FULL CLAIM: “New study links mRNA vaccine to cardiomyopathy”; “Nakahara and colleagues showed that the cardiac muscle changes its preference from free fatty acids to glucose [...] this was a very disturbing study”; “What this is adding up to is the vaccines clearly cause myocarditis [...] in some, but more globally, they may cause a form of a metabolic cardiomyopathy [...] And it may explain sudden cardiac death in the absence of myocarditis”
REVIEW
Cardiologist Peter McCullough, who has a history of propagating inaccurate and misleading claims about COVID-19, appeared on One America News Network on 27 October 2023 in an interview with host Alison Steinberg. Excerpts from the interview were uploaded on social media, including Instagram.
During the interview, McCullough claimed that three studies—one from Krauson et al., another from Nakahara et al., and the other from Schreckenberg et al.—were evidence that the COVID-19 mRNA vaccines caused “a form of metabolic cardiomyopathy” that could explain “sudden cardiac death”[1-3].
In fact, McCullough has repeatedly drawn on these studies to build the case that COVID-19 mRNA vaccines are dangerous and linked to deaths, as evidenced by these tweets. We explain in this review how his claims distort and misrepresent the findings of these studies in a bid to push the false narrative that COVID-19 vaccines are dangerous.
Study by Krauson et al. found no association between vaccine mRNA in the heart and death
McCullough interpreted the study by Krauson et al. as showing that “messenger RNA is directly in the human heart” and that this has been “identified with inflammation around it”. While both statements on their own are true, they leave out important details that contradict McCullough’s wider claim of harm from the vaccine mRNA.
Krauson and colleagues collected tissue from the lymph nodes, liver, spleen and heart muscle during autopsies of patients who had also been recently vaccinated with COVID-19 mRNA vaccines[1]. The aim was to assess how long mRNA from the vaccines could persist in different parts of the body.
Twenty patients who were vaccinated and five who were unvaccinated were included (as a control). The authors clarified that “In none of the vaccinated patients was the cause of death linked to the vaccine”.
The authors reported that they didn’t detect vaccine mRNA in the spleen and liver. But in the case of heart tissue, vaccine mRNA could be detected in three of the 20 vaccinated patients. All three had been vaccinated within 30 days of their death.
The authors wanted to understand what set these three patients apart from the other vaccinated patients who had also been vaccinated within 30 days of death but showed no vaccine mRNA in the heart.
We reached out to the study’s corresponding author, James Stone, an associate professor of pathology at Harvard Medical School, to better understand the study’s findings.
Stone explained that while they did observe inflammation in the heart of these three patients, “it was not the right type of inflammation for myocarditis”. He also clarified that “The vaccine was associated with the presence of healing myocardial injury that was present at the time of vaccination” and that in at least one of the three patients, the injury had clearly occurred before vaccination. Simply put, these results indicate that the heart injury occurred before vaccination and wasn’t caused by the vaccine.
Moreover, the study contains an analysis of the likely cause of death in these three patients. One had an intracranial bleed and lung cancer; one had a history of heart failure and died from non-ischemic cardiomyopathy; and the third died from severe coronary artery disease. Thus, all three patients had medical conditions that could result in heart injury.
The study did find that vaccine mRNA tended to be located around areas of heart injury, but given that the heart injury was already present at the time of vaccination, the authors hypothesized that vaccine mRNA had been carried to these areas by immune cells reacting to the heart injury as a result of inflammation.
Stone emphasized that none of these deaths were found to be caused by the vaccine.
To summarize, the study by Krauson et al. detected vaccine mRNA in the heart tissue of three of 20 vaccinated patients. Vaccine mRNA was detected specifically in areas of the heart that were injured, but the study’s findings indicated that the injury had occurred before vaccination and that all three had pre-existing medical conditions that could explain the injury. None of the deaths were linked to the vaccines.
Therefore, the study doesn’t support McCullough’s claim that COVID-19 mRNA vaccines damage the heart and cause sudden cardiac death. In fact, the study’s findings speak against his claim.
Study by Nakahara et al. didn’t show that vaccines caused a change in heart metabolism
McCullough asserted that the study by Nakahara et al. showed “the cardiac muscle changes its preference from free fatty acids to glucose”, calling it “a very disturbing study”. But a closer look at the study’s findings places this interpretation into question.
This was a retrospective study, published in the journal Radiology, that took advantage of a large database of existing PET/CT scans to see if people who received the COVID-19 mRNA vaccines but didn’t develop myocarditis also showed changes in the heart[2]. The scans were performed on a mix of patients, such as cancer patients and people undergoing a medical checkup.
