Systematic review of leadless pacemaker

Conventional pacing systems consist of a pacemaker and one or more leads threaded from the device pocket through veins into the heart conducting the pacing therapy to the desired pacing site. Although these devices are effective, approximately one in eight patients treated with these traditional pacing systems experiences a complication attributed to the pacemaker pocket or leads. With the technological advances in electronics, leadless pacemakers that small enough to implant within the heart were introduced. Leadless pacemakers have been developed to overcome many of the challenges of transvenous pacing including complications related to leads or pacemaker pockets. This review aims to provide an overview of advantages of leadless pacemaker, complications and limitations of leadless pacemaker, leadless pacemaker candidate, and future directions of this promising technology.

Left bundle branch area pacing for heart failure patients requiring cardiac resynchronization therapy: A meta-analysis

INTRODUCTION

Left bundle branch area pacing (LBBP) is a novel conduction system pacing method to achieve effective physiological pacing and an alternative to cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) for patients with heart failure with reduced ejection fraction (HFrEF). We conduted this meta-analysis and systemic review to review current data comparing BVP and LBBP in patients with HFrEF and indications for CRT.

METHODS

We searched PubMed/Medline, Web of Science, and Cochrane Library from the inception of the database to November 2022. All studies that compared LBBP with BVP in patients with HFrEF and indications for CRT were included. Two reviewers performed study selection, data abstraction, and risk of bias assessment. We calculated risk ratios (RRs) with the Mantel-Haenszel method and mean difference (MD) with inverse variance using random effect models. We assessed heterogeneity using the I2 index, with I2  > 50% indicating significant heterogeneity.

RESULTS

Ten studies (9 observational studies and 1 randomized controlled trial; 616 patients; 15 centers) published between 2020 and 2022 were included. We observed a shorter fluoroscopy time (MD: 9.68, 95% confidence interval [CI]: 4.49-14.87, I2  = 95%, p < .01, minutes) as well as a shorter procedural time (MD 33.68, 95% CI: 17.80-49.55, I2  = 73%, p < .01, minutes) during the implantation of LBBP CRT compared to conventional BVP CRT. LBBP was shown to have a greater reduction in QRS duration (MD 25.13, 95% CI: 20.06-30.20, I2  = 51%, p < .01, milliseconds), a greater left ventricular ejection fraction improvement (MD: 5.80, 95% CI: 4.81-6.78, I2  = 0%, p < .01, percentage), and a greater left ventricular end-diastolic diameter reduction (MD: 2.11, 95% CI: 0.12-4.10, I2  = 18%, p = .04, millimeter). There was a greater improvement in New York Heart Association function class with LBBP (MD: 0.37, 95% CI: 0.05-0.68, I2  = 61%, p = .02). LBBP was also associated with a lower risk of a composite of heart failure hospitalizations (HFH) and all-cause mortality (RR: 0.48, 95% CI: 0.25-0.90, I2  = 0%, p = .02) driven by reduced HFH (RR: 0.39, 95% CI: 0.19-0.82, I2  = 0%, p = .01). However, all-cause mortality rates were low in both groups (1.52% vs. 1.13%) and similar (RR: 0.98, 95% CI: 0.21-4.68, I2  = 0%, p = .87).

CONCLUSION

This meta-analysis of primarily nonrandomized studies suggests that LBBP is associated with a greater improvement in left ventricular systolic function and a lower rate of HFH compared to BVP. There was uniformity of these findings in all of the included studies. However, it would be premature to conclude based solely on the current meta-analysis alone, given the limitations stated. Dedicated, well-designed, randomized controlled trials and observational studies are needed to elucidate better the comparative long-term efficacy and safety of LBBP CRT versus BIV CRT.

Comparison of Left Bundle Branch Area Pacing and Biventricular Pacing in Candidates for Resynchronization Therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is a well established therapy in patients with reduced left ventricular ejection fraction (LVEF), heart failure, and wide QRS or expected frequent ventricular pacing. Left bundle branch area pacing (LBBAP) has recently been shown to be a safe alternative to BVP.

OBJECTIVES

The aim of this study was to compare the clinical outcomes between BVP and LBBAP among patients undergoing CRT.

METHODS

This observational study included patients with LVEF ≤35% who underwent BVP or LBBAP for the first time for Class I or II indications for CRT from January 2018 to June 2022 at 15 international centers. The primary outcome was the composite endpoint of time to death or heart failure hospitalization (HFH). Secondary outcomes included endpoints of death, HFH, and echocardiographic changes.

