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Clinical Outcomes Associated With Various Microvascular Injury Patterns Identified by CMR After STEMI
Ivan Lechner1, Martin Reindl1, Thomas Stiermaier2
1University Clinic of Internal Medicine III, Cardiology and Angiology, Medical University of Innsbruck, Innsbruck, Austria.
Insights
Microvascular injury (MVI) after ST-segment elevation myocardial infarction (STEMI) is only linked to adverse outcomes when intramyocardial hemorrhage (IMH) is present. Isolated microvascular obstruction (MVO) shows a similar prognosis to no MVI.
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.
Background:
The prognostic significance of various microvascular injury (MVI) patterns after ST-segment elevation myocardial infarction (STEMI) is not well known.
Objectives:
This study sought to investigate the prognostic implications of different MVI patterns in STEMI patients.
Methods:
The authors analyzed 1,109 STEMI patients included in 3 prospective studies. Cardiac magnetic resonance (CMR) was performed 3 days (Q1-Q3: 2-5 days) after percutaneous coronary intervention (PCI) and included late gadolinium enhancement imaging for microvascular obstruction (MVO) and T2∗ mapping for intramyocardial hemorrhage (IMH). Patients were categorized into those without MVI (MVO-/IMH-), those with MVO but no IMH (MVO+/IMH-), and those with IMH (IMH+).
Results:
MVI occurred in 633 (57%) patients, of whom 274 (25%) had an MVO+/IMH- pattern and 359 (32%) had an IMH+ pattern. Infarct size was larger and ejection fraction lower in IMH+ than in MVO+/IMH- and MVO-/IMH- (infarct size: 27% vs 19% vs 18% [P < 0.001]; ejection fraction: 45% vs 50% vs 54% [P < 0.001]). During a median follow-up of 12 months (Q1-Q3: 12-35 months), a clinical outcome event occurred more frequently in IMH+ than in MVO+/IMH- and MVO-/IMH- subgroups (19.5% vs 3.6% vs 4.4%; P < 0.001). IMH+ was the sole independent MVI parameter predicting major adverse cardiovascular events (HR: 3.88; 95% CI: 1.93-7.80; P < 0.001).
Conclusions:
MVI is associated with future adverse outcomes only in patients with a hemorrhagic phenotype (IMH+). Patients with only MVO (MVO+/IMH-) had a prognosis similar to patients without MVI (MVO-/IMH-). This highlights the independent prognostic importance of IMH in assessing and managing risk after STEMI.
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