Abstract 9397: Sonothrombolysis Improves Cardiac Segmental Contractility, Myocardial Perfusion and Baroreflex Gain in Patients With ST-segment Elevation Myocardial Infarction (stemi) in Long-Term Follow-Up

Abstract

Sonothrombolysis (Sono) has improved microvascular obstruction, global contractility and infarct area after STEMI. Objective: To evaluate the long-term effect of Sono and its physiologic mechanisms in a subgroup of 51 STEMI patients (percutaneous coronary intervention-PCI (N=24) and PCI+Sono (N=27)) from previous randomized study. All patient were treated with PCI and those also treated with Sono received frequent image-guided diagnostic high mechanic index impulses applied to the myocardial contrast-enhanced areas (microbubbles) in the apical views (1.8 MHz; 1.1 to 1.3 MI; <5-μ pulse duration). Evaluations were at pre-treatment, 1 month (ultrasound-US with contrast agent) and at averaged 34±17 months after STEMI (US with contrast agent; cardiac and peripheral sympathetic activity by means of 123 I-MIBG cardiac scintigraphy and microneurography; baroreflex gain of heart rate (HR) control by means of transfer function analysis). (For significance: P level ≤ 0.05). US values are on table. Adding, PCI+Sono showed lower left ventricular end-diastolic volume (LVEDV) remodelling (22±36 vs. 44±42%, P<0.05). Cardiac scintigraphy showed similar late Heart/Mediastinum ratio and similar washout rate between groups. Muscle sympathetic nervous activity was also similar in both groups. PCI+Sono showed higher baroreflex gain of HR control (8±3 vs. 6±2 ms/mmHg, P=0.05), indicating an improved baroreflex sensitivity. In addition, perfusion score index correlated positively with wall motion score index (r=0.97, P<0.001) and washout rate (r=0.30, P=0.04). LV ejection fraction correlated negatively with wall motion score index (r=-0.53), perfusion score index (r=-0.48) and LVEDV (r=-0.29) (P<0.05). In conclusion, Sono added to PCI improved contractility and myocardial perfusion in STEMI. Despite high level of sympathetic activity, baroreflex gain of HR was ameliorated in PCI+Sono patients, probably due to better myocardial perfusion and lower LV remodelling.