148: HIGH PREVALENCE OF ELEVATED LACTATE IN PULMONARY EMBOLISM PATIENTS WITH LOW-RISK SPESI SCORES

Abstract

Introduction: Elevated lactate, a possible early marker of hemodynamic collapse, is associated with high 30-day mortality in pulmonary embolism (PE) patients. However, lactate is not included in common PE risk stratification schemes such as the simplified Pulmonary Embolism Severity Index (sPESI). The objective of this study is to assess the prevalence of elevated lactate by sPESI score in PE patients who were undergoing mechanical thrombectomy with the FlowTriever System (Inari Medical). Methods: FLASH is a prospective, multi-center registry assessing FlowTriever mechanical thrombectomy outcomes in PE. FLASH patients were risk-stratified using various methods including sPESI. Lactate was measured pre-thrombectomy, and patients were grouped into normal (< 2 mM) and elevated lactate (≥2 mM). On-table hemodynamics and 30-day safety and mortality outcomes were assessed by lactate group. Results: Lactate measurements were available in 186 patients: 110 (59%) had normal and 76 (41%) had elevated lactate. Mean sPESI scores did not differentiate between those with normal and elevated lactate (1.7±1.1 vs. 1.9±1.2; p=0.171). There was a high prevalence of elevated lactate in patients classified as low-risk: 30% (6/20) of patients with sPESI scores of 0 had elevated lactate. Mechanical thrombectomy resulted in significant on-table improvements in mean PA pressure in patients with normal lactate (31.0±8.3 to 24.1±8.4 mmHg; p< 0.0001) as well as elevated lactate (33.5±9.6 to 25.8±9.2 mmHg; p< 0.0001). Major adverse events through 48 hours occurred in no patients with normal lactate and in 3 (3.9%) with elevated lactate. Post-procedure ICU stays were short overall: median 0.0 days [IQR: 0.0-1.0] in the normal lactate group and 0.5 days [IQR: 0.0-2.0] in the elevated lactate group. Mortality through 30 days was low regardless of lactate status, occurring in 2 (2.0%) patients with normal lactate and 1 (1.4%) with elevated lactate. Conclusions: PE patients classified as low-risk via sPESI had elevated lactate in 30% of cases, suggesting that additional risk factors for decompensation may be missed. While underutilized, assessment of elevated lactate may enhance common risk stratification tools. In patients with elevated lactate, mechanical thrombectomy resulted in hemodynamic improvements and low 30-day mortality.