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ST-segment/heart rate loop analysis on treadmill exercise testing can provide diagnostic and prognostic information
1Second Department of Internal Medicine, Iwate Medical University, Morioka, Japan.
Insights
ST/HR loop analysis offers a simple yet effective method for diagnosing coronary artery disease (CAD) severity in patients with stable effort angina. This technique provides valuable diagnostic and prognostic information, improving upon traditional treadmill exercise testing (TMET) methods.
Area of Science:
- Cardiology
- Diagnostic Imaging
- Exercise Physiology
Background:
- Traditional treadmill exercise testing (TMET) relies on ST-segment depression magnitude for assessing myocardial ischemia and coronary artery disease (CAD) severity.
- Distinguishing true from false-positive ST-segment depression and accurately gauging CAD severity can be challenging with conventional TMET parameters.
Purpose of the Study:
- To evaluate the diagnostic and prognostic capabilities of ST-segment/heart rate (ST/HR) loop analysis in patients experiencing stable effort angina.
Main Methods:
- ST/HR loop analysis was performed on 118 patients with stable effort angina, categorizing them into four distinct patterns (Type A, B, C, D).
- Patterns were compared against conventional TMET parameters, coronary angiography findings, exercise thallium-201 myocardial single-photon emission computed tomography (SPECT) for ischemia severity, and short-term prognosis via follow-up.
Main Results:
- Type A ST/HR loop patterns showed a significantly higher ST-segment depression index and greater ischemic size (47.6%) compared to other types.
- Type A patients frequently had multi-vessel CAD (68%), while Type D patients often had single-vessel or no significant stenosis (88%).
- Type A patients exhibited a significantly worse short-term prognosis with more cardiac events compared to Type D and control groups.
Conclusions:
- ST/HR loop analysis is a straightforward and valuable tool for enhancing diagnostic accuracy in stable effort angina.
- The ST/HR loop analysis provides significant prognostic information, aiding in risk stratification for patients with stable effort angina.
Background:
In the assessment of myocardial ischemia and its severity using treadmill exercise testing (TMET), the magnitude of ST-segment depression is conventionally used. It is often difficult to distinguish false-positive from true ST-segment depression and to assess the severity of coronary artery disease (CAD). The purpose of the present study was to assess the ability of ST-segment/heart rate loop (ST/HR loop) analysis to provide diagnostic and prognostic information in patients with stable effort angina.
Methods:
ST/HR loop analysis was studied in 118 patients with stable effort angina without previous myocardial infarction who were taking medication. ST/HR loop patterns were classified into four types: type A (n = 38), simple clockwise rotation; type B (n = 34), clockwise rotation with quick ST recovery in the first half; type C (n = 21), ST-segment depression that recovered at a constant rate; and type D (n = 25), simple counter-clockwise rotation. The control group consisted of 40 patients who had no ST-segment depression but were proved to have significant stenosis on coronary angiography. The ST/HR loop types were compared with (1) the conventional TMET parameters, (2) findings of coronary angiography, (3) severity of ischemia evaluated by exercise thallium-201 myocardial single-photon emission computed tomography (exercise TI-201 myocardial SPECT), and (4) short-term prognosis by follow-up study.
Results:
The value of the simple heart-rate-adjusted ST-segment depression index (delta ST/HR index) in the type A group (6.1 +/- 5.8 microV/bpm) was higher (P < 0.05) than in the type C and D groups (2.7 +/- 2.0 microV/bpm and 1.7 +/- 1.2 microV/bpm, respectively). In the type A group, 68% of the patients had multiple diseased coronary arteries. In the type D group, 88% of the patients had either no significant coronary artery stenosis or significant stenosis in a single coronary artery. The ischemic size calculated by exercise TI-201 myocardial SPECT was higher (P < 0.05) in the type A group (47.6 +/- 24.6%) than in the type B, C, and D groups (21.4 +/- 16.6%, 14.9 +/- 15.8% and 7.8 +/- 7.4%, respectively). During the follow-up study nine cardiac events occurred in the type A group, three in the type B group, and one in the type C group. The prognosis of the type A patients was significantly worse than that of the type D and control patients (P < 0.01).
Conclusion:
We conclude that the ST/HR loop analysis is a simple and useful parameter for providing diagnostic and prognostic information for patients with stable effort angina.