The accuracy of the electrocardiogram during exercise stress test based on heart size
Jason C Siegler1, Shafiq Rehman, Geetha P Bhumireddy
1Department of Sport, Health & Exercise Science, University of Hull, Hull, United Kingdom.
Insights
Smaller heart size, common in women, is linked to more false positives on exercise electrocardiograms (ECG). This finding may explain the lower accuracy of exercise ECG testing, particularly in female patients.
Area of Science:
- Cardiology
- Diagnostic Imaging
Background:
- Exercise electrocardiogram (ECG) diagnostic accuracy for ischemia is suboptimal, particularly in women.
- Heart size is a potential confounding factor influencing exercise ECG accuracy.
Purpose of the Study:
- To investigate the relationship between heart size and the diagnostic accuracy of exercise ECG.
- To determine if left ventricular end diastolic volume (LVEDV) impacts exercise ECG outcomes.
Main Methods:
- 1,011 patients undergoing exercise nuclear stress tests were analyzed.
- Patients were stratified into small (<65 mL LVEDV) and normal (≥65 mL LVEDV) heart size groups.
- SPECT myocardial perfusion imaging served as the gold standard for coronary artery disease (CAD) detection.
Main Results:
- A significant association (p=0.03) was found between heart size and ECG outcome.
- Patients with smaller heart sizes exhibited a higher rate of false-positive exercise ECG results.
- 123 of 142 patients with small heart size were female.
Conclusions:
- Small heart size, predominantly observed in women, is associated with increased false positives on exercise ECG.
- This may offer a physiological explanation for the reduced accuracy of exercise stress testing in women.
- Further research into heart size-adjusted exercise ECG interpretation is warranted.
Background:
Multiple studies have shown that the exercise electrocardiogram (ECG) is less accurate for predicting ischemia, especially in women, and there is additional evidence to suggest that heart size may affect its diagnostic accuracy.
Hypothesis:
The purpose of this investigation was to assess the diagnostic accuracy of the exercise ECG based on heart size.
Methods:
We evaluated 1,011 consecutive patients who were referred for an exercise nuclear stress test. Patients were divided into two groups: small heart size defined as left ventricular end diastolic volume (LVEDV) <65 mL (Group A) and normal heart size defined as LVEDV ≥65 mL (Group B) and associations between ECG outcome (false positive vs. no false positive) and heart size (small vs. normal) were analyzed using the Chi square test for independence, with a Yates continuity correction. LVEDV calculations were performed via a computer-processing algorithm. SPECT myocardial perfusion imaging was used as the gold standard for the presence of coronary artery disease (CAD).
Results:
Small heart size was found in 142 patients, 123 female and 19 male patients. There was a significant association between ECG outcome and heart size (χ(2) = 4.7, p = 0.03), where smaller hearts were associated with a significantly greater number of false positives.
Conclusions:
This study suggests a possible explanation for the poor diagnostic accuracy of exercise stress testing, especially in women, as the overwhelming majority of patients with small heart size were women.
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