Phrenic nerve stimulation in CRT patients and benefits of electronic lead repositioning: the ERACE trial

Left bundle branch pacing versus biventricular pacing for cardiac resynchronization therapy: A systematic review and meta-analysis

INTRODUCTION

Cardiac resynchronization therapy (CRT) reduces heart failure (HF) hospitalization and all-cause mortality in HF patients with left bundle branch block (LBBB). Biventricular pacing (BVP) is the gold standard for achieving CRT, but about 30%-40% of patients do not respond to BVP-CRT. Recent studies showed that left bundle branch pacing (LBBP) provided remarkable results in CRT. Therefore, we conducted a meta-analysis aiming to compare LBBP-CRT versus BVP-CRT in HF patients.

METHODS

We systematically searched the electronic databases for studies published from inception to December 29, 2022 and focusing on LBBP-CRT versus BVP-CRT in HF patients. The primary endpoint was HF hospitalization. The effect size was estimated using a random-effect model as Risk Ratio (RR) and mean difference (MD).

RESULTS

Ten studies enrolling 1063 patients met the inclusion criteria. Compared to BVP-CRT, LBBP-CRT led to significant reduction in HF hospitalization [7.9% vs.14.5%; RR: 0.60 (95%CI: 0.39-0.93); p = .02], QRSd [MD: 30.26 ms (95%CI: 26.68-33.84); p < .00001] and pacing threshold [MD: -0.60 (95%CI: -0.71 to -0.48); p < .00001] at follow up. Furthermore, LBBP-CRT improved LVEF [MD: 5.78% (95%CI: 4.78-6.77); p < .00001], the rate of responder [88.5% vs.72.5%; RR: 1.19 (95%CI: 1.07-1.32); p = .002] and super-responder [60.8% vs. 36.5%; RR: 1.56 (95%CI: 1.27-1.91); p < .0001] patients and the NYHA class [MD: -0.42 (95%CI: -0.71 to -0.14); p < .00001] compared to BVP-CRT.

CONCLUSION

In HF patients, LBBP-CRT was superior to BVP-CRT in reducing HF hospitalization. Further significant benefits occurred within the LBBP-CRT group in terms of QRSd, LVEF, pacing thresholds, NYHA class and the rate of responder and super-responder patients.

Case report: An unusual case of phrenic nerve stimulation in a patient with single chamber implantable cardioverter defibrillator

Background

Phrenic nerve stimulation is a well-recognized complication related to cardiac implantable electronic devices, in particular with left ventricular coronary sinus pacing leads for cardiac resynchronization therapy.

Case presentation

We report an unusual case of symptomatic phrenic nerve stimulation due to inadvertent placement of a right ventricular defibrillation lead in coronary sinus posterior branch in a patient with heart failure with reduced ejection fraction with a recently implanted single-chamber cardioverter defibrillator.

Discussion

Phrenic nerve stimulation is a relatively common complication of left ventricular pacing. Inadvertent placement of a right ventricular lead in a coronary sinus branch is a rare but possible cause of phrenic nerve stimulation. Careful evaluation of intraprocedural fluoroscopic and electrocardiographic appearance of pacing and defibrillation leads during implantation may prevent inadvertent placement of a right ventricular lead in the coronary sinus.

Impact of intraoperative mechanical ventilation on left ventricular lead function in cardiac resynchronization therapy

BACKGROUND

Intraoperative controlled mechanical ventilation (CMV) changes the intrathoracic geometry and may impact postoperative left ventricular (LV) lead function after CRT implantation. This multicenter study investigates the effect of intraoperative ventilation setting (spontaneous breathing [SB] vs CMV) on postoperative LV lead function taking into account patients' body mass index (BMI).

METHODS

CRT implantation was performed at two centers during SB in 92 and during CMV in 73 patients. Follow-up was carried out after 3 ± 5 and 36 ± 53 days. Functional lead parameters (FLP; pacing threshold and impedance), postoperative adverse events (A;  phrenic nerve stimulation [PNS] and lead malfunction), and patients' BMI were assessed. Delta values of FLP between baseline and follow-up visits were analyzed applying an analysis of covariance model to detect subclinical alterations in LV lead function.

