Patients infected with Beta and Delta COVID-19 variants, and those who required hospital stays for the infection, are more likely to experience heart issues associated with long COVID, according to a recent study.

The study, published in the European Heart Journal, Cardiovascular Imaging, showed that patients recovering from the Omicron variant were least likely to have microvascular involvement.

Microvascular dysfunction is a type of non-obstructive coronary artery disease that causes the small blood vessels feeding the heart muscle to not work as they should.

"This new data expand our understanding of myocardial flow reserve as an important prognostic marker in general and specifically in COVID-19," said Mouaz Al-Mallah, corresponding author and director of cardiovascular PET at Houston Methodist DeBakey Heart and Vascular Center in the US.

"This is good news for individuals who had Omicron and are concerned about long COVID. Patients with lingering symptoms such as chest pain or shortness of breath following a severe infection may want to have a PET scan with blood flow assessment to check for microvascular dysfunction," Al-Mallah said.

The study included 271 cases matched to 815 controls and found that microvascular dysfunction started to be seen less often after nine months to one year following infection suggesting that this type of abnormality may be reversible.

The American Society for Nuclear Cardiology's PET scan guidelines now recommends including blood flow assessment routinely.

Last year, Al-Mallah and team published an initial study in JACC: Cardiovascular Imaging examining the coronary microvasculature health of 393 patients, including 101 with prior COVID infection who had lingering symptoms. This was the first study linking reduced blood flow reserve in the heart and COVID.

With over 600 million confirmed cases and nearly seven million deaths, the COVID-19 pandemic has left a lasting mark on the world. While the World Health Organisation (WHO) ended the global health emergency declaration in May, long COVID remains largely a mystery.

According to Al-Mallah, more studies are needed to further assess the microvascular health of patients with prior COVID and identify how these findings could influence patient care in the context of long-haul COVID.