RESULTS

A total of 1,778 patients met inclusion criteria: 981 BVP, 797 LBBAP. The mean age was 69 ± 12 years, 32% were female, 48% had coronary artery disease, and mean LVEF was 27% ± 6%. Paced QRS duration in LBBAP was significantly narrower than baseline (128 ± 19 ms vs 161 ± 28 ms; P < 0.001) and significantly narrower compared to BVP (144 ± 23 ms; P < 0.001). Following CRT, LVEF improved from 27% ± 6% to 41% ± 13% (P < 0.001) with LBBAP compared with an increase from 27% ± 7% to 37% ± 12% (P < 0.001) with BVP, with significantly greater change from baseline with LBBAP (13% ± 12% vs 10% ± 12%; P < 0.001). On multivariable regression analysis, the primary outcome was significantly reduced with LBBAP compared with BVP (20.8% vs 28%; HR: 1.495; 95% CI: 1.213-1.842; P < 0.001).

CONCLUSIONS

LBBAP improved clinical outcomes compared with BVP in patients with CRT indications and may be a reasonable alternative to BVP.

The Year in Electrophysiology: Selected Highlights From 2022

This special article is the fifth in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors would like to thank the Editor-in-Chief, Dr Kaplan, the Associate Editor-in-Chief, Dr Augoustides, and the editorial board for the opportunity to author this series, which summarizes the key research papers in the electrophysiology (EP) field relevant to cardiothoracic and vascular anesthesiologists. These articles are shaping perioperative EP procedures and practices, such as pulsed-field ablation, cryoablation for first-line treatment for atrial fibrillation, advancements in conduction system pacing, safety issues related to smartphones and cardiac implantable electronic devices, and alterations in EP workflow as the world emerges from the COVID-19 pandemic. Special emphasis is placed on the implications of these advancements for the anesthetic care of patients undergoing EP procedures.

Pulmonary hemorrhage after cardiac resynchronization therapy device implantation - A systematic review

Cardiac implantable electronic devices are being increasingly used for a variety of cardiovascular diseases. We describe a rare case of massive hemoptysis after device implantation. The patient was managed conservatively with reversal of anticoagulation and inhaled tranexamic acid and had a successful recovery. A systematic review accompanies the case presentation. The modality and difficulty of access appear to play a significant role in precipitating bleeding, believed to be the result of direct injury to the pulmonary parenchyma and vasculature. The condition is often self-limiting; however, anticoagulation reversal, intubation, endobronchial intervention, and transarterial embolization may be indicated in more severe pulmonary hemorrhage.

Usefulness of Decapolar catheter via femoral approach on CS cannulation during CRT device implantation

Introduction

Cardiac resynchronization therapy (CRT) device insertion comprises of a transvenous pacing lead implanted in posterolateral branch of the coronary sinus (CS) for left ventricular (LV) pacing, in addition to leads in the right ventricle and right atrium. In patients undergoing CRT device implantation, failure of CS cannulation was earlier reported to be around 10% but has come down to about 4% in recent years. Although the use of electrophysiology (EP) catheter has been reported during CRT procedures but femoral approach to place decapolar catheter as fluoroscopic guide for CS ostium cannulation during LV lead implantation has not been evaluated.

Materials and methods

The aim of the study was to compare fluoroscopy time during CRT procedure between conventional technique and using decapolar EP catheter via femoral approach as fluoroscopic marker to cannulate CS.

Results

This study included 21 patients. Group 1 (using decapolar catheter) had 12 patients and group 2 (using the conventional technique) had 9 patients. CS cannulation was successful in all 21 cases. The mean fluoroscopy time for the CS cannulation and LV lead placement in group 1 was 10.7 (±1.03) min and in group 2 was 19.1 (±1.51) min. This difference in mean fluoroscopy time for the CS cannulation and LV lead placement was statistically significant with p < .05.

Conclusion

This study highlights the usefulness of decapolar catheter via femoral approach as a fluoroscopic guide for CS cannulation during CRT device implantation. The decreased fluoroscopic time results in decreased radiation exposure to not only the patient but also to the operator.

Rescue left bundle branch area pacing in coronary venous lead failure or nonresponse to biventricular pacing: Results from International LBBAP Collaborative Study Group

BACKGROUND

Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) is effective in patients with heart failure, left bundle branch block (LBBB), and reduced left ventricular function. Left bundle branch area pacing (LBBAP) has been reported as an alternative option for CRT.

OBJECTIVE

The purpose of this study was to assess the feasibility and outcomes of LBBAP in patients who failed conventional BVP because of coronary venous (CV) lead complications or who were nonresponders to BVP.

METHODS

At 16 international centers, LBBAP was attempted in patients with conventional CRT indication who failed BVP because of CV lead complications or lack of therapeutic response to BVP. Heart failure hospitalization (HFH) and death, echocardiographic outcomes, procedural data, pacing parameters, and lead complications including CV lead failure are reported.

