Elsevier

International Journal of Cardiology

Volume 295, 15 November 2019, Pages 36-41
International Journal of Cardiology

Incidental abnormal ECG findings and long-term cardiovascular morbidity and all-cause mortality: A population based prospective study

https://doi.org/10.1016/j.ijcard.2019.08.015Get rights and content

Highlights

  • Incidental abnormal ECG findings were associated with mortality and CVD risk.

  • The abnormal ECG findings improved 23-year CVD risk classification of 7.4% adults.

  • Non-specific T-wave changes and left-axis deviation associated with increased mortality risk.

  • Screening ECG in low risk healthy adults may improve CVD risk stratification.

Abstract

Background

The additional prognostic value of resting electrocardiogram (ECG) in long-term cardiovascular disease (CVD)-risk-assessment is unclear. We evaluated the association of incidental abnormal ECG findings with long-term CVD-risk and all-cause mortality, and assessed the additional prognostic value of ECG as a screening tool in adults without known CVD.

Methods

A cohort of 2601 Israeli men and women without known CVD were actively followed from 1976 to 1982 for 23-year cumulative CVD-incidence, and until May 2017 for all-cause mortality. At baseline and follow-up, participants underwent interviews, physical examinations, blood tests and ECG.

Results

At baseline, 1199 (46.1%) had incidental abnormal ECG findings (exposed-group). CVD cumulative incidence reached 31.6% among the 930 survivors who participated in the active follow-up (294/930). During a 31-year median follow-up, 1719 (66.1%) of the total cohort died. Incidental abnormal ECG findings were associated with 46% greater CVD-risk (odds ratio = 1.46, 95%CI = 1.09–1.97). The net reclassification improvement (NRI) of CVD-risk was 7.4% (95%CINRI = 1.5%–13.3%, p = 0.01) following the addition of ECG findings, but the C-index improvement was not statistically significant [C-index = 0.656 (0.619–0.694) vs. C-index = 0.666 (0.629–0.703), p = 0.14]. Multivariable Cox regression demonstrated an all-cause mortality hazard ratio (HR) of 1.18 (95%CI = 1.07–1.30) for exposed vs. unexposed individuals. Non-specific T-wave changes and left-axis deviation are the incidental ECG abnormalities that were associated with all-cause mortality [HR = 1.18 (95%CI = 1.05–1.33) and HR = 1.19 (95%CI = 1.00–1.42), respectively].

Conclusion

Incidental abnormal ECG findings, mainly non-specific T-wave changes and left-axis deviation, were associated with increased long-term CVD-risk and all-cause mortality among individuals without known CVD, and demonstrated net reclassification improvement for CVD-risk.

Section snippets

Background

Cardiovascular disease (CVD) is the leading cause of death globally, accounting for 23.4% of all deaths in the US in 2015 [1]. In Europe, it is the leading cause of death among older adults [2]. Annual costs of CVD in the US and the European-Union were estimated at $316.6 and $210 billion, respectively, which is more than every other group of diseases [3].

The Framingham study (1998) introduced the primary coronary heart disease risk calculator in the US, based on CVD risk factors: age, gender,

Study design and population

A subsample of 2769 men and women (Supplementary Fig. 1– study flowchart) from the Israel Study of Glucose Intolerance, Obesity and Hypertension (GOH) were included in the current follow-up study. The subsample was representative of the original cohort, which was randomly selected during 1967 from the Israel population registry, stratified according to sex, birth decade and ethnic origin (Supplementary 1- study methods) [14]. During 1976–1982 (“Phase-2”), participants underwent medical

Baseline characteristics

The mean baseline age was 54.5 ± 8.0 years, 52% were women, and 1199 (46.1%) were found to have incidental abnormal ECG findings ([15], Table 3). Sex and ethnic origin distributions, smoking habits, diabetes frequencies, and serum creatinine mean values were similar between individuals with incidental abnormal ECG findings and those with completely normal ECG results (Table 1). Mean age, blood pressure, total cholesterol and BMI were significantly lower in individuals with normal ECG results.

All-cause mortality

Discussion

Our results demonstrate that incidental abnormal ECG findings, in adults randomly selected from a population without known preexisting CVD, are associated with an increased risk of CVD, during a median follow-up of 23-years, and overall mortality during a median of 31-years. Moreover, incidental abnormal ECG findings conferred increased risk of CVD and all-cause mortality beyond any other CVD risk factor. We found ECG incidental abnormal findings at baseline to be associated with an 18%

Conclusion

Our findings demonstrate that incidental ECG abnormal findings in asymptomatic adults significantly increase the long-term risk of CVD and all-cause mortality. NST changes and left-axis deviation were the changes found to have the most significant association with the outcomes of interest. ECG abnormalities are linked to various pathological processes and may be the first sign of an underlying cardiac morbidity. Therefore, resting ECG screening tests can contribute to the identification of

Acknowledgement

\This study is part of the Master's thesis of Mr. Adam Goldman in fulfillment of his M.D. M.P.H. studies at the School of Public Health at the Sackler School for Medicine, the Tel Aviv University, Israel.

Declaration of competing interest

None to declare.

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    This author takes responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation.

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