To the Editor.
—Dr Goldhaber and colleagues1 report a 93.3% sensitivity and 91.4% negative predictive value for a fibrin D-dimer value less than 500 ng/mL (Asserachrom D-Di enzyme immunoassay kit, Diagnostica Stago, Asniéres-sur-Seine, France) for acute pulmonary embolism using pulmonary angiography as the diagnostic reference standard. The authors report "no significant relationship between heparin use and D-dimer levels (P=.78)," but do not report the duration of heparin therapy or duration of symptoms prior to D-dimer measurement. Using the same assay, Bounameaux et al2 found D-dimer levels to be significantly lower on days 3 and 7 compared with the day of presentation (day 1). Speiser et al3 reported that elevated levels of D-dimer decrease within 24 hours in patients with acute deep vein thrombosis who are treated with heparin. Therefore, the D-dimer sensitivity for acute pulmonary embolism may be appreciably reduced in patients who have been symptomatic
Heit JA, Nichols WL. Plasma D-Dimer Levels and Diagnosis of Pulmonary Embolism. JAMA. 1994;271(18):1404. doi:10.1001/jama.1994.03510420036028