RESULTS

LBBAP was successfully performed in 200 patients (CV lead failures 156; nonresponders 44) (age 68 ± 11 years; female 35%; LBBB 55%; right ventricular pacing 23%; ischemic cardiomyopathy 28%; nonischemic cardiomyopathy 63%; left ventricular ejection fraction [LVEF] ≤35% in 80%). Procedural duration was 119.5 ± 59.6 minutes, and fluoroscopy duration was 25.7 ± 18.5 minutes. LBBAP threshold and R-wave amplitudes were 0.68 ± 0.35 V @ 0.45 ms and 10.4 ± 5 mV at implant, respectively, and remained stable during mean follow-up of 12 ± 10.1 months. LBBAP resulted in significant QRS narrowing from 170 ± 28 ms to 139 ± 25 ms (P <.001) with V₆ R-wave peak times of 85 ± 17 ms. LVEF improved from 29% ± 10% at baseline to 40% ± 12% (P <.001) during follow-up. The risk of death or HFH was lower in those with CV lead failure than in nonresponders (hazard ratio 0.357; 95% confidence interval 0.168-0.756; P = .007) CONCLUSION: LBBAP is a viable alternative to CRT in patients who failed conventional BVP due to CV lead failure or who were nonresponders.

Leadless left ventricular stimulation with WiSE-CRT System - Initial experience and results from phase I of SOLVE-CRT Study (nonrandomized, roll-in phase)

BACKGROUND

Left ventricular (LV) endocardial pacing is a promising method to deliver cardiac resynchronization therapy (CRT). WiSE-CRT is a wireless LV endocardial pacing system, and delivers ultrasonic energy to an LV electrode.

OBJECTIVE

The purpose of this study was to present short-term outcomes with the WiSE-CRT system in centers with no prior implanting experience.

METHODS

Data were prospectively collected from 19 centers where WiSE-CRT systems were implanted during the roll-in phase of the SOLVE-CRT trial. Patients were followed at 1, 3, and 6 months, including transthoracic echo (TTE) at 6 months.

RESULTS

The WiSE-CRT was successfully implanted in all 31 attempted cases, and 30 patients completed the 6-month follow-up. One patient underwent heart transplantation 1 month after implantation, and was excluded. Fourteen (46.7%) patients demonstrated ≥1 NYHA class improvement. TTE data were available in 29 patients. LV ejection fraction, LV end-systolic volume, and LV end-diastolic volume improved from 28.3% ± 6.7% to 33.5% ± 6.9% (P < .001), 134.9 ± 51.3 mL to 111.1 ± 40.3 mL (P = .0004), and 185.4 ± 58.8 mL to 164.9 ± 50.6 mL (P = .0017), respectively. There were 3 (9.7%) device-related type 1 complications: 1 insufficient LV pacing, 1 embolization of an unanchored LV electrode, and 1 skin infection.

CONCLUSIONS

We demonstrated a high success rate of LV endocardial electrode placement in centers with no prior implanting experience. Favorable clinical responses in heart failure symptoms and significant LV reverse remodeling were noted.

Left ventricular lead placement using inner guiding catheter alone in cardiac resynchronization therapy device implantation

BACKGROUND

Subselection inner catheters (Inner-Cath) are used adjunctively with outer guiding catheters (Outer-Cath) during cardiac resynchronization therapy (CRT) device implantation. This study aims to investigate the feasibility and efficacy of left ventricular lead placement (LV-LP) guided by Inner-Cath alone.

METHODS

A total of 74 patients undergoing de novo CRT implantation were investigated. LV-LP was initially guided by Inner-Cath in 42 patients (Inner-Cath group) and Outer-Cath in 32 patients (Outer-Cath group). In the Inner-Cath group, a 7Fr Inner-Cath was advanced to the coronary sinus through a 7 Fr sheath inserted in a subclavian vein. In the Outer-Cath group, 9Fr or 10Fr Outer-Caths were used. Success rate of LV-LP, additional use of inner or outer catheters and procedure-related complications were compared between groups.

RESULTS

LV-LP was successful in all patients in the Inner-Cath group, while LV-LP had to be abandoned in two patients (6.3%) of the Outer-Cath group due to CS perforation caused by Outer-Cath manipulation. Procedure time was significantly shorter in the Inner-Cath group (148 vs. 168 min; p = .024). Deployment of both an inner and outer cath became necessary less frequently for the Inner-Cath group (4.8% vs. 56.3%; p < .001). Mechanical CS injuries due to guiding catheter manipulation were only observed in the Outer-Cath group (0% vs. 15.6%, p = .013).

CONCLUSION

LV-LP guided by Inner-Cath alone was feasible in over 95% of the patients without severe complications. This methodology for LV-LP may be preferable in CRT candidates with severe LV dysfunction in terms of shorter procedure time, smaller guiding sheath, and less procedure-related complications.

