Postmortem coronary artery calcium score in cases of myocardial infarction

Abstract

Sudden cardiac death (SCD) related to atherosclerotic coronary artery disease (ACAD) resulting in myocardial infarction is the most prevalent cause of death in western countries. In clinical practice, coronary artery calcium score (CACS) is considered an independent predictor of coronary events, closely related to atherosclerotic burden and is quantified radiologically by the Agatston score being calculated through computed tomography. Postmortem computed tomography (PMCT) allows the visualization and quantification of coronary calcifications before the autopsy. However, it was reported that some patients who died from severe ACAD had a zero CACS in PMCT. In this study, a retrospective evaluation of CACS in adult's myocardial infarction cases related to ACAD, with available CACS and histological slides of coronary arteries, was performed in order to gain a deeper understanding of coronary calcifications and their role in myocardial infarction cases. The CACS was calculated by using the software Smartscore 4.0 after the radiological examination on a 64-row CT unit using a specific cardiac protocol. Thirty-six cases were identified out of 582 autopsies, recorded during a 2-year study period (29 men, 7 women; age 56.3 ± 11.7). CACS was 0-10 in 5 cases (5 men, 44.8 ± 13.7), 11-100 in 8 cases (6 men, 2 women, 53.1 ± 7.7), 101-400 in 13 cases (11 men, 2 women, 57.4 ± 9.6), and > 400 in 10 cases (9 men, 1 woman, 63.1 ± 11.9). Coronary thrombosis was found in 28 cases, histologically identified as plaque erosions in 6 cases and as plaque ruptures in 22 cases. Statistical analyses showed that CACS increases significantly with age (p-value < 0.05) and does not show significant correlation with gender, body weight, body mass index, and heart weight. CACS was significantly higher in plaque ruptures than in plaque erosions (p-value < 0.01). Zero or low CACS on unenhanced PMCT cannot exclude the presence of myocardial infarction related to ACAD. This paradoxical discrepancy between imaging and autopsy findings can be explained considering the histological aspect of fatal coronary plaques.

Keywords: Coronary artery calcium score; Coronary calcifications; Postmortem imaging; Sudden cardiac death.

Fig. 1

Measurement of CACS. Case of a 56-year-old man known for chronic ischemic disease. The total CACS was 5319. Image analysis was performed using the software Smartscore 4.0, running on the GE Advantage Windows Workstation. a When selecting a vessel name from the list, a separate calcium score is generated for each vessel, as well as a total calcium score. The color varies according to the vessel selected (in pink LAD, left ascending artery; in yellow LCX, left circumflex artery; in red RCA, right coronary artery). b Percentage of the calcifications for each scored vessel. c The graph shows the total CACS (blue square in the red circle) and places the patient into a percentile rank, based on the population database. Each colored line represents an age range. LMA-left marginal artery, LAD- left anterior descending, LCX- left circumflex artery, PDA- posterior descending artery

Fig. 2

Distribution of CACS as a function of the age (a), body weight (b), heart weight (c), and in different type of coronary plaques (d); E: erosion; R: rupture

Fig. 3

Coronary plaque erosion. A 30-year-old man complaining for some weeks of pain in the left arm and found dead at home. a PMCT without calcification on the proximal part of the anterior interventricular artery (red circle). b CACS for this case was zero. c Macroscopic view of a thrombosis on plaque of the proximal part of the left anterior descending artery. d Histologic slide showing a subocclusive thrombosis on an eroded plaque (H&E staining)

Fig. 4

Coronary plaque rupture. A 49-year-old woman found dead home, known for hypertension and obesity. a PMCT with some calcifications on the circumflex artery (red circle). b CACS was 115, above the reference value. c Histology of the circumflex artery showing the rupture of the plaque (blue arrow) and protrusion of the thrombotic material into the lumen (H&E staining). d Thrombotic material in the lumen of the circumflex artery, some calcifications are observed in the wall (H&E staining)