Nearly three years ago, actor John Ritter collapsed on the set of his sitcom, the victim of a rare but often deadly condition called aortic dissection - a tear in the largest blood vessel in the body. His death brought international attention to the catastrophic condition, which strikes 10,000 Americans a year and is often linked to high blood pressure and genetic disorders. 

Now, researchers have published some rare good news about aortic dissection, showing that 90 percent of patients who survive emergency surgery and hospitalization for its most serious form will still be alive three years later. Those without pre-existing heart and blood vessel problems were even more likely to survive. The findings are published in a supplement to the journal Circulation.

The study, performed by an international team led by specialists at the University of Michigan Cardiovascular Center, involved data from 303 patients. All were treated in the late 1990s and early 2000s for the most serious form of aortic dissection, called Type A, which occurs in the upper part of the aorta near the heart.

It’s a unique study looking at survival among Type A aortic dissection patients who live through their initial crisis. The authors say the results offer hope that with proper rapid diagnosis and successful surgery, more patients can survive.

However, because aortic dissection is rare and its symptoms can mimic those of a heart attack, it is often not diagnosed or treated quickly - contributing to a 30 percent in-hospital death rate that includes a 25 percent risk of death during surgery. But less is known about the fate of those who survive long enough to leave the hospital.

“Clearly, this is one of those diseases where if you catch it early you can save lives in the hospital, and with successful surgery your outlook after discharge can look quite good,” says lead author Thomas Tsai, M.D., a cardiovascular research fellow at the U-M Medical School. “Of course, those who do survive will have a diagnosis for life of aortic disease, and will need medication and aggressive monitoring of their aorta.”

Tsai and senior author Kim Eagle, M.D., co-director of the U-M CVC, 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.

“Aortic dissection is still very much a lethal health crisis, with mortality approaching 2 percent per hour. But these results show we’re doing a pretty good job in helping patients after they weather the storm of diagnosis and surgery,” says Eagle.

The new study drew its patients from a group of 885 Type A aortic dissection patients who came or were transferred to IRAD centers. Nearly 30 percent of the Type A patients died before leaving the hospital, and long-term follow-up data were available on many of the 617 who left the hospital after surgical or non-surgical treatment. The patients included in the final analysis were treated at eight IRAD centers that compiled long-term follow-up data on most of their patients. 

Ninety percent of the 303 patients in the study had surgery; the rest received medical treatment because of advanced age, pre-existing conditions that made surgery too risky, or patients’ refusal to have surgery. Death rates were much higher among the non-surgical patients.

The average age of all the patients was 59, but a quarter of the patients were over age 70 - reflecting the fact that aortic dissection can strike relatively young patients with genetic diseases such as Marfan syndrome that prematurely weaken the walls of their aorta, or can arise from a lifetime of high blood pressure that stresses the aorta and creates weak spots.

Seventy-two percent of the patients in the study had hypertension before their dissection. Nearly 25 percent had atherosclerosis (clogged, stiffened blood vessels often linked to High cholesterol and blood pressure) and just under 13 percent had had some sort of cardiovascular surgery in the past.

These underlying problems - and not any aspect of their in-hospital complications - appear to have made a big impact on patients’ risk of dying after leaving the hospital. In fact, patients who had atherosclerosis or previous cardiovascular surgery had twice the risk of dying in the three-year follow-up period as patients without these characteristics. “What predicts an aortic dissection patient’s death after hospitalization are the risk factors they came in with,” says Tsai.

Tsai and Eagle note that the good news of the new result may have a lot to do with recent advances in emergency diagnosis, surgical and anesthesiology techniques, and intensive-care practices, as well as better post-hospital care of patients using drugs and regular medical imaging. Because IRAD has collected data on so many patients treated within a seven-year period, the authors say, the study reflects the modern treatment of the condition, compared with other studies that have compiled data from patients treated over several decades at one or two medical centers.

Now, the researchers are hopeful that early diagnosis and rapid treatment will increase as more hospitals use advanced medical imaging to determine what is causing chest pain in patients who come to emergency rooms. Advanced CT scanners, for example, can make a “triple rule-out” scan that can quickly tell if a patient is experiencing a heart attack, an aortic dissection, or a blood clot in the lung. But, says Tsai, doctors need to order the right kind of scan or a dissection can be missed.

A “swat team” approach that combines the talents of emergency room doctors and nurses, cardiologists, radiologists, surgeons and anesthesiologists to make rapid diagnostic and treatment decisions may also help, says Eagle. Such an approach is now in place at the U-M Health System.

The IRAD team is also working to improve the screening tools that might be used to determine who is at high risk of an aortic dissection. Currently, people with Marfan syndrome, connective tissue disorders and some other conditions are known to have an elevated risk, as are people with long-term blood pressure problems. It can also occur during pregnancy or childbirth, or in cocaine users.

IRAD researchers are currently developing tests that would examine DNA or blood to screen high-risk people or the relatives of dissection patients, to make a rapid diagnosis in the emergency room, or to add to long-term monitoring of survivors. Better screening for aneurysms in the aorta, which are involved in a large percentage of dissections, could also help nip more dissections in the bud.

The study was funded by the U-M Faculty Group Practice, the U-M CVC Varbedian Fund for Aortic Research; and the National Institutes of Health. Reference: Circulation, 114 [Suppl I]: I-350 - I-356

Written by Kara Gavin

http://www.med.umich.edu