Five-year follow-up of transvenous and epicardial left ventricular leads: experience with more than 1000 leads

OBJECTIVES

Transvenous coronary sinus leads are considered to be the gold standard for cardiac resynchronization therapy (CRT). However, in patients with abnormal coronary vein anatomy, the epicardial leads can be an alternative. Data comparing durability and performance of these 2 lead types are limited. In order to provide clarity, we investigated patients receiving CRT system in our centre.

METHODS

One thousand and fifty-three consecutive patients scheduled for CRT implantation were retrospectively analysed. From these, 895 received transvenous coronary sinus and 158 epicardial left ventricular (LV) leads. Lead-specific as well as LV functional parameters have been evaluated in 60 months' follow-up.

RESULTS

Technical characteristics (pacing threshold, impedance and sensing) of both lead types remained stable during the whole observation period. Whereas an early revision (<6 month) was noted in 5.4% of transvenous leads, no reintervention has been necessary for epicardial leads. During the 5-year observation period, a lead revisions rate of 10.2% for transvenous leads and 1.9% for epicardial leads were detected. Regarding CRT efficacy, excellent results were achieved for both electrode types. In both groups, a statistically significant reduction of New York Heart Association class (2.85-2.13 and 2.96-2.09), increase in left ventricular ejection fraction (24.6-32.6% and 27.2-34.6%), reduction of left ventricular end-systolic diameter/left ventricular end-diastolic diameter and reduction in degree of mitral valve insufficiency could be observed over the time.

CONCLUSIONS

Our data demonstrate safety and functional efficacy of both transvenous and epicardial leads. Moreover, in long-term follow-up, a commendable durability and performance were found for both lead types. Thus, epicardial leads represent a good alternative when transvenous implantation fails.

Implant Characteristics of Quadripolar and Bipolar Left Ventricular Leads for Cardiac Resynchronization Therapy

Several studies have reported that the left ventricular (LV) lead implant success rate ranges between 88.0% and 92.4%. Coronary venous anatomy differs among patients thus, necessitating multiple types of leads. To date, the implant success rate among Japanese patients utilizing a pre-specified family LV leads (including bipolar and quadripolar) is not well known. The Attain Success Japan Study enrolled patients indicated for a de novo or an upgrade cardiac resynchronization therapy implant. Patients were followed for 3 months, and the implant success rates with Medtronic Attain family LV leads as well as the incidence of complications related to the LV lead were evaluated.Three hundred 53 patients were enrolled from 29 sites in Japan; 346 patients had LV lead implant attempts. The LV lead was successfully implanted in 336 patients (97.1%). Bipolar and quadripolar LV lead implants were successful in 97.2% and 99.2% of patients, respectively (P = 0.43). Four complications (1.2%) related to the LV leads were reported; all of which occurred in patients receiving bipolar LV leads. The quadripolar LV leads were more frequently implanted in the apical segment compared with bipolar leads (21.6% versus 3.8%, P < 0.01). This study demonstrated a high implant success rate and a low LV lead-related complication rate, regardless of bipolar, or quadripolar in a Japanese cohort of patients.

Electrophysiology Catheter-Facilitated coronary sinus cannulation and implantation of cardiac resynchronization therapy systems

BACKGROUND

Cardiac resynchronization therapy (CRT) device implantation is hampered by difficult placement of the left ventricular (LV) lead. We have routinely used a steerable electrophysiology catheter to guide coronary sinus (CS) cannulation and facilitate LV lead positioning. The aim of this prospective study is to present our results with this approach in 138 consecutive patients receiving a CRT device over 10 years.

METHODS

The study included 120 men and 18 women, aged 64.8±11.4 years, with coronary disease (n=63), cardiomyopathy (n=72), or other disease (n=3), and mean ejection fraction of 24.5±4.5%. Devices were implanted for refractory heart failure and dyssynchrony, all but 2 in the presence of left bundle branch block. Implanted devices included biventricular pacemakers (CRT-P) (n=33) and cardioverter defibrillators (CRT-D) (n=105).

RESULTS

Using the electrophysiology catheter, the CS could be engaged in 134 (97.1%) patients. In 4 patients failing CS cannulation, a dual-chamber device was implanted in 2, and bifocal right ventricular pacing was effected in 2. Bifocal (n=2) or conventional (n=1) systems were implanted in another 3 patients, in whom the LV lead got dislodged (n=2) or removed because of local dissection (n=1). Thus, finally, a CRT system was successfully established in 131 (94.9%) patients. There were 3 patients with CS dissection, of whom 1 was complicated by cardiac tamponade managed with pericardiocentesis. There were no perioperative deaths. During follow-up (31.0±21.2 months), clinical improvement was reported by 108 (82.4%) patients.

CONCLUSION

Routine use of an electrophysiology catheter greatly facilitated CS cannulation and successful LV lead placement in ∼95% of patients undergoing CRT system implantation.