PET imaging helps assess coronary microvascular dysfunction in long COVID patients
Some patients who had COVID-19 end up with long-term, chronic symptoms such as chest pain, palpitations and shortness or breath that remain unexplained. Researchers at Houston Methodist DeBakey Heart and Vascular Center used positron emission tomography (PET) nuclear perfusion imaging to see if the cause might be coronary microvascular dysfunction, publishing their findings in the European Heart Journal - Cardiovascular Imaging earlier this year.[1]
The study identified a prevalence of impaired myocardial flow reserve (MFR), which can show issues with microvascular circulation in PET imaging. The impairment was seen in patients from the time of infection up to one year and it was seen with all SARS-CoV-2 variants. But, the level of impaired MFR varied significantly based on the severity of the patient's infection.
Cardiovascular Business discussed the study with one of its authors, American Society of Nuclear Cardiology (ASNC) President Mouaz Al-Mallah, MD. He is the Beverly B. and Daniel C. Arnold Distinguished Chair, director of cardiovascular PET and associate director of nuclear cardiology for the department of cardiology at Houston Methodist DeBakey Heart and Vascular Center. He is also a professor of cardiology at the Houston Methodist Academic Institute Center.
Al-Mallah was seeing patients in his clinic who said they were feeling normal before COVID, but after infection, they were having palpitations and shortness of breath.
"At first, we thought this was myocarditis like with any other virus, so we did a lot of MRIs on these patients and we found they were mildly abnormal, and many others were normal. This was not myocarditis, so we asked if maybe it was with the vasculature. We knew that COVID did have some interaction on the endothelial cells, which are responsible for vasodilation," Al-Mallah explained. "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."
They performed PET on 271 patients with long-COVID symptoms. Each was matched with a group of 815 control subjects with similar ages and comorbidities who had normal PET scans.
"We found they were not able to dilate their arteries as much as a matched normal cohort of patients," Al-Mallah said. "This phenomena happened in the sicker patients, so if a patient was admitted to the hospital or to the ICU, then they had the higher odds of having this. We also noted this was much less prevalent with the Omicron variant, but was seen more with the Delta and Beta variants."
Patients do appear to slowly recover, based on the study. Al-Mallah said patients scanned nine months after infection had half the prevalence of microvascular dysfunction compared to patients who were more recently sick.
"This is at least giving us a hint that this is most likely starting to fade away. And clinically, I am seeing less of these patients at my clinic. Most of these symptoms appear in the first year after infection," he said.
The authors of the study noted that it is limited by its single-center design, use of chart review for follow-up and a high prevalence of cardiovascular risk factors, including obesity. But the findings are particularly relevant to long-haul COVID-19 patients, and may explain the persistence of cardiopulmonary symptoms.
Teams from Washington University and Brigham and Women's Hospital also conducted similar PET studies and reached the same conclusions in recent months, Al-Mallah added.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: dfornell@innovatehealthcare.com