The PET/CT scans used by the researchers relied on the radioactive marker called fluorine-18 fluorodeoxyglucose, or 18F-FDG for short. It is a glucose analog used to visualize tissues that rely on glucose as an energy source or whose dependence on glucose increases due to disease. As such, it is used for cancer imaging, as well as imaging of the heart and brain. It can also be used to detect inflammation in the heart.
Because this method of imaging is sensitive to the way our body metabolizes glucose, certain preparations need to be made beforehand to ensure accurate results. An editorial in the journal, commenting on the study by Nakahara et al., explained that “in routine clinical practice, 18F FDG PET/CT is a terrible tracer with which to evaluate myocardial inflammation. This is because glucose is the normal source of energy for the myocardium—almost all patients have high myocardial uptake.” We can contrast this with McCullough’s claim implying that heart tissue using glucose is abnormal.
Heart cells can use alternative sources of energy, such as lipids, when a person is in a fasting state. The editorial went into more detail: “In the fasting state, the preferred myocardial energy source is lipids rather than glucose. The trick is to combine a low carbohydrate and high fat diet the day before the FDG PET scan with 12 hours of fasting immediately before imaging”.
This was indeed the approach taken with the 18F-FDG PET/CT scans analyzed by Nakahara et al. Using this method, they found that vaccinated people who showed no signs of myocarditis had a greater uptake of 18F-FDG in the heart than people who weren’t vaccinated. This increase could be seen regardless of the patient’s age, sex, and the vaccine brand received.
Thus, the editorial explained, the findings suggest that mild levels of heart inflammation may be “more common than we ever expected” in people who received a COVID-19 mRNA vaccine, and that the minority of vaccinated people who developed myocarditis simply experienced more severe inflammation than the majority that didn’t develop myocarditis.
The authors did acknowledge some limitations, such as the fact that this was a retrospective study from a single hospital, and so may not apply to the general population.
The editorial also pointed to a few others, such as the fact that the study had no information on the level of myocardial enzyme (a measure of heart injury) or cardiac function in the patients, and that “the authors did not scrutinize the oncologic histories and treatments of their patient groups”.
There’s no indication in the study that the findings were “disturbing”, as McCullough put it. Contrary to his claim, the study didn’t show that heart tissue had changed its preference “from free fatty acids to glucose”. It also didn’t report metabolic cardiomyopathy or sudden cardiac death in vaccinated people.
Study by Schreckenberg et al. used large amounts of vaccine mRNA not representative of human doses
McCullough claimed that the study by Schreckenberg et al. showed both the Pfizer-BioNTech and Moderna COVID-19 vaccines, when “directly applied on the heart muscle cells, caused […] the heart muscle cells to [contract] in abnormal ways”[3]. Again, while in itself true, this statement leaves out the fact that the researchers found this effect only with vaccine doses that were much higher than are given to people.
The aim of this study was to understand how the COVID-19 mRNA vaccines could potentially affect the heart. To do this, they grew heart muscle cells isolated from rats in cell cultures (cells growing in dishes) and added the vaccines directly into the cell cultures.
No changes were seen in the first 24 hours after adding the vaccines, but 48 hours after the vaccines were added, the researchers found that the way the heart muscle cells contracted changed. It should be noted that the amount of vaccine used in this experiment was much higher than what adults receive during vaccination. The two doses tested were one and 3.3 micrograms, added to one milliliter of culture medium (a liquid containing nutrients and other chemicals needed to maintain cell cultures). A microgram is a millionth of a gram.
In contrast, an adult dose of the Pfizer-BioNTech COVID-19 vaccine is 30 micrograms and 50 micrograms for the Moderna COVID-19 vaccine. The volume of the average human is about 65 liters; the average human adult has about four to five liters of circulating blood. While we know the vaccine isn’t distributed evenly throughout the body, remaining mainly at the site of injection, this is still a far cry from the the experimental conditions in the study.
Marc Veldoen, an immunologist and professor at the University of Lisbon, wrote a thread on X (formerly Twitter) on the study, explaining that “This would be like directly injecting in the heart, or a very large quantity of vaccine in the bloodstream to soak the heart with Spike-coding RNA”, neither of which occurs during vaccination.
Pediatric cardiologist Frank Han also wrote about the study in a thread on X/Twitter. He wrote that the study was “an important project” for better understanding vaccine-related myocarditis. But he also pointed out that the researchers had to “soak the heart cells in vaccine, to get the effects they found in this experiment. None of us humans are getting the vaccine this way”.
