Coronary sinus activation patterns in patients with and without left bundle branch block undergoing electroanatomic mapping system-guided cardiac resynchronization therapy device implantation

Electrophysiological demonstration of nonselective His-Purkinje system capture with para-Hisian pacing

BACKGROUND

The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited.

METHODS AND RESULTS

We included 152 consecutive patients (mean age 61 ± 24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n = 54), para-Hisian region (n = 66), or mid interventricular septum (n = 17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12‑lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI).

RESULTS

QRS duration was prolonged in all pacing sites: from 114 ± 28 to 160 ± 29 (RV apex), from 110 ± 28 to 122 ± 29 (para-Hisian), and from 121 ± 24 to 154 ± 30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48 h after implantation but did not require repositioning.

CONCLUSIONS

QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.

Computational electrophysiology of the coronary sinus branches based on electro-anatomical mapping for the prediction of the latest activated region

This work dealt with the assessment of a computational tool to estimate the electrical activation in the left ventricle focusing on the latest electrically activated segment (LEAS) in patients with left bundle branch block and possible myocardial fibrosis. We considered the Eikonal-diffusion equation and to recover the electrical activation maps in the myocardium. The model was calibrated by using activation times acquired in the coronary sinus (CS) branches or in the CS solely with an electroanatomic mapping system (EAMS) during cardiac resynchronization therapy (CRT). We applied our computational tool to ten patients founding an excellent accordance with EAMS measures; in particular, the error for LEAS location was less than 4 mm. We also calibrated our model using only information in the CS, still obtaining an excellent agreement with the measured LEAS. The proposed tool was able to accurately reproduce the electrical activation maps and in particular LEAS location in the CS branches, with an almost real-time computational effort, regardless of the presence of myocardial fibrosis, even when information only at CS was used to calibrate the model. This could be useful in the clinical practice since LEAS is often used as a target site for the left lead placement during CRT.

Targeting the latest site of left ventricular mechanical activation is associated with improved long-term outcomes for recipients of Cardiac Resynchronization Therapy

Background

Previous studies have suggested that targeting the site of latest mechanical activation of the left ventricle (LV) results in improved cardiac resynchronization therapy (CRT) outcomes. It is not known whether these benefits are sustained over medium-term follow-up.

Objective

To assess the clinical outcome of imaging-guided LV lead position.

Methods

We sought to assess the medium-term clinical outcome by performing a patient-level meta-analysis of 2 previously published randomized controlled trials (the “STARTER” trial and the “CRT Clinic” trial). These 2 trials compared imaging-guided LV lead placement in the latest activated scar-free segment (intervention group) to standard of care (control). Mortality and heart failure hospitalization outcomes over extended follow-up were gathered from the medical records and merged. Results were stratified for native electrocardiogram (ECG) morphology.

Results

A total of 289 patients were followed for a median of 6.3 years. Seven years post implant, 47 (28%) in the intervention group had died, vs 47 (38%) in the control group (P = .13); 49 (30%) vs 53 (42%) had been hospitalized for heart failure (P = .035); and 47% vs 59% (P = .057) had reached the combined endpoint. In Kaplan-Meier analysis, patients in the intervention group had better survival free of heart failure hospitalization (P = .045) and lower risk of heart failure hospitalization (P = .019).

Conclusion

Targeting the latest mechanically activated segment in CRT results in better medium-term clinical outcome, mainly driven by a reduced risk of hospitalization for heart failure. The effect was seen regardless of native ECG morphology.

Electroanatomical mapping- and CT scan image integration-guided pacing lead implantation: A case series and review of the recent literature

Background

We present a case series and short review of electroanatomical mapping (EAM)–guided pacing lead implantation. The cases illustrate different aspects of EAM use in special circumstances and summarizes our experience with EAM-guided His lead implantation in 32 consecutive patients. Advantages and caveats encountered when using EAM in device procedures are discussed.

Objective

To illustrate usefulness of EAM-guided lead implantation and computed tomography (CT) image integration in a case series.

Methods

Lead implantation was performed targeting different anatomically defined regions using EAM for mapping and lead navigation, as well as using the system for image integration for 2 cardiac resynchronization therapy implantations.

Results

For His bundle pacing lead implantation, a steep learning curve for successful His bundle lead placement seems obtainable (91%) for new implanters using EAM-guided implantation. Successful lead placements in other locations guided by anatomical or physiologically defined positions are demonstrated in individual cases. However, map shifts are frequently encountered and should be recognized and corrected.

Conclusion

EAM-guided His bundle lead implantation seems to be a useful tool for arriving at high success rates for new His lead implanters with a steep learning curve, if appropriate precautions are undertaken. In selected cases EAM and CT scan image integration can be of benefit in lead implantation in other locations. Knowledge of specific problems in using EAM for device procedures should be recognized.