title: Q-wave evolution of a first acute myocardial infarction without significant ST segment elevation.
abstract: BACKGROUND
  Some patients with acute myocardial infarction presenting without significant ST segment elevation develop a Q-wave infarction. It is unclear whether these patients can be identified from the admission electrocardiogram (ECG) and whether they differ in their in-hospital prognosis from those who retain a non-Q-wave myocardial infarction.
  
  
  METHODS
  In 432 consecutive patients admitted to our centre with a first acute myocardial infarction without Q waves and with ST segment amplitudes < or =0.1 mV on admission, we assessed the frequency, the electrocardiographic predictors and the short-term implications of a Q-wave evolution.
  
  
  RESULTS
  In 94 patients (22%), a Q-wave myocardial infarction evolved before hospital discharge (14 anterior, 26 inferior, six lateral, and 48 posterior). Minor anterior ST segment elevation was 36% sensitive and 95% specific in predicting anterior Q waves; minor inferior ST segment elevation, 42% and 89%, respectively, for inferior Q waves; and a maximal ST segment depression > or =0.2 mV in leads V2-V3 with upright T waves and without remote ST segment depression, 38% and 97%, respectively, for posterior R waves. Although patients with a Q-wave evolution had a greater creatinkinase MB peak than those retaining a non-Q-wave pattern (191+/-113 vs. 105+/-77 IU/l, respectively, P<0.001), they experienced a benign in-hospital course, with similar risk of severe complications after adjustment for the baseline clinical predictors than non-Q-wave patients.
  
  
  CONCLUSIONS
  About one fifth of patients with a first acute myocardial infarction without a significant ST segment elevation develop a Q-wave infarction and the admission ECG can help identify them. This evolution, however, is not associated with a worse in-hospital outcome.
authors.affiliation: Unitat Coronària, Servicio de Cardiología, Hospital General Universitari Vall d'Hebron, Pg. Vall d'Hebron 119-129, 08035, Barcelona, Spain. jbarra@hg.vhebron.es
authors.forename: J A
authors.initials: JA
authors.lastname: Barrabés
authors.forename: J
authors.initials: J
authors.lastname: Figueras
authors.forename: C
authors.initials: C
authors.lastname: Moure
authors.forename: J
authors.initials: J
authors.lastname: Cortadellas
authors.forename: J
authors.initials: J
authors.lastname: Soler-Soler
mesh_terms: D015415:Biomarkers / Q000097:blood; D003402:Creatine Kinase / Q000097:blood; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000201:enzymology / Q000401:mortality / Q000503:physiopathology*; D020115:Pepsinogen C; D012189:Retrospective Studies; D015996:Survival Rate
chemical_list: D015415:Biomarkers; D020115:Pepsinogen C; D003402:Creatine Kinase