In what researchers are calling “particularly relevant to long-haul COVID-19,” a new study demonstrates that people with prior COVID-19 infection and cardiovascular risk factors have a significantly higher risk of low myocardial flow reserve (MFR).

Comparing 101 patients with prior COVID-19 infection to 292 control patients, the study authors assessed myocardial perfusion at rest and peak hyperemia via positron emission tomography (PET). The study population had a high prevalence of cardiovascular risk factors such as diabetes (43 percent), hypertension (61 percent) and obesity (55 percent), but the authors noted the percentages of these conditions were similar between the two study groups.

Fifty-eight percent of patients with prior COVID-19 infection had a reduced global MFR in comparison to 28 percent of the control patients, according to the study, which was recently published in JACC: Cardiovascular Imaging.

Noting that the higher rates of reduced MFR are likely due to exacerbation of preexisting endothelial dysfunction or new onset endothelial injury, the study authors suggest the findings are “particularly relevant to long-haul COVID-19.”

“ … Persistence of the acute endotheliopathy and inflammation can hypothetically lead to endothelial dysfunction and potentially explain long-haul COVID-19 cardiopulmonary symptoms,” wrote Mouaz H. Al-Mallah, M.D., MSc, the director of Cardiovascular PET at Houston Methodist DeBakey Heart and Vascular Center, and colleagues.

After adjustments for matching variables and subsequent sensitivity analyses, including one of patients with diabetes, the study authors found a higher likelihood of MFR < 2 and normalized MFR < 2 in patients with past COVID-19 infection. A median follow-up period of 323 days revealed higher annualized cardiovascular event rates among patients with past COVID-19 infection and those with MFR < 2, according to the study.

“Our analysis suggests that patients with prior COVID-19 infection have higher rates of reduced MFR … and that reduced MFR is a marker of a poor prognosis,” noted Al-Mallah and colleagues.

Maintaining that future research is necessary to corroborate the study findings, the researchers said study limitations included the use of chart review to assess follow-up and the data coming from a single institution. They also acknowledged a high prevalence of cardiovascular risk factors in their study population.