Prognostic significance of electrocardiographic Q-waves in a low-risk population

Abstract

In individuals without known heart disease, electrocardiographic Q-waves predict a poor prognosis. We aimed to examine whether prognostic information can be derived from the size and location of Q-waves in persons from the general population without known ischaemic heart disease (IHD) or heart failure (HF). Electrocardiograms (ECGs) of 5381 persons without known IHD or HF from the 4th Copenhagen City Heart Study were reviewed and Q-waves were classified according to their size and location. Multivariate Cox proportional hazards regression models were used to examine the associations of Q-waves adjusted for age, hypertension, diabetes, and estimated glomerular filtration rate with the risk of the combined endpoint of death and hospitalization for IHD. During a median of 7.8 years of follow-up, 1003 persons reached the combined endpoint. One hundred and fourteen (2.1%) had pathological Q-waves, of whom 44% suffered from an event compared with 18% from the control group, P< 0.001. Persons with hypertension, diabetes, and impaired renal function were more likely to have Q-waves. Even small Q-waves (i.e. Minnesota code 1.2.x-1.3.x) were associated with a poor prognosis, hazard ratio (HR) 1.4 [95% confidence interval (CI): 1.0–2.0; P< 0.05], though not as grave as large Q-waves (i.e. Minnesota code 1.1.x) HR 2.8 (95%CI: 1.6–5.0; P< 0.001). Conversely, there was no difference in the outcome of patients with anteriorly HR 1.6 (95%CI: 1.1–2.4) vs. posteriorly HR 1.5 (95%CI: 0.9–2.4) located Q-waves (P= 0.85). In the general population without known IHD or HF, even small Q-waves in the ECG are associated with a poor prognosis.