Beat-to-beat spatiotemporal variability in the T vector is associated with sudden cardiac death in participants without left ventricular hypertrophy: the Atherosclerosis Risk in Communities (ARIC) study

Background: despite advances in prevention and treatment of cardiovascular disease,sudden cardiac death (scd) remains a clinical challenge. risk stratification in the general population is needed. methods and results-beat-to-beat spatiotemporal variability in the t vector was measured as the mean angle between consecutive t-wave vectors (mean tt' angle) on standard 12-lead ecgs in 14 024 participants in the atherosclerosis risk in communities (aric) study. subjects with left ventricular hypertrophy,atrial arrhythmias,frequent ectopy,ventricular pacing,or qrs duration ≥120 ms were excluded. the mean spatial tt' angle was 5.21±3.55°. during a median of 14 years of follow-up,235 scds occurred (1.24 per 1000 person-years). after adjustment for demographics,coronary heart disease risk factors,and known ecg markers for scd,mean tt' angle was independently associated with scd (hazard ratio 1.089; 95% ci 1.044 to 1.137; p<0.0001). a mean tt' angle >90th percentile (>9.57°) was associated with a 2-fold increase in the hazard for scd (hazard ratio 2.01; 95% ci 1.28 to 3.16; p=0.002). in a subgroup of patients with t-vector amplitude =0.2 mv,the association with scd was almost twice as strong (hazard ratio 3.92; 95% ci 1.91 to 8.05; p<0.0001). a significant interaction between mean tt' angle and age was found: tt' angle was associated with scd in participants aged <55 years (hazard ratio 1.096; 95% ci 0.043 to 1.152; p<0.0001) but not in participants aged ≥55 years (pinteraction=0.009). conclusions-in a large,prospective,community-based cohort of left ventricular hypertrophy-free participants,increased beat-tobeat spatiotemporal variability in the t vector,as assessed by increasing tt' angle,was associated with scd. © 2015 the authors.