title: Salvage assessment with cardiac MRI following acute myocardial infarction underestimates potential for recovery of systolic strain.
abstract: OBJECTIVE
  Our aim was to evaluate the relationship between the degree of salvage following acute ST elevation myocardial infarction (STEMI) and subsequent reversible contractile dysfunction using cardiac magnetic resonance (CMR) imaging.
  
  
  METHODS
  Thirty-four patients underwent CMR examination 1-7 days after primary percutaneous coronary intervention (PPCI) for acute STEMI with follow-up at 1 year. The ischaemic area-at-risk (AAR) was assessed with T2-weighted imaging and myocardial necrosis with late gadolinium enhancement. Myocardial strain was quantified with complementary spatial modulation of magnetisation (CSPAMM) tagging.
  
  
  RESULTS
  Ischaemic segments with poor (<25 %) or intermediate (26-50 %) salvage index were associated with worse Eulerian circumferential (Ecc) strain immediately post-PPCI (-9.1 % ± 0.6, P = 0.033 and -11.8 % ± 1.3, P = 0.003, respectively) than those with a high (51-100 %) salvage index (-14.4 % ± 1.3). Mean strain in ischaemic myocardium improved between baseline and follow-up (-10.1 % ± 0.5 vs. -16.2 % ± 0.5 %, P < 0.0001). Segments with poor salvage also showed an improvement in strain by 1 year (-9.1 % ± 0.6 vs. -15.3 % ± 0.6, P = 0.033) although they remained the most functionally impaired.
  
  
  CONCLUSIONS
  Partial recovery of peak systolic strain following PPCI is observed even when apparent salvage is less than 25 %. Late gadolinium enhancement (LGE) may not equate to irreversibly injured myocardium and salvage assessment performed within the first week of revascularisation may underestimate the potential for functional recovery.
  
  
  CONCLUSIONS
  • MRI can measure how much myocardium is damaged after a heart attack. • Heart muscle that appears initially non-viable may sometimes partially recover. • Enhancement around the edges of infarcts may resolve over time. • Evaluating new cardio-protective treatments with MRI requires appreciation of its limitations.
authors.affiliation: Robert Steiner MRI Unit, MRC Clinical Sciences Centre, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK. declan.oregan@imperial.ac.uk
authors.forename: Declan P
authors.initials: DP
authors.lastname: O'Regan
authors.forename: Ben
authors.initials: B
authors.lastname: Ariff
authors.forename: A John
authors.initials: AJ
authors.lastname: Baksi
authors.forename: Fabiana
authors.initials: F
authors.lastname: Gordon
authors.forename: Giuliana
authors.initials: G
authors.lastname: Durighel
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Cook
mesh_terms: D000328:Adult; D000465:Algorithms; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D020127:Recovery of Function; D015203:Reproducibility of Results; D016879:Salvage Therapy / Q000379:methods*; D012680:Sensitivity and Specificity; D016896:Treatment Outcome