Non‐Invasive Methods for Identifying Electrical Responders to Conduction System Pacing Cardiac Resynchronization Therapy

BACKGROUND: Conduction system pacing (CSP) is an emerging alternative modality of cardiac resynchronization therapy (CRT). However, not all patients obtain electrical resynchronization with CSP, there is a clinical need for reliable non-invasive predictors of response. We aimed to assess the ability of several non-invasive modalities to predict electrical resynchronization with CSP-CRT. METHODS: Patients with standard heart failure CRT indications (excluding right-bundle branch block) underwent CSP-CRT using His-bundle and left-bundle branch pacing. Electrical resynchronization was defined as a >10 ms reduction in left ventricular activation time or conversion to a physiological left ventricular activation pattern on non-invasive multi-electrode mapping. We assessed whether 12-lead ECG morphology, vector electrocardiogram (VCG) derived QRS area, Ultra High Frequency (UHF)-ECG parameters or MRI scar burden predicted electrical resynchronization. RESULTS: Thirty four patients were analyzed (mean age 69±10 years; 82% male; LVEF 30±6%; QRS duration 161±23 ms; 32% ischemic cardiomyopathy). Electrical resynchronization was achieved in 24/34 (71%; 95%CI 53-85). Strauss criteria positivity on 12-lead ECG yielded a positive predictive value (PPV) of 83% (95%CI 61-95%) and negative predictive value (NPV) of 55% (95%CI 23-83%). VCG QRS area >100µVs demonstrated PPV 100% (95% CI 81-100%) and NPV 73% (95%CI 85-100%). UHF-ECG e-DYS >50 ms gave PPV 93% (95%CI 66-100%) and NPV 47% (23%-72%); >60 ms gave PPV 90% (95%CI 66-100%) and NPV 38% (95%CI 18-62%). MRI scar burden <15% resulted in PPV 88% (95%CI 64-99%) and NPV 56% (95%CI 21-86%). Lines of propagation discontinuity on multi-electrode mapping showed PPV 100% (95%CI 85-100%) and NPV 83% (95%CI 52-98%). CONCLUSIONS: Multiple non-invasive markers, including QRS morphology, VCG QRS area, UHF-ECG e-DYS, MRI scar burden showed potential to identify patients who are likely to electrically resynchronize with CSP-CRT, although their NPVs were generally modest. Non-invasive propagation mapping had the highest PPV and NPV.