Dr. Sumeet Chugh of Cedars-Sinai Medical Center in Los Angeles started the Oregon Sudden Unexpected Death Study in 2002, when he was based at Oregon Health & Science University in Portland. A study tracking Portland-area sudden cardiac arrests has revealed a gene variant that may protect against the unpredictable and deadly problem.
Since 2002, researchers leading the Oregon Sudden Unexpected Death Study have gathered every relevant detail they can find on every case of sudden cardiac arrest that occurs in Multnomah County. In a new analysis, the researchers sequenced the genes of 424 cardiac arrest patients and compared them to sequences from 226 control subjects who had been diagnosed with coronary artery disease but never experienced a cardiac arrest.
A variation in a gene called GPC5 appeared to lower the risk of sudden cardiac arrest by about 15 percent. The gene directs the production of a cell-surface protein that is known to be produced at high levels in some heart and blood vessel tissues. It remains to be determined how the gene might change the heart's susceptibility to rhythm disturbance.
Researchers from Cedars Sinai Medical Center in Los Angeles, Oregon Health & Science University in Portland, and five other institutes published the findings in the journal PLoS ONE.
The authors point out some problems that need to be cleared up in the study. First, they say, it's not known whether the gene variation is significant in itself or just a marker that happens to reside on the same stretch of chromosome near a gene that really plays a role. Confirmation of the protective effect will require replication of the findings in a different population, they say.
As it stands, about 90 percent of cardiac arrest sufferers never regain consciousness. Researchers leading the Oregon study hope to find clues that may lead to ways to improve survival. Since the study began, it has produced several eye-opening results.
Contrary to long-held assumptions, vigorous physical activity seldom seems to trigger cardiac arrest. An analysis of 300 cases in the Oregon study found that many people were sleeping or engaged in light activities at the time of their cardiac arrest while vigorous exercise was a potential factor in only 5 percent of cases.
Women are about half as likely as men to show an important warning sign – decreased heart pumping ability – before cardiac arrest, suggesting that women at risk are probably less likely than men to receive protective implantable defibrillators.
Residents of poor neighborhoods face a much higher risk of sudden cardiac arrest than those in higher income areas, the Oregon study revealed in 2006.
SOURCE: OregonLive