Lauri Holmström’s research while affiliated with University of Oulu and other places

Background Hypertrophic cardiomyopathy is a common cause of non-ischaemic sudden cardiac death (SCD). Left ventricular hypertrophy (LVH) without cardiomyopathy-related myocardial disarray is a common autopsy finding and is often associated with prior hypertension in SCD subjects. Our aim was to investigate novel rare gene variants among SCD subjects with presumably hypertension-related LVH and myocardial fibrosis at autopsy. Methods Whole exome sequencing was used to study rare variants (minor allele frequency<0.005) estimated to be deleterious in 96 non-ischaemic SCD subjects with presumably hypertension-related LVH and myocardial fibrosis. Associations of the identified variants with cardiac disease endpoints were replicated in the Finnish national genetic study (FinnGen) dataset. Results 18 variants were estimated likely to affect protein function and 14 of these were associated with cardiomyopathies, heart failure, conduction abnormalities, hypertension and/or cardiac arrest in Finnish population (FinnGen). Three of the variants were classified as pathogenic or likely pathogenic. These include the splice site variant NM_000449.3:c.234-1G>A in regulatory factor X5 and frameshift variants NM_000449.3:c.234-1G>A in dehydrogenase/reductase 7C and NM_015873.3:c.1164del in villin like. Conclusions We identified rare deleterious variants associated with LVH in SCD subjects. Several of the identified rare variants associated with cardiovascular endpoints including heart failure, cardiomyopathies, cardiac arrest and hypertension in general population.

Myocardial fibrosis is a common finding in victims of sudden cardiac death (SCD). Whole exome sequencing was performed in 127 victims of SCD with primary myocardial fibrosis as the only pathological finding. These cases are derived from the Fingesture study which has collected data from autopsy-verified SCD victims in Northern Finland. A computational approach was used to identify protein interactions in cardiomyocytes. Associations of the identified variants with cardiac disease endpoints were investigated in the Finnish national genetic study (FinnGen) dataset. We identified 21 missense and one nonsense variant. Four variants were estimated to affect protein function, significantly associated with SCD/primary myocardial fibrosis (Fingesture) and associated with cardiac diseases in Finnish population (FinnGen). These variants locate in cartilage acidic protein 1 (CRATC1), calpain 1 (CAPN1), unc-45 myosin chaperone A (UNC45A) and unc-45 myosin chaperone B (UNC45B). The variants identified contribute to function of extracellular matrix and cardiomyocytes. Graphical Abstract

Background. Sudden cardiac death (SCD) remains a major cause of death despite progress in prevention and intervention of cardiac diseases. The most common cause of non-ischemic SCD in young individuals in Northern Finland is primary myocardial fibrosis (PMF). Methods. Fingesture study consists of 5,869 systematically autopsied subjects with SCD from Northern Finland collected from 1998 to 2017. Nonischemic etiology was the cause of SCD in 1477 (25%) subjects out of which primary myocardial fibrosis was the cause of SCD in 184 (12%) subjects (65% men, median age 55±16 years). Medico-legal autopsies in PMF subjects showed no other noncardiac organ changes or prior diseases that could have caused myocardial fibrosis detected at gross dissection and histological analyses. We examined the ante mortem ECG and medical history of the subjects to discover preceding symptoms and ECG changes. Results. Prior health care contact in electronic health record system was found for 89 (48%) subjects and ECG was available for 52 (28%) subjects; 20 subjects both medical history and ECG were available. We observed that transient loss of consciousness (TLOC) was the most common symptom recorded and was reported by 33 (37%) subjects. ECG was abnormal in 38 (73%) subjects. Fragmented QRS (fQRS) complex was found in 26 (50%) subjects. Other ECG findings were prolonged QTc (>450ms in men and >470ms in women) in 10 (19%), T-inversions in 4 (8%), pathological Q-waves in 3 (6%), and prolonged QRS (> 110 ms) in 3 subjects. Vast majority, 87% of subjects had either TLOC or abnormal ECG. Only 7 subjects with ECG or ERS history available had normal ECG and did not have previous TLOC. Conclusions. Most subjects with PMF had abnormal ECG or previous TLOC. The results suggest that the combination should generate careful cardiovascular examination in order to detect underlying myocardial disease and possibly prevent SCD.

Background There has been some controversy about the day-of-the-week (septadian) variation of unexpected sudden cardiac death (SCD). Methods We evaluated the incidence of unexpected SCD on different days of the week in a consecutive series of 5869 SCD victims from Northern Finland [the FINGESTURE study (Finnish Genetic Study of Arrhythmic Events)]. As it is mandatory in Finland, a medico-legal autopsy was performed on all unexpected sudden death victims. The autopsies were performed between the years 1998–2017. Results The mean incidence of unexpected SCD was higher at weekends (during the days from Friday to Sunday, peaking on Saturday) than during the days from Monday to Thursday (8.54 ± 0.72 vs. 7.22 ± 0.19 SCDs per day of the week per 100,000 inhabitants per year, p < 0.001). Regardless of sex or ischemic versus non-ischemic etiology of SCD, the distribution of the occurrence of SCD among the days of the week was similar compared with the whole SCD cohort. Conclusion The incidence of unexpected SCD was highest at weekends (during the days from Friday to Sunday, peaking on Saturday).

Background Sudden cardiac death (SCD) is a significant mode of death causing 15-20% of all deaths in high-income countries. Coronary artery disease (CAD) is the most common cause of SCD in both sexes, and SCD is often the first manifestation of underlying CAD in women. This case-control study aimed to determine the factors associated with SCD due to CAD in women. Methods The study group consisted of women with CAD-related SCD (N = 888) derived from the Fingesture study conducted in Northern Finland from 1998 to 2017. All SCDs underwent medicolegal autopsy. The control group consisted of women with angiographically verified CAD without SCD occurring during the 5-year-follow-up (N = 610). To compare these groups, we used medical records, autopsy findings, echocardiograms, and electrocardiograms (ECGs). Results Subjects with SCD were older (73.2 ± 11.3 vs. 68.8 ± 8.0, p < 0.001) and were more likely to be smokers or ex-smokers (37.1% vs. 27.6%, p = 0.045) compared to control patients. The proportion of subjects with prior myocardial infarction (MI) was higher in controls (46.9% vs. 41.4% in SCD subjects, p = 0.037), but in contrast, SCD subjects were more likely to have underlying silent MI (25.6% vs. 2.4% in CAD controls, p < 0.001). Left ventricular hypertrophy (LVH) was more common finding in SCD subjects (70.9% vs. 55.1% in controls, p < 0.001). Various electrocardiographic abnormalities were more common in subjects with SCD, including higher heart rate, atrial fibrillation, prolonged QTc interval, wide or fragmented QRS complex and early repolarization. The prevalence of Q waves and T inversions did not differ between the groups. Conclusions Underlying LVH and previous MI with myocardial scarring are common and often undiagnosed in women with CAD-related SCD. These results suggest that untreated CAD with concomitant myocardial disease is an important factor in SCD in women.