Key result
Baseline Q waves linked to ~55% higher CV risk in stable CAD without prior MI.
Why the study?
Does the presence of Q waves on ECG predict cardiovascular events in patients with stable CAD and no prior history of MI?
Cohort (n=462)
Yes
Does the presence of Q waves on ECG predict cardiovascular events in patients with stable CAD and no prior history of MI?
Hazard Ratio: 1.55 (95% CI 1.06–2.26)
Absolute Event Rate: 6.2% vs 4.5%
p-value: p=0.02
In patients with stable CAD and no prior MI, the presence of Q waves on a baseline ECG is an independent predictor of adverse cardiovascular events.
May aid risk stratification in stable CAD without prior MI; extends prior findings but leaves open prospective validation.
Unrecognized myocardial infarction (MI) carries a poor prognosis in the general population, but its prognostic value is less clear in high-risk patients. We sought to determine whether Q waves on electrocardiogram (ECG), suggestive of unrecognized MI, predict cardiovascular events in patients with stable coronary artery disease (CAD), but without a prior history of MI. We studied 462 patients enrolled in the Heart and Soul Study with stable CAD but without a prior history of MI. All patients had baseline ECGs. The baseline prevalence of unrecognized myocardial infarction was 36%. After a mean of 6.3 years of follow-up, there were a total of 141 cardiovascular events. The presence of Q waves in any ECG lead territory predicted cardiovascular events before (unadjusted HR 1.41, 95% CI 1.01-1.97) and after adjustment for demographics, medical history, diastolic function, and ejection fraction (HR 1.55, 95% CI 1.06-2.26). This association was partly attenuated after adjustment for the presence of inducible ischemia at baseline (HR 1.43, 95% CI 0.96-2.12). When specific territories were analyzed separately, Q waves in anterior leads were predictive of cardiovascular events in both unadjusted and adjusted models (adjusted HR 1.85, 95% CI 1.14-3.00), and this association was partly attenuated after adjustment for inducible ischemia. In conclusion, in patients with CAD but no history of prior MI, the presence of any Q waves or anterior Q waves alone is independently predictive of adverse cardiovascular events.
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Kehl et al. (2010) conducted a cohort in Stable coronary artery disease without prior history of myocardial infarction (n=462). Presence of Q waves on baseline ECG (unrecognized myocardial infarction) vs. Absence of Q waves on baseline ECG was evaluated on Cardiovascular events (composite of all-cause death, nonfatal myocardial infarction, and stroke) (HR 1.55, 95% CI 1.06-2.26, p=0.02). The presence of Q waves on baseline electrocardiogram was associated with a 55% increased risk of cardiovascular events in patients with stable coronary artery disease and no prior history of myocardial infarction (adjusted HR 1.55).
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