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Usefulness of exercise-induced ST-segment depression in the inferior leads during exercise testing as a marker for
1Cardiology Department, Long Beach Veterans Affairs Medical Center, California.
Insights
Precordial lead V5 demonstrates superior diagnostic accuracy for detecting coronary artery disease (CAD) during exercise stress tests compared to inferior limb lead II. This finding highlights V5
Area of Science:
- Cardiology
- Diagnostic Imaging
- Exercise Physiology
Background:
- Multiple lead systems offer higher sensitivity for detecting coronary artery disease (CAD) during exercise testing.
- The diagnostic value of ST-segment depression isolated to inferior leads remains questionable.
Purpose of the Study:
- To ascertain the diagnostic accuracy of inferior limb lead II compared with precordial lead V5 for detecting CAD.
- To evaluate the effectiveness of different ECG leads in exercise testing for CAD diagnosis.
Main Methods:
- Retrospective analysis of 173 men undergoing exercise testing and coronary angiography.
- Comparison of sensitivity and specificity of lead II versus lead V5 at single and multiple cut points.
- Receiver-operating characteristic (ROC) curve analysis to assess diagnostic performance.
Main Results:
- Lead V5 showed significantly better specificity (84%) and sensitivity (65%) than lead II (specificity 44%, sensitivity 71%) (p < 0.001).
- ROC analysis confirmed lead V5 (area = 0.759) was markedly superior to lead II (area = 0.582) (z = 3.032; 2p = 0.002).
- Improved specificity with lead V5 was substantial, with a 95% confidence interval for the difference of 22% to 58%.
Conclusions:
- Precordial lead V5 offers superior diagnostic accuracy for detecting coronary artery disease during exercise testing compared to inferior limb lead II.
- The diagnostic utility of ST-segment depression in lead II for CAD is limited, underscoring the importance of lead V5 in exercise electrocardiography.
Abstract:
Multiple lead systems are shown to have a higher sensitivity than that of single leads for detecting coronary artery disease (CAD) during exercise testing, but the value of ST-segment depression isolated to the inferior leads is questionable. To ascertain the diagnostic accuracy of inferior limb lead II compared with that of precordial lead V5, a retrospective analysis of 173 men was performed (108 in a training population and 65 in a validation cohort). All patients had a standard exercise test and underwent diagnostic coronary angiography within 15 days of the exercise test (range 1 to 65). Sixty-three patients had greater than or equal to 1 coronary stenoses greater than or equal to 70%, or left main lesion greater than or equal to 50%, whereas 45 patients in the training population did not. Exclusion criteria were female sex, left ventricular hypertrophy, left bundle branch block or resting ST-segment depression on the baseline electrocardiogram, previous myocardial infarction or revascularization procedures, and any significant valvular or congenital heart disease. Lead V5 had a better combination of sensitivity (65%) and specificity (84%) (chi-square = 24.11; p less than 0.001) than that of lead II (sensitivity 71%, specificity 44%) (chi-square = 2.25; p = 0.13) at a single cut point, and this improved specificity was substantial (95% confidence interval for observed difference 22 to 58%). Receiver-operating characteristic curve analysis also revealed that lead V5 (area = 0.759) was markedly superior to lead II (area = 0.582) over multiple cut points (z = 3.032; 2p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)