(3): p. 247-250.