Context The diagnosis of acute thoracic aortic dissection is difficult to make
and often missed.
Objective To review the accuracy of clinical history taking, physical examination,
and plain chest radiograph in the diagnosis of acute thoracic aortic dissection.
Data Sources A comprehensive review of the English-language literature was conducted
using MEDLINE for the years 1966 through 2000. Additional sources were identified
from the references of retrieved articles.
Study Selection The search revealed 274 potential sources, which were reviewed for pertinence
and quality. Articles included were original investigations describing the
clinical findings for 18 or more consecutive patients with confirmed thoracic
aortic dissection. Twenty-one studies were identified that met selection criteria.
Data Extraction Critical appraisal and data extraction were performed by the author.
Data Synthesis Most patients with thoracic aortic dissection have severe pain (pooled
sensitivity, 90%) of sudden onset (sensitivity, 84%). The absence of sudden
pain onset lowers the likelihood of dissection (negative likelihood ratio
[LR], 0.3; 95% confidence interval [CI], 0.2-0.5). On examination, 49% of
patients have an elevated blood pressure, 28% have a diastolic murmur, 31%
have pulse deficits or blood pressure differentials, and 17% have focal neurological
deficits. Presence of a diastolic murmur does little to change the pretest
probability of dissection (positive LR, 1.4; 95% CI, 1.0-2.0), whereas pulse
or blood pressure differentials and neurological deficits increase the likelihood
of disease (positive LRs, 5.7 and 6.6-33.0, respectively). The plain chest
radiograph results are usually abnormal (sensitivity, 90%); hence, the presence
of a normal aorta and mediastinum decreases the probability of dissection
(negative LR, 0.3; 95% CI, 0.2-0.4). Combinations of findings increase the
likelihood of disease.
Conclusions The presence of pulse deficits or focal neurological deficits increases
the likelihood of an acute thoracic aortic dissection in the appropriate clinical
setting. Conversely, a completely normal chest radiograph result or the absence
of pain of sudden onset lowers the likelihood. Overall, however, the clinical
examination is insufficiently sensitive to rule out aortic dissection given
the high morbidity of missed diagnosis.