Evolution of gray zone after acute myocardial infarction: Influence of microvascular obstruction
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KeywordsPercutaneous Coronary Intervention Acute Myocardial Infarction Acute Myocardial Infarction Primary Percutaneous Coronary Intervention Gray Zone
The presence of ischemia-induced microvascular obstruction (MVO) despite successful coronary revascularization, has been associated with poor functional recovery and adverse left ventricular remodeling after acute myocardial infarction (AMI). Additionally, the extent of the infarct gray zone is a strong independent predictor of post-AMI mortality. However, the evolution of gray zone after AMI has not been investigated and its relationship with MVO in terms of risk stratification is unknown.
To characterize the evolution of gray zone and determine its correlation with the presence of MVO during infarct healing in patients treated with primary percutaneous coronary intervention (PCI).
Patients were enrolled post-PCI and underwent MRI examination on a 1.5T scanner (GE Signa Excite) at day 2, week 4 and month 6 following AMI. Cardiac function [Ejection fraction (EF), End-diastolic volume (EDV)] was evaluated using a steady-state-free-precession (SSFP) sequence in cine mode. A T1-weighted IR-GRE sequence was used for delayed-hyperenhancement (DHE) of infarcted myocardium. Infarct core (IC) and gray zone (GZ) volumes were quantified using the full-width-half-maximum technique as previously described; both quantities were expressed as a percentage of myocardial volume. MVO’s were manually traced and included in the infarct core calculation.
All patients (N=10)
non-MVO patients (N=6)
MVO patients (N=4)
The increase in infarct gray zone or arrhythmogenic substrate may be one of the possible mechanisms responsible for adverse remodeling and poor clinical prognosis in patients with MVO. Monitoring the early evolution of gray zone in the high-risk patients could also potentially help identify the optimal timing and candidates for placement of implantable cardioverter-defibrillator.
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