Mortality Risk Established for Genetic Heart Rhythm Disorders

Sudden Cardiac Death risk estimated for Inherited Heart Arrhythmias

(RxWiki News) Investigators have found a method for predicting the mortality risk among patients with inherited heart rhythm disorders. The finding is also expected to help doctors know when to screen and treat family members.

Patients with inherited heart arrhythmias are susceptible to sudden cardiac death following severe heart rhythm disturbances.

However, the risk level for those without symptoms such as fainting was unknown prior to the study.

"Talk to your doctor about family history of heart arrhythmia."

Dr. Eline A. Nannenberg, lead researcher of the study and a clinical geneticist at the Academic Medical Centre in The Netherlands, said such research would aid with knowing the appropriate time to screen and treat those with varying gene mutations.

Researchers used Dutch archives dating back to 1811 to reconstruct family trees for patients with different types of heart arrhythmias. They compared the mortality statistics in 266 individuals who carried a gene mutation linked to arrhythmia, 904 family members with a 50 percent of having the mutation, and the general population.

Investigators were able to identify age ranges during which the risk of dying was increased in those with the rare genetic mutation and their family members, even if they had not yet been diagnosed or treated for the condition.

They discovered that in individuals with long QT syndrome, which is related to sudden infant death syndrome, the mortality risk was high throughout childhood, between the ages of 1 and 19, but particularly through age 10 for one mutation called LQTS1.

However for two other mutations causing the syndrome -- LQTS2 and LQTS3 -- the risk of dying does not increase significantly until teen years or adulthood.

For a condition called SCN5a-overlap syndrome, in which the SCN5A gene mutation affects the way cardiac cells respond to the heart’s internal electrical current, the risk of dying increases at age 5, and remains significant between the ages of 10 and 59, with a peak between 20 and 39.

Among patients with catecholaminergic polymorphic ventricular tachycardia, which often causes fainting during exercise or strong emotions, death risk was highest from ages 20 to 39.

Patients with Brugada syndrome, an arrhythmia disorder that leads to fainting and a rapid heart rhythm that can cause sudden cardiac death, were most at risk of dying between ages 40 and 59, and were mostly men.

“We have to be careful not to draw conclusions for families with arrhythmias caused by different mutations,” Dr. Nannenberg said. “However, this new data can guide screening. In LQTS1, we advise starting genetic and heart screening of first-degree family members (children, siblings, parents) at a very young age.”

The study was recently published in Circulation: Cardiovascular Genetics, a journal of the American Heart Association.