Sudden cardiac death. Histological features of myocardial disease
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
Auditorium 10 of Oulu University Hospital
Topic of the dissertation
Sudden cardiac death. Histological features of myocardial disease
Doctoral candidate
Licentiate of Medicine Henrik Appel
Faculty and unit
University of Oulu Graduate School, Faculty of Medicine, Research Unit of Biomedicine and Internal Medicine
Subject of study
Cardiology
Opponent
Docent Ville Kytö, University of Turku, Turku University Hospital
Custos
Professor Juhani Junttila, University of Oulu, Oulu University Hospital
Histological features of myocardial disease in sudden cardiac death
Myocardial fibrosis, excessive accumulation of extracellular matrix proteins in the myocardium, is a common autopsy finding among sudden cardiac death subjects. Although postmortem examination allows the opportunity to identify the etiology of myocardial fibrosis, various autopsy-based studies have reported findings of myocardial fibrosis of unknown cause. This nonspecific myocardial fibrosis was later referred to as primary myocardial fibrosis (PMF), which is the leading cause of non-ischemic sudden cardiac death in subjects under 40 years of age in Northern Finland. Although fibrosis is known to increase the risk of life-threatening arrhythmias, recent studies suggest that intramyocardial adipose tissue may contribute more significantly to the development of these fatal arrhythmias than previously thought.
In this thesis, we examined subjects who died of sudden cardiac death between 1998 and 2017 in Northern Finland. Myocardial tissue samples were collected as part of the routine forensic protocol. The most representative samples were stained to visualize specific tissue structures or cell types and were then digitized to enable analysis using microscopy software.
In this thesis, we found that the histopathological features of PMF were heterogeneous, and fibrotic lesions affected the whole myocardium. These variable findings might reflect the possible mechanisms of PMF or different disease stages therein. Moreover, we found that intramyocardial adipose tissue deposits were present in 39% of the ischemic subjects and were more often present in subjects with prior myocardial infarction scar, and the body mass index were higher among subjects with than without intramyocardial adipose tissue. Obesity might influence the adverse remodeling of the ischemic myocardium and intramyocardial adipose tissue may contribute to sudden cardiac death.
Our studies provided novel information on the previously unknown histology of primary myocardial fibrosis and increased the knowledge of intramyocardial adipose tissue deposits in ischemic heart disease leading to sudden cardiac death. Moreover, the findings of this thesis underline the importance of histological analyses as a part of medicolegal autopsy.
In this thesis, we examined subjects who died of sudden cardiac death between 1998 and 2017 in Northern Finland. Myocardial tissue samples were collected as part of the routine forensic protocol. The most representative samples were stained to visualize specific tissue structures or cell types and were then digitized to enable analysis using microscopy software.
In this thesis, we found that the histopathological features of PMF were heterogeneous, and fibrotic lesions affected the whole myocardium. These variable findings might reflect the possible mechanisms of PMF or different disease stages therein. Moreover, we found that intramyocardial adipose tissue deposits were present in 39% of the ischemic subjects and were more often present in subjects with prior myocardial infarction scar, and the body mass index were higher among subjects with than without intramyocardial adipose tissue. Obesity might influence the adverse remodeling of the ischemic myocardium and intramyocardial adipose tissue may contribute to sudden cardiac death.
Our studies provided novel information on the previously unknown histology of primary myocardial fibrosis and increased the knowledge of intramyocardial adipose tissue deposits in ischemic heart disease leading to sudden cardiac death. Moreover, the findings of this thesis underline the importance of histological analyses as a part of medicolegal autopsy.
Created 22.10.2026 | Updated 23.10.2026