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Routine ECGs for the general population had clinical utility in a study of Japan's unique health screening program, with screening results tied to subsequent health outcomes.

Out of more than 3.5 million generally healthy working adults in Japan, those with any ECG abnormality on routine screening in 2016 had significantly higher rates of combined death and cardiovascular disease (CVD) admission during a median 5.5 years of follow-up:

• Normal ECG: 92.7 events per 10,000 person-years (reference)
• One minor ECG abnormality: 128.5 events per 10,000 person-years (adjusted HR 1.19, 95% CI 1.18-1.20)
• Two or more minor ECG abnormalities: 159.7 events per 10,000 person-years (adjusted HR 1.37, 95% CI 1.34-1.39)
• Major ECG abnormality: 266.3 events per 10,000 person-years (adjusted HR 1.96, 95% CI 1.92-2.02)

The finding was consistent across key subgroups and persisted after accounting for medication use. Additionally, study results were basically unchanged when death and CVD admission were considered as separate outcomes, according to a group of researchers led by Kosuke Inoue, MD, PhD, of Kyoto University in Japan, reporting in .

The investigators contrasted the large contemporary population-based cohort against those from the smaller, older studies on ECG screening that had been conducted before the last 2 decades of CVD preventive therapy advances.

Implications for Practice

However, even this study alone is likely not enough to change the U.S. Preventive Services Task Force (USPSTF) and European Society of Cardiology determinations that there is insufficient evidence to recommend screening ECGs for individuals at low risk of CVD.

"For clinicians and patients, merely knowing that someone is at risk for an adverse event is not helpful without knowing what should be done to reduce that risk," according to an by Alex Krist, MD, MPH, of Virginia Commonwealth University, Richmond, who was a USPSTF member who helped draft the group's recommendation against routine ECGs.

"There are multiple effective and recommended strategies to reduce people's risk of CVD, including statin use for people at risk, screening for and managing hypertension, and counseling for healthy diet, exercise, and smoking cessation," the editorialist wrote. "Clinicians should routinely offer all of these preventive services to patients irrespective of whether their ECG result is normal or abnormal."

There is also the concern of harm from incidental ECG findings setting off an unnecessary cascade of testing and overtreatment -- including exercise ECG, angiography, or revascularization in some cases.

"There is growing evidence that these tests and procedures may cause more harm than benefit in people without symptoms, and medical management may be more appropriate," Krist stressed.

Inoue's team acknowledged that availability of appropriate interventions following the identification of high-risk cases by ECG is a "critical challenge. "Although our findings indicate an association between ECG results and CVD events, they do not imply that ECG results themselves or additional interventions based on the ECG results mitigate the outcomes of CVD," the group cautioned.

Krist urged that future studies test interventions such as "initiating the currently recommended CVD preventive services at a lower risk threshold than traditional risk calculators would suggest, more intensively delivering existing interventions, or offering some new CVD preventive service."

Study Details

The study was possible because of Japan's unique requirement since 1989 that all working-age individuals get an annual ECG.

The nationwide cohort study relied on the Japan Health Insurance Association database, which covers approximately 40% of the working-age population in Japan. It included nearly 3.7 million people age 35-65 with no history of CVD or major ECG abnormalities who took part in the annual health check program in 2016. Average age was 47.1 years, and two-thirds were men. At baseline, 16.8% had one minor ECG abnormality, 3.9% had two or more minor abnormalities, and 1.5% had major abnormalities.

The primary endpoint was the composite of overall death and CVD hospital admission due to myocardial infarction, stroke, or heart failure.

Inoue's group reported that minor ECG abnormalities were associated with development of a new major ECG abnormality (adjusted HR 2.52 for one and 3.61 for two or more minor abnormalities).

Study authors acknowledged that there is no consensus on which are considered major vs minor ECG abnormalities, although they used the divisions defined by the Japan Society of Ningen-Dock guidelines used for screening there. Moreover, the analysis may have been impacted by miscoding in the database and, to some degree, selection bias as well, considering that not all socioeconomic groups are likely to participate in screenings.

"This very large study is truly representative of a screen-detected working age population in Japan, which is likely generalizable to other countries," Krist noted. "While it remains premature to recommend screening for CVD risk with ECG, this study provides key data to inform future studies needed to fill critical evidence gaps."

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