Abstract 13090: Increased U Vector Magnitude is Associated With Increased Risk of Sudden Cardiac Death - The Atherosclerosis Risk in Communities Study
Introduction: The U wave is a poorly understood electrocardiographic (ECG) manifestation of late ventricular repolarization. The association between U waves and sudden cardiac death (SCD) in the general population is unclear.
Hypothesis: Large U vector magnitude is associated with increased SCD risk.
Methods: Data from the Atherosclerosis Risk in Communities study (n=13,705; mean age 54.1±5.8 y; 73% male; 55% white; median follow-up 14 y) were analyzed. U wave onset and offset were identified using a semi-automated approach on XYZ transformed ECG leads. The 3-dimensional U wave loop was reconstructed and smoothed to reduce noise. U loop origin was defined as the point halfway between U-onset and U-offset in 3-dimensional space. Maximum U vector magnitude (UVMmax) was measured as the 3-dimensional distance between U loop origin and the point on the smoothed U loop farthest from the origin (Figure A). Participants with UVMmax >100 μV were excluded due to difficulty differentiating the T wave and U wave on these ECGs. Adjusted Cox proportional hazards models were used to investigate the association between UVMmax and adjudicated SCD.
Results: Median UVMmax was 9.4 μV. After adjustment for multiple demographic and clinical characteristics, electrolytes, and ECG parameters associated with SCD, UVMmax remained associated with SCD. Each 1 standard deviation increase in UVMmax was associated with an increase in the hazard of SCD (HR 1.53, 95% CI 1.29-1.81, p<0.0001). Using cubic splines, the HR for SCD increased as UVMmax increased (Figure B). A minority of participants with the highest UVMmax values had SCD risk that was 4-5 times that of participants with UVMmax of ~10 μV.
Conclusions: Larger U-waves as assessed vectorcardiographically by higher UVMmax are independently associated with SCD in a large community based cohort. VCG analysis of the U wave is useful, and further study of the association between U waves and ventricular arrhythmias/SCD is warranted.
Author Disclosures: J.W. Waks: None. M. Kabir: None. G. Sedaghat: None. J. Thomas: None. T. Biering-Sørensen: None. N. Sotoodehnia: None. C.M. Sitlani: None. M.L. Biggs: None. C.A. Henrikson: Other; Significant; St Jude, Medtronic, Boston Scientific. E.Z. Soliman: None. S.D. Solomon,: None. W.S. Post: None. D.S. Siscovick: None. A.E. Buxton: Research Grant; Significant; Medtronic research grant; not in this subject area. M.E. Josephson: None. L.G. Tereshchenko: Research Grant; Significant; Medtronic, inc, Boston Scientific. Consultant/Advisory Board; Significant; Medtronic, inc.
- © 2016 by American Heart Association, Inc.