Clinical Outcomes Associated With Various Microvascular Injury Patterns Identified by CMR After STEMI

Area of Science:

• Cardiology
• Cardiovascular Imaging
• Biomarkers

Background:

• Prognostic significance of microvascular injury (MVI) patterns post-ST-segment elevation myocardial infarction (STEMI) remains unclear.
• Understanding MVI's impact is crucial for risk stratification after myocardial infarction.

Purpose of the Study:

• To investigate the prognostic implications of different microvascular injury (MVI) patterns in STEMI patients.
• To differentiate outcomes based on the presence of microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH).

Main Methods:

• Analysis of 1,109 STEMI patients from 3 prospective studies.
• Cardiac magnetic resonance (CMR) including late gadolinium enhancement and T2* mapping performed post-percutaneous coronary intervention (PCI).
• Categorization into no MVI (MVO-/IMH-), MVO only (MVO+/IMH-), and IMH (IMH+) groups.

Main Results:

• MVI observed in 57% of patients; 32% had IMH+ pattern.
• IMH+ group exhibited larger infarct size and lower ejection fraction compared to MVO+/IMH- and MVO-/IMH- groups.
• Higher incidence of major adverse cardiovascular events in IMH+ group (19.5%) versus MVO+/IMH- (3.6%) and MVO-/IMH- (4.4%) during 12-month follow-up.

Conclusions:

• Microvascular injury (MVI) is associated with adverse outcomes exclusively in patients with intramyocardial hemorrhage (IMH+).
• Patients with only microvascular obstruction (MVO+/IMH-) have a similar prognosis to those without MVI (MVO-/IMH-).
• Intramyocardial hemorrhage (IMH) is an independent predictor of adverse events, highlighting its prognostic importance post-STEMI.