title: Intracoronary ECG ST-segment recovery during primary percutaneous intervention for ST-segment myocardial infarction: insights from a cardiac MRI study.
abstract: BACKGROUND
  ST-segment-resolution (STR) on surface electrocardiogram (ECG) is a good surrogate for myocardial reperfusion in patients with acute ST-segment-elevation-myocardial-infarction (STEMI). We sort to determine the optimal criteria of measuring STR on intracoronary-ECG (IC-ECG) for prediction of myocardial injury evaluated by cardiac MRI (CMR).
  
  
  METHODS
  Measurements of IC-ECG ST-segments were performed at baseline, immediately after (early) and 15 min (late) after achieving TIMI-3 flow during primary-PCI. The degree of ST-segment-shift from baseline noted upon the IC-ECG was divided into four groups: (group 1) ST-segment-resolution >1 mm, (group 2) <30% resolution, (group 3) >50% resolution, (group 4) >70% resolution at both early and late time points. Patients had CMR at days 3 and 90 postprimary-PCI.
  
  
  RESULTS
  Fifty two patients (aged 60 ± 11 years; 43 males) were evaluated. Early intracoronary-ECG ST-segment resolution (early IC-STR >1 mm) correlated with smaller scar mass (P = 0.003), nonviable myocardial mass (P < 0.001), and microvascular obstruction (MVO) (P = 0.004) on CMR at day 3. Ejection fraction (EF) was also better at day 3 (P = 0.026) and 90 (P = 0.039). Patients with poor early IC-STR (IC-STR <30%) conversely is associated with larger scar mass (P = 0.017), nonviable myocardial mass (P = 0.01), and MVO (P = 0.021) at day 3. This was also associated with worse EF at day 90 (P = 0.044). Neither group 3 or 4, or the late measurements of late IC-STR correlated with CMR markers of myocardial injury.
  
  
  CONCLUSIONS
  The degree of early IC-STR (defined by IC-STR > 1 mm or <30%) successfully predicts myocardial damage following primary-PCI for an acute STEMI. Further studies are required to investigate its potential utility.
authors.affiliation: Cardiovascular Research Centre, Royal Adelaide Hospital Department of Cardiology and Discipline of Medicine, University of Adelaide, Adelaide, South Australia.
authors.forename: Dennis T L
authors.initials: DT
authors.lastname: Wong
authors.forename: Michael C H
authors.initials: MC
authors.lastname: Leung
authors.forename: Rajiv
authors.initials: R
authors.lastname: Das
authors.forename: Rishi
authors.initials: R
authors.lastname: Puri
authors.forename: Gary Y H
authors.initials: GY
authors.lastname: Liew
authors.forename: Karen S L
authors.initials: KS
authors.lastname: Teo
authors.forename: Derek P
authors.initials: DP
authors.lastname: Chew
authors.forename: Ian T
authors.initials: IT
authors.lastname: Meredith
authors.forename: Matthew I
authors.initials: MI
authors.lastname: Worthley
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Worthley
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects; D017023:Coronary Angiography; D003326:Coronary Circulation; D004562:Electrocardiography; D005260:Female; D006801:Humans; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D009206:Myocardium / Q000473:pathology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015607:Stents; D013318:Stroke Volume; D013997:Time Factors; D014022:Tissue Survival; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling