Resting ST-segment depression predicts exercise-induced subendocardial ischemia in patients with hypertrophic
Tatsuya Kawasaki1, Akihiro Azuma, Toshiro Kuribayashi
1Department of Cardiology, Matsushita Memorial Hospital, Sotojima 5-55, Moriguchi, Osaka 570-85406, Japan. js-k@wf6.so-net.ne.jp
Insights
Resting ST-segment depression in hypertrophic cardiomyopathy (HCM) patients predicts exercise-induced subendocardial ischemia. This finding suggests a predisposition to exertional ischemia in the subendocardium of HCM patients.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Hypertrophic cardiomyopathy (HCM) patients may exhibit characteristic ECG findings and develop exercise-induced subendocardial ischemia without coronary artery disease.
- The relationship between resting ECG abnormalities and exercise-induced ischemia in HCM remains incompletely understood.
Purpose of the Study:
- To investigate the association between resting electrocardiographic (ECG) findings and exercise-induced subendocardial ischemia in patients with non-obstructive hypertrophic cardiomyopathy (HCM).
- To determine if specific ECG markers at rest can predict myocardial perfusion abnormalities during exercise.
Main Methods:
- Exercise technetium-99m-tetrofosmin myocardial scintigraphy was performed in 48 patients with non-obstructive HCM.
- Transient left ventricular cavity dilation (LVCD), an indicator of subendocardial ischemia, was quantified and correlated with resting and exercise ECG parameters.
Main Results:
- Exercise-induced transient LVCD occurred in 35% of HCM patients.
- Transient LVCD was significantly associated with ST-segment depression at rest, particularly with a greater number of leads showing depression (P=0.012).
- Resting ST-segment depression (cutoff of 3 leads) accurately predicted transient LVCD with 81% accuracy.
Conclusions:
- Resting ST-segment depression in HCM patients is linked to exercise-induced subendocardial perfusion defects.
- Resting ST-segment depression serves as a potential indicator of subendocardial predisposition to ischemia during exertion in HCM.
Background:
Patients with hypertrophic cardiomyopathy (HCM) sometimes display characteristic electrocardiographic (ECG) findings at rest and develop subendocardial ischemia during exercise in the absence of coronary lesions. However, their relationship has not yet been fully clarified.
Methods:
Exercise Tc-99m-tetrofosmin myocardial scintigraphy was performed in 48 patients with non-obstructive HCM. We quantified transient left ventricular cavity dilation (LVCD) on exercise scintigrams, a parameter of subendocardial ischemia, and correlated the results with the ECG findings at rest and during exercise.
Results:
Transient LVCD occurred during exercise in 17 (35%) patients with HCM. Hemodynamic parameters during exercise did not differ between HCM patients with and without transient LVCD. Multiple logistic regression analysis showed that transient LVCD was significantly associated with ST-segment depression at rest (chi2=5.00, odds ratio=5.70, 95% confidence intervals 1.24-26.18, P=0.025) and a greater total number of leads with resting ST-segment depression (chi2=6.38, odds ratio=1.60, 95% confidence intervals 1.12-2.42, P=0.012). The degree of LVCD was correlated with the total number of leads with ST-segment depression at rest (P=0.002); the optimal cutoff for the diagnosis of transient LVCD was 3 with a sensitivity of 65%, a specificity of 90%, and an accuracy of 81%.
Conclusions:
In patients with HCM, ST-segment depression at rest was accompanied by exercise-induced subendocardial perfusion abnormality as detected by myocardial scintigraphy. ST-segment depression at rest suggests that the subendocardium is predisposed to exertional ischemia.
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