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Published on: April 17, 2021
Dynamic Changes in ST Segment Resolution After Myocardial Infarction and the Association with Microvascular Injury on
James C Weaver1, David D Ramsay, David Rees
1Department of Cardiology, St. George Hospital, Sydney, Australia. james.weaver@sesiahs.health.nsw.gov.au
Background:
persistent ST elevation after reperfused ST elevation myocardial infarction (STEMI) is believed to be related to poor microvascular perfusion. Cardiac magnetic resonance imaging (CMR) can evaluate microvascular obstruction (MVO) and intramyocardial haemorrhage (IMH) both of which represent severe microvascular damage, have independent prognostic value and are dynamic and evolving over the first 48hours after reperfusion. The aim of this study was to assess whether the development of MVO or IMH has an impact upon ST segment resolution.
Methods:
patients undergoing primary percutaneous coronary intervention (PCI) for STEMI had serial 12 lead electrocardiograms (ECG) from one hour after PCI until discharge. Persistent single lead maximal residual ST elevation (maxSTE) at each time point was calculated. ST segment deterioration (re-elevation) was calculated on each ECG until discharge compared with one hour post PCI ECG. CMR was performed within seven days post infarct utilising T2 weighted imaging to evaluate culprit artery area at risk (AAR) and IMH. Gadolinium delayed enhancement CMR quantified infarct size and MVO.
Results:
in the 41 patients studied 58% had MVO and 41% had IMH. ST segment deterioration was more common in those with MVO or IMH (p=0.03 and p=0.008 respectively). MaxSTE was higher at each time point after PCI in those with MVO but only became statistically significant after 24hours. The measurement of maxSTE at 48 or 72hours after revascularisation provided the best correlation with the combination of infarct size, AAR, MVO and intramyocardial haemorrhage.
Conclusion:
microvascular injury as defined on CMR is associated with dynamic changes and persistence of ST segment elevation in the first 72hours after reperfusion.
Insights
Persistent ST elevation after myocardial infarction is linked to microvascular injury. Cardiac MRI findings of microvascular obstruction or intramyocardial hemorrhage correlate with ongoing ST elevation, impacting patient prognosis.
Area of Science:
- Cardiology
- Medical Imaging
Background:
- Persistent ST elevation post-STEMI suggests poor microvascular perfusion.
- Cardiac MRI (CMR) assesses microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH), indicators of microvascular damage with prognostic value.
- MVO and IMH are dynamic in the initial 48 hours post-reperfusion.
Purpose of the Study:
- To determine if MVO or IMH development impacts ST segment resolution after reperfused STEMI.
- To investigate the relationship between microvascular injury and ST segment changes.
Main Methods:
- Serial ECGs were recorded post-PCI in STEMI patients to calculate maximal ST elevation (maxSTE) and deterioration.
- CMR was used within seven days to assess area at risk (AAR), IMH, infarct size, and MVO.
- Correlation between ST segment changes and CMR findings was analyzed.
Main Results:
- 58% of patients had MVO and 41% had IMH.
- ST segment deterioration was more frequent in patients with MVO or IMH (p=0.03 and p=0.008).
- MaxSTE was consistently higher in MVO patients after 24 hours; maxSTE at 48-72 hours best correlated with infarct size and microvascular injury.
Conclusions:
- Microvascular injury, identified by CMR, is associated with persistent ST segment elevation in the first 72 hours post-reperfusion.
- These findings highlight the prognostic significance of microvascular integrity in STEMI recovery.
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