SAN FRANCISCO – Genetic testing for the cardiomyopathies and channelopathies has entered the realm of daily clinical practice with the release of comprehensive joint guidelines by the Heart Rhythm Society and the European Heart Rhythm Association.
"These are not research or investigational tests any longer," Dr. Michael J. Ackerman declared in presenting the new guidelines at the annual scientific sessions of the Heart Rhythm Society.
Dr. Michael J. Ackerman
Genetic tests are commercially available for the 13 distinct entities detailed in the guidelines. The new guidelines recommend provision of genetic counseling, including consideration of genetic testing, for all patients and relatives having these familial heart diseases, said Dr. Ackerman, professor of medicine, pediatrics, and pharmacology at the Mayo Clinic in Rochester, Minn.
Because the genetics of familial heart disease is a fast-moving field and at present relatively few cardiologists are up to speed, the guidelines recommend that pretest counseling, genetic testing, and interpretation of test results be conducted at centers of excellence that are experienced in the genetics and family-based management of heritable arrhythmia syndromes and cardiomyopathies, noted Dr. Silvia G. Priori, who together with Dr. Ackerman cochaired the international, 21-member, expert panel responsible for the guidelines.
"Genetic disease experts are not present in every state or medical school, but a major educational effort is being made in that direction. Many university cardiology departments are sending young people to train at centers of excellence," explained Dr. Priori of the University of Pavia (Italy).
The guidelines contain in-depth information on the diagnostic, prognostic, and therapeutic impact of genetic testing for five cardiomyopathies and six channelopathies. The guidelines also address the role of genetic testing in survivors of out-of-hospital cardiac arrest, as well as postmortem testing in the setting of sudden death.
The cardiomyopathies covered in the guidelines are hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy/arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, and left ventricular noncompaction cardiomyopathy.
Dr. Silvia G. Priori
The channelopathies included in the guidelines are long QT syndrome, short QT syndrome, Brugada syndrome, progressive cardiac conduction disease, catecholaminergic polymorphic ventricular tachycardia, and atrial fibrillation.
The benefits of genetic testing differ for the various conditions covered in the guidelines, Dr. Priori emphasized. Testing is not a one-size-fits-all solution. Take, for example, long QT syndrome: a genetic disease with an estimated incidence of at least 1 in 2,500 people and one of the most important causes of sudden death in young people, with a mean age of death of just 12 years. The comprehensive triple-testing for the KCNQ1, KCNH2, and SCN5A genes routinely recommended for long QT syndrome has a diagnostic yield of 80% and a signal-to-noise ratio of 19:1.
In marked contrast, the yield of genetic testing for atrial fibrillation remains unknown at present, as does the test signal-to-noise ratio. So the guidelines state that genetic testing is not indicated for atrial fibrillation at this time.
The full 76-page guidelines will be published in the August issues of HeartRhythm and Europace.
Dr. Ackerman and Dr. Priori disclosed that they both serve as consultants to multiple medical device and genetic test companies.