Cardiac resynchronization therapy guided by activation mapping in non-left bundle branch block patients

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. INTRODUCTION: Various studies have questioned the magnitude of the benefit of cardiac resynchronization therapy (CRT) in patients without left bundle branch block (LBBB). This worse response could be due to the suboptimal location of the electrodes. PURPOSE: We hypothesize that in non-LBBB patients, an implant guided by ventricular electroanatomic mapping by locating the areas with the greatest activation delay will improve the outcome of CRT. MATERIAL AND METHODS: We included 7 patients non-LBBB. To locate the most delayed activation zones, an electromagnetic activation map was created using the Ensite Precision navigator connected to the right ventricular catheter and to a guidewire with electrical recording capacity at its distal end. ECG, clinical, and echocardiographic data were recorded at baseline and post-implantation, compared with 7 patients LBBB (control group). RESULTS: In non-LBBB patients, several activation patterns could be defined according to the conduction disorder, including right bundle branch block (RBBB)+left anterior hemiblock (figure 1A) or RBBB alone (figure 1B). All patients with non-LBBB improved at follow-up in the NYHA functional class (p=0,011) and in the Minnesota test (7,85±4,63; p=0.004). The mean reduction in QRS duration was 14,57±9,86 ms (p=0.008), LVEF increased 8.22±4.62 ms (p=0.003), LVOTS decreased by 15,71±12,23 ml (p=0.015) and the LVEDV in 10,42±5,15 ml (p=0.002). There were no significant differences between the response to CTR in non-LBBB patients and LBBB patients (table 1), including LVEF (8.22±4.62 vs 11.54±5.54, p=0.248) and difference in Minnesota test (7.85±4.63 vs 9.71±5.87, p=0.524). CONCLUSIONS: CRT guided by electroanatomical mapping produced significant clinical and structural improvement in non-LBBB patients. This improvement was of a similar magnitude to LBBB patients. Various patterns of ventricular activation according to the conduction disorder were observed. [Figure: see text] [Figure: see text]