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Zdenek Vrozina Profile picture
@ZdenekVrozina
Oct 28 • 5 tweets • 1 min read • Read on X
MRI alone may not be enough to rule out post-COVID heart inflammation.
A new JACC 2025 study found that even young, previously healthy adults with normal ECG, echo, and MRI can have microscopic heart damage - inflammation, microvascular damage, and cell necrosis.🧵
The study evaluated 423 long-COVID patients with persistent chest pain.
Most had normal or near-normal cardiac MRI, with only subtle changes in strain or perfusion.
A smaller subgroup (25 patients) whose symptoms persisted despite normal imaging underwent endomyocardial biopsy, revealing -
microangiopathy
necrosis of cardiomyocytes (76%) (!)
fibrotic changes
and in some cases, SARS-CoV-2 N-protein still present in cardiac tissue.
Lab results (troponin I, IL-6, ANA, D-dimer) showed ongoing immune and endothelial activation,
but interpretation is limited by an unknown time since infection - we don’t know if this reflects a late-phase response or chronic injury (still no public access).
Authors concluded that persistent chest pain after COVID may reflect ongoing microvascular and immune-mediated injury - even when standard imaging looks normal.
Chest pain after COVID isn’t always just stress - sometimes it’s microscopic heart damage that leaves scars invisible to MRI.

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More from @ZdenekVrozina

Zdenek Vrozina Profile picture
Oct 27
A new Russian review in IJMS shows how SARS-CoV-2 reshapes the epigenome - weaving together known mechanisms into something deeper.
It’s not just long COVID.
It’s a virus that rewrites the factory that makes immune cells - the bone marrow🧵
Zolotarenko puts special emphasis on this point.
The changes don’t appear in mature immune cells -
they start in their progenitors.
These hematopoietic precursors are born misprogrammed inside the marrow.
That’s why, even after infection clears, the body keeps producing confused immune cells.
The virus is gone, but its instructions remain.
An epigenetic imprint continues to guide new cells months later.
Read 24 tweets
Zdenek Vrozina Profile picture
Oct 25
A new important study in Frontiers in Immunology shows that repeated SARS-CoV-2 infections are beginning to display the same patterns seen in chronic viral infections - narrowing of the T-cell repertoire, exhaustion, and loss of immune flexibility (!)🧵
The immune repertoire doesn’t fully recover after infection. Diversity shrinks, and with reinfection the system no longer returns to balance.
The study analyzed T-cell receptors in people after a first infection and after reinfection with SARS-CoV-2.
The result?
Reinfection isn’t just another infection - it leaves a measurable imprint on the immune system.
Read 17 tweets
Zdenek Vrozina Profile picture
Oct 24
A study from Krakow followed hospitalized COVID-19 patients for five years to see if their initial immune profiles - T, B, and NK cells - could predict who would
die in the following years, or develop long COVID.🧵
Out of 103 patients from 2020, researchers followed 80 over 54 months.
23 had died, 57 were alive - and about half of those survivors (29 people) still lived with long COVID symptoms.
That’s one of the longest immune follow-ups after COVID-19 so far.
During the acute infection, those with severe disease showed a collapse of T and NK cells.
Their total T cells dropped to a median of 340 per µl (vs 705 in milder cases).
CD4+ helper T cells fell to 183 vs 452, and CD8+ cytotoxic T cells to 109 vs 227.
Even NK cells were lower (107 vs 157).
Meanwhile, the proportion of B cells was paradoxically higher - 18.5% vs 12.5%.
Read 9 tweets
Zdenek Vrozina Profile picture
Oct 23
A new preprint from Aarhus University shows something striking:
people with post-COVID, MCS, and functional disorders all share the same brain pattern -
split hemispheres, weakened bridges between left and right (!),
overloaded smell and sensory circuits🧵
The study scanned 57 women (post-COVID, MCS, FSD, controls) using diffusion MRI (DTI).
It didn’t measure brain activity, but rather its wiring - the white-matter highways that carry information between regions.
Result.
Interhemispheric connectivity - the bridge between left and right hemispheres - was reduced by 70% in all three patient groups.
That means information flow across the brain is slower, less coordinated, and less efficient.
Read 19 tweets
Zdenek Vrozina Profile picture
Oct 22
A new study strengthens the view that SARS-CoV-2:
disrupts brain homeostasis,
alters ionic & neurotransmitter balance,
and triggers lasting epigenetic reprogramming.
Researchers exposed human primary astrocytes to Delta and Omicron.
The results are striking🧵
Astrocytes were infected with Delta and Omicron at a very low viral load (MOI 0.2).
After just 6 hours, RNA-seq revealed major transcriptional shifts
Omicron deregulated 346 genes (197 ↑, 149 ↓)
Delta deregulated 341 (215 ↑, 126 ↓)
About half of the changes overlapped.
Even minimal exposure triggered broad molecular changes within hours.
Viral sensing and immune response.
Astrocytes primarily activated TLR2, but not RIG-I or NLRP3 - meaning they sensed the virus without launching a full antiviral storm.
Only 16 genes involved in interferon and interleukin signaling were affected.
Read 18 tweets
Zdenek Vrozina Profile picture
Oct 22
Even though Omicron often causes milder illness, it leaves a clear metabolic footprint disrupting liver, immune, and energy metabolism.
A new study shows that even 2-4 weeks after recovery, the body does not return to normal metabolic state🧵
Researchers analyzed blood serum from 300 Omicron patients, 200 recovered, and 380 healthy controls.
Using LC-MS metabolomics, they tracked hundreds of molecules revealing how the infection affects the liver, mitochondria, and immune system.
Over 100 metabolites were significantly altered during infection - that’s expected in any acute illness.
What’s not expected?
Most of these changes did not return to normal even after clinical recovery.
Read 13 tweets

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