What is the clinical evidence from this study?

Study design: Cohort. Population: Healthy employed men (n=980). Intervention: ECG abnormalities vs. Normal ECG. Primary outcome: First myocardial infarction (OR 3.16, 95% CI 1.74-5.73, p=0.0001).

October 30, 2020Open Access

Prospective associations between ECG abnormalities and death or myocardial infarction in a cohort of 980 employed, middle-aged Swedish men

Key Result

The presence of one or more resting ECG abnormalities in middle-aged men was associated with a significantly increased risk of myocardial infarction over 25 years (OR 3.16).

Study Design

Type

Cohort (n=980)

Structured PICO

Does the presence of resting ECG abnormalities predict myocardial infarction or death in middle-aged employed men?

Population

980 employed Swedish men aged 45-50 years followed for 25 years to assess the association between resting ECG abnormalities and myocardial infarction or death.

Exposure

Presence of at least one resting 12-lead ECG abnormality (classified by the Minnesota Code) in 1993 or 1998.

Comparator

Two normal resting 12-lead ECGs (in 1993 and 1998).

Outcome

First myocardial infarction and all-cause death over 25 years follow-up.hard clinical

The presence of resting ECG abnormalities in middle-aged men is independently associated with a 3- to 4-fold increased risk of myocardial infarction over 25 years, suggesting potential utility in individualized risk assessment.

Main Result

Odds Ratio: 3.16 (95% CI 1.74–5.73)

Absolute Event Rate: 22.4% vs 8.35%

p-value: p=0.0001

Limitations

External validity is limited as the study is confined to males in a certain age range in a particular industry and country.
Comparably small sample size and small number of outcome events.
Use of the Framingham Risk Index, which has been superseded by better predictive tools.
The Minnesota Code used for classification does not register QTc.

Abstract

BACKGROUND: In 1993, 1000 randomly selected employed Swedish men aged 45-50 years were invited to a nurse-led health examination with a survey on life style, fasting lab tests, and a 12-lead ECG. A repeat examination was offered in 1998. The ECGs were classified according to the Minnesota Code. Upon ethical approval, endpoints in terms of MI and death over 25 years were collected from Swedish national registers with the purpose of analyzing the independent association of ECG abnormalities as risk factors for myocardial infarction and death. RESULTS: Seventy-nine of 977 participants had at least one ECG abnormality 1993 or 1998. One hundred participants had a first MI over the 25 years. Odds ratio for having an MI in the group that had one or more ECG abnormality compared with the group with two normal ECGs was estimated to 3.16. 95%CI (1.74; 5.73), p value 0.0001. One hundred fifty-seven participants had died before 2019. For death, similarly no statistically significant difference was shown, OR 1.52, 95%CI (0.83; 2.76). CONCLUSIONS: Our study suggests that presence of ST- and R-wave changes is associated with an independent 3-4-fold increased risk of MI after 25 years follow-up, but not of death. A 12-lead resting ECG should be included in any MI risk calculation on an individual level.

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