Development and assessment of a histopathological stability score for atheroma plaques

Vulnerable atherosclerotic plaques are central to the onset of acute coronary events and abrupt cardiac fatalities. Although significant strides have been made in understanding cardiovascular (CV) diseases, the field continues to require reliable, quantifiable approaches to assess plaque instability.

The purpose of this study was to develop and confirm a novel tissue-based scoring system for evaluating the stability of atherosclerotic plaques, based on an in-depth examination of cases involving sudden cardiac death (SCD).

We conducted a retrospective analysis of coronary artery specimens from 1189 instances of SCD, which were autopsied at the Institute of Forensic Medicine, Cluj-Napoca, Romania, from 2014 to 2018. The microscopic evaluation focused on key markers of plaque vulnerability, including the thickness of the fibrous cap, the extent of the necrotic core, the degree of inflammatory activity, the presence of bleeding within the plaque, and the nature of calcified deposits. These features were scored separately and integrated into an overall vulnerability metric. The score's consistency and accuracy were tested against expert pathologist evaluations and evidence of plaque rupture or clot formation.

Macroscopic examination revealed diffuse cardiosclerosis in 94.9%, myocardial infarctions (26.4% healed, 13.62% acute), and myocardial hypertrophy in 7.82%. Microscopic analysis of atherosclerotic plaques showed high vulnerability with hemorrhage (76.0%), necrotic core (92.6%), cholesterol crystals (61.6%), plaque erosion (42.7%), and rupture (15.3%), despite a median fibrous cap thickness of 149.1 μm and 76.6% of plaques classified as moderately stable by histopathological stability score (HSS).

This extensive validation establishes the new histopathology-based stability score as a trustworthy, repeatable, and efficient method for assessing atherosclerotic plaque vulnerability. Its use could standardize diagnoses in forensic pathology and support future studies on CV risk assessment.