How Old Is Atherosclerosis?

By Michael H. Crawford, MD, Editor

SYNOPSIS: Computed tomography of mummified human remains exhibits vascular calcium in almost 40% across multiple eras and geographies, which included non-elites.

SOURCE: Thompson RC, Sutherland ML, Allam AH, et al. Atherosclerosis in ancient, mummified humans: The global HORUS study. Eur Heart J 2024;45:2259-2262. (Erratum in: Eur Heart J 2024; Aug 13. doi: 10.1093/eurheartj/ehae536. [Online ahead of print].)

Reports of detecting arterial calcifications by computed tomography (CT) scans in Egyptian mummies have stimulated interest in the prevalence of atherosclerosis in other ancient peoples. Thus, this report from the HORUS (ancient Egyptian deity) study is of interest.

CT scans performed between 1999 and 2022 on a variety of machines at numerous museums and collections were reviewed for evidence of atherosclerosis. The presence of calcium in the wall of an artery was considered definite atherosclerosis, and calcium along the expected course of an artery was probable atherosclerosis. The extent of atherosclerosis was assessed as the number of vascular beds involved (aorta, coronary, ileo-femoral, popliteal-tibial, and carotid). Age at death and sex were determined by standard criteria.

The 237 subjects examined were from seven different ancient populations: 161 Egyptians, 54 lowland Peruvian farmer-fishermen, three highland Andean Bolivian farmer-pastoralists, four 19th century Unangan/Aleutian Islander hunter-gatherers, four 16th century Greenlandic Inuit hunter-gatherers, five ancestral Puebloans, four Middle-Ages Gobi Desert pastoralists, one 19th century African American, and one 19th century Indigenous Australian.

Of these, 59% were men and mean age at death was 40 years. Atherosclerosis was found in all cultures and epochs, except the one Indigenous Australian mummy, in whom no vascular tissue could be identified. The incidence of atherosclerosis in the remaining mummies was 38% and was equal in men and women (38% vs. 39%) and Egyptian and non-Egyptian (both 39%). Also, mild to moderate atherosclerosis (one or two vascular beds) was more common than severe involvement (three to five vascular beds). The aorta was the most common vascular bed involved (22%), followed by ilio-femoral (21%), then popliteal-tibial (16%), carotid (14%), and, finally, coronary (0.4%). The authors concluded that atherosclerotic calcifications were common in the mummified remains of humans across multiple eras and geographies.

Commentary

The studies of Egyptian mummies that demonstrated calcified arteries raised the issue that mummified Egyptians were the elites of their societies and may have had different diets and exercise habits compared to the non-elites. Therefore, the presence of evidence of atherosclerosis in these elites may just confirm what we know about risk factors for atherosclerosis. Thus, one of the strengths of the HORUS study is that it included subjects from seven different cultures, which included non-elites. Also, this is the largest study of mummified remains by CT scans. In addition, it shows that atherosclerosis is present, stretching back thousands of years.

Previous studies comparing CT scans to autopsy have shown that the detection of calcium by CT is accurate at identifying atherosclerosis. The frequency of atherosclerosis may be surprising, but these were younger individuals with mainly one vascular territory involvement, which would be similar to what we observe in current populations.

There are limitations to the HORUS study. The degree of preservation of the bodies was variable and, in most cases, only a few vascular beds could be identified. So, no true prevalence could be determined. Late-stage syphilis can cause nonatherosclerotic calcifications of the ascending aorta, but involvement of the ascending aorta was not observed in the HORUS study. Also, Monckeberg’s medial arteriosclerosis was seen in the leg arteries of some mummies, but they also had atherosclerosis in other vascular beds. In addition, no arterial aneurysms or other causes of vascular calcification could be identified. Finally, the HORUS study does not include all ancient civilizations, since many did not preserve human remains.

In some ways, the HORUS findings are not surprising. We know that atherosclerosis and atherosclerotic events involve lipid metabolism, the immune system, and the blood coagulation system. Early humans needed all three of these systems to be robust to survive war, disease, and famine. Thus, in societies developed enough to mummify their dead, these challenges were probably minimal, providing the opportunity to develop the most common disease of advanced societies.