Glycaemic status and reperfusion injury in patients with ST-segment elevation myocardial infarction
Authors: Reindl M , Lechner I , Tiller C , Holzknecht M , Rangger A , Mayr A , Theurl M , Klug G , Brenner C , Bauer A , Metzler B , Reinstadler S J 
Published: October 2021

Abstract

Background
Failed myocardial tissue reperfusion due to microvascular injury despite successful culprit lesion percutaneous coronary intervention (PCI) is associated with poor clinical outcome in patients with ST-elevation myocardial infarction (STEMI). A possible influence of dysglycaemia on myocardial reperfusion injury is unclear.

Objectives
To investigate the association between glycaemic status and microvascular injury determined by magnetic resonance imaging in STEMI patients.

Methods
This prospective observational cohort study included 260 consecutive STEMI patients undergoing primary PCI between 2016 and 2019. Peripheral venous blood samples for glucose and HbA1c measurements were drawn on admission. Primary microvascular injury endpoint was defined as presence of intramyocardial haemorrhage (IMH) assessed by cardiac magnetic resonance T2* mapping at 4 (interquartile range [IQR]:2–5) days after PCI.

Results
HbA1c (odds ratio [OR]: 1.73 [95% CI: 1.24–2.40]; p=0.001), pre-diagnosis of diabetes (OR: 2.63 [95% CI: 1.18–5.90]; p=0.02) and glucose concentration (OR: 1.01 [95% CI: 1.00–1.01]; p=0.01) significantly predicted IMH, which was present in 90 (35%) patients. Of these three parameters, only HbA1c remained significantly associated with IMH (OR: 2.12 [95% CI: 1.12–3.99]; p=0.02) after adjusting for total ischemic time, culprit lesion location, pre- and post-interventional TIMI flow and peak biomarker concentrations (troponin, N-terminal pro-B-type natriuretic peptide and C-reactive protein). The rate of IMH was 24% in patients with HbA1c &lt;5.7%, 43% in patients with HbA1c ≥5.7 to 6.4% and 59% in patients with HbA1c ≥6.5% (p&lt;0.001).

Conclusions
In STEMI patients undergoing primary PCI, admission HbA1c was independently associated with reperfusion injury as determined by IMH. These findings suggest that IMH could represent the underlying pathophysiological link between dysglycaemia and adverse outcomes following STEMI.

Funding Acknowledgement
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): FWF - Austrian Science Fund; ÖKG - Austrian Society of Cardiology Figure 1. This figure illustrates the relation between HbA1c and IMH by two patient examples successfully treated with PCI (intervention with stent implantation schematically shown on the very left side). The first patient (upper line), representing the patient group with HbA1c &lt;5.7% (associated IMH risk 24%), showed an anterior wall STEMI without IMH (T2* mapping on the very right, corresponding schematic picture of the infarct area without IMH next on the left). The second patient (lower line), representing the patients with HbA1c ≥5.7% (associated IMH risk 47%), showed an anterior wall STEMI with large IMH (arrows point to the hypo-intense core on the T2* mapping image and to the corresponding dark-red area in the schematic illustration). The zoomed view of one microvessel indicates the complex pathophysiology of IMH (including endothelial destruction, embolisation of thrombotic material and inflammation). (Created with BioRender)