Impact of blood pressure on the extent of microvascular damage in the setting of reperfusion injury in STEMI asessed with magnetic resonance imaging
Authors: Igual Munoz B , Fernandez Diaz C F D , Ferre Vallverdu M F V , Berenguer Jofesa A B J , Sanchez Lacuesta E S C , Pirola A P , Ridocci Soriano F R S , Forner Giner J F G , Ontoria Oviedo I O O , Sepulveda Sanchez P S S , Paya Serrano R P S 
Published: October 2021

Abstract

Hypertension is a poor prognostic factor following STEMI, however the impact of blood pressure (BP) on the extent of microvascular damage in the setting of acute ischemia -reperfusion injury has not yet been fully evaluated and this evaluation is the purpose of the present study.

Methods
A cohort of patients with acute STEMI referred to primary percutaneus intervention were prospectively included. Angiographic analysis were performed according to standard clinical practice and decision regarding type of stent and antiplatelet drugs was left to the discretion of cardiologist. Information about high blood pressure needing drug therapy before acute event and also BP levels at catheterization laboratory during reperfusion procedures were assessed. All patients underwent cardiac MRI during the first week post reperfusion with a standardized protocol including 8–10 short axis slices in order to asses: area of myocardium at risk (AR) as an area of signal hyperintensity &gt;2sd with respect to the remote one in TSE-T2 sequences, necrosis size (NS) as signal hyperintensity &gt;5 SDs relative to the remote in IR-FGE sequences, microvascular obstruction (MVO) as signal hypointensity in the infarct core in IR-FGE sequences and intra-infarct haemorrhage (IIH) as an area with T2*&lt;20msec in T2* mapping sequences. The extent was quantified using a semi-automatic approach and expressed as a percentage of left ventricular mass.

Results
94 patients,mean age 62,SD 13, 67% males were included. Hypertensive patients were more likely to have diabetes mellitus 43 vs 28% (p&lt;0.05) while smoking was more frequent in non-hypertensive patients 41% vs 80%. (p&lt;0.05). No differencies were found in extent of AR o rmyocardial salvage between groups, nevertheless hypertensive patients had significantly lower extent of NS, MVO and IIH. Regarding microvascular damage, hypertension showed a protective effect and presence of IIH was observed in 35% of hypertensive patients vs. 65% of non-hypertensive patients (p=0.019 OR: 0.9, p=0.04, CI: 0.1–0.9) and MVO in 40% vs 70% (OR: 0.2, p=0.02, CI: 0.1–0.6). Furthermore patients with BP levels below 120mmhg at cathetherization laboratory showed higher percentage of MVO (62% vs 36%, p&lt;0.05) and IIH (36 vs 15%, p&gt;0.05).

Conclusions
1. Hypertension is associated with lower extent of necrosis and microvascular damage without differences in myocardial salvage and area of myocardium at risk.
2. Low BP levels at catheterization laboratory were associated with a significantly higher extent of microvascular damage, so maintaining systolic blood pressure over 120mmhg during reperfusion procedures should be advised.

Funding Acknowledgement
Type of funding sources: None. Typical CMR sequences: T2w, T2*, IR-FGRCMR segmental analysis with T2* mapping