Frontal QRS-T angle predicts cardiac syncope in the emergency department

Rapid identification of cardiac etiology in syncope remains a major challenge in emergency departments (EDs), and objective electrocardiographic markers may aid early risk stratification.

To evaluate the diagnostic value of the frontal QRS-T angle (fQRST) in distinguishing cardiac syncope from non-cardiac causes in ED patients.

In this retrospective single-center study, 278 patients with confirmed syncope were analyzed. Clinical, laboratory, and electrocardiographic parameters were compared across syncope subtypes. Receiver operating characteristic (ROC) analysis and logistic regression were used to assess predictors of cardiac syncope.

Cardiac syncope was identified in 52 patients (18.8%). The fQRST angle was significantly higher in cardiac syncope compared with reflex and orthostatic types (p < 0.001). In ROC analysis, fQRST showed the highest discriminative performance (AUC=0.737), with an optimal cutoff of 43.5° In multivariable analysis, fQRST ≥43.5°, troponin positivity, and atrial fibrillation were independently associated with cardiac syncope after adjustment for available clinical and electrocardiographic covariates. The combination of fQRST and troponin improved diagnostic performance. Subgroup analysis suggested that the association between fQRST and cardiac syncope was more pronounced in younger patients and those without atrial fibrillation.

The frontal QRS-T angle may serve as a useful electrocardiographic marker for identifying cardiac syncope in the ED. When combined with troponin, it may provide additional supportive information for early clinical assessment and risk stratification. These findings should be considered preliminary and require validation in larger, multicenter prospective studies.