Left Ventricular Stimulation With Electrical Latency Predicts Mortality in Patients Undergoing Cardiac Resynchronization Therapy

Abstract Objectives This study sought to evaluate the prognostic value of the time interval from left ventricular (LV) pacing to the earliest onset of QRS complex (S-QRS) for long-term clinical outcomes in patients who underwent cardiac resynchronization therapy (CRT). Background The electrical latency during LV pacing evaluated by S-QRS is associated with local tissue property, and the S-QRS ≥37 ms has been previously proposed as an independent predictor of mechanical response to CRT. Methods This study included 82 consecutive patients with heart failure with reduced LV ejection fraction (≤35%) and a wide QRS complex (≥120 ms) who underwent CRT. Patients were divided into a short S-QRS group (SS-QRS;  Results S-QRS was 25.9 ± 5.3 ms in SS-QRS and 51.5 ± 13.7 ms in LS-QRS (p  Conclusions The S-QRS ≥37 ms at the LV pacing site was a significant predictor of total mortality and HF hospitalization. S-QRS−guided optimal LV lead placement is critical in patients who receive CRT.