P1051: clinical characteristics of pulmonary embolism in patients with chronic myeloproliferative neoplasms

Topic: 16. Myeloproliferative neoplasms - Clinical Background: Pulmonary embolism (PE) is a rare disease complication of chronic myeloproliferative neoplasms (MPNs) and it is unclear if clinical presentation of PE in MPNs differs from that of the general population, and whether MPN patients should be scored as having a malignant disease during PE prognostication. Aims: This study analyzed clinical presentation, treatment patterns, and PE-related outcomes in MPN patients. Methods: This was a multicenter retrospective study conducted in seven hematology centers in Croatia. MPN diagnosis was reassessed for all patients according to the 2016 WHO criteria. Patients presenting with scintigraphy- and/or computed tomography angiography-confirmed PE were retrospectively included in the period between 2005 and 2022. A total of 177 non-MPN PE patients served as controls. Clinical and laboratory data were collected at the time of PE diagnosis through medical chart review. All subjects were treated in the hospital and MPN patients additionally received hydroxycarbamide (HU) after PE diagnosis. The simplified Pulmonary Embolism Severity Index (sPESI) score was calculated at the time of admission. This simple bedside tool assesses PE severity through 6 items (age >80 years, history of cancer, history of cardiopulmonary disease, heart rate ≥110 per minute, oxygen saturation <90%, and systolic blood pressure <100 mmHg) and may be used to predict 30-day survival; for low-risk patients (sPESI=0) outpatient management may be possible. Statistical calculations were performed with MedCalc Statistical Software®. The Mann-Whitney U test was used to assess the differences between two continuous variables and categorical variables were analyzed using the χ2-test. Results: We screened more than 1000 MPN patients and identified 39 MPN patients (16 ET, 16 PV, 3 primary MF, 3 post-ET MF and 2 post-PV MF patients) with PE. MPN patients more often had unprovoked PE (p=0.007), higher median sPESI (p=0.028), high-risk PE (p=0.003), were more likely to be treated with low molecular weight heparin (p=0.003) and warfarin (p=0.046), but were less likely to receive direct oral anticoagulants (DOACs; p<0.001). Higher sPESI score in MPN patients was primarily due to higher frequency of cardiopulmonary disease in MPN patients (p=0.001), especially chronic heart failure (p=0.027). There were no statistically significant differences between the two groups according to the presence of concomitant deep vein thrombosis of the extremities at diagnosis, PE laterality and extension, shock, secondary pneumonia, pulmonary infarction, cardiac damage, need for mechanical ventilation, or the length of hospital stay (p>0.050 for all analyses). The 30-day overall survival of MPN patients was comparable to that of non-MPN patients with only 3 patients (all ET) dying from PE (Figure 1A, p=0.176). There was a significant interaction between sPESI, having MPN and death (p=0.001) as shown in Figure 1B, with sPESI being able to significantly stratify survival in non-MPN (p=0.004), but not in MPN patients (p=0.964). None of the MPN patients with low sPESI (n=7) died. Post-PE survival was also not different between MPN and non-MPN patients (median not reached vs. 89 months, p=0.273) and was not affected by the type of anticoagulant used (p=0.539). Permanent anticoagulant treatment was given to 87.2% of MPN patients; 11 (28.2%) and 6 (15.4%) patients experienced recurrent thrombotic or bleeding events, respectively, which were not affected by disease phenotype (p=0.453) nor by the type of anticoagulation (p=0.310). Summary/Conclusion: This study shows that clinical presentation and outcomes of PE in MPNs do not differ from that in the general population and that MPNs should not be counted as cancer during sPESI assessement which seems to perform suboptimally in MPNs. The type of anticoagulation did not affect long-term survival, providing further evidence regarding the safety and efficacy of DOACs in MPN patients suffering from venous thromboembolism. Finally, none of the low-risk MPN patients died from PE providing some reassurance regarding the potential outpatient management of such patients. Limitations of this study are its retrospective design and the limited number of patients included.Keywords: Myeloproliferative disorder, Therapy, Thrombosis, Survival