Comparative trends in acute pulmonary embolism before and after the COVID 19 pandemic: a UK retrospective case control study

Background Acute pulmonary embolism (PE), one of the leading causes of cardiovascular mortality and sudden death, is a condition influenced by many factors including age, comorbidities, and lifestyle.1 COVID-19 has drawn great attention from its link to hypercoagulability inducing both arterial and venous thromboses,2,3 and post-vaccination thrombotic events have also been reported.4 How this truly compares to pre-pandemic levels is unknown. Purpose To compare the incidence, clinical characteristics, and outcomes of acute PE in the few years before and after the COVID-19 pandemic in adults presenting to an acute secondary care hospital, thereby, highlighting the potential impact of the pandemic on PE occurrence. Methods We retrospectively investigated all adult patients diagnosed with PE at our institution over a 7-year period (Oct 2016–Oct 2023). We divided the patients into two cohorts (pre- and post-COVID) referencing time zero as the onset of the declared SARS-COV-2 pandemic in the UK (March 2020) with an equal timeline either side of this milestone. Demographics, comorbidities, multimodality investigations and clinical outcomes were compared between the two groups in a case control fashion. Results Of the 2022 patients we screened, coded to have a diagnosis of PE, we included 1,423 who met diagnostic eligibility criteria; 517 were pre-COVID and 906 (63.7%) were post-COVID. While age (65.1 vs 63.8 years, p=0.082) and gender distributions (males; 48% pre vs 51% post COVID) were similar, the incidence of obesity was found to be significantly higher in the post-COVID cohort (27.7% in the pre- vs 34.4% in the post-COVID group, p=0.008). Moreover, active cancer rates in those presenting with PE declined by 10.3% in the post-pandemic years. Almost a third of patients in the post-COVID group (n= 268, 29.6%) had active infection confirmed by PCR testing and 174 (19.2%) had received a COVID-19 vaccine within 3 months of PE diagnosis. Mean D-dimer levels were much higher in the post-COVID cohort (86.2 µg/ml vs 5.64 µg/ml, p=0.05), accompanied by a rise in right ventricular strain (11.4% vs 17.4%, p=0.001), although pro-BNP and Troponin levels did not differ significantly between the groups. The need for mechanical ventilation, thrombolysis, rates of cardiac arrest, major hemorrhage, in-hospital mortality, and overall survival to discharge remained comparable. Conclusions In the post-COVID-19 years, non-malignancy-related acute PE rose 75% compared to pre-pandemic levels, despite an unchanged catchment area and similar population demographics. Increased clot burden and right ventricular strain did not increase ICU admissions, major adverse events, or mortality. COVID-19–related thrombo-inflammatory effects, possibly combined with pandemic lifestyle changes, may have promoted prothrombosis, contributing to the rise in PE incidence. Additionally, the surge in obesity (7% in our study) would have significantly contributed to this rise.