Acute Microvascular Impairment Post-Reperfused STEMI Is Reversible and Has Additional Clinical Predictive Value

Figure 1. Perfusion Quantification for Assessment of Resting Segmental MBF (A to F) Case #1, anterior infarct with microvascular obstruction (MVO); (G to L) Case #2, inferior infarct with no microvascular obstruction. T1 maps and late gadolinium enhancement (LGE) images show the infarcted regions (A and B, anterior with microvascular obstruction; G and H, inferior) with hypoperfusion in the corresponding myocardium on first-pass perfusion (FPP) images (C and I). From segmental quantification (D and J), the myocardial tissue curves for myocardial blood flow (MBF) (F and L) demonstrated a reduced myocardial blood flow in the infarcted region (red arrow, red curve) compared with the remote myocardium (blue arrow, blue curve). (E and K) The arterial input function calculated in the blood pool. a.u. = arbitrary units; LV = left ventricular.

Figure 2. MBFcor Changes Over 6M in Acutely Infarcted Myocardium Myocardial blood flow corrected (MBFcor) improves significantly at 6 months (6M) in all segments, with the exception of segments with an acute presentation with microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH). Bars are SEM. Mean values in the bars are reported with SD. ∗p < 0.001. LGE = late gadolinium enhancement.

Figure 3. Relationship Between MBFcor and Native T1 Over 6M The lines show the prediction from a linear mixed effects model for myocardial blood flow corrected (MBFcor), with native T1 and time point (with interaction term included) as predictors. The model included a random intercept by patient. The dashed lines show the 95th percentile ranges for the predictions from the linear mixed effects model. If regression coefficients for the effect of native T1 on myocardial blood flow are estimated for each tissue state, the association between myocardial blood flow and native T1 is significant only in the acute phase for late gadolinium enhancement with edema, and at 6 months (6M) for edema, late gadolinium enhancement (LGE), and late gadolinium enhancement with edema. MVO = microvascular obstruction.

Figure 4. Predictive Value of MBFcor for Final IS and 6M Functional Recovery (A) The lines show the predictions for acute myocardial blood flow corrected (MBFcor) equal to 0.3, 0.8, and 1.3 ml/min/g. (B) The observed proportions of segments with no 6-month (6M) late gadolinium enhancement (LGE) are shown by quartile of acute myocardial blood flow corrected, with 95% confidence intervals. The lines show the prediction for no 6-month late gadolinium enhancement as a function of acute myocardial blood flow corrected and acute late gadolinium enhancement of 0%, 10%, and 20%. (C) The continuous lines show prediction for acute myocardial blood flow corrected equal to 0.35, 0.70, and 1.40 ml/min/g. (D) The observed proportions of segments with wall thickening (WT) <45% are shown by quartile of acute myocardial blood flow corrected, with 95% confidence intervals. The lines show the predictions for wall thickening <45% as a function of acute myocardial blood flow corrected, and 0% and 50% late gadolinium enhancement, and with and without microvascular obstruction in the case of 50% acute late gadolinium enhancement. IS = infarct size.

Figure 5. Relationship Between Acute MBFCULPRIT and EF 6M (A) Per patient analysis. (B) Receiver-operating characteristic curves showing the diagnostic performance of acute average myocardial blood flow in the culprit territory (MBFCULPRIT) and late gadolinium enhancement (LGE), index of microvascular resistance (IMR), coronary flow reserve (CFR), and transit time at rest (Tmn) in predicting left ventricular (LV) dysfunction (ejection fraction [EF] <50%) at 6 months (6M) in patients with index of microvascular resistance <40 or coronary flow reserve >2 at the time of primary percutaneous coronary intervention. AUC = area under the curve; PPCI = primary percutaneous coronary intervention.