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[The ST/HR slope and coronary stenoses]
P Allibardi1, F Dainese, C Burelli
1Servizio di Cardiologia, Ospedale Civile, Mirano, Venezia.
Insights
The ST/HR Slope method accurately detects coronary artery disease using treadmill exercise electrocardiograms. This approach shows high sensitivity and specificity, improving diagnostic capabilities for patients with suspected coronary artery disease.
Area of Science:
- Cardiology
- Exercise Physiology
- Diagnostic Imaging
Background:
- Treadmill exercise electrocardiograms (ECG) are used to identify coronary artery disease (CAD).
- The ST/HR Slope, an adjustment for heart rate in ST depression, has shown potential to improve ECG accuracy for CAD detection.
- Conflicting results exist in the literature regarding the efficacy of the ST/HR Slope method.
Discussion:
- This study compares the ST/HR Slope method's performance in a specific laboratory setting against existing literature data.
- The methodology involved 50 patients with suspected CAD undergoing a modified Bruce protocol for ST/HR Slope calculation.
- Strict exclusion criteria were applied to ensure a homogeneous study population, minimizing confounding factors.
Key Insights:
- The ST/HR Slope method demonstrated high diagnostic accuracy in this cohort.
- Sensitivity was 93%, specificity 97%, positive predictive value 93%, and negative predictive value 97% for detecting severe coronary artery disease.
- The method correctly identified most patients with multivessel and less severe coronary artery disease, with minimal false positives/negatives.
Outlook:
- The ST/HR Slope method shows promise for enhancing the clinical utility of treadmill ECGs in diagnosing coronary artery disease.
- Further validation in diverse patient populations and comparison with other advanced diagnostic techniques may be warranted.
- Real-time computerized calculation of ST/HR Slope facilitates its integration into routine clinical practice.
Background:
The heart rate adjustment of ST depression (ST/HR Slope) has been shown by some authors to markedly improve the accuracy of treadmill exercise electrocardiogram for identifying and quantifying coronary artery disease. However, other authors have obtained different results. In the present study the results of our exercise electrocardiography laboratory are compared with the data obtained from the literature.
Methods:
Fifty patients (46 males and 4 females, age range 60 +/- 7 years) with suspect or certain coronary artery disease were referred for a routine treadmill exercise electrocardiogram, and subsequently underwent cardiac catheterization and selective coronary cineangiography to assess the severity of coronary obstruction. All patients exercised according to a recently reported modification of the standard Bruce protocol, proposed by Kligfield et al, for a more accurate evaluation of the ST/HR Slope, which was calculated in real time by a computerized system. Patients with coexisting valvular heart disease, cardiomyopathy, left bundle-branch block on the resting ECG, myocardial infarction within 8 weeks, diabetes mellitus, hypertensive response during exercise testing (diastolic blood pressure > 95 mm Hg and/or systolic blood pressure > 190 mm Hg), abnormalities or variations of the coronary arteries, were excluded from this study.
Results:
This method correctly identified 13 of 14 patients with multivessel coronary artery disease and 35 of 36 with less severe disease: one patient was false negative and another one false positive. Thus, in our exercise electrocardiography laboratory this approach shows a sensitivity of 93%, a specificity of 97%, a positive predictive value of 93% and a negative predictive value of 97% for the detection of severe coronary disease.
Conclusions:
These findings suggest that, in patients selected as in this study, the ST/HR slope is a good method which improves the clinical usefulness of the treadmill exercise electrocardiogram in coronary artery disease.