The Acute Effects of Esmolol in Intact and Infarcted Myocardium–Experimental Study

Abstract

Aim: Early intravenous use of b-blockers within the first hours of STEMI is less firmly established. The aim of this study was to evaluate the effect of esmolol on left ventricular (LV) haemodynamic, rotational and strain parameters in intact myocardium and early post an experimental acute anterior myocardial infarction (MI). Methods: In 20 healthy pigs LV torsional and strain parameters were calculated from basal and apical short axis epicardial planes with speckle tracking technique using EchoPAC platform. LV measurements at baseline and during esmolol infusion (0.5 mg/kg for 1 min, then 0.05 mg/kg/min for 5 min) were compared in intact myocardium and repeated without b-blocker and during esmolol infusion 2 hours post LAD ligation. Results: LV function was highly dependent on the esmolol infusion, in the intact and even more in the infarcted myocardium. LV ejection fraction, LV dP/dtmax and LV end-systolic pressure decreased significantly, a deterioration produced by the administration of esmolol. Torsion-twist and untwisting rate also presented significant reduction in correlation with ejection fraction and cardiac output, appearing to affect especially the apex torsional and strain parameters. Conclusion: Esmolol infusion significantly reduces LV haemodynamic, torsional and strain parameters in intact myocardium and early post MI. These results suggest that early intravenous use of esmolol in patients with STEMI is risky and it is prudent to wait for the patient to stabilize before starting esmolol.