Cardiology Heart Beat Concept

Are you at risk of sudden cardiac arrest? Condition kills 9 out of 10 victims

New research could enable families around the world to discover if they carry genetic mutations that cause sudden cardiac arrest, a serious and usually fatal medical emergency.

New screening test for people at risk of sudden cardiac arrest

Many people think that cardiac arrest and heart attack are the same things, but they are actually different conditions. In sudden cardiac arrest, the heart stops working abruptly and stops beating unexpectedly, while a heart attack occurs when the blood supply to the heart is blocked.

Both are serious conditions, but 70%-90% of sudden cardiac arrest victims die before reaching the hospital. According to the CDC, cardiac arrest is a public health problem with a widespread incidence and serious consequences for human health and well-being. About 357,000 people experienced out-of-hospital cardiac arrest (OHCA) in the United States in 2015.

Now, new research from the Victor Chang Cardiac Research Institute may enable families around the world to discover whether they carry genetic mutations that cause sudden cardiac arrest — a serious condition that kills 9 out of 10 victims.

Researchers at the Institute have developed a new electrical test that can screen hundreds of gene mutations to detect the exact mutations that harm the hearts of people suffering from hereditary heart disease, which can cause sudden death.

The breakthrough is a major step forward in the[{” attribute=””>accuracy and precision of genetic testing that has profound implications for not only inherited heart disorders but a wide range of neurological conditions, and muscle and kidney diseases.

Professor Jamie Vandenberg, who led the research published in two back-to-back papers in the American Journal of Human Geneticssays: “It is mainly young people with otherwise healthy hearts who die from these hereditary heart conditions and although the number is small, the consequences are long-lasting.

“When a person dies young, in the prime of life, it is much more than just the death of one person. The impact is felt on the family and their friends and it lasts forever.”

Fellow author Dr. Chai-Ann Ng, of the Victor Chang Cardiac Research Institute, says being able to identify these dangerous mutations will prevent people from dying of sudden cardiac arrest and ensure more people receive treatment for this life-threatening condition.

Jamie Vandenberg

Professor Jamie Vandenberg operates the Syncropatch of the Victor Chang Cardiac Research Institute. Credit: Victor Chang Cardiac Research Institute

“If you can isolate the mutation and identify the groups at risk, there are lifestyle changes people can make, as well as taking beta blockers or even using a defibrillator. Family members can also get tested,” says Dr. Ng.

“Genetic sequencing has revealed that we all contain a wide variety of genetic variants, but we have not always been able to determine whether these variants are dangerous or not, just that they are different.

“So when genes are currently being tested, the clinical genetics lab can tell the patient: There is a variant, but we don’t know if it increases your risk of cardiac arrest. That creates an enormous amount of fear, not only for the patient, but also for the rest of the family who may also have inherited the mutation. We can now remove that uncertainty, which is a major development.”

Key Statistics

  • inherited arrhythmia conditions account for more than half of all initially unexplained cases of sudden cardiac death in young people.
  • About 20,000 Australians suffer from a cardiac arrest outside a hospital every year. Only 10% of people survive a cardiac arrest outside the hospital.

Professor Vandenberg’s team investigated variants in genes that code for ion channels, proteins that control the movement of electrical signals between cells. Most genetic conditions that lead to an increased risk of sudden cardiac arrest are caused by these mutations.

Jamie Vandenberg team

Professor Vandenberg’s team at the Victor Chang Cardiac Research Institute. Credit: Victor Chang Cardiac Research Institute

Key findings

  • In the first study, they developed a fast and accurate electrical test that assesses variants in an ion channel gene that causes an inherited heart rhythm disorder called Long QT Syndrome type 2. They are now classifying all known variants in this gene to determine which are benign and which are dangerous and will upload the findings to a massive genetic database that will be accessible to clinicians around the world.
  • The test they developed could easily be adapted to test other ion channel genes – not just genes linked to sudden cardiac arrest, but a wide variety of other diseases that include neurological, kidney and muscle disorders.
  • In the second paper, Professor Vandenberg and his team collaborated with Dr. Kroncke of Vanderbilt University Medical Center to develop a new method based on high-throughput genome sequencing technology. This allows them to estimate the impact of each possible missense variant in KCNH2 within one to two years, which amounts to approximately 22,000 variants.

Influence

Professor Vandenberg says: “We hope that within five years, once someone has tested their genes or sequenced their genomes, they will immediately discover whether their variant is dangerous.

“It’s incredible to think that we can screen and diagnose family members not just across Australia but anywhere in the world. Ultimately, this genetic database will reduce the number of cardiac arrests and deaths from genetic disorders.

“In the short term, cardiology patients at risk of sudden death will benefit the most. But in the longer term, the research could be adapted to assess each of about 400 different ion channel genes in the human genome that are linked to a wide variety of neural, muscle and kidney problems.”

References:

“A calibrated functional patch clamp assay to aid the interpretation of clinical variants in KCNH2-related long QT syndrome” by Connie Jiang, Ebony Richardson, Jessica Farr, Adam P. Hill, Rizwan Ullah, Brett M. Kroncke, Steven M. Harrison, Kate L. Thomson, Jodie Ingles, Jamie I. Vandenberg, and Chai- Ann ng, June 9, 2022, American Journal of Human Genetics
DOI: 10.116/j.ajhg.2022.05.002

“A massively parallel assay accurately distinguishes between functionally normal and abnormal variants in a hotspot domain of KCNH2” by Chai-Ann Ng, Rizwan Ullah, Jessica Farr, Adam P. Hill, Krystian A. Kozek, Loren R. Vanags, Devyn W. Mitchell, Brett M. Kroncke, and Jamie I. Vandenberg, June 9, 2022, American Journal of Human Genetics
DOI: 10.1016/j.ajhg.2022.05.003


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