By AMERICAN HEART ASSOCIATION NEWS
Editor’s note: This is one in a series of Cardiovascular Genome-Phenome Study Discovery grants to speed personalized treatments and prevention for heart disease.
A hereditary heart disorder that strikes children or young adults who seem otherwise healthy is getting a deeper look, as researchers look for a way to detect the sometimes fatal condition in people without symptoms.
At least several thousand children and young adults die every year because of long QT syndrome, according to Brian Delisle, Ph.D., the study’s lead investigator.
“It’s not difficult to treat, but it can be difficult to diagnose before a deadly arrhythmia occurs,” said Delisle, an associate professor of physiology at the University of Kentucky in Lexington.
When the heart contracts, it emits an electrical signal that can be recorded on an electrocardiogram in the form of a characteristic waveform. The different parts of the waveform are designated by the letters P, Q, R, S and T. The Q-T interval represents the time for electrical activation of the ventricles, the lower chambers of the heart. If the Q-T interval takes longer than normal, it’s called a prolonged Q-T interval.
Delisle, who is conducting research funded by the American Heart Association in partnership with Geisenger Health System and Michael Murray, M.D., wants to improve diagnostic testing for LQTS and other inherited arrhythmia syndromes.
Delisle is among 10 researchers each recently awarded $160,000 to study new ways to individualize the treatment and prevention of heart disease. The grants, funded by AstraZeneca, probe three areas: heart failure, “good” HDL cholesterol and predicting cardiovascular disease.
“Many times people don’t know they have long QT syndrome until syncope (fainting), sudden death or some other tragic event, so the goal is to identify people with long QT syndrome before those tragic events occur,” Delisle said. “People look like they’re in really good health. It’s like a bolt of lightning.”
But, he said, the risk of sudden death from LQTS decreases dramatically when diagnosed and treated properly with medications such as beta blockers that slow the heart rate.
Delisle and Murray’s teams aim to identify possible LQTS-causing mutations from a genetic biobank that stores blood and other samples for research. They’ll comb through 30,000 patient sequences to look for mutations in the genes of patients 18 and older.
“We have the genetic information on many, many people, so we’re able to look for the disease in people who haven’t yet presented with any symptoms,” Delisle said.
Once they identify at-risk patients, researchers can test family members to see if they have LQTS. Delisle said if someone has the disease, there’s a 50 percent chance they could pass it on.
“What’s good about this disease is that once we identify a patient, it’s treatable,” he said.