The University Record, February 21, 2000

Largest-ever study of killer heart ailment raises serious concerns

By Pete Barkey
Health System Public Relations

Researchers at the U-M and several other leading medical centers are reporting that a high percentage of patients with a life-threatening heart condition are still dying in the hospital in spite of recent medical advances. Their findings are published in the Feb. 16 issue of the Journal of the American Medical Association.

The ailment is called acute aortic dissection—a rare, but often fatal condition, characterized by separation of the aortic walls. Aortic dissection occurs in two forms: Type A dissection involves the ascending aorta; type B occurs near the left subclavian artery and down the descending aorta.

“Despite recent advances in diagnosis and treatment of aortic dissection, the morbidity and mortality for this rare cardiovascular disorder remain unacceptably high,” says Kim Eagle, interim chief of the Division of Cardiology and lead author on the new study.

Speaking on behalf of 18 leading aortic centers around the world that are working together to understand and treat aortic dissection, Eagle and colleagues reported on nearly 500 patients treated in the past three years. Researchers at the Health System coordinated the report from the International Registry of Aortic Dissection (IRAD).

Eagle says the study emphasizes the need for emergency cardiac surgery for dissection involving the ascending aorta and the promise of new catheter-based procedures for complicated patients with dissection of the descending aorta.

Aortic dissection can occur anywhere in the aorta and has a wide range of symptoms that often mimic more common disorders like myocardial ischemia or stroke. In addition, physical evidence may be absent or difficult to diagnose. This means, Eagle says, that dissection is hard to diagnose and medical personnel must be highly suspicious, especially due to the critical need for timely response in cases of aortic dissection.

Investigators studied 464 patients treated at the 18 IRAD centers. Two-thirds were male, the mean age was 63.1 years and nearly two-thirds of the patients had type A dissection.

Severe pain was the most common presenting symptom, with type A patients complaining of chest pain, while more localized abdominal or back pain was predominant in type B dissection cases.

Eagle says it’s important to note that most patients reported a sharp pain, rather than a ripping or tearing pain, which is thought to be the classical symptom. Seventy-two percent of the type A patients were managed surgically while 20 percent of type B patients required surgery. A minority of type B patients who did not undergo surgery were treated by a technique called percutaneous fenestration—a catheter procedure designed to improve blood flow to vital organs. This procedure is in addition to standard medical therapy for type B dissection.

They found that overall in-hospital mortality was 27.4 percent, with the highest mortality in patients with type A dissection who did not receive surgery (58 percent)—primarily due to advanced age or other health concerns. Patients with type B dissection treated medically had the lowest mortality rate (10.7 percent), while patients with type B dissection who underwent surgery had a 31.4 percent in-hospital mortality rate.

Investigators also found that several of the accepted symptoms and markers of aortic dissection were not as commonplace as previously reported.

For example, earlier studies point to the value of an abnormal chest x-ray in evaluating suspected dissection. However, Eagle says, he and his colleagues found that a substantial number of patients did not have abnormal chest X-rays. In addition, presence of a normal ECG is touted as a marker that would move a clinician away from a diagnosis of myocardial ischemia toward one of aortic dissection. Once again, investigators found this to be untrue in the present study group. A normal ECG was present in less than one-third of the patients in this study.

Eagle says there was wide variability in the choice of imaging technique used. Investigators found that computerized axial tomography (CT) was most commonly used. Two other widely used diagnostic imaging methods—MRI and transesophageal echocardiography—were used less frequently. The study authors believe the discrepancy may reflect ready availability, rather than a preference.

Eagle says the highest mortality occurred soon after onset of symptoms, necessitating the urgent need for quick diagnosis and appropriate therapy, particularly surgery for acute ascending dissection at an aortic center of excellence.

“Acute aortic dissection is uncommon, but complications develop rapidly and the outcome is often fatal,” Eagle says. “Despite significant medical advances, in-hospital death for aortic dissection remains high. This study confirms the need for further improvements in our ability to understand, diagnose and manage this devastating condition.”