Viral presence without myocarditis
The accompanying report featured a postmortem analysis of hearts from 39 patients with mostly severe COVID-19 that pointed to a significant SARS-CoV-2 presence and signs that the virus vigorously replicated in the myocardium.
But there was no evidence that the infection led to fulminant myocarditis. Rather, the virus had apparently infiltrated the heart by localizing in interstitial cells or in macrophages that took up in the myocardium without actually entering myocytes, concluded the report’s authors, led by Diana Lindner, PhD, from the University Heart and Vascular Centre, Hamburg (Germany).
The findings suggest “that the presence of SARS-CoV-2 in cardiac tissue does not necessarily cause an inflammatory reaction consistent with clinical myocarditis,” the group wrote.
Previously in the literature, in “cases in which myocardial inflammation was present, there was also evidence of clinical myocarditis, and therefore the current cases underlie a different pathophysiology,” they concluded.
No evidence of the virus was seen in 15 cases, about 61% of the group. In 16 of the remaining 24 hearts, the viral load exceeded 1,000 copies per mcg of RNA, a substantial presence. Those 16 showed increased expression of inflammatory cytokines but no inflammatory cell infiltrates or changes in leukocyte counts, the researchers noted.
“Findings of suggested viral replication in the cases with a very high viral load are showing that we need to do more studies to find out long-term consequences, which we do not know right now,” senior author Dirk Westermann, MD, also from the University Heart and Vascular Centre, Hamburg, said.
Implications for heart failure
The postmortem findings from Dr. Lindner and associates “provide intriguing evidence that COVID-19 is associated with at least some component of myocardial injury, perhaps as the result of direct viral infection of the heart,” wrote Clyde W. Yancy, MD, MSc, from Northwestern University, Chicago, and Gregg C. Fonarow, MD, from the University of California, Los Angeles, in an editorial accompanying both reports.
The CMR study from Dr. Püntmann and colleagues – on the backdrop of earlier COVID-19 observations – suggests the potential for “residual left ventricular dysfunction and ongoing inflammation” in the months following a COVID-19 diagnosis. Both developments may be “of sufficient concern to represent a nidus for new-onset heart failure and other cardiovascular complications,” contend Dr. Yancy and Dr. Fonarow.
“When added to the postmortem pathological findings from Lindner et al, we see the plot thickening and we are inclined to raise a new and very evident concern that cardiomyopathy and heart failure related to COVID-19 may potentially evolve as the natural history of this infection becomes clearer,” they wrote.
Some patients, having recovered from the acute illness, may be left with a chronic inflammatory state that probably puts them at increased risk for future heart failure, agreed Dr. Bozkurt when interviewed. “They could show further decline in cardiac function, and their recovery might take longer than with the usual viral illnesses that we see,” she said.
“There could also be a risk of sudden death. Inflammation sometimes gives rise to sudden death and ventricular arrhythmia, which I would be very worried about, especially if the myocardium is stressed,” Dr. Bozkurt said. “So competitive sports in those patients potentially could be risky.”