RESULTS

AE occurred in a total of 36 (21%) patients. PNS was observed in 26 (15%) patients and LV lead repositioning due to malfunction was necessary in 10 (6%) patients. Both AE and FLP delta values between baseline and follow-up were not associated with intraoperative ventilation settings nor the patients' BMI.

CONCLUSIONS

This study demonstrates that there is no impact of the intraoperative ventilation setting (SB vs CMV) on postoperative FLP or the occurrence of AE. This is also the case taking into account the BMI. With respect to these findings both approaches-sedation only or general anaesthesia including CMV-can be safely implemented during CRT implantation.

Current Technology to Maximize Cardiac Resynchronization Therapy Benefit for Patients With Symptomatic Heart Failure

The incidence of heart failure (HF) continues to increase, affecting millions of people in the United States each year. Cardiac resynchronization therapy (CRT) has been used and studied for patients with symptomatic HF for more than 20 years. The purpose of this article is to review technologies and developments to help maximize CRT for patients with symptomatic HF. Although most interventions to optimize CRT are physician directed, nurses also have an important role in the care and education of patients with symptomatic HF and can affect clinical outcomes. Therefore, nurses’ understanding of CRT and measures to maximize this lifesaving therapy is critical in HF management.

Percutaneous Epicardial Pacing using a Novel Insulated Multi-electrode Lead

INTRODUCTION

Epicardial cardiac resynchronization therapy (CRT) permits unrestricted electrode positioning. However, this requires surgical placement of device leads and the risk of unwanted phrenic nerve stimulation. We hypothesized that shielded electrodes can capture myocardium without extracardiac stimulation.

METHODS

In 6 dog and 5 swine experiments, we used a percutaneous approach to access the epicardial surface of the heart, and deploy novel leads housing multiple electrodes with selective insulation. Bipolar pacing thresholds at prespecified sites were tested compare electrode threshold data both facing towards and away from the epicardial surface.

RESULTS

In 151 paired electrode recordings (70 in 6 dogs; 81 in 5 swine), thresholds facing myocardium were lower than facing away (median [IQR] mA: dogs 0.9 [0.4-1.6] vs 4.6 [2.1 to >10], p<0.0001; swine 0.5 [0.2-1] vs 2.5 [0.5-6.8], p<0.0001). Myocardial capture was feasible without extracardiac stimulation at all tested sites, with mean ± SE threshold margin 3.6±0.7 mA at sites of high output extracardiac stimulation (p=0.004).

CONCLUSION

Selective electrode insulation confers directional pacing to a multielectrode epicardial pacing lead. This device has the potential for a novel percutaneous epicardial resynchronization therapy that permits placement at an optimal pacing site, irrespective of the anatomy of the coronary veins or phrenic nerves.

Left ventricular three-dimensional quadripolar lead acute clinical study: the LILAC study

AIMS

This multicenter acute clinical study was designed to verify novel three-dimensional (3D) quadripolar lead designs that can achieve ≤2.5 V average pacing capture threshold (PCT) not only at the apex, but also at the base of the left ventricle with phrenic nerve stimulation (PNS) avoidance for cardiac resynchronization.

METHODS

During the implant procedure, up to two different left ventricular investigational leads were introduced and tested in the same target coronary vein based on the coronary sinus venogram in a wedged and unwedged position. Adverse events were collected in 30 days following the procedure.

RESULTS

Eighty-seven leads were tested in 50 patients. When the best performing spiral electrode was chosen from each lead testing, the average of the best PCT on spiral in a wedged position was similar to the unwedged position (1.7 ± 1.5 V vs 1.9 ± 1.5 V, P = ns) and was similar to the wedged tip electrode average PCT (1.7 ± 1.5 V vs 1.6 ± 1.6 V, P = ns). In the majority of patients (89-96%), pacing was achievable in a mid-basal ventricular location without PNS.

CONCLUSIONS

This acute study demonstrated that a 3D quadripolar spiral lead design can achieve acceptable PCTs and avoid PNS without repositioning the lead at implant in the vast majority of patients. It also demonstrated that this lead design can achieve mid-basal ventricular stimulation with low PCT and good acute stability.