Usefulness of Intracardiac Local Ventricular Electrogram to Predict Responders in Patients Undergoing Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) is a well-established, efficient strategy for medically-refractory congestive heart failure (HF) with ventricular conduction disturbances. However, about 30% of patients who undergo CRT do not receive any benefit. Therefore, we investigated the usefulness of the QRS-left ventricle (LV) interval for predicting responders during CRT implantation. This study included 66 patients who underwent CRT implantation. The definition of responder was a ≥15% reduction in LV end-systolic volume or ≥20% increase in LV ejection fraction. The QRS-LV interval was measured from the beginning of the body surface electrocardiogram QRS complex to the LV potential recorded by LV leads. We analyzed the correlations between the QRS-LV intervals and CRT responders, admission for HF and mortality. The patients were 67±12 years old, and their mean LV ejection fraction was 26.3%±8.3%. During follow-up (27.2±19.9 months), 27 patients were admitted for HF (40.1%), and 17 died (25.7%); the median QRS-LV interval was 103±33 msec. Patients were divided into 2 groups: wide QRS-LV (>103 msec), and narrow QRS-LV (<103 msec). The wide QRS-LV group had a lower mortality rate than the narrow QRS-LV group (77% vs. 53%, P<0.05). In patients with dilated cardiomyopathy, the QRS-LV interval was significantly wider in responders, compared to non-responders (112±9.2 vs. 80.0±10 msec, P