Relationship between microvascular obstruction and infarct size assessed early after primary PCI and all-cause mortality, reinfarction and hospitalization for heart failure
Authors: Brasseur P 
Published: October 2022

Abstract

Background
Rapid reperfusion of the epicardial coronary artery by primary percutaneous coronary intervention (PCI) is the guideline-recommended treatment for ST-segment elevation myocardial infarction (STEMI). However, in a substantial proportion of patients, despite restored patency of the epicardial coronary artery, perfusion to the distal coronary microvasculature is not fully achieved. The principal cause of this phenomenon is severe microvascular dysfunction or loss of integrity leading to microvascular obstruction (MVO).

Objectives
Aim of the research was to understand the relationship between microvascular obstruction (MVO) and/or infarct size (IS) and/or left ventricular ejection fraction (LVEF) assessed early after PCI in STEMI patients and subsequent all-cause mortality, reinfarction, and hospitalization for heart failure (HF).

Methods
A literature review was performed with no restrictions in terms of geography or design of study. Publications related to the validation and/or comparison of methods to quantify microvascular obstruction or infarct size were discarded.

Results
Search criteria yielded 23 references. After exclusion of validation studies, 13 publications were retained. Most of these papers were authored by the same group of investigators.
A pooled patient-level analysis from 10 randomized primary PCI trials (total 2,632 patients) established that IS was strongly associated with all-cause mortality and hospitalization for HF but not significantly related to subsequent infarction.
Pooled analysis of patient data from 7 of these 10 randomized primary PCI studies showed that MVO was also significantly associated with all-cause mortality and hospitalization for HF but not related to subsequent infarction.
5 of these 10 randomized primary PCI trials allowed categorization of patients by time of the day of the primary PCI intervention. No association was found between the time of day and IS, MVO, or prognosis after STEMI.
A similar analysis concluded that recent smoking was unrelated to IS or MVO but was associated with a worse prognosis after primary PCI in STEMI.
No correlation was established between body mass index and IS, MVO or LVEF, or one-year rates of death or HF hospitalization.
A sub-study of a nationwide randomized investigation in Denmark assessed the impact of age of STEMI on IS and LVEF and the composite endpoint of death and re-hospitalization for HF. Patients &lt;60 had smaller final infarcts and higher LVEF, but after adjusting for confounders, age did not remain significantly associated with IS and LVEF. During 4-year follow-up, the composite endpoint depended on both age and IS.

Conclusions
MVO and IS assessed early after primary PCI in STEMI are strongly associated with death and hospitalization for HF within one year. Innovative technologies that limit IS by improving microcirculation function during STEMI are of great individual and socioeconomic value.

Funding Acknowledgement
Type of funding sources: Private company.