Value of ventilation/perfusion SPECT in evaluation of anticoagulant therapy for patients with pulmonary embolism and the influencing factors of treatment effect

Abstract

Objective To investigate the value of pulmonary ventilation/perfusion (V/Q) SPECT in evaluation of anticoagulant therapy for patients with pulmonary embolism (PE) and identify factors which may affect the therapy. Methods From July 2014 to December 2016, sixty-three patients (23 males, 40 females, age (60±14) years), who were clinically diagnosed as PE and underwent V/Q SPECT before and after anticoagulant therapy, were recruited retrospectively in this study. According to the percentage of lung perfusion defect (PD) out of total lung volume, the patients were divided into mild ( 50%) PE groups. The lung PD decreased≥50% after anticoagulant therapy and no new PD detected was defined as the standard of effective therapy, otherwise the treatment were defined as ineffective. Data of different groups were compared. Factors that may predict the severity of PD or affect the treatment were analyzed. χ2 test and logistic regression were used for data analysis. Results PE were detected in 476 pulmonary segments and sub segments. The distribution of PE in different lung lobes had no statistically significant difference (χ2=4.995, P>0.05). More pulmonary arterial hypertension (PAH) were detected in patients with severe PE (80%, 12/15) and moderate PE (66.7%, 16/24) in comparison with patients with mild PE (41.7%, 10/24; χ2=7.062, P<0.05). The occurrence of PAH was related to the severity of PD, with odds ratio (OR) value of 2.680 (95% CI: 1.115-6.446, P<0.05). PAH was an independent risk factor for treatment effect (OR value: 3.134(95% CI: 1.341-7.324), P<0.05). Conclusions V/Q SPECT has an important value for evaluating the effect of anticoagulant therapy and guiding individual therapy. The more extent of PE involved, the higher prevalence of PAH. Anticoagulant therapy may be ineffective in PE patients with moderate or severe PAH. Key words: Pulmonary embolism; Anticoagulants; Treatment outcome; Tomography, emission-computed, single-photon; Technetium Tc 99m aggregated albumin