Published studies show that the benefits of the COVID-19 vaccines outweigh their risks
All medical interventions come with side effects and COVID-19 vaccines are no exception. COVID-19 mRNA vaccines are linked to an increased risk of heart inflammation in adolescent and young adult males, although most recover without any long-term effects.
However, the risk of heart complications, along with other health problems like blood clotting disorders, associated with getting COVID-19 is well-documented to be higher than that associated with vaccination[4-11]. Therefore, on balance, COVID-19 vaccines offer more benefits than drawbacks.
The scientific evidence thus far doesn’t support the claim that COVID-19 mRNA vaccines lead to a greater risk of sudden death or sudden cardiac death. A study performed in Australia found no association between out-of-hospital cardiac arrests and COVID-19 vaccination[12].
A study published in the journal Circulation, which tracked the trends in sudden cardiac deaths in U.S. college athletes over a 20-year period, actually reported a net decrease in sudden cardiac death[13]. Of the 143 cases of sudden cardiac death during the 20 years up to 30 June 2022, just eight were attributable to myocarditis, and only one case occurred during the COVID-19 pandemic.
Published studies so far have also found no association between COVID-19 vaccination and a greater risk of all-cause mortality[14,15].
Conclusion
The claim that these three studies point to COVID-19 mRNA vaccines causing “metabolic cardiomyopathy” and “sudden cardiac death” is baseless. As we explained above, McCullough’s statements about the studies misrepresent their findings or leave out important information that contradicts his claim. In fact, none of the studies found any association between COVID-19 mRNA vaccines and sudden cardiac death or metabolic cardiomyopathy. Other published studies have also found no association between COVID-19 vaccination and sudden death or an increase in all-cause mortality.
REFERENCES
- 1 – Krauson et al. (2023) Duration of SARS-CoV-2 mRNA vaccine persistence and factors associated with cardiac involvement in recently vaccinated patients. NPJ Vaccines.
- 2 – Nakahara et al. (2023) Assessment of Myocardial 18F-FDG Uptake at PET/CT in Asymptomatic SARS-CoV-2–vaccinated and Nonvaccinated Patients. Radiology.
- 3 – Schreckenberg et al. (2023) Cardiac side effects of RNA-based SARS-CoV-2 vaccines: Hidden cardiotoxic effects of mRNA-1273 and BNT162b2 on ventricular myocyte function and structure. British Journal of Pharmacology.
- 4 – Hippisley-Cox et al. (2021) Risk of thrombocytopenia and thromboembolism after covid-19 vaccination and SARS-CoV-2 positive testing: self-controlled case series study. BMJ.
- 5 – Knight et al. (2022) Association of COVID-19 With Major Arterial and Venous Thrombotic Diseases: A Population-Wide Cohort Study of 48 Million Adults in England and Wales. Circulation.
- 6 – Barda et al. (2021) Safety of the BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Setting. New England Journal of Medicine.
- 7 – Bozkurt et al. (2021) Myocarditis With COVID-19 mRNA Vaccines. Circulation.
- 8 – Raisi-Estabragh et al. (2022) Cardiovascular disease and mortality sequelae of COVID-19 in the UK Biobank. Heart.
- 9 – Xie et al. (2022) Long-term cardiovascular outcomes of COVID-19. Nature Medicine.
- 10 – Patone et al. (2022) Risk of Myocarditis After Sequential Doses of COVID-19 Vaccine and SARS-CoV-2 Infection by Age and Sex. Circulation.
- 11 – Writing Committee. (2022) 2022 ACC Expert Consensus Decision Pathway on Cardiovascular Sequelae of COVID-19 in Adults: Myocarditis and Other Myocardial Involvement, Post-Acute Sequelae of SARS-CoV-2 Infection, and Return to Play: A Report of the American College of Cardiology Solution Set Oversight Committee. Journal of the American College of Cardiology.
- 12 – Paratz et al. (2023) No Association Between Out-of-Hospital Cardiac Arrest and COVID-19 Vaccination. Circulation.
- 13 – Petek et al. (2023) Sudden Cardiac Death in National Collegiate Athletic Association Athletes: A 20-Year Study. Circulation.
- 14 – Bilinski et al. (2023) COVID-19 and Excess All-Cause Mortality in the US and 20 Comparison Countries, June 2021-March 2022. JAMA Network.
- 15 – Xu et al. (2021) COVID-19 Vaccination and Non–COVID-19 Mortality Risk — Seven Integrated Health Care Organizations, United States, December 14, 2020–July 31, 2021. Morbidity and Mortality Weekly Report.
