RT Journal A1 Greenfield LJ T1 FRee-floating thrombus and pulmonary embolism JF Archives of Internal Medicine JO Archives of Internal Medicine YR 1997 FD December 8 VO 157 IS 22 SP 2661 OP 2662 DO 10.1001/archinte.1997.00440430143017 UL http://dx.doi.org/10.1001/archinte.1997.00440430143017 AB The recent article by Pacouret et al1 and the accompanying editorial by Goldhaber2 raise issues that deserve comment. In their prospective, observational study of patients with a free-floating thrombus (FFT), Pacouret and colleagues were able to demonstrate a low incidence of recurrent thromboembolic events relative to a comparable group of patients with occlusive thrombus. They used anticoagulation as the primary method of treatment and should be congratulated for contributing this experience to our knowledge of FFT. However, their conclusion, based on 62 cases of FFT, that filter placement should be avoided until randomized clinical trials can be done is an unjustified leap that grossly overgeneralizes their data. Their definition of FFT may help to explain the difference in better patient outcomes compared with the observations made by other investigators who found a much higher incidence of pulmonary embolism (PE).3-6 When the definition included movement of the unattached