The study examined cardiac MRI scans in 31 patients before and after having COVID-19 infection and found no new evidence of myocardial injury in the post-COVID scans relative to the pre-COVID scans.
“To the best of our knowledge this is the first cardiac MRI study to assess myocardial injury pre- and post-COVID-19,” the authors stated.
They say that while this study cannot rule out the possibility of rare events of COVID-19–induced myocardial injury, “the complete absence of de novo late gadolinium enhancement lesions after COVID-19 in this cohort indicates that outside special circumstances, COVID-19–induced myocardial injury may be much less common than suggested by previous studies.”
The study was published online in JACC: Cardiovascular Imaging.
Coauthor Till F. Althoff, MD, Cardiovascular Institute, Clínic–University Hospital Barcelona, said in an interview that previous reports have found a high rate of cardiac lesions in patients undergoing imaging after having had COVID-19 infection.
“In some reports, this has been as high as 80% of patients even though they have not had severe COVID disease. These reports have been interpreted as showing the majority of patients have some COVID-induced cardiac damage, which is an alarming message,” he commented.
However, he pointed out that the patients in these reports did not undergo a cardiac MRI scan before they had COVID-19 so it wasn’t known whether these cardiac lesions were present before infection or not.
To try and gain more accurate information, the current study examined cardiac MRI scans in the same patients before and after they had COVID-19.
The researchers, from an arrhythmia unit, made use of the fact that all their patients have cardiac MRI data, so they used their large registry of patients in whom cardiac MRI had been performed, and cross referenced this to a health care database to identify those patients who had confirmed COVID-19 after they obtaining a cardiac scan at the arrhythmia unit. They then conducted another cardiac MRI scan in the 31 patients identified a median of 5 months after their COVID-19 infection.
“These 31 patients had a cardiac MRI scan pre-COVID and post COVID using exactly the same scanner with identical sequences, so the scans were absolutely comparable,” Dr. Althoff noted.
Of these 31 patients, 7 had been hospitalized at the time of acute presentation with COVID-19, of whom 2 required intensive care. Most patients (29) had been symptomatic, but none reported cardiac symptoms.
Results showed that, on the post–COVID-19 scan, late gadolinium enhancement lesions indicative of residual myocardial injury were encountered in 15 of the 31 patients (48%), which the researchers said is in line with previous reports.
However, intraindividual comparison with the pre–COVID-19 cardiac MRI scans showed all these lesions were preexisting with identical localization, pattern, and transmural distribution, and thus not COVID-19 related.
Quantitative analyses, performed independently, detected no increase in the size of individual lesions nor in the global left ventricular late gadolinium enhancement extent.
Comparison of pre- and post COVID-19 imaging sequences did not show any differences in ventricular functional or structural parameters.
“While this study only has 31 patients, the fact that we are conducting intra-individual comparisons, which rules out bias, means that we don’t need a large number of patients for reliable results,” Dr. Althoff said.
“These types of lesions are normal to see. We know that individuals without cardiac disease have these types of lesions, and they are not necessarily an indication of any specific pathology. I was kind of surprised by the interpretation of previous data, which is why we did the current study,” he added.
Dr. Althoff acknowledged that some cardiac injury may have been seen if much larger numbers of patients had been included. “But I think we can say from this data that COVID-induced cardiac damage is much less of an issue than we may have previously thought,” he added.
He also noted that most of the patients in this study had mild COVID-19, so the results cannot be extrapolated to severe COVID-19 infection.
However, Dr. Althoff pointed out that all the patients already had atrial fibrillation, so would have been at higher risk of cardiac injury from COVID-19.
“These patients had preexisting cardiac risk factors, and thus they would have been more susceptible to both a more severe course of COVID and an increased risk of myocardial damage due to COVID. The fact that we don’t find any myocardial injury due to COVID in this group is even more reassuring. The general population will be at even lower risk,” he commented.
“I think we can say that, in COVID patients who do not have any cardiac symptoms, our study suggests that the incidence of cardiac injury is very low,” Dr. Althoff said.
“Even in patients with severe COVID and myocardial involvement reflected by increased troponin levels, I wouldn’t be sure that they have any residual cardiac injury. While it has been reported that cardiac lesions have been found in such patients, pre-COVID MRI scans were not available so we don’t know if they were there before,” he added.
“We do not know the true incidence of cardiac injury after COVID, but I think we can say from this data that it is definitely not anywhere near the 40%-50% or even greater that some of the previous reports have suggested,” he stated.
Dr. Althoff suggested that, based on these data, some of the recommendations based on previous reports such the need for follow-up cardiac scans and caution about partaking in sports again after COVID-19 infection, are probably not necessary.
“Our data suggest that these concerns are unfounded, and we need to step back a bit and stop alarming patients about the risk of cardiac damage after COVID,” he said. “Yes, if patients have cardiac symptoms during or after COVID infection they should get checked out, but I do not think we need to do a cardiac risk assessment in patients without cardiac symptoms in COVID.”
This work is supported in part by grants from Instituto de Salud Carlos III, the Spanish government, Madrid, and Fundació la Marató de TV3 in Catalonia. Dr. Althoff has received research grants for investigator-initiated trials from Biosense Webster.
A version of this article first appeared on Medscape.com.