Consideration of left ventricular septal morphology using echocardiography in addition to genetic testing can nearly double the power to detect heritable hypertrophic cardiomyopathy, according to an article in the April issue of the Mayo Clinic Proceedings.

Currently genetic testing correctly detects the condition in only 40 percent of patients. But coupled with imaging information, the detection power of the test nearly doubles, to 79 percent, said Steve Ommen, MD, director of Mayo’s hypertrophic cardiomyopathy Clinic and co-lead investigator of the research team.

Hypertrophic cardiomyopathy is usually a hereditary condition. It affects 1 in 500 people and is the most common identifiable cause of sudden death in young people, particularly athletes. Genetic screening for mutations that cause the condition gives parents advance knowledge they can use to prepare for treatment, ranging from medication to defibrillator implantation, to surgery and lifelong medical surveillance for worsening symptoms.

“Our finding helps families two ways: short term and in the future, Ommen said. “In terms of the most immediate application, the echocardiographic shape of the heart can help physicians give families more meaningful and accurate information about the role of genetic testing for that specific family. In terms of the future, it presents a research opportunity to explore how and why this distinct trait of heart anatomy occurs - which hopefully will give us a better handle on hypertrophic cardiomyopathy all around and help us design interventions to prevent or correct this defect.”

In the current work, researchers examined distinct anatomical subtypes of septum morphology found largely in patients diagnosed after age 50 years.

The hearts of younger affected people generally lack a sigmoid ventricular septum. This variant has long been associated with a milder form of the disease. By comparison, reverse curvature of the ventricular septum dramatically alters the contours of the chamber. However, until the current era of genomic medicine brought the ability to link structural changes with specific gene activity, it was not clear that this distinctive structural feature was linked to specific mutations that cause the condition.

The researchers examined 382 unrelated patients over a four-year period, analyzing eight known hypertrophic cardiomyopathy-susceptibility genes. These eight genes comprise available clinical genetic testing. Blind to the genetic test results, researchers evaluated traditional medical exam data, including patient medical history, and anatomical and functional findings, such as blood pressure and echocardiography images.

In the final step, the researchers matched the gene screening results to traditional exam results and found a consistent correlation between septal morphology and the presence of cardiomyopathy-associated mutations. Regardless of age, if the sigmoid shape was present, the yield of the genetic test was 8 percent, compared with a yield of 79 percent when the shape was reverse curvature.