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Spatial QRS-T angle and quantified ischemia burden in ischemia with nonobstructive coronary arteries
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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