Death, Heart Failure Occurred Among Vaccinated With Heart Inflammation: Study

Death, Heart Failure Occurred Among Vaccinated With Heart Inflammation: Study
A health worker fills a syringe with a Pfizer-BioNTech COVID-19 vaccine in a file image. (Emmi Korhonen/Lehtikuva/AFP via Getty Images)
Zachary Stieber

Heart failure and even death have occurred among people who received a COVID-19 vaccine, according to a new study.

Six people across the four Nordic countries died from myocarditis, a form of heart inflammation, within 90 days of hospital admission after being vaccinated with a messenger RNA (mRNA) vaccine, researchers reported. Twenty-two vaccinated people were diagnosed with heart failure within 90 days of hospital admission with myocarditis.

Myocarditis is caused by the mRNA COVID-19 vaccines made by Pfizer and Moderna, experts in the United States and elsewhere have said. Death is a known outcome. Many people diagnosed with the condition are hospitalized.

Many of those heart failure or death diagnoses happened in those 40 and older. Eight occurred among 12- to 39-year-olds.

Autopsies conducted in multiple countries have found that vaccine-induced myocarditis led to deaths in the young and middle-aged, and previous observational papers have identified post-vaccination deaths among those with heart inflammation.

The researchers also found that 62 people who experienced heart inflammation following vaccination were readmitted to a hospital within 90 days of discharge. Of the readmissions, 41 percent were among the younger age group.

The new study, published in the British Medical Journal on Feb. 1, drew from nationwide register data from Denmark, Finland, Norway, and Sweden. The data covered people aged 12 and up who had myocarditis listed as a primary or secondary diagnosis for hospital admission since the start of the pandemic. Each country had different end dates for its portion of the study; the latest was April 30, 2022.
Because of the nature of the study, researchers said they couldn't say whether the six deaths following vaccination were caused by the vaccination "because these deaths could have been from other causes or from conventional myocarditis occurring by chance within 28 days of vaccination."


More people experienced myocarditis after COVID-19 vaccination than after COVID-19 infection—530 versus 109—according to the new paper.

Researchers took those numbers, and figures representing myocarditis cases prior to the pandemic. They then looked at what percentage led to heart failure or death and calculated the risk for each category.

Myocarditis after COVID-19 vaccination was less likely to lead to a diagnosis of heart failure or death when compared to the historical myocarditis cases, the study estimated. On the other hand, myocarditis after a COVID-19 infection was more likely to lead to heart failure or death.

The risk of readmission to a hospital was lower for people with heart inflammation after COVID-19 vaccination or COVID-19 infection. Among certain groups, though, such as vaccinated women, the risk was about the same as it was for those with conventional myocarditis.

"Taken together, our findings suggested that the outcomes of myocarditis after vaccination were less severe than other types of myocarditis during the first 90 days after the onset of myocarditis," Anders Husby, a Danish epidemiologist, and the other researchers said.

Despite the death and heart failure cases among the vaccinated, the researchers said their results were "reassuring" and "should be considered when weighing the benefits and potential risks of mRNA vaccines against the SARS-CoV-2 virus at the individual and population levels." SARS-CoV-2 causes COVID-19.

Limitations of the paper include not having access to cardiac magnetic resonance imaging or other evaluation data that would give insight into the severity of each myocarditis case.

Pfizer and Moderna didn't respond to requests for comment.

Cardiologists who reviewed the paper and others like it said they've seen key differences between myocarditis after COVID-19 and historical myocarditis. Dr. Anish Koka, a Philadelphia cardiologist, wrote on Twitter that post-COVID-19-infection myocarditis usually occurs in patients who have elevated troponin levels, which signals cardiac cell damage. Traditional myocarditis is a viral illness resulting in chest pain and heart failure.

The post-COVID-19-infection heart injury "reflects patients with bad hearts getting very ill," Koka said. On the other hand, post-COVID-19-vaccination myocarditis often strikes young, healthy males without a disposition to heart injury.

Dr. Tracy Høeg, a California epidemiologist, said she disagreed with the conclusions of the study's authors.

"I'm not getting the same degree of reassurance from their findings," she said, noting that more people developed myocarditis after vaccination than after infection and that the number of heart failure incidents was also higher among the vaccinated.

Update From CDC

The U.S. Centers for Disease Control and Prevention (CDC) identified a higher-than-expected rate of myocarditis in many age groups, particularly among males, in 2021.
The highest rate was 105.9 per million doses of the Pfizer vaccine in males aged 16 or 17, as calculated from reports to the Vaccine Adverse Event Reporting System (VAERS), the CDC reported in a study published by the Journal of the American Medical Association on Jan. 25.

The reports were lodged between December 2020 and August 2021.

Studies on the reporting rates to VAERS have estimated that the rate of post-vaccination problems is underreported to the system and the researchers largely agreed, pointing to how most reports of myocarditis after COVID-19 vaccination had been verified.

"Therefore, the actual rates of myocarditis per million doses of vaccine are likely higher than estimated," they said.

In another recent paper, through surveys of young Americans who suffered post-vaccination myocarditis, and through the patients' health care providers, the CDC discovered that magnetic resonance imaging scans (MRI) done in follow-up visits returned abnormal results for a majority of the patients.

A significant portion, or 46 percent, also suffered from depression, and others suffered from pain and trouble performing usual activities, according to the surveys.

On Feb. 3, Ian Kracalik, a CDC researcher and the lead author of that paper, presented an update of the surveys to the National Vaccine Advisory Committee.

In a new round of surveys collected at least one-year post-myocarditis, 23 percent of 60 patients who responded said they were experiencing chest pain, and others still struggle with symptoms such as fatigue and heart palpitations.

The percentage of patients reporting at least one symptom, 33 percent, was down from 68 percent in the previous round of surveys.

"We're seeing a reduction in the number of patients we're seeing reporting at least one symptom," Kracalik said.

Still, 41 percent of the patients said they have depression, and another 32 percent reported experiencing pain.

Health care providers who completed a separate set of surveys 5 to 13 months after the myocarditis reported no patient deaths but that 14 percent of the patients, primarily young males, weren't cleared for all physical activity and that four had the same status or had worsened since the last surveys, including one who was readmitted to a hospital.

Abnormal findings were reported for multiple patients from cardiac MRIs and other measures, such as electrocardiograms.

Limitations of the ongoing study include there being no standard of care for myocarditis after mRNA vaccination.

The presented results were described as preliminary and haven't been published elsewhere as of yet.

Problem With New Vaccines

Because they aren't as effective against newer variants, the original Moderna and Pfizer vaccines were updated in 2022 to target some of the new strains in addition to the Wuhan variant. The updated shots were introduced as boosters, only available for people who received a primary series.
Initial surveillance indicated that myocarditis could also be an issue with the updated Pfizer shot, a U.S. government official revealed in January.
During a meeting in which advisers recommended the government replace the original vaccines entirely with the updated shots, Richard Forshee of the Food and Drug Administration said the safety signal for myocarditis was triggered among people aged 18 to 35 after receipt of the new Pfizer booster.

Officials still need to investigate more to determine a link but have described the new shots as being similar to the original vaccines.