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CLINICAL RESEARCH: INTERVENTIONAL CARDIOLOGY

Baseline Q-Wave Surpasses Time From Symptom Onset as a Prognostic Marker in ST-Segment Elevation Myocardial Infarction Patients Treated With Primary Percutaneous Coronary Intervention

Paul W. Armstrong, MD^_*,_*, Yuling Fu, MD^_*, Cynthia M. Westerhout, PhD^_*, Michael P. Hudson, MD, Kenneth W. Mahaffey, MD, Harvey D. White, DSc, Thomas G. Todaro, MD^||, Peter X. Adams, MD^¶, Philip E.G. Aylward, MD^# and Christopher B. Granger, MD

^_* University of Alberta, Edmonton, Alberta, Canada
Henry Ford Heart and Vascular Institute, Detroit, Michigan
Duke Clinical Research Institute, Durham, North Carolina
Green Lane Coordinating Centre, Auckland, New Zealand
^|| Procter & Gamble Health Care Research Centre, Mason, Ohio
^¶ Alexion Pharmaceuticals, Cheshire, Connecticut
^# Flinders Medical Centre, Bedford Park, Australia

Manuscript received December 4, 2008; revised manuscript received January 23, 2009, accepted January 25, 2009.

^_* Reprint requests and correspondence: Dr. Paul W. Armstrong, Department of Medicine, Division of Cardiology, University of Alberta, 2-51 Medical Sciences Building, Edmonton, Alberta T6G 2H7, Canada (Email: paul.armstrong{at}ualberta.ca).

Objectives: We assessed the incremental value of baseline Q waves over time from symptom onset as a marker of clinical outcome in ST-segment elevation myocardial infarction (STEMI).

Background: Time from symptom onset is a central focus in STEMI patients. The presence of Q waves on the baseline electrocardiogram (ECG) has been suggested to be of incremental value to time from symptom onset in evaluating clinical outcomes.

Methods: We evaluated baseline Q waves and ST-segment resolution 30 min after primary percutaneous intervention (PCI) ECGs in 4,530 STEMI patients without prior infarction. Additionally, peak biomarkers; 90-day mortality; and the composite of death, congestive heart failure (CHF), or cardiogenic shock were assessed.

Results: Fifty-six percent of patients had baseline Q waves: they were older, more frequently male and diabetic, and had a more advanced Killip class. Patients with baseline Q waves had greater mortality and a higher composite rate of death, CHF, and shock versus patients without baseline Q waves at 90 days (5.3% vs. 2.1% and 12.1% vs. 4.8%, respectively, both p < 0.001). Complete ST-segment resolution was highest, whereas 90-day mortality and the composite outcome were lowest among those randomized 3 h without baseline Q waves. After multivariable adjustment, baseline Q-wave but not time from symptom onset was significantly associated with a 78% relative increase in the hazard of 90-day mortality and a 90% relative increase in the hazard of death, shock, and CHF.

Conclusions: Baseline Q waves in STEMI patients treated with primary PCI provide an independent prognostic marker of clinical outcome. These data might be useful in designing future clinical trials as well as in evaluating patients for triage and potential transfer for planned primary PCI. (Pexelizumab in Conjunction With Angioplasty in Acute Myocardial Infarction [APEX-AMI]; NCT00091637)

Key Words: infarction • prognosis • Q-wave

Abbreviations and Acronyms   CHF = congestive heart failure   ECG = electrocardiogram   MI = myocardial infarction   PCI = percutaneous coronary intervention   STEMI = ST-segment elevation myocardial infarction

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J. Am. Coll. Cardiol. 2009 53: A28. [Full Text] [PDF]