ABSTRACT

Objective: In addition to QRS duration, a new marker is needed for selection of patients who will respond favorably to cardiac resynchronization therapy (CRT) in patients with nonleft bundle brunch block (LBBB) morphology. This study aimed to analyze the predictive ability of R-wave amplitude in V1 and compare its efficacy to previously suggested criteria in patients with non-LBBB morphology.

Material and Methods: We retrospectively included 433-patients with heart failure (HF) diagnosis, QRS≥ 120 ms, NYHA II-IV, LVEF< 35% and previous CRT implantation. Patients were divided into three-groups as patients with LBBB (Group-I), patients with right-bundle branch block (Group-II) and patients with nonspecific-intraventricular conduction delay (Group-III).

Results: The R-wave amplitude in V1, presence of R > S in V1 and RV1S1 were higher in Group-I than in the other two-groups (p< 0.05, for all). R-wave amplitude in V1, presence of R > S in V1, RV1S1, R < S in D1-aVL, QS in V5-V6-D1 were lower in patients with mortality (p< 0.05, for all). Only R-wave amplitude in V1 was found to be independently associated with mortality in logistic regression analysis (p< 0.001, OR= 0.575). Every 1-mV decrease in R-wave amplitude in V1 was associated with 42.5% increase in the risk of mortality. The cut-off value of R-wave amplitude in V1 obtained by ROC curve analysis was 2.5 mV for prediction of mortality (sensitivity= 81.5%, specificity= 81.8%).

Conclusion: R-wave amplitude in V1 is negatively and independently associated with mortality. Strong predictive ability of the R-wave amplitude in V1 gives the operator the chance to intraoperatively improve prognosis by orienting the implantation process according to the biggest possible R-wave in coronary sinus (CS) branches.

Keywords: Cardiac resynchronization therapy, R wave amplitude in V1, right bundle branch block