Role of First Pass (FP) and delayed enhancement in functional recovery assessment after Acute Myocardial Infarction (AMI)

Purpose

To define contrast enhanced MRI role in functional recovery prediction after acute myocardial infarction.

Materials and methods

46 patients with first AMI (65 ± 8 yrs., 39 anterior, 4 inferior, 3 lateral) underwent cardiac MRI after primary PTCA 5 to 7 days after onset. MRI Protocol: SA Cine (FIESTA), 8–10 slices; SA first pass (FGRE-ET) (iv 0.1 mmol/kg Gd-DTPA, 3 mL/s), 3 slices; SA delayed imaging (IR-prep FGRE), 8–10 slices, 15 mins after 0,2 mmol/Kg Gd-DTPA. FP and DE were evaluated together (736 segments) as: normal FP, DE absent or up to 50% of transmural extension (TME) (Pattern 1); delayed hyperenhancement >50% without FP hypoenhancement (Pattern 2a); delayed hyperenhancement >50% with FP hypoenhancement (Pattern 2b); hypoenhancement both at FP and DE(Pattern 3). 828 segments out of first-pass slices were classified on the basis of DE as normal or hyperenhanced 50% TME (= pattern 2) and hypoenhanced (= pattern 3). Patterns 2, 2a, 2b and 3 were considered non viable. Six months follow up MRI assessed functional recovery as improvement of segmental WMSI.

Results

Pattern 1: 1167 segments, functional recovery in 1065 (91,3%). Pattern 3: 132 segments, recovery in 9 (6,8%) Pattern 2: 265 segments, recovery in 78 (29,4%). Pattern 2a showed recovery in 23 segments out of 42 (54,8%); Pattern 2b did not recover in 61 out of 80 (76,3%).

Conclusion

Patterns 1 and 3 respectively identify viable and non viable tissue. Pattern 2 is less specific early after AMI; the presence of FP hypoenhancement is often associated with failed recovery.