Background: The TIMI myocardial blush grade (MBG) has been shown to be a strong angiographic predictor of mortality in patients with TIMI 3 flow after primary angioplasty. This study was conducted to evaluate the relationship between regional myocardial perfusion quantified by cardiac magnetic resonance and angiographic reperfusion score defined by MBG.
Methods: We studied 29 consecutive patients (25 men, age 63±13 years) with ST-segment elevation acute myocardial infarction (LAD lesion: 12, RCA lesion: 16, LCx lesion: 2) who underwent primary angioplasty within 6 hours from the onset and showed TIMI grade 3. MBG was determined on angiography at the end of angioplasty. All patients underwent rest myocardial perfusion MRI during initial hospitalization, and regional MBF (ml/min/g) was quantified by using a Patlak plot method. Myocardial perfusion (MP) ratio was calculated from quantitative perfusion MRI, as MBF in infarction area/MBF in normal area. The optimal cut-off value of MP ratio that can predict MBG 3 on coronary angiography was determined by using a receiver-operating characteristic (ROC) analysis.
Results: In 29 patients with TIMI 3 flow after angioplasty, 4 patients had MBG 0–1, 7 had MBG 2 and 18 had MBG 3. The MP ratio in MBG 3 group calculated from quantitative perfusion MRI was significantly higher than the MP ratios in MBG 0 –1 group and MBG 2 group (0.96±0.18 vs. 0.48±0.25, P<0.001; 0.96±0.18 vs. 0.66±0.19, P=0.003, respectively). There was no significant difference between the MP ratios in MBG 0 –1 group and MBG 2 group. The ROC curve revealed that MP ratio of 0.74 is an optimal threshold to distinguish MBG 3 from MBG 0 –2, with a high area under the curve of 0.90.
Conclusions: The result of this study demonstrates that MP ratio quantified from rest perfusion MRI correlated well with MBG on coronary angiography.
Feasibility of multiple-view myocardial perfusion MRI using radial simultaneous multi-slice acquisitions