Study shows rare good news about aortic dissection

One of the largest studies examining aortic dissection suggests a simple blood test can help with diagnosis


Kim Eagle, M.D.

ANN ARBOR, Mich. - The death of actor John Ritter, who collapsed on the set of his sitcom in 2003, the victim of an aortic dissection, set off rounds of questions: How could a seemingly healthy man die from heart disease? Was there a way to predict that he faced such a catastrophic event?

A study published today in Circulation gives clues to identifying patients with aortic dissection ­- a tear in the largest blood vessel of the body - using a simple blood test. It's rare good news about a lethal disease that affects 10,000 Americans a year, and is often linked to high blood pressure and genetic disorders.

In a study performed by an international team led by specialists at the University of Michigan Cardiovascular Center, patients suspected of having AD had dramatically elevated results on the D-Dimer blood test, which is commonly used to rule out dangerous blood clots.
Combined with other blood testing, routine use of D-Dimer could help distinguish patients with an AD from those experiencing an acute heart attack. Treatments for the two conditions are totally different, and rapid diagnosis can be life-saving for AD patients.
"Because aortic dissection is a disease that's rare and symptoms can mimic those of a heart attack, it is often overlooked or misdiagnosed," says senior investigator  Kim Eagle, M.D , director of the U-M Cardiovascular Center and the Albion Walter Hewlett Professor of Internal Medicine. "This test will change how we manage patients with sudden chest or back pain presenting to our emergency departments."
Previous U-M studies have shown a high survival rate for patients who live through the initial crisis and survive emergency surgery and hospitalization for AD. 
Further, the study suggests that D-dimer could be useful in settings where doctors do not have ready access to computed tomography, magnetic resonance imaging and other imaging tests that could rule out aortic dissection.
Eagle and lead author Toru Suzuki, M.D., of the University of Tokyo, conducted the research with colleagues from the International Registry of Aortic Dissection, or IRAD, using data on patients treated at 21 medical centers in 11 countries. U-M is the coordinating center for IRAD.
IRAD pools data on treatment and patient outcomes for this relatively rare condition, to allow researchers to draw more scientific conclusions based on larger amounts of data than can be gathered at a single center.
The new study is one of the largest to examine the use of blood testing in AD and evaluated 87 patients with acute aortic dissection and compared them with patients with other causes of chest or back discomfort. A total of 220 patients were enrolled.
Investigators used the Triage D-Dimer Test, produced by San Diego, Calif.-based Biosite, to evaluate patients for AD. They developed a cut-off level for ruling out aortic dissection or pulmonary embolism, if the test is given within the first 24 hours of symptom outset.  This study suggests that patients with D-Dimer levels below this cut-off are very unlikely to have an AD. Patients with markedly elevated levels of D-dimer would need urgent imaging of the chest to rule-out either AD, or an acute pulmonary embolus which is a blood clot to the lung.
Identifying a cost-effective and technically simple method to diagnose AD would be welcome relief for patients and the doctors caring for them. Because of its relative rarity and high mortality rate, AD is often cited in lawsuits with physicians and hospitals accused of malpractice, according to the study.
Additional authors:  Alessandro Distante, M.D.; Antonella Zizza, M.S.; Santi Trimarchi, M.D., IRCCS; Massimo Villani, M.D.; Jorge Antonio Salerno Uriarte, M.D.; Luigi De Luca Tupputi Schinosa, M.D.; Attilio Renzulli, M.D.; Federico Sabino, M.D.; Richard Nowak, M.D.; Robert Birkhahn, M.D.; Judd E. Hollander, M.D.; Francis Counselman, M.D.; Ravi Vijayendran, Ph.D.; and Eduardo Bossone, M.D.
Funding:  Biosite, along with grants from the Mardigian Foundation and an anonymous donor to IRAD.
Reference: Circulation, doi: 10.1161

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