The wail of an ambulance pierced the quiet streets of a major Japanese city as paramedics rushed a 75-year-old woman with a history of bronchiectasis from her apartment to the nearest emergency ward. She had collapsed when her heart inexplicably stopped beating. After three cycles of cardiopulmonary resuscitation, doctors restored her heartbeat, yet something was not quite right. Her ECG showed unusual electrical patterns, premature ventricular contractions, and ventricular tachycardia, yet her cardiac enzymes were normal. Despite aggressive intervention, she soon experienced another cardiac arrest and passed away.
The cause of death remained a mystery until Japanese pathologists conducted a thorough autopsy, including microscopic examination of her heart tissue. What they discovered stunned the global medical community: countless tiny scars scattered throughout her heart muscle, a condition never before documented in medical literature.
This woman was one of three patients described in a groundbreaking Japanese study published in March 2025 that has uncovered a potentially alarming connection between COVID-19 vaccination and microscopic heart damage.
“As usual, the Japanese seem to be the only ones who are really asking hard questions. They’re doing the work that needs to be done in terms of doing autopsies,” explains Dr. Philip McMillan, a clinician and researcher who brought attention to this paper shortly after its publication.
What Are Cardiac Multiple Microscars?
Unlike the large scars typically seen after heart attacks, these microscars are tiny, scattered throughout the heart muscle, and invisible to the naked eye. They can only be detected through histological examination, looking at tissue samples under a microscope.
The Japanese researchers behind this study noted that in over 30 years of conducting autopsies, they had never observed this pattern before. “At our clinical pathological conferences spanning about 30 years, multiple myocardial scars in the myocardium other than in cases of myocardial infarction had never been observed,” their report states. They coined the term “Cardiac Multiple Micro-Scars” (MMS) to describe this phenomenon.
What makes these microscars concerning is their potential to disrupt the heart’s electrical system. The heart relies on organized electrical signals to maintain its rhythm. When these signals are disrupted by scarring, they can trigger dangerous arrhythmias like atrial fibrillation or ventricular fibrillation, conditions that can lead to sudden cardiac arrest.
A Pattern Emerges
The Japanese study examined three patients who died from unexplained cardiac arrest. All three had received multiple COVID-19 booster vaccinations, with only one having a documented history of COVID-19 infection.
Besides the 75-year-old woman, the researchers also studied a 91-year-old woman who had been hospitalized for worsening heart failure with no apparent cause. She developed new-onset atrial fibrillation before her death.
The third patient was a 73-year-old man who had been treated for T-cell lymphoma and later contracted COVID-19, after which his condition worsened, and arrhythmias were recorded.
Remarkably, standard tests such as echocardiograms revealed normal cardiac function in these patients, despite the pervasive microscars throughout the myocardium. External examination of the hearts during autopsy revealed no visible abnormalities. It was only when tissue samples were examined under a microscope that the microscars became apparent.
“If you’re doing a simple external autopsy, you’ll never see it because you can only see it on histology, looking under the microscope,” Dr. McMillan points out. “You would never see it by something like an MRI, which can sometimes pick up myocarditis.”
Long-term Effects on Public Health
The discovery raises serious questions about the long-term cardiac effects of COVID-19 vaccinations, particularly for those who have received multiple booster shots.
The researchers found an average of 64 microscars in the left ventricle alone, with an average diameter of 211 micrometers. These scars were distributed throughout all four chambers of the heart, potentially creating multiple points where electrical signals could be disrupted.
While the Japanese team was careful not to make definitive claims about causation, they noted: “All three patients had histories of booster vaccinations, six or seven, five or six, up to the last admission.”
They also referenced “a global survey showing that any type of COVID vaccine appears to instigate cardiac arrhythmias and COVID-19 vaccines may lead to cardiac conduction abnormalities.”
This finding is particularly concerning given the billions of people worldwide who have received multiple COVID-19 vaccine doses. If these microscars are indeed linked to vaccination, how many people might be walking around with undetected heart damage that could increase their risk of sudden cardiac arrest?
The Need for More Research
The Japanese researchers concluded that “cardiac multiple microscars should be considered one of the differential findings for cardiac arrest” and that “further study is needed to identify and understand the characteristics of this disease state.”
Dr. McMillan echoes this sentiment: “There is no excuse for not doing autopsies. Novel virus, novel technology, unusual patterns of death, and no autopsies? That’s almost negligent.”
This study highlights a critical gap in our understanding of vaccine safety. Without thorough histological examinations of heart tissue from deceased vaccinated individuals, conditions like cardiac multiple microscars could remain undetected and underreported.
As this research gains attention, medical professionals and public health officials should consider several important steps:
1. Increase the number of thorough histological autopsies performed on individuals who die from sudden cardiac arrest, particularly those who have received multiple COVID-19 vaccinations.
2. Develop screening methods to identify those who might have developed these microscars and may be at higher risk for cardiac arrhythmias.
3. Conduct larger studies comparing the prevalence of these microscars in vaccinated versus unvaccinated populations.
For those concerned about unexplained cardiac symptoms or with family members who have experienced sudden cardiac events, requesting comprehensive histological examination may provide answers that standard testing cannot. While this research is still preliminary, it serves as an important reminder of the need for ongoing safety monitoring of all medical interventions, including vaccines.
WOW! Great work Dr. McMillan on bringing these important issues to the forefront so consistently!