Prevalence and severity of atherosclerosis in extra cranial carotid arteries in Nigeria: an autopsy study

BACKGROUND There has been a paucity of autopsy studies on atherosclerotic lesions in Nigerians, the last one conducted at our centre being more than four decades ago. There has also been considerable epidemiological transition. The objective of the study was to determine the frequency, severity, pattern and distribution of atherosclerotic lesions in extra cranial carotid arteries (ECCA) in Nigerians at autopsy. METHODS ECCA of 30 consecutive Nigerian patients undergoing autopsy at a University teaching hospital were examined using the American Heart Association (AHA) histological grading and classification of atherosclerosis. RESULTS Atherosclerotic lesions of ECCA were present in 73.3% of the subjects with the right and the left carotid bifurcations (28.3%) being the most frequently affected sites. Using the AHA classification of atherosclerosis, a total of 176(73.3%) lesions were found in the 240 histological sections of blood vessels examined. Of these, 22.5% were types I, 22.5% were types II, 15.4% were type V, and 7.5% were type III. The VII to type IX lesions were rare. When these atherosclerotic lesions were grouped into mild, moderate and severe, 52.5% were mild lesions (types I-III); 18.3% were moderate lesions (types IV and V); and 2.5% were severe lesions (types VI to IX). The severe lesions were most frequently observed in the left carotid bifurcation (50%) and they first appeared in the age group 45-49 years. Age, hypertension and diabetes mellitus were strong risk factors for atherosclerosis. CONCLUSIONS Compared with four decades ago there has been an apparent increase in severity and extent of ECCA atherosclerosis especially after the age of 45 years in autopsies from our centre. This change in the amount of atherosclerosis over time is possibly due to the epidemiologic transition. This may worsen the rise in stoke incidence within this community and as such, great effort should be made to follow-up and manage CVD risk factors within the community.