The systemic infusion of thrombolytic agents, used earlier as a standard medical therapy for treating massive pulmonary embolism (PE), carries an unacceptable hemorrhagic risk. Now, the results of a recent systemic review and meta-analysis voices catheter-directed therapy (CDT) as a life-saving alternative for treating acute massive PE. The findings of this analysis are published in the latest issue of the Journal of Vascular and Interventional Radiology.
In order to evaluate the safety and efficacy of modern CDT, William T Kuo, Assistant Professor, Department of Radiology at the Stanford University Medical Center, California, and colleagues, reviewed electronic literatures published in MEDLINE and EMBASE between January 1990 and September 2008. Based on the inclusion criteria, 594 patients across 35 (six prospective and 29 retrospective) studies treated with CDT for acute massive PE were selected for the analysis. The CDT technique involved the intraclot injection of a fibrinolytic agent, mechanical fragmentation and/or suctioning of emboli including rheolytic thrombectomy, and the use of low-profile devices. Pooled estimates of procedural complications and clinical success rates were calculated and analyzed using random effects models. Factors that determined the clinical success rate of CDT primarily included:
• Stabilization of hemodynamics
• Resolution of shock
• Survival until discharge from the hospital
CDT exhibited a pooled clinical success rate of 86.5% with minor and major technique complications accounting to 7.9% and 2.4%, respectively. Of the 571 patients treated with systemic anticoagulation before CDT, 546 had CDT as the first complement to heparin without prior intravenous thrombolysis. The analysis therefore concluded on the safety and efficacy of CDT in treating acute massive PE, and recommending it as a first-line treatment.
In another retrospective cohort study, Kim et al (Journal of Vascular Surgery, 2008) concluded that the use of percutaneous catheter-directed thrombolysis for the treatment of acute deep venous thrombosis (DVT) is equally safe in both, cancer and non-cancer patients. The study conducted on 202 limbs of 178 patients was reported to accomplish grade III and grade II thrombolysis in equal proportion, in patients with and without cancer. The duration of therapy also remained the same for acute DVT patients of the two study groups with very minimal complication rates.
Furthermore, Chamsuddin et al (Journal of Vascular and Interventional Radiology, 2008) conducted a retrospective multicenter case series to assess the efficiency of ultrasonography (US)-assisted CDT with the EndoWave system, in treating massive acute PE. The study on 17 lesions reported complete clot removal in 76% (n=13), near complete thrombolysis in 18% (n=3), and partial thrombolysis in 6% (n=1) of the lesions. The efficacy of this technique was attributed to the shortened time of thrombolysis and reduced dose of clot busting agents.
Massive pulmonary embolism, though not always a fatal condition, is the third most leading cause of death in the United States. According to the National Hospital Discharge Survey, a total of 101,000 Americans were hospitalized with primary diagnosis of PE, contributing to 676,700 inpatient days, in 2002.
Several reports indicate CDT as a highly effective technique of restoring circulation within a vein without the need for obvious surgical incision. The efficacy of this therapy in eliminating related symptoms such as pain and swelling and re-establishing circulation has been found to be more than 85%. Thus in the event of massive PE, complicated by hemodynamic shock, CDT could be life-saving in patients who fail to respond or cannot tolerate systemic thrombolysis.
References
1. Kuo WT, Gould MK, Louie JD, Rosenberg JK, Sze DY, Hofmann LV. Catheter-directed therapy for the treatment of massive pulmonary embolism: systematic review and meta-analysis of modern techniques. J Vasc Interv Radiol. 2009 Nov;20(11):1431-40.
2. Kim HS, Preece SR, Black JH, Pham LD, Streiff MB. Safety of catheter-directed thrombolysis for deep venous thrombosis in cancer patients. J Vasc Surg. 2008 Feb;47(2):388-94.
3. Chamsuddin A, Nazzal L, Kang B, et al. Catheter-directed thrombolysis with the Endowave system in the treatment of acute massive pulmonary embolism: a retrospective multicenter case series. J Vasc Interv Radiol. 2008 Mar;19(3):372-6.
