Spatial QRS-T angle and quantified ischemia burden in ischemia with nonobstructive coronary arteries
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Published on: September 16, 2017
Alp Yıldırım1, Muhammet Salih Ateş1, Erdoğan Sökmen1
1Department of Cardiology, Kırşehir Ahi Evran University Medical Faculty, Kırşehir, Turkey.
Insights
The spatial QRS-T angle effectively predicts severe ischemia in patients with Ischemia with Non-Obstructive Coronary Arteries (INOCA). A combined ECG model using dispersion markers improves risk stratification for these patients.
Area of Science:
- Cardiology
- Electrocardiography
- Ischemic Heart Disease
Background:
- Ischemia with Non-Obstructive Coronary Arteries (INOCA) is a recognized clinical condition requiring better risk stratification.
- The spatial QRS-T (sQRS-T) angle may offer a more accurate assessment of ischemic burden compared to traditional ECG markers.
Purpose of the Study:
- To evaluate the association between the spatial QRS-T angle and myocardial ischemic burden in INOCA patients.
- To assess the predictive value of various ECG dispersion markers for severe ischemia in INOCA.
Main Methods:
- Retrospective analysis of 1432 INOCA patients with reversible perfusion defects on myocardial perfusion scintigraphy (MPS).
- Quantification of ischemic burden as a percentage of left ventricular (LV) myocardium with reversible defects.
- Measurement of spatial and frontal QRS-T angles, QT dispersion (QTd), and other ECG parameters on resting ECGs.
Main Results:
- The spatial QRS-T angle, QTd, and Tpe/QTc ratio increased significantly with higher categories of ischemic burden.
- The spatial QRS-T angle was an independent predictor of severe ischemia (OR 1.27 per 10° increase, p < 0.001).
- A combined ECG model including sQRS-T angle, QTd, and Tpe/QTc demonstrated improved discrimination (AUC 0.83).
Conclusions:
- The spatial QRS-T angle is independently associated with myocardial ischemic burden in INOCA patients.
- An ECG-based model incorporating dispersion markers enhances the identification of patients with significant ischemia.
- This approach may aid in identifying INOCA patients who require closer monitoring and follow-up.
Background:
Ischemia with non-obstructive coronary arteries (INOCA) is increasingly recognized as a clinically relevant entity, yet effective risk stratification remains limited. The spatial QRS-T (sQRS-T) angle integrates global depolarization-repolarization heterogeneity and may reflect ischemic burden more accurately than conventional ECG markers.
Methods:
This retrospective study included 1432 INOCA patients with reversible perfusion defects on myocardial perfusion scintigraphy (MPS) and no ≥50% epicardial stenosis on angiography. Ischemic burden was quantified as the percentage of left ventricular (LV) myocardium with reversible defects and categorized as <5%, 5-10%, or > 10%. Spatial and frontal QRS-T angles, QT dispersion (QTd), QTc, P-wave dispersion, Tpe interval, and Tpe/QTc ratio were measured on resting ECGs. Echocardiographic indices and routine laboratory markers were also recorded. Severe ischemia (>10% LV) was the primary logistic regression outcome. Four hierarchical multivariable models incorporated ECG, clinical, echocardiographic, and laboratory parameters. ROC analyses with DeLong testing evaluated discrimination.
Results:
Among 1432 patients, 52.4% had <5% ischemia, 27.9% had 5-10%, and 19.7% had >10%. The sQRS-T angle, QTd, Tpe, and Tpe/QTc increased stepwise across ischemia categories (all p < 0.001). In multivariable models, the sQRS-T angle remained an independent predictor of severe ischemia (OR 1.27 per 10° increase, 95% CI 1.16-1.40; p < 0.001). QTd and Tpe/QTc also retained significance, whereas frontal QRS-T angle, QTc, Tpe interval, and P-wave dispersion did not. The sQRS-T angle showed good discrimination (AUC 0.78), and a combined ECG model integrating sQRS-T angle, QTd, and Tpe/QTc improved performance (AUC 0.83; p = 0.008).
Conclusion:
The sQRS-T angle is independently associated with MPS-derived ischemic burden in INOCA. A simple ECG-based model combining dispersion markers provides incremental discriminatory value and may help identify patients with a high ischemic burden who require closer follow-up.
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