Title: Bova Risk Score May Not Identify Normotensive Pulmonary Embolism Patients with Low Cardiac Index
INTRODUCTION/HYPOTHESIS:
Recent studies have shown that various pulmonary embolism (PE) risk stratification schemes have limitations in identifying patients at high risk for mortality. One such risk stratification tool used to triage normotensive PE patients is the Bova score, which is derived from measurements of blood pressure, heart rate, cardiac troponin levels, and right ventricular dysfunction. The objective of this research is to assess the prevalence of low cardiac index (CI) in normotensive PE patients who are risk-stratified using the Bova score.
Methods: PE patients were enrolled in FLASH, a prospective registry evaluating the safety and effectiveness of percutaneous mechanical thrombectomy with the FlowTriever System (Inari Medical, Irvine, CA; NCT03761173). Using the Bova scoring algorithm, patients were stratified in order of increasing risk into Stage I (score < 3), Stage II (score 3 or 4), and Stage III (score > 4) risk groups. Immediately prior to thrombectomy, CI was measured via right heart catheterization. Mean CI and the proportion of patients with low CI (< 2 l/min/m2) were calculated for each of the three risk stages.
Results: Of the 201 FLASH patients with available data, 23 (11.4%) were Stage I (mean score 2.0 ± 0.2), 106 (52.7%) were Stage II (mean score 3.9 ± 0.3), and 72 (35.8%) were Stage III (mean score 5.3 ± 0.6). In the higher-risk Stage II and III groups, no meaningful difference was observed in mean CI (2.6 ± 0.8 vs. 2.6 ± 0.8 l/min/m2) or in the proportion of patients with low CI (23.6% vs. 22.2%). The Stage I group had higher CI (3.4 ± 1.8 l/min/m2) and a lower proportion of patients with low CI (4.3%).
Conclusions: Despite being normotensive, approximately 23% of patients in the Stage II and III groups had low CI, suggesting that when risk stratified using the Bova score, certain patients who appear to be stable may be at high risk of hemodynamic decompensation. Furthermore, patients in the Stage II and III groups had equivalent CI on average, indicating that stratification by Bova score did not discriminate for underlying cardiac index differences. These data highlight the need for better risk stratification in PE in order to identify patients who may be in subclinical shock and may benefit from advanced treatment.
