THROMBOLYTIC AND ANTICOAGULANT THERAPY FOR PULMONARY EMBOLISM: AN EFFECT ON PULMONARY PERFUSION (PART 2)

Abstract

Background.Perfusion scintigraphy reveals perfusion defects in the occlusion of pulmonary vessels of any caliber and makes it possible to quantify pulmonary blood flow disorders, which allows the method to be used for the comparison of the thrombolytic and anticoagulant therapy efficacy in patients with acute pulmonary embolism.Aim of study .To compare the efficacy of thrombolytic and anticoagulant therapy in the treatment of acute pulmonary embolism in the dynamics of pulmonary perfusion disorders.Study Design.A prospective non-randomized study. The quantitative result of pulmonary perfusion deficiency obtained during perfusion scintigraphy was compared in patients with pulmonary embolism treated with thrombolytics or anticoagulants before treatment and in dynamics. The dynamics was evaluated the next day after administration of thrombolytics and on day 4–5 after initiating anticoagulant therapy. Preliminary analysis of these parameters in the group with anticoagulant therapy a day after the start of administration (by analogy with TLT) revealed no statistically significant differences.Description of the method.Radionuclide and CT studies were performed on a hybrid system SPECT/CT “Discovery NM/CT 670” (GE, USA): perfusion was evaluated with 80–120 MBq of Macrotech 99mTc radiopharmaceutical (RP), CT angiography was performed with 70-100 ml of radiopaque substance “Visipaque.” To determine the total perfusion deficiency, each defect of accumulation with an area equal to the segment was taken as a perfusion deficiency of 5% (subsegmental — 2.5%), equal to the lower lobe — 25%, an area equal to the right lung — 55%, the left lung — 45%. Characteristics of the sample.The perfusion scintigraphy was performed in 381 cases out of 503 patients with a diagnosis of pulmonary embolism of high/intermediate risk of early death, treated in the Intensive Care Unit for Surgical Patients from 2011 to 2016. In 166 cases out of 381, thrombolysis was performed; in 215 cases, an anticoagulant was prescribed. The groups did not differ in age and gender composition: 60±16 years; Me 61 (50; 71) and 62±15 years; Me 63 (53; 74); p=0.22, Mann-Whitney test; men/women: 73/93 and 89/126; p=0.68, the Fisher test.Results of the study.In 96.1% (366/381), perfusion disorders were observed in both lungs; in 3.9% (15/381) there was a unilateral lesion. The comparison of the treatment efficacy was conducted in 169 patients: in 127 cases the next day after introduction of a thrombolytic and in 42 cases on day 4–5 of anticoagulant therapy. In the group with thrombolysis, the initial perfusion deficiency was statistically significantly higher than in the anticoagulant group: 50±10%; Me 50 (40; 60) vs. 39±10; Me 40 (30; 45); p<0.00001, the Mann–Whitney test. The level of pulmonary hypertension was also higher: the systolic pressure in the pulmonary artery was 56±17 Me 54 (45, 68) versus 40±24 Me 40 (22; 56); p<0.00001, the Mann–Whitney test. As a result of treatment, the perfusion deficiency statistically significantly decreased in both groups: in the group with TLT from 50±10%, Me 50 (40; 60) to 26±14%; Me 25 (15; 35); p<0.00000.1, Wilcoxon test; and in the treatment with anticoagulant it decreased from 39±10%, Me 40 (30; 45) to 23±15%; Me 15 (15; 30); p<0.0001, Wilcoxon test. In the TLT group, the perfusion disorders regression was stronger compared to ACT and was registered the next day after administration of a thrombolytic: the standardized effect Es=2.0 and Es=1.2. In the treatment with anticoagulants, statistically significant differences were detected only on day 4–5 from the beginning of its administration. The study power for both groups was 1.00. After thrombolysis the systolic pressure in the pulmonary artery decreased statistically significantly within the next 24 hours: from 56±17 mmHg, Me 54 (45, 68) to 36±14 mmHg, Me 35 (25; 43); p=0.0002, Wilcoxon test; Es=1.3; P=1.00. With anticoagulant treatment, no statistically significant changes in pulmonary arterial pressure occurred 4-5 days after the initiation of treatment: 40±24 mmHg, Me 40 (22; 56) and 50±31 mm Hg, Me 48 (30; 58) ); p=0.72, Wilcoxon test.Conclusion.The advantage of thrombolysis over anticoagulant therapy was the ability to improve pulmonary blood flow, reduce pulmonary hypertension, and stabilize the patients’ condition quickly. Anticoagulant therapy did not allow this effect to be achieved in a short time: the statistically significant reduction in pulmonary perfusion deficiency occurred only on day 4–5 of treatment and was less significant; the statistically significant regression of pulmonary hypertension did not occur at that time.