An Electrocardiogram-Based Risk Equation for Incident Cardiovascular Disease From the National Health and Nutrition Examination Survey

Abstract

IMPORTANCE Electrocardiography (ECG) may detect subclinical cardiovascular disease (CVD) in asymptomatic individuals, but its role in assessing adverse events beyond traditional risk factors is not clear. Interval and vector data that are commonly available on modern ECGs may offer independent prognostic information that improves risk classification. OBJECTIVES To derive and validate a CVD risk equation based on ECG metrics and to determine its incremental benefit in addition to the Framingham risk score (FRS). DESIGN, SETTING, AND PARTICIPANTS This study included 3640 randomly selected community-based adults aged 40 to 74 years without known CVD from the First National Health and Nutrition Examination Survey (NHANES I) cohort (1971–1975) and 6329 from the NHANES III cohort (1988–1994). Participants were sampled from across the United States. A risk score to assess incident nonfatal and fatal CVD events was derived based on computer-generated ECG data, including frontal P, R, and T axes; heart rate; and PR, QRS, and QT intervals from NHANES I. The most prognostic variables, along with age and sex, were incorporated into the NHANES ECG risk equation. The equation was evaluated in the NHANES III cohort for an independent validation. Follow-up in the NHANES III cohort was completed on December 31, 2006. Data for this study were analyzed from August 11, 2015, to May 20, 2016. MAIN OUTCOMES AND MEASURES The primary end point was CVD death. Secondary outcomes included 10-year ischemic heart disease and all-cause death. RESULTS The final study sample included 9969 participants (4714 men [47.3%]; 5255 women [52.7%]; mean [SD] age, 55.3 [10.1] years) from both cohorts. Frontal T axis, heart rate, and heart rate–corrected QT interval were the most significant ECG factors in the NHANES I cohort. In the validation cohort (NHANES III), the equation provided for prognostic information for fatal CVD with a hazard ratio (HR) of 3.23 (95% CI, 2.82–3.72); the C statistic was 0.79 (95% CI, 0.76–0.81). When added to the FRS in Cox proportional hazards regression models, the categorical (1%, 5%, and 10% cutoffs) net reclassification improvement was 24%. When the FRS and ECG scores were combined in a single model, the C statistic improved by 0.04 (95% CI, 0.02–0.06) to 0.80 (95% CI, 0.77–0.82). Similar improvements were noted when the ECG score was added to the pooled cohort equation. When the equation for prognostic information about ischemic heart disease and all-cause death was evaluated, the results were similar. CONCLUSIONS AND RELEVANCE An ECG risk score based on age, sex, heart rate, frontal T axis, and QT interval assesses the risk for CVD and compares favorably with the FRS alone in an independent cohort of asymptomatic individuals. Although the ECG risk equation is low cost, further research is needed to ascertain whether this additional step in risk stratification may improve prevention efforts and reduce CVD events.

Ischemic ECG abnormalities are associated with an increased risk for death among subjects with COPD, also among those without known heart disease

“…The value of ECG screening in subjects with elevated risk for CVD is unclear, 37 but recent studies have shown that ECG contributes to an improved risk prediction. 13 , 38 Early identification of IHD and treatment of cardiovascular risk factors may have a beneficial impact on morbidity and prevent mortality. However, systemic inflammation has been suggested as a link between cardiovascular disease and COPD, 39 and the underlying pathophysiological mechanisms are not fully understood.…”

Age at Menarche and Cardiometabolic Health: A Sibling Analysis in the Scottish Family Health Study

“…One was the Framingham 10‐year risk score, which includes age, total cholesterol, HDL cholesterol, systolic blood pressure, smoking, and diabetes mellitus 28. The second was a new validated 10‐year risk score for CVD from the NHANES (National Health and Nutrition Examination Survey) cohort that uses age and a range of measurements from ECG readings, including positive deflection of the T axis, negative deflection of the T axis, heart rate, and corrected QT interval 29. The risk scores were calculated only for individuals who were between 30 and 74 years of age (81% of those included in this analysis) because the original risk scores were generated for this age group.…”

“…28 The second was a new validated 10-year risk score for CVD from the NHANES (National Health and Nutrition Examination Survey) cohort that uses age and a range of measurements from ECG readings, including positive deflection of the T axis, negative deflection of the T axis, heart rate, and corrected QT interval. 29 The risk scores were calculated only for individuals who were between 30 and 74 years of age (81% of those included in this analysis) because the original risk scores were generated for this age group. Individuals with self-reported history of heart disease or stroke were excluded from the analysis of 10-year risk of CVD.…”

The Association and Predictive Ability of ECG Abnormalities with Cardiovascular Diseases: A Prospective Analysis

“…Although the USPSTF recommended against use of routine ECG as a screening tool to prevent CVD events in asymptomatic adults at low risk and concluded evidence insufficient in asymptomatic adults at intermediate or high risk [9], studies on how the addition of ECG to traditional risk factors affects CVD risk reclassification are limited. Several previous studies have reported similar associations between single and multiple ECG abnormalities and CVD outcomes, but few have examined the improvement in CVD risk discrimination, reclassification, and calibration by adding the overall CVD-related ECG abnormalities to traditional risk factors [8,[21][22][23][24]. When examining the single ECG abnormalities, there were 946 (12.0%) left ventricular hypertrophies, 249 (3.2%) bundle or interventricular blocks, and 779 (9.9%) ST-T abnormalities and 333 (4.2%) possible myocardial infarctions in the current study, all of which were associated with increased risks of CVD events (adjusted HR: 1.12 to 1.54), although some of them were not statistically significant.…”