There are roughly around 300,000-350,000 cases of out-of-hospital sudden cardiac arrest deaths every year in the United States, and about one-third of those being in adults under the age of 60. As sudden cardiac arrest can become deadly if left unattended for more than a few minutes, a stronger understanding of genetic conditions is necessary to identify the risks associated with this fatal phenomenon. Recent studies conducted by researchers Stephanie L. Harris and Steven A. Lubitz, both of whom are affiliated with the Cardiovascular Genetics Program based in Massachusetts General Hospital, suggest that the passage of sudden cardiac arrest through genetics not only establish genetic susceptibility to sudden cardiac arrest, but recognize genetic mutations, genetic variants, and modifier genes as significant contributors to cardiac problems.
The topic of genetic predispositions is very complex and has many dimensions. One of the leading causes of cardiovascular mortality is of sudden cardiac arrest due to ventricular fibrillation. Although there’s a lack of understanding on the genetic predisposition to ventricular fibrillation, many genetic variants exist that are linked to sudden cardiac arrest due to ventricular fibrillation. (Tfelt-Hansen et al. 2016) Ventricular fibrillation is a type of arrhythmia that, according to the journal article Clinical and Genetic Evaluation After Sudden Cardiac Arrest (Lubitz et al. 2020), can be caused by genetic cardiovascular diseases that often go unnoticed. This study by the National Library of Medicine identified the cardiovascular disorders that increase susceptibility to sudden cardiac arrest and evaluated families after the event to collect data regarding the familial genetic testing. Previous studies by the National Library of Medicine (Charlotte et al. 2016) confirmed that typically people who do not exhibit prior symptoms of cardiovascular disease represent the greater number of sudden cardiac arrest cases due to ventricular fibrillation. Family history and the awareness of cardiovascular disorders can serve as predispositions to sudden cardiac arrest and must be taken into consideration.
A study conducted in by Stephanie L. Harris and Steven A. Lubitz, both of whom are affiliated with the Cardiovascular Genetics Program based in Massachusetts General Hospital (2020) addressed the process of genetic testing and how their results are incorporated into the care of individuals and relatives. This study explored the studies of current inherited cardiovascular conditions by breaking down their clinical features and genetic principles. The article begins by introducing a three hypothetical cases in which three individuals are subject to cardiovascular evaluation, each of which having apparent family history of sudden cardiac arrest or suspicion of. Following these cases, this article explores the inner workings of inherited cardiovascular diseases, genetic testing, various cardiac evaluations, and patient implications. The information within the article suggests the probability of inherited cardiovascular disease based on the degree of relative and number of variants.
The study reveals which forms of genetic testing are most effective in determining inherited cardiovascular disease based on factors such as evidence of familial disease, number of affected relative samples, or distinct phenotypes. At the end of the article, the same 3 hypothetical cases from the beginning are reproduced with appropriate diagnoses based on the various findings throughout the study. These studies ultimately prove that the most suitable approach for the examination of patient and family is done through clinical and genetic assessments. They examine the utility of current and prior genetic testing practices. These genetic testing practices include post-mortem genetic testing and next generation sequencing. The authors cite the authors of a variety of studies that examine the specifics of certain genetic testing methods, however, they do not address trends or public concerns or opinions.
The current gaps in knowledge have to do with the current technology we use to research genetic testing, and what we can use to improve genetic testing methods. This study is very specific to genetic evaluations, which includes genetic testing, background information on inherited cardiovascular disorders, and post-cardiac arrest assessments.There are a few limitations within their research that are made known. The study can improve in the future if more experiments are executed that consider multiple samples together. When it comes to evidence of familial disease through genetic testing, or more specifically genome and exome sequencing, it is assumed that we would receive more effective results if more samples are being examined. However, a flaw that the author acknowledges in this study is that the overall advantage of consistent genome and exome sequencing procedures is not established. In other words, at the moment it is unknown how productive this routine practice will be in the grand scheme of focused genetic testing. Nonetheless, this study is still valid as the author analyzes many different forms of genetic testing as well.
More recently, risk stratification is another subtopic as many studies are searching for means of prevention. Despite the advancement in technology, there still exists ethical problems with the process of cardiopulmonary resuscitation (CPR). Because the causes of sudden cardiac arrest are so dynamic and complex, and every individual’s cases are different, this requires bigger numbers of control groups research and experimental purposes. The need for lengthy, extensive research to improve prevention for this major health concern spurs controversy. Since emergency treatment options are not always accessible, most treatments that are merely clinical recommendations do not suffice.
The importance of sudden cardiac arrest research lies within the fact that genetic testing has proved applicable in determining unexplained cases of sudden cardiac arrest. Disease severity, including the risk of sudden cardiac arrest, depend on factors that could remain unknown to us unless we receive a diagnosis and treatment early on. Individuals may have underlying medical conditions that put them at risk for sudden cardiac arrest due to ventricular fibrillation. Due the increasing amount of information about human genetics and how to identify genetic material through DNA sequencing, this information provides a significant opportunity to improve care. Although the occurrence of sudden cardiac arrest due to ventricular fibrillation is more common with middle-aged individuals, awareness of familial inheritance can save lives in the future. The more we know about the modification of genetics, the more we know about how to treat individuals who could be predisposed to sudden cardiac arrest.
References
Glinge, Charlotte. 2016. Epidemiology and Genetics of Ventricular Fibrillation during Acute Myocardial Infarction. Journal of Geriatric Cardiology: JGC, vol. 13, no. 9, pp. 789– 97. PubMed, https://doi.org/10.11909/j.issn.1671-5411.2016.09.006.
Harris, Stephanie L., and Steven A. Lubitz. 2020. Clinical and Genetic Evaluation after Sudden Cardiac Arrest. Journal of Cardiovascular Electrophysiology, vol. 31, no. 2, pp. 570– 78. PubMed, https://doi.org/10.1111/jce.14333.
Baudhuin, Linnea M. 2017. Technical Advances for the Clinical Genomic Evaluation of Sudden Cardiac Death: Verification of Next-Generation Sequencing Panels for Hereditary Cardiovascular Conditions Using Formalin-Fixed Paraffin-Embedded Tissues and Dried Blood Spots. Circulation: Cardiovascular Genetics, vol. 10, no. 6, p. e001844. DOI.org (Crossref), https://doi.org/10.1161/CIRCGENETICS.117.001844.
Bagnall, Richard D. 2018. Whole Genome Sequencing Improves Outcomes of Genetic Testing in Patients With Hypertrophic Cardiomyopathy. Journal of the American College of Cardiology, vol. 72, no. 4, pp. 419–29. DOI.org (Crossref),
https://doi.org/10.1016/j.jacc.2018.04.078.
Wijeyeratne, Yanushi D., and Elijah R. Behr. 2017. Sudden Death and Cardiac Arrest without Phenotype: The Utility of Genetic Testing. Trends in Cardiovascular Medicine, vol. 27, no. 3, pp. 207–13. DOI.org (Crossref), https://doi.org/10.1016/j.tcm.2016.08.010.
Lahrouchi, Najim, 2017. Utility of Post-Mortem Genetic Testing in Cases of Sudden Arrhythmic Death Syndrome. Journal of the American College of Cardiology, vol. 69, no. 17, pp. 2134–45. PubMed, https://doi.org/10.1016/j.jacc.2017.02.046.
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