title: Baseline Q waves as a prognostic modulator in patients with ST-segment elevation: insights from the PLATO trial.
abstract: BACKGROUND
  Baseline Q waves may provide additional value compared with time from the onset of symptoms in predicting outcomes for patients with ST-segment elevation. We evaluated whether baseline Q waves superseded time from symptom onset as a prognostic marker of one-year mortality in patients with ST-segment elevation acute coronary syndrome. Our study was derived from data from patients undergoing primary percutaneous coronary intervention within 24 hours in the PLATelet inhibition and patient Outcomes trial
  
  
  METHODS
  Q waves on the baseline electrocardiogram were evaluated by a blinded core laboratory. We assessed the associations between baseline Q waves and time from symptom onset to percutaneous coronary intervention with peak biomarkers, ST-segment resolution on the discharge electrocardiogram, and one-year all-cause and vascular mortality.
  
  
  RESULTS
  Of 4341 patients with ST-segment elevation, 46% had baseline Q waves. Compared to those without Q waves, those with baseline Q waves were older, more frequently male, had higher heart rates, more advanced Killip class and had a longer time between the onset of symptoms and percutaneous coronary intervention. They also had higher one-year all-cause mortality than patients without baseline Q waves (baseline Q waves: 4.9%; no baseline Q waves: 2.8%; hazard ratio [HR] 1.78, 95% confidence interval [CI] 1.29-2.45, p < 0.001). Complete ST-segment resolution was greatest and all-cause mortality lowest among those with symptom onset three hours or less before percutaneous coronary intervention and no baseline Q waves. After multivariable adjustment, baseline Q waves, but not time from symptom onset, were associated with a significant increase in all-cause mortality (adjusted HR 1.42, 95% CI 1.10-2.01, p = 0.046) and vascular mortality (adjusted HR 1.58, 95% CI 1.09-2.28, p = 0.02).
  
  
  CONCLUSIONS
  The presence of baseline Q waves provides useful additional prognostic insight into the clinical outcome of patients with ST-segment elevation. Clinical Trials.gov registration no. NCT00391872.
authors.affiliation: University of Alberta, Edmonton, Alta.
authors.forename: Hany
authors.initials: H
authors.lastname: Siha
authors.forename: Debraj
authors.initials: D
authors.lastname: Das
authors.forename: Yuling
authors.initials: Y
authors.lastname: Fu
authors.forename: Yinggan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Westerhout
authors.forename: Robert F
authors.initials: RF
authors.lastname: Storey
authors.forename: Stefan
authors.initials: S
authors.lastname: James
authors.forename: Lars
authors.initials: L
authors.lastname: Wallentin
authors.forename: Paul W
authors.initials: PW
authors.lastname: Armstrong
mesh_terms: D054058:Acute Coronary Syndrome / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D000241:Adenosine / Q000031:analogs & derivatives / Q000627:therapeutic use; D015906:Angioplasty, Balloon, Coronary; D015415:Biomarkers / Q000097:blood; D000077144:Clopidogrel; D052279:Creatine Kinase, MB Form / Q000097:blood; D004311:Double-Blind Method; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D011379:Prognosis; D011446:Prospective Studies; D058921:Purinergic P2Y Receptor Antagonists / Q000627:therapeutic use; D016019:Survival Analysis; D000077486:Ticagrelor; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D013997:Time Factors; D016896:Treatment Outcome; D019210:Troponin I / Q000097:blood; D020107:Troponin T / Q000097:blood
chemical_list: D015415:Biomarkers; D058921:Purinergic P2Y Receptor Antagonists; D019210:Troponin I; D020107:Troponin T; D000077144:Clopidogrel; D052279:Creatine Kinase, MB Form; D000077486:Ticagrelor; D000241:Adenosine; D013988:Ticlopidine