Applying the Seaport criteria to 93 autopsy hearts yielded 36 diffuse, 27 multifocal, and 2 focal myocarditis, plus 28 lymphocytic infiltrates of unknown significance, according to a recent study.
Researchers evaluated the practical applicability of the Seaport criteria for diagnosing lymphocytic myocarditis in autopsy hearts. In a retrospective review of 93 forensic autopsies with lymphocyte-predominant myocardial inflammation, the criteria were applied to reclassify the extent of inflammation and to compare results with recorded causes of death. The study, published in Cardiovascular Pathology, also assessed adherence to minimum technical sampling requirements and the content of original histology reports.
The Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology finalized the Seaport criteria in March 2025 for non-biopsy specimens. The cohort included cases in which myocarditis was listed as the cause of death (45), an unascertained cause of death (34), or drug toxicity (14). Most cases met the minimum sampling standard of at least six full-thickness ventricular sections across five or six blocks (76 of 93, or 82 percent). Pediatric cases were disproportionately noncompliant, reflecting smaller heart size and fewer blocks despite sampling of the prescribed regions. A mid-ventricular short-axis section was retained in 58 cases, and additional tissue was submitted in 13.
Among deaths attributed to myocarditis, 9 were multifocal and 3 were lymphocytic infiltrates of unknown significance (LIUS); in the unascertained cohort, diagnoses included 1 diffuse, 16 multifocal, 2 focal, and 15 LIUS (with one focal case adjacent to the atrioventricular node and LIUS elsewhere). In drug-related deaths, diagnoses included 2 diffuse, 2 multifocal, and 10 LIUS.
Original histology narratives varied in terminology and detail. Only a minority documented the presence or absence of myocyte injury, and descriptions of extent were often brief and imprecise. Evidence of chronicity was explicitly described in three cases. Classification was performed using the highest applicable grade when prerequisites were met. Recognition of myocyte injury was sometimes difficult and, in dense infiltrates, could be obscured.
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