Prevalence of ECGs Exceeding Thresholds for ST-Segment-Elevation Myocardial Infarction in Apparently Healthy Individuals: The Role of Ethnicity

Abstract

Background Early prehospital recognition of critical conditions such as ST-segment-elevation myocardial infarction (STEMI) has prognostic relevance. Current international electrocardiographic STEMI thresholds are predominantly based on individuals of Western European descent. However, because of ethnic electrocardiographic variability both in health and disease, there is a need to reevaluate diagnostic ST-segment elevation thresholds for different populations. We hypothesized that fulfillment of ST-segment elevation thresholds of STEMI criteria (STE-ECGs) in apparently healthy individuals is ethnicity dependent. Methods and Results HELIUS (Healthy Life in an Urban Setting) is a multiethnic cohort study including 10 783 apparently healthy subjects of 6 different ethnicities (African Surinamese, Dutch, Ghanaian, Moroccan, South Asian Surinamese, and Turkish). Prevalence of STE-ECGs across ethnicities, sexes, and age groups was assessed with respect to the 2 international STEMI thresholds: sex and age specific versus sex specific. Mean prevalence of STE-ECGs was 2.8% to 3.4% (age/sex-specific and sex-specific thresholds, respectively), although with large ethnicity-dependent variability. Prevalences in Western European Dutch were 2.3% to 3.0%, but excessively higher in young (<40 years) Ghanaian males (21.7%-27.5%) and lowest in older (≥40 years) Turkish females (0.0%). Ethnicity (sub-Saharan African origin) and other variables (eg, younger age, male sex, high QRS voltages, or anterolateral early repolarization pattern) were positively associated with STE-ECG occurrence, resulting in subgroups with >45% STE-ECGs. Conclusions The accuracy of diagnostic tests partly relies on background prevalence in healthy individuals. In apparently healthy subjects, there is a highly variable ethnicity-dependent prevalence of ECGs with ST-segment elevations exceeding STEMI thresholds. This has potential consequences for STEMI evaluations in individuals who are not of Western European descent, putatively resulting in adverse outcomes with both over- and underdiagnosis of STEMI.

Keywords: ECG; HELIUS study; STEMI; ethnicity; population study.

Figure 1. Inclusion and exclusion flowchart.

^†ECG abnormalities: overt tachycardia (>110/min), supraventricular arrhythmia, second‐ or third‐degree atrioventricular block, left, right, extreme or indeterminate axis, pathological Q‐waves or high R‐waves V1/V2, low QRS voltages, T‐wave abnormalities, very long or very short QTc, suspicion of cardiomyopathy or other overt ECG abnormalities (eg, dextrocardia).

Figure 2. STE‐ECG prevalence stratified per ethnicity, sex, and age group.

Application of the 2 STEMI thresholds for the different ethnicity, sex, and age groups. ACCF/AHA sex‐specific STEMI thresholds: lead V2 to V3 ≥0.2 mV [men], ≥0.15 mV [women], other leads ≥0.1 mV. ESC age‐ and sex‐specific STEMI thresholds: lead V2‐V3 ≥0.25 mV [men <40 y], ≥0.20 mV [women ≥40 y], ≥0.15 mV [women], other leads ≥0.1 mV. Note the increase in prevalence when using only sex‐specific thresholds. Furthermore, note the higher prevalence with younger age, male sex (despite sex‐specific thresholds), and in certain ethnicities. ACCF/AHA indicates American College of Cardiology Foundation/American Heart Association; ESC, European Society of Cardiology; STE‐ECG, ECG that fulfills thresholds for STEMI; and STEMI, ST‐segment–elevation myocardial infarction.

Figure 3. Corrected distribution of ethnicity and sex within the STE‐ECGs.

Distribution of ethnicity‐ and sex‐ based subgroups within the STE‐ECGs plotted after correction for the study population distribution regarding ethnicity, sex, and the 2 age groups (cutoff 40 years). ACC/AHA sex‐specific STEMI thresholds: lead V2‐V3 ≥0.2 mV [men], ≥0.15 mV [women], other leads ≥0.1 mV. ESC age‐ and sex‐specific STEMI thresholds: lead V2‐V3 ≥0.25 mV [men <40 y], ≥0.20 mV [men ≥40 y], ≥0.15 mV [women], other leads ≥0.1 mV. Note that subjects originating from Western Africa account for more than half (sex‐specific or thresholds) or up to two thirds (age‐ and sex‐specific thresholds) of all STE‐ECGs. ACCF/AHA indicates American College of Cardiology Foundation/American Heart Association; ESC, European Society of Cardiology; STE‐ECG, ECG that fulfills thresholds for STEMI; and STEMI, ST‐segment–elevation myocardial infarction.

Figure 4. J‐point amplitudes and ST‐segment elevation location.

A, The colored lines represent the current age‐ and sex‐specific STEMI thresholds for each lead. Black stripes box: Q1, Q2, Q3, whiskers: Q1–1.5·interquartile range and Q3+1.5·interquartile range. Boxplots of the J‐point amplitudes in the total apparently healthy population (N=10 783). Appreciate the amount of J‐point amplitudes above the STEMI threshold in leads V2, V3, and V4. (B and C) general: The directions of the 3‐dimentional ST vectors of all subjects are shown on a sphere in the 2‐dimensional plane by cordiform Stab‐Werner projections. Lead vector projections are marked with dashed lines. B, Density plot. Note the precordial orientation of most ST vectors. C, ST vector of all subjects in which the marker size represents the size of the ST vector. Interquartile ellipses of a combination of azimuth and elevation are stratified per ethnicity. Because the direction of small ST vectors is rather unreliable, small markers with a deviant direction should, in our opinion, not be seen as actual outliers. No evident ethnic difference in spatial ST vector distribution can be appreciated. Jp indicates J‐point; STEMI, ST‐segment–elevation myocardial infarction; and y, years old.