Refractory Out-of-Hospital Cardiac Arrest in Patients With Pulmonary Embolism and Use of Extracorporeal Membrane Oxygenation: Prague OHCA Study Subanalysis

Introduction: Refractory out-of-hospital cardiac arrest (r-OHCA) in patients with pulmonary embolism (PE) has poor outcome. Data about use of extracorporeal membrane oxygenation (ECMO) in PE are heterogenous and there is minimal evidence for its use in patients presenting with r-OHCA. Hypothesis: To describe in detail profile, initial settings of cardiac arrest (CA) and clinical course of patients with PE presenting with r-OHCA and its specifics in comparison to patients with r-OHCA of other cause. The special attention was paid to the use of ECMO and its potential benefit for patient prognosis. Methods: We reanalyzed subgroup of patients with PE from Prague OHCA study - a randomized control trial evaluating the effect of hyperinvasive approach including the use of ECMO in r-OHCA. Patients characteristics, the specifics of CA settings and the outcome were compared to the patients with other cause of r-OHCA. The neurologically favorable survival was then compared between PE patients randomized to Hyperinvasive and Standard arm of the study. Results: The PE was identified as a cause of CA in 24 (9.4 %) patients in Prague OHCA study. PE patients were more likely women (12 [50 %] vs 32 [13.8 %]) with non-shockable initial rhythm (23 [95.8 %] vs 77 [33.2 %]; P < 0.0001). The CA occurs more frequently after arrival of emergency medical service (14 [58.3 %], vs 22 [9.5 %]; P < 0.0001), had shorter time to hospital admission (median in minutes [IQR], 40 [34.5-57.8] vs 54 [46-64]; P = 0.01) with more severe acidosis at admission (median pH [IQR]; 6.83 [6.75-6.88] vs 6.98 [6.82-7.14] P = 0.0008). The primary outcome of patients with PE - CPC 1 or 2 at 180 days - was significantly worse (2 [8.3 %] vs 66 [28.4 %]; P = 0.049). There was non-significant difference in primary outcome - CPC 1 or 2 at 180 days - between PE patients in Hyperinvasive (12 [50%]) and Standard arm of the study (2 [16.7 %] vs 0; P = 0.24). Conclusion: The initial profile of patients and the settings of CA in patients with r-OHCA and PE differs from patients with other CA cause and their prognosis is significantly worse. The Hyperinvasive approach did not improved outcome in this subgroup of patients.