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D-dimer measurement useful for ruling out acute aortic dissection

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – A D-dimer level below 500 ng/mL reliably rules out acute aortic dissection, although the positive predictive value of a higher concentration is quite low, according to the results of a meta-analysis reported in the American Journal of Cardiology online February 8.

The authors point out that there have been many studies examining the use of D-dimer to screen for acute aortic dissection (AAD), but they have been small and inconclusive. Dr. Avi Shimony at Jewish General Hospital/McGill University, in Montreal, Quebec, Canada and colleagues therefore conducted a meta-analysis of seven such studies to pool the data.

The studies included 298 subjects with AAD and 436 without. The investigators used a cutoff of 500 ng/mL for a positive D-dimer result, as this value is widely used in screening for pulmonary embolism.

The results indicate that D-dimer measurement has a sensitivity of 97% and negative predictive value of 96% for AAD. Specificity and positive predictive value, however, are low at 56% and 60%, respectively, according to the report.

“In conclusion, our meta-analysis suggests that plasma D-dimer <500 ng/ml is a useful screening tool to identify patients who do not have AAD,” Dr. Shimony and colleagues write. “Plasma D-dimer may thus be used to identify subjects who are unlikely to benefit from further aortic imaging.” Am J Cardiol 2011.