title: QRS distortion in pre-reperfusion electrocardiogram is a bedside predictor of large myocardium at risk and infarct size (a METOCARD-CNIC trial substudy).
abstract: BACKGROUND
  QRS distortion is an electrocardiographic (ECG) sign of severe ongoing ischemia in the setting of ST-segment elevation acute myocardial infarction (STEMI). We sought to evaluate the association between the degree of QRS distortion and myocardium at risk and final infarct size, measured by cardiac magnetic resonance (CMR).
  
  
  METHODS
  A total of 174 patients with a first anterior STEMI reperfused by primary angioplasty were prospectively recruited. Pre-reperfusion ECG was used to divide the study population into three groups according to the absence of QRS distortion (D0) or its presence in a single lead (D1) or in 2 or more contiguous leads (D2+). Myocardium at risk and infarct size were determined by CMR one week after STEMI. Multiple regression analysis was used to study the association of QRS distortion with myocardium at risk and infarct size, with adjustment for relevant clinical and ECG variables.
  
  
  RESULTS
  101 patients (58%) were in group D0, 30 (17%) in group D1, and 43 (25%) in group D2+. Compared with group D0, presence of QRS distortion (groups D2+ and D1) was associated with a significantly adjusted larger extent of myocardium at risk (group D2+: absolute increase 10.4%, 95% CI 6.1-14.8%, p<0.001; group D1: absolute increase 3.3%, 95% CI 1.3-7.9%, p=0.157) and larger infarct size (group D2+: absolute increase 10.1%, 95% CI 5.5-14.7%, p<0.001; group D1: absolute increase 4.9%, 95% CI 0.08-9.8%, p=0.046).
  
  
  CONCLUSIONS
  Distortion in the terminal portion of the QRS complex on pre-reperfusion ECG in two or more leads is independently associated with larger myocardium at risk and infarct size in the setting of primary angioplasty-reperfused anterior STEMI. QRS distortion in only one lead is independently associated with larger infarct size in this setting. Our findings suggest that QRS distortion analysis could be included in risk-stratification of patients presenting with anterior STEMI.
authors.affiliation: Virgen Macarena University Hospital, Sevilla, Spain.
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Valle-Caballero
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain; Hospital Universitario Clínico San Carlos, Madrid, Spain.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Fernández-Jiménez
authors.affiliation: Consultorio de Quijorna (Centro de Salud de Villanueva de la Cañada), Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Díaz-Munoz
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain; Servicio de Urgencia Médica de Madrid (SUMMA112), Spain; Universidad Francisco de Vitoria, Madrid, Spain.
authors.forename: Alonso
authors.initials: A
authors.lastname: Mateos
authors.affiliation: Complejo Hospitalario Universitario de Vigo-Meixoeiro, Pontevedra, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Rodríguez-Álvarez
authors.affiliation: Servicio de Emergencia Médica 061 de Galicia, Spain.
authors.forename: José A
authors.initials: JA
authors.lastname: Iglesias-Vázquez
authors.affiliation: Complejo Hospitalario Universitario de Vigo-Meixoeiro, Pontevedra, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Saborido
authors.affiliation: Servicio de Urgencia Médica de Madrid (SUMMA112), Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Navarro
authors.affiliation: Servicio de Urgencia Médica de Madrid (SUMMA112), Spain.
authors.forename: M Luisa
authors.initials: ML
authors.lastname: Dominguez
authors.affiliation: Servicio de Emergencia Médica 061 de Galicia, Spain.
authors.forename: Luisa
authors.initials: L
authors.lastname: Gorjón
authors.affiliation: Servicio de Emergencia Médica 061 de Galicia, Spain.
authors.forename: José C
authors.initials: JC
authors.lastname: Fontoira
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain; The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, NY, USA.
authors.forename: Valentín
authors.initials: V
authors.lastname: Fuster
authors.affiliation: Virgen Macarena University Hospital, Sevilla, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: García-Rubira
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain; IIS, Fundación Jiménez Díaz Hospital, Madrid, Spain. Electronic address: bibanez@cnic.es.
authors.forename: Borja
authors.initials: B
authors.lastname: Ibanez
mesh_terms: D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D009206:Myocardium / Q000473:pathology*; D000067716:Point-of-Care Testing; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012720:Severity of Illness Index
keywords: Electrocardiogram; Infarct size; Magnetic resonance; Myocardial infarction; Myocardium at risk; QRS distortion