Prevalence and Prognostic Significance of Negative U-waves in a 12-lead Electrocardiogram in the General Population.

Negative U-waves are a relatively rare finding in an electrocardiogram (ECG), but are often associated with cardiac disease. The prognostic significance of negative U-waves in the general population is unknown. We evaluated 12-lead ECGs of 6,518 adults (45% male, mean age 50.9 ± 13.8 years) for the presence of U-waves, and followed the subjects for 24.5 ± 10.3 years. Primary end points were all-cause mortality, cardiac mortality, and sudden cardiac death; secondary end point was hospitalization due to cardiac causes. Negative U-waves (amplitude ≥0.05 mV) were present in 231 subjects (3.5%), minor negative (amplitude <0.05 mV) or discordant U-waves in 1,004 subjects (15.4%), normal positive U-waves in 3,950 (60.6%) subjects, and no U-waves were observed in 603 subjects (9.3%). In 730 subjects (11.2%), U-waves were unassessable. When adjusted for age and gender, negative U-waves were associated with all end points (p <0.01). In an analysis adjusted for multiple demographic and clinical factors, in men, negative U-waves were associated with increased risk of all-cause mortality (hazard ratio [HR] 1.60; 95% confidence interval [CI] 1.26 to 2.03; p <0.001), cardiac mortality (HR 1.74; 95% CI 1.26 to 2.39; p = 0.001), and cardiac hospitalization (HR 1.67; 95% CI 1.27 to 2.18; p <0.001), but not with sudden cardiac death, whereas women did not show a significant association to any of the end points (p >0.30). In conclusion, negative U-waves are associated with adverse events in the general population. In men, this association is independent of cardiovascular risk factors.