Mobile thrombi of the right heart in pulmonary embolism - Delayed disappearance after thrombolytic treatment

Background and objective: In patients presenting with pulmonary embolism (PE), echocardiography, in some cases, reveals mobile clots in right heart (RH) cavities. How these clots evolve after treatment, in particular after thrombolytic treatment (TT), is unknown. We sought to determine the outcome of these mobile clots in the RH during TT. Methods and results: Of a series of 343 patients who had been hospitalized for PE in our department, echocardiography performed on hospital admittance showed a mobile clot in the RH in IS patients (mobile clot incidence, 5.2%). This subgroup of IS patients presented with a more severe form of PE than the 325 patients without mobile clots in the RH. In our series, 16 patients were treated with thrombolytic agents. Close echocardiography monitoring showed the outcomes of these mobile clots during and after TT. In 50% of cases, the clot disappeared rapidly in < 2 h after the end of TT. In 50% of the remaining cases, the clot disappeared later, half within 12 h following the completion of TT, and the other half within 24 h. All patients were alive on day 30 without any clinical sequellae. Conclusion: In these particular forms of PE with mobile clots in the RH, the short time lag required to disperse the clot after TT makes it imperative to delay any decision about new aggressive therapy.