Optimal management, prevalence, and clinical behavior of saddle pulmonary embolism: A systematic review and meta-analysis

Introduction: The central location, size, and instability of saddle pulmonary embolism (SPE) have raised significant concerns regarding its clinical, hemodynamic effects as well as optimal management. Pulmonary embolism (PE) guidelines barely address such concerns. We aimed to pool the available data on the clinical behavior and outcomes of SPE and study the effects of various treatment modalities on mortality outcomes. Methods: PubMed, Scopus, and Google Scholar were searched for articles (any date up to February 28, 2022) reporting patients with SPE. Data on SPE demographics, clinical characteristics, management, and outcomes were extracted and analyzed. Results: Results from all SPE cases: A total of 5251 patients from 194 studies were included in the review. Dyspnea (57 %) was the most prevalent symptom. Massive and submassive PE comprised 9.7 % and 45.8% of cases, respectively. Thrombolytic therapy (TT) was administered in 18.1 %, and thrombectomy was performed in 16 % of cases. SPE-related mortality was observed in 4.6 %, late decompensation in 9.5 %, and PE recurrence in 4.5 % of cases. Female sex (61.5 % vs. 41.3 %, p = 0.019), hypoxemia (90 % vs. 59.2 %, p < 0.001), massive PE features (89.7 % vs. 30.1 %, p < 0.001), associated chronic kidney disease (CKD) (10.3 % vs. 1.4 %, p = 0.002), and the need for mechanical ventilation (28.2 % vs. 13.1 %, p = 0.02) were significantly associated with increased mortality. The use of TT was significantly associated with increased survival (27.1 % vs. 12.5 %, p < 0.001). In a multivariate logistic regression model, massive PE features significantly increased the odds of death (OR: 29.3, CI: 4.86-181.81, p < 0.001), whereas, treatment with anticoagulation (AC) alone (OR: 0.1, CI: 0.027-0.356, p < 0.001), TT (OR: 0.065, CI: 0.019-0.26, p < 0.001), surgical thrombectomy (ST) (OR: 0.047, CI: (0.010-0.23), p < 0.001), or percutaneous thrombectomy (PT) (OR: 0.12, CI: 0.020-0.84, p = 0.032) significantly decreased odds of death. Results from a meta-analysis of observational studies: Meta-analysis of the included 17 observational studies revealed an overall 10 % (95 % CI: 4.56-16.89) SPE prevalence among all PE cases. The overall SPE-related mortality rate was 8 % (95 % CI: 5.26-10.96). Massive PE was observed in 13.3 % (95 % CI: 5.56-23.70), PE recurrence in 5.1 % (95 % CI: 2.22-9.05), and late decompensation in 11 % (95 % CI: 3.43-22.34) of patients. Conclusions: SPE comprises 10 % of all PE cases. Despite its ominous radiologic appearance, the clinical, hemodynamic, and mortality outcomes of SPE seem comparable to that of other PE types in general. The presence of massive PE features is the main predictor of mortality in SPE patients. AC, TT, ST, and PT are all associated with decreased odds of death from SPE.