BOSTON People who already face a high possibility of sudden death because their largest artery has developed a detour have an even greater risk of death if the detour becomes partially clogged, researchers said on Wednesday.
The finding, published in the New England Journal of Medicine, may help physicians make better decisions in treating patients whose aorta has parallel pathways for the blood flowing from the heart to the abdomen. The aorta is the large blood vessel arising from the left ventricle of the heart that brings oxygen-rich blood to the body.
Having a aorta detour is always dangerous. It killed actor John Ritter in 2003, and 10,000 Americans develop a tear in the aorta each year.
Today, most doctors decide whether to recommend surgery based on the size of the detour alone.
"Once it gets bigger than the diameter of a pop can, most surgeons will want to operate on those patients because of the risk of rupture and death," said cardiologist Dr. Thomas Tsai of the University of Michigan Medical Center, who led the study.
"But we don't know, beyond the size, if there are any other features that might predict which one of those patients needs the operation," he said.
To find out, Tsai's team evaluated the cases of 201 people with so-called type B acute aortic dissection. Three quarters of such patients are sent home with pills for cholesterol and blood pressure.
"Mortality is high after discharge from the hospital, with nearly one in four patients dying within 3 years," they concluded.
But they also found that the risk varied according to the characteristics of the problem.
In about 57 percent of the patients, the parallel pathway carried blood as freely as the aorta itself. That was the best-case scenario. Nearly 14 percent died within three years.
In nearly 10 percent of the people studied, the detour had completely clotted up. Nearly 23 percent of them were dead within three years.
But when there was a partial blockage of the detour, as was seen in the remaining patients, the risk of sudden death over three years was 32 percent, possibly because the partial blockage produced higher pressures in the aorta, increasing the risk of a tear.
Surgery to correct the problem carries risks. Tsai said in a telephone interview that doctors don't automatically operate unless they find that the problem occurs in the portion of the aorta that feeds blood to the brain.
But this study looked at cases where the detour occurred further down the line, after the aorta has taken a turn and is diving toward the belly.
"This arms the physician with information to decide if it may be best to be more aggressive," he said.