Post-mortem CT: is coronary angiography required in the presence of a high coronary artery calcium score?

Impact of the COVID-19 pandemic on a post-mortem CT service for adult non-suspicious death

Due to the COVID-19 pandemic, the post-mortem computed tomography (PMCT) service was expanded from three to seven cases per day to help mortuary services and avoid invasive autopsy. Additional targeted angiography and pulmonary ventilation procedures were stopped and triage rules relaxed to allow more indications to be scanned, including those requiring toxicology. A service evaluation was performed for the first 3-months of the COVID-19 pandemic compared to the equivalent period the previous year to study the impact of these changes. It was found that, despite the increase in deaths regionally, coronial referrals remained about 100 per month, a reduction in referral rate. The number undergoing PMCT rose from 28% to 74% of cases. Turnaround time remained the same. For cases triaged to PMCT, the need for subsequent autopsy increased from 7.9% to 15.8%. No significant changes were seen in diagnosis rates, including cardiac or respiratory. There was an increase in patients with coronary death without severe coronary calcification who underwent autopsy after PMCT. These may have been diagnosed by targeted coronary angiography. Fifty-three cases requiring toxicology/biochemistry had PMCT, with 38 having PMCT only. In 8/11 (72.7%) cases with normal PMCT and toxicology as the key diagnostic test, autopsy was performed prior to results. This suggests the pathology team were reluctant to risk an "unascertained" outcome. This study shows that it is possible to increase PMCT services by widening referral criteria and by limiting the use of enhanced imaging techniques, without significantly changing diagnosis rates of key diseases; however, selectively restarting targeted angiography may help avoid autopsy in some cases.

Postmortem coronary artery calcium score in cases of myocardial infarction

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.