Subacute Pulmonary Embolism: Insights from a National Registry of Catheter-Directed Interventions

Background: Pulmonary embolism (PE) has classically been divided, on the basis of symptom duration, into acute (<2 weeks), subacute (2–12 weeks) and chronic (>12 weeks) forms. Subacute PE remains poorly characterised, is frequently underdiagnosed, and is largely absent from randomised trials and dedicated guideline recommendations. Whether the efficacy and safety of catheter-directed therapy (CDT) extend to subacute presentations, in which the thrombus is older, more organised and potentially more adherent, is unknown. We aimed to describe the clinical profile, management and early outcomes of patients with subacute PE selected for CDT within a national interventional registry. Methods: We analysed the National Registry of Catheter-Directed Interventions for the Management of Acute PE (NCT06348459), an investigator-initiated, multicentre registry promoted by the Interventional Cardiology Association of the Spanish Society of Cardiology (ACI-SEC). Subacute PE was defined as a symptom duration >14 days and <12 weeks. Baseline characteristics, echocardiographic variables, biomarkers, invasive pulmonary artery pressures, procedural data and early outcomes were described for the subacute group and set alongside the acute presentations treated in the same cohort. All between-group comparisons are descriptive and exploratory and are not intended to characterise subacute PE beyond this selected population. Continuous variables are median [interquartile range]. Results: Among 447 PE cases treated with catheter-directed therapy, 11 (2.5%) met the criteria for subacute PE and 436 (97.5%) for acute PE. Subacute patients presented with progressive dyspnoea (73%) over a median symptom duration of 21 [18–28] days and infrequent syncope (9%); two patients (18%) fulfilled ESC criteria for high-risk PE and three (27%) required vasoactive amines. Subacute patients showed a right ventricular (RV) basal diameter of 50 [48–52] mm (echocardiographic data available in 7 of 11) and an echocardiographic pulmonary artery systolic pressure of 60 [46–60] mmHg, with a high-sensitivity troponin I of 455 [85–767] ng/L and an NT-proBNP of 1433 [256–1970] pg/mL; corresponding values in acute PE were 47 [44–50] mm, 50 [43–60] mmHg, 237 [97–853] ng/L and 2200 [626–5535] pg/mL. None of the between-group differences reached statistical significance. Catheter-directed therapy achieved 100% procedural success in the subacute group, with invasive systolic pulmonary artery pressure falling from 58 [53–60] to 48 [39–51] mmHg and peripheral oxygen saturation improving from 92% [89–95] to 95% [92–98], with no major periprocedural complications, no circulatory support and no in-hospital deaths. Conclusions: Subacute PE was an infrequent but clinically recognisable presentation among patients treated with catheter-directed therapy, accounting for 2.5% of the cohort and characterised by weeks of progressive symptoms before referral and by a substantial right ventricular and pulmonary pressure load at presentation. Mechanical thrombectomy was safe and effective in this subgroup, with favourable early outcomes comparable to those of acute PE. These hypothesis-generating findings support dedicated study of the diagnosis, risk stratification and interventional management of subacute PE.