Frontal QRS-T angle identifies non-responders to cardiac resynchronisation therapy even among ideal candidates with heart failure
C Tunca, B,E Yencilek, B Ozlek, V,O TanikAbstract
Background
Cardiac resynchronisation therapy (CRT) improves outcomes in selected patients with heart failure with reduced ejection fraction (HFrEF); however, a substantial proportion fail to demonstrate meaningful reverse remodelling despite fulfilling guideline-based criteria. In non-ischaemic cardiomyopathy, where myocardial scar burden is limited, mechanisms other than structural damage may contribute to CRT non-response. Conventional electrocardiographic parameters such as QRS duration and left bundle branch block (LBBB) morphology primarily reflect depolarisation delay and may not fully capture underlying electrical heterogeneity. The frontal QRS–T angle, integrating ventricular depolarisation and repolarisation vectors, represents a global marker of electrical dispersion and may provide incremental prognostic information regarding CRT response.
Purpose
To investigate whether baseline frontal QRS–T angle predicts echocardiographic non-response to CRT in patients with non-ischaemic HFrEF, including those meeting guideline-based indications for CRT implantation.
Methods
In this retrospective cohort, consecutive patients with non-ischaemic HFrEF (left ventricular ejection fraction ≤35%) who underwent CRT implantation between 2018 and 2024 were analysed. Baseline frontal QRS–T angle was calculated from standard 12-lead electrocardiograms using automated frontal QRS and T-wave axes. CRT response was defined as a ≥15% reduction in left ventricular end-systolic volume at 6-month follow-up. Multivariable logistic regression analysis adjusted for established predictors of CRT response, including age, atrial fibrillation, QRS duration, LBBB morphology, and baseline left ventricular ejection fraction. A predefined subgroup analysis was conducted in patients with sinus rhythm, true LBBB, and QRS duration ≥150 ms.
Results
A total of 214 patients with non-ischaemic HFrEF (mean age 64±11 years, 28% female) were included, of whom 124 (58%) met criteria for CRT response. Baseline frontal QRS–T angle was significantly wider in non-responders compared with responders (median 128° vs. 92°, p<0.001). Frontal QRS–T angle independently predicted CRT non-response after multivariable adjustment (adjusted odds ratio per 10° increase: 1.19, 95% CI 1.08–1.31; p<0.001), irrespective of QRS duration and LBBB morphology. In the subgroup of ideal CRT candidates, a wider frontal QRS–T angle remained strongly associated with non-response.
Conclusion
Baseline frontal QRS–T angle is a powerful and independent predictor of CRT non-response in patients with non-ischaemic HFrEF, even among those fulfilling guideline-based criteria. This simple electrocardiographic marker reflects advanced electrical heterogeneity and may help refine patient selection and counselling for CRT.Predictors of CRT non-responseFor image description, please refer to the figure legend and surrounding text.