Impact of intraaortic counterpulsation on microcirculatory impairment in cardiogenic shock complicating myocardial infarction - an IABP-Shock II substudy

Abstract

Introduction: Mortality in cardiogenic shock (CS) caused by acute myocardial infarction (AMI) remains high despite the different modern treatment modalities. One reason is the global microcirculatory impairment. Previous studies showed that an option to improve microvascular perfusion is the use of mechanical assist devices. The aim of the current study was to evaluate the influence of intraaortic balloon pump (IABP) on the microcirculation (MC). Material and methods: The randomized controlled IABP-Shock II trial evaluated the use of IABP in CS due to AMI in 600 patients. In 36 of these patients included in Leipzig and Jena, sublingual MC was measured at three different time points (within 24 hours, after 48 hours, after 72 hours) using sidestream darkfield intravital microscopy. In addition, patients randomized to IABP treatment underwent an on-off protocol (five minutes without support) at all time points. Recorded sequences were analyzed blinded in a core lab giving the perfused capillary density (vessel diameter: <20mum, PCD) as well as perfused vessel density (vessel diameter: 20-100 mum, PVD). Furthermore, different clinical parameters were recorded including lactate, catecholamines and hemodynamic parameters and correlated to microcirculatory parameters. Results: Twenty-four patients were randomized to IABP support and twelve patients were treated without IABP. The overall PCD was 0,02 mm/mm 2 (Median) and PVD at 0,32 mm/mm 2, indicating a severe impaired MC. The intention-to-treat analysis revealed that there was no difference between the two groups (PCD; IABP median: 1,2 [0,0; 5,9, Interquartile range]; controls: 0,22 [0,0; 3,1] mm/mm 2; p=0,17). In addition, there were no MC changes seen when IABP support was halted. Especially after 48 hours, there was a strong inverse correlation between MC parameters and lactate and noradrenaline dose. Discussion: MC in CS is severely impaired. However, IABP support did not lead to microvascular improvement in this randomized study.