Major Prognostic Impact of Persistent Microvascular Obstruction as Assessed by Contrast-Enhanced Cardiac Magnetic Resonance in Reperfused Acute Myocardial Infarction

OBJECTIVES: The aim of this study was to compare the prognostic significance of microvascular obstruction (MO) and persistent microvascular obstruction (PMO) as assessed by cardiac magnetic resonance (CMR) in patients with acute myocardial infarction (AMI).

METHODS: CMR was performed in 184 patients within the week following successfully reperfused first AMI. First-pass images were performed to evaluate extent of MO and late gadolinium-enhanced images to assess PMO and infarct size (IS). Major adverse cardiac events (MACE) were collected at 1-year follow-up.

RESULTS: MO and PMO were found in 127 (69%) and 87 (47%) patients, respectively. By using univariate logistic regression analysis, high Global Registry of Acute Coronary Events (GRACE) risk score (odds ratio [OR] 95% confidence interval [CI]: 3.6 [1.8-7.4], p < 0.001), IS greater than 10% (OR [95% CI]: 2.7 [1.1-6.9], p = 0.036), left ventricular ejection fraction less than 40% (OR [95% CI]: 2.4 [1.1-5.2], p = 0.027), presence of MO (OR [95% CI]: 3.1 [1.3-7.3], p = 0.004) and presence of PMO (OR [95% CI]:10 [4.1-23.9], p < 0.001) were shown to be significantly associated with the outcome. By using multivariate analysis, presence of MO (OR [95% CI]: 2.5 [1.0-6.2], p = 0.045) or of PMO (OR [95% CI]: 8.7 [3.6-21.1], p < 0.001), associated with GRACE score, were predictors of MACE.

CONCLUSIONS: Presence of microvascular obstruction and persistent microvascular obstruction is very common in AMI patients even after successful reperfusion and is associated with a dramatically higher risk of subsequent cardiovascular events, beyond established prognostic markers. Moreover, our data suggest that the prognostic impact of PMO might be superior to MO.

PMID: 19350245

Posted in Magnetic Resonance Imaging and tagged , , , .

3 Comments

  1. Very well designed study in a large number of patients (184) reveals that microvascular obstruction represents a strong independent predictor of major adverse cardiac effects.
    Prior reports had already reported this area of no-reflow as a good predictor for negative LV remodeling after an AMI.
    One limitation of the study, mentioned by the authors, is the lack of comparison with other exams to detect the no-reflow, such as myocardial blush grade by TIMI. However, another recent paper (PMID: 19620437) suggests the superior accuracy of MRI over MBG for the assessment of myocardial reperfusion injury.

  2. It has been shown that studies using non-specific agents (such as gadolinium) overestimate true infarct size when compared with ex-vivo staining methods. This overestimation has been reported to be between 9% and 12% in some papers.

    A recent article by Mather, et al. (PMID: 19698105) shows that MO during first-pass perfusion is smaller than in the delayed imaging sequences and propose that high resolution first-pass perfusion imaging may be the most accurate method to quantify MO.

  3. Nice study with 184 patients with further data supporting the import of persistent microvascular obstruction in ischemic heart disease.

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