A research group in clinical cardiology led by Professor Heikki Huikuri and Associate Professor Juhani Junttila has collected material on persons who have died of sudden cardiac arrests over the past 20 years. Cooperation has taken place with researchers of forensic medicine, among others. So far the researchers have collected material on more than five thousand sudden death subjects in the north of Finland.
A topic of interest from the very beginning has been a phenomenon in which a sudden cardiac arrest is linked with the accumulation of deviant connective tissue, or fibrosis, in the cardiac muscle i.e. myocardium.
In material collected by the researchers over the years, myocardial fibrosis was the cause of death of 145 persons, a significant portion of whom were under 40 years of age.
The research group recently reported on the discovery of gene mutations, which probably explains many of the sudden deaths. Genetic mutations had been found in more than a quarter of the deceased who had been studied. The recent findings were published in the prestigious scientific journal Circulation.
Several different mutations in the background
The most significant genetic mutations were located in genes producing important structural proteins for the heart. Different mutations in the same genes had previously been seen to cause cardiac diseases that expose the heart to arrhythmia.
"This is the first genetic study linked with sudden deaths in which the genetic background of different cardiac diseases are shown to be mixed together, causing different discoveries in the myocardium," Junttila says. "Fibrosis is also detected in traditional myocardial diseases, and fibrosis may be a common factor in all myocardial diseases which expose people to sudden death."
According to Junttila the role of genetic factors in myocardial fibrosis should always be considered, even if no other structural deviations typical of hereditary myocardial disease are to be seen.
Sudden deaths can be prevented
Next the study will continue with MRI scans of close relatives of those with the genetic anomaly. The purpose is to get an understanding of the mechanisms that lead to cardiac diseases and to develop ways of preventing fibrosis from accumulating in the heart.
"Our aim is to identify patients in a risk group already at an early stage and to prevent sudden deaths in the future," Junttila says. For instance, an implantable defibrillating pacemaker would be an effective preventative treatment, but according to Junttila, the most important thing now would be to identify the individuals who need such a device.
Finally Junttila observes that myocardial fibrosis, which leads to sudden death, is a rare occurrence and that not all genetic anomalies are fatal, even if they might expose a person to myocardial disease.
Fibrosis diseasome is one of the research profiling areas of the University of Oulu. The research gets funding from the Academy of Finland.
Associate Professor Juhani Junttila
Research Unit of Internal Medicine
Faculty of Medicine, University of Oulu
Research article: Junttila M.J. et al. Primary Myocardial Fibrosis as an Alternative Phenotype Pathway of Inherited Cardiac Structural Disorders. Circulation. 2018 Jun 19;137(25):2716-2726. Link to the article.
Last updated: 3.7.2018