Abstract & Commentary
Source: Park SW, et al. Association of painless acute aortic dissection with increased mortality. Mayo Clin Proc 2004;79: 1252-1257.
Although painless acute aortic dissection (AAD) has been described, there has been no systematic study of this condition. Park and colleagues from the International Registry of Acute Aortic Dissection assessed the clinical characteristics and outcomes of this condition to see if clinical recognition could be improved. Between 1997 and 2001, 977 patients with primary AAD were recorded in the database from 18 centers worldwide. The patients were divided into those presenting without pain (63, 6.4%) and those with pain. The painless patients were older (67 vs 62 years), and more often had an aneurysm prior to cardiac surgery. Type A dissection (ascending aorta) was more common in the painless group (75% vs 61%), and more of them were normotensive. The most common presentations of painless AAD were syncope, heart failure, and stroke. Mediastinal widening on chest x-ray was less common in painless AAD (40% vs 62%), and the time from symptom onset to diagnosis was 19 hours longer on average. Hospital mortality was higher in the painless group (33% vs 23%), and was due to a higher mortality in the painless patients who had type B dissection because of aortic rupture.
The researchers concluded that patients with painless AAD are more likely to present with syncope, congestive heart failure, or stroke, and have a higher mortality, especially with type B dissection.
Commentary by Michael Crawford, MD
The major message of this study is that painless AAD presents as other types of cardiovascular disease, which delays the diagnosis and increases the mortality. The mechanism of painlessness was not discernable in this database study, but it is interesting that the mediastinum often was not widened in the painless group. Perhaps dissection was slower, as opposed to more rapid expansion, which may cause pain more often. However, this slow dissection delayed the diagnosis, increasing the incidence of rupture in type B dissections. The last such patient I saw presented as a stroke, and a type A dissection was detected on a routine echocardiogram. Most patients with heart failure, stroke, or syncope receive transthoracic echocardiography (TTE), but the sensitivity of TTE for AAD, in general, is not high. In this study, both transesophageal echocardiography and computerized tomography were used equally to make the diagnosis, but the reason these tests were ordered is not described in the report. Clearly, a high index of suspicion is going to be needed not to miss this diagnosis.
Dr. Crawford, Professor of Medicine, Associate Chief of Cardiology for Clinical Programs University of California San Francisco, is Editor of Clinical Cardiology Alert.