We present the postmortem findings of an unexpected death due to acute myocardial infarction (AMI) with microthrombi and thrombosis in other vessels after the first dose of coronavirus disease 2019 (COVID-19) vaccination (ChAdOx1 nCov-19). The deceased was a 69-year-old woman who complained of nonspecific symptoms shortly after vaccination and was found dead on the sixth day. Postmortem examination revealed AMI and complications (left ventricular rupture, hemopericardium) with microthrombi in small cardiac vessels, which are similar to the characteristic findings of myocardial injury caused by microthrombi in patients with COVID-19. Nonobstructive thromboembolism in the pulmonary arteries and inferior vena cava, and fibrin microthrombi in some small vessels in the brain were also observed. It is unclear whether these findings are associated with COVID-19 vaccination, and further comprehensive studies are needed.
Since the coronavirus disease 2019 (COVID-19) vaccine (ChAdOx1 nCov-19) was introduced in South Korea, various adverse events have been reported in healthcare workers, but most of them were not fatal [
The deceased was a 69-year-old woman who was found unresponsive kneeling down before the toilet in the restroom in the early morning. The deceased received the first dose of COVID-19 vaccination (ChAdOx1 nCov-19) 6 days prior to her death. The deceased complained of nausea on the day of vaccination and then some pain in the vaccinated site of the arm for the next 3 days. On the fifth day after vaccination, she felt herself unwell with general weakness and back pain. On the sixth day, the deceased was found dead by her daughter. Cardiopulmonary resuscitation was not performed. The deceased had medical history of uterine cervical cancer (cured), diabetes mellitus, hypothyroidism, and osteoporosis. The deceased was consulted to our institute for postmortem examination because of her unexpected death after vaccination and the anticipated medicolegal issues.
On external examination, the deceased appeared well-nourished and clean. The body mass index was 26.8 kg/m2 (height, 160 cm; weight, 68 kg). The injection site for vaccination was not clearly detected on the left arm. No significant injury was identified and otherwise unremarkable.
On internal examination, hemopericardium (mostly blood clots, approximately 400 mL) was identified in the pericardium (
Hemopericardium is observed in the pericardium (
Microscopic examination revealed multifocal (not confluent) myocardial necrosis with focal rupture, hemorrhage, and acute inflammation (
On microscopic examination, focal myocardial necrosis with rupture and hemorrhage is observed, and the length of the area is <1 cm (H&E, ×40) (
In the postmortem toxicological tests, a statin drug and acetaminophen were found to be positive within the therapeutic levels. The glycosylated hemoglobin level in the postmortem blood was also increased (7.1%; reference range <5.6%) which is consistent with the history of diabetes mellitus. In other postmortem ancillary tests including blood alcohol level, ketone bodies, biochemistry, C-reactive protein, and thyroid function tests, the results were unremarkable. The anti-heparin/platelet factor 4 (PF4) antibody test was attempted by sending the sample to the outside hospital; however, the test could not be performed because of postmortem changes in the blood sample.
The cause of death was determined as acute myocardial infarction and acute complications (focal rupture of the left ventricle and hemopericardium) in a woman with thrombosis.
This case illustrates an unexpected sudden cardiac death occurring on the sixth day after COVID-19 vaccination (ChAdOx1 nCov-19), an unusual pattern of focal myocardial infarction with focal rupture of the left ventricle, which was attributed to microthrombi in small vessels in the myocardium, without any epicardial coronary artery disease. In addition, acute nonobstructive thromboemboli in the right and left pulmonary arteries and inferior vena cava, and fibrin microthrombi in some small vessels of the cerebrum were observed. There was no medical history of cardiovascular diseases, venous thrombosis, a recent trauma, or recent surgery. The deceased did not have any disability in her daily life and was not bedridden.
Microthrombi in myocardial microvessels and focal myocardial necrosis in this case are unusual, compared with the usual features of typical cases of acute coronary syndrome, usually transmural myocardial infarction caused by epicardial coronary atherosclerosis and thrombosis. Microthrombi are microemboli chipped away from the epicardial coronary artery thrombosis and eroded plaque, which was proven by autopsy and clinicopathologic studies [
Myocardial necrosis with microthrombi in cardiac small vessels in this case was similar to the cardiac findings in patients with COVID-19. Microthrombi led to focal myocardial necrosis occupying an area of <1 cm2, which is different from the usual transmural myocardial infarction caused by epicardial coronary artery thrombi [
It is unclear whether the postmortem findings in this case could be considered as vaccine-induced immune thrombotic thrombocytopenia (VITT). Thrombotic events in the cerebral veins, deep veins of the leg, pulmonary arteries, and splanchnic vessels after COVID-19 vaccination (ChAdOx1 nCov-19) were reported as the clinical manifestations of VITT [
Given that the deceased was a postmenopausal woman and the myocardial necrosis was observed in the apex of the heart, and ventricular thrombi was observed in other vasculature, Takotusbo cardiomyopathy (T-CMP) may be considered [
This case revealed that postmortem examination is critical to confirm the cause of death in the cases of unexpected death after vaccination. Most major characteristic findings in this case could be identified only by postmortem examination. The clinical diagnosis of microthrombi in cardiac small vessels is difficult, and there is no laboratory method to diagnose it specifically. Clinical manifestations can be nonspecific and misleading. In patients with COVID-19, the sensitivity of the electrocardiogram approach to patients with myocardial injury was poor, and their clinical manifestations were variable and masked by respiratory symptoms [
In summary, we present a case of unusual myocardial infarction with microthrombi and thrombosis after COVID-19 vaccination (ChAdOx1 nCov-19), whose findings are similar to those of myocardial injury in patients with COVID-19, accompanied by thrombosis in other organs. Further studies are necessary to understand the pathogenesis and to clarify the causal relationship with COVID-19 vaccination. Given that the major unique features of this case were identified only by postmortem findings, meticulous postmortem examination is essential for unexpected death after vaccination.
No potential conflict of interest relevant to this article was reported.
This study was approved by the National Forensic Service Institutional Review Board (906-210914-BR-001-01).