Introduction: Electrocardiographic (ECG) measures of myocardial global electrical heterogeneity (GEH) are associated with sudden cardiac death (SCD) in middle-age adults.
Hypothesis: We hypothesized that time-updated ECG GEH measures are associated with SCD in elderly adults after LVEF adjustment.
Methods: We analyzed data from 2 prospective cohorts: The Atherosclerosis Risk in Communities (ARIC, n=15,366; mean age 54.1±5.8 y; 44.6% male; 73.2% white) and the Cardiovascular Health Study (CHS, n=5,016; mean age 72.8±5.6 y; 43.1% male; 95.3% white). Mean spatial QRS-T angle, azimuth, elevation, and magnitude of spatial ventricular gradient (SVG), and sum absolute QRST integral (SAI QRST) were calculated from digital 12-lead ECGs and analyzed as baseline variables in ARIC and as time-updated longitudinal variables in CHS (measured yearly at 10 consecutive visits). The primary outcome was adjudicated SCD. Cox regression models were constructed: Model 1 adjusted for age, sex and race. Model 2 further adjusted for cardiovascular disease, beta-blocker use, creatinine, BMI, hypertension, diabetes, smoking, total cholesterol, HDL, triglycerides, physical activity and alcohol use. Model 3 included Model 2 variables and heart rate, QTc, LV hypertrophy and bundle branch block or intra-ventricular conduction delay. Model 4 in CHS included all Model 3 variables plus baseline LVEF and time-updated incident HF and coronary heart disease.
Results: During median 13-14 y of follow-up SCD incidence was 1.51 (95%CI 1.35-1.69) per 1,000 person-yrs in ARIC, and 2.78 (95%CI 2.41-3.21) per 1,000 person-yrs in CHS. In both cohorts (Table) QRS-T angle, SVG and SAI QRST were associated with SCD. Among older adults (CHS), longitudinal SAI QRST, QRS-T angle and SVG magnitude were associated with SCD independent of LVEF.
Conclusions: Baseline and longitudinal GEH ECG parameters are independently associated with SCD in middle-age and older adults, respectively. In older adults, GEH ECG parameters provide information on SCD risk beyond LVEF.