Early improvement in left ventricular microvascular flow post sonothrombolysis is associated with better left ventricular systolic function in st elevation myocardial infarction patients
Authors: Azevedo L F , Rolim J P E , Abduch M C D , Le Bihan D , Barretto R B M , Lima M S M , Stangenhaus C , Ribeiro H B , Aguiar M O D , Tavares B G , Sbano J C N , Kamp O , Becher H , Porter T R , Mathias Jr W 
Published: October 2024

Abstract

Background/Introduction
Acute coronary syndromes are the main cause of death worldwide and the timely application of proper therapy is critical for patient outcome. However, even when state of the art treatment is implemented, significant no-reflow phenomenon may occur. In this scenario, sonothrombolysis, which consists of a continuous infusion of an ultrasound-enhancing agent associated with high-energy intermittent ultrasound impulses, may restore cardiac microcirculation and improve left ventricular (LV) systolic function.

Purpose
We aimed to evaluate LV segmental microvascular flow, LV mechanics and function in patients with ST-elevation myocardial infarction (STEMI) after sonothrombolysis therapy and evaluate whether an early (immediately post percutaneous coronary intervention – PCI or PCI+Sonothrombolysis) improvement in myocardial microvascular flow could predict better LV systolic function at 1-month.

Methods
STEMI patients receiving conventional treatment (PCI with or without previous fibrinolytic therapy) were randomized to sonothrombolysis (therapy group - TG) or conventional treatment (control group - CG). This study included 143 patients (interim analysis) who compose the HUBBLE I databank (High-intensity Ultrasonic impulses and microbuBBles to Limit the Extent of acute myocardial infarction I) and were randomized from two clinical trials (NCT04732091 and NCT02410330): CG, N=74 and TG, N=69 patients. There were 25 patients treated previously with fibrinolytic therapy (14 in CG and 11 in TG) and the percentage of left anterior descending artery as culprit vessel was similar between groups (59 vs. 54%, P=0.482). Sonothrombolysis was initiated after patient admission to the emergency room and continued after PCI for a total of 50 minutes. Echocardiography was carried out immediately after PCI or PCI+Sonothrombolysis and at 1-month for assessing LV ejection fraction (LVEF) and perfusion score index (PSI) in contrasted imaging and global longitudinal strain (GLS) in 2D imaging, that was presented in [module].

Results
Demographic characteristics, cardiovascular risk factors and echocardiographic variables immediately after PCI or PCI+Sonothrombolysis were similar between groups (P&gt;0.05). At 1-month follow up, TG presented higher LVEF (46.4±10.5 vs. 50.9±11.1%, P=0.018) and GLS (13.0±3.6 vs. 14.9±4.3%, P=0.008) and lower PSI (1.56±0.4 vs. 1.39±0.3, P=0.007) and number of segments with perfusion defects (5.8±3.7 vs. 4.6±3.3, P=0.050) compared with CG. There was a negative correlation between early PSI and 1-month LVEF (r=-0.701, p&lt;0.0001).

Conclusions
The preliminary data indicates that sonothrombolysis can be an effective adjuvant treatment in STEMI patients previously treated or not with fibrinolytic therapy, contributing to a better myocardial microvascular flow and LV systolic performance. Early myocardial microvascular reperfusion improvement can predict whether cardiac function will improve in this setting.