The Mt FUJI study was a multicenter, prospective, randomized, single-blind, controlled trial comparing delivery catheter-based and stylet-based right ventricular (RV) lead placement at the RV septum. This study extended the follow-up duration to 1 year after implantation.

Seventy patients with pacemaker indications for atrioventricular block were randomly assigned to the delivery catheter and stylet groups. We compared the mid-term efficacy and safety between the two groups at 1 year after implantation. The primary outcome was the change in the left ventricular ejection fraction (LVEF), and the secondary outcomes were changes in brain natriuretic peptide (BNP) levels, lead parameters, paced QRS duration, and the incidence of adverse events.

At the 1-year follow-up, no significant differences were observed in the changes in the LVEF (+1.0% ± 8.6% vs. +3.1% ± 8.1%, p = .332), BNP levels (+8.0 [-11.1, 26.5] pg/mL vs. -8.7 [-15.3, 13.2] pg/mL, p = .193), or lead performance between the delivery catheter and stylet groups. The QRS duration was significantly shorter in the delivery catheter group than in the stylet group (128 ± 23 ms vs. 146 ± 17 ms, p < .001). All-cause death, hospitalization for heart failure, new development of atrial fibrillation, and pacing-induced cardiomyopathy occurred in seven patients in the delivery catheter group and five in the stylet group.

The delivery catheter system was similarly useful and safe compared to the stylet system in the mid-term follow-up from the Mt FUJI trial. Further long-term evaluations are warranted.

Data regarding permanent pacemaker (PPM) implantation following tricuspid valve surgery (TVS) are limited. We sought to evaluate its incidence, risk factors, and outcomes.

Medicare beneficiaries who underwent TVS from 2013 to 2020 were identified. Patients who underwent TVS for endocarditis were excluded. The primary exposure of interest was new PPM after TVS. Outcomes included all-cause mortality and readmission with endocarditis or heart failure on follow-up. Among the 13 294 patients who underwent TVS, 2518 (18.9%) required PPM placement. Risk factors included female sex (relative risk [RR], 1.26 [95% CI, 1.17-1.36], P<0.0001), prior sternotomy (RR, 1.12 [95% CI, 1.02-1.23], P=0.02), preoperative second-degree heart block (RR, 2.20 [95% CI, 1.81-2.69], P<0.0001), right bundle-branch block (RR, 1.21 [95% CI, 1.03-1.41], P=0.019), bifascicular block (RR, 1.43 [95% CI, 1.06-1.93], P=0.02), and prior malignancy (RR, 1.23 [95% CI, 1.01-1.49], P=0.04). Tricuspid valve (TV) replacement was associated with a significantly higher risk of PPM implantation when compared with TV repair (RR, 3.20 [95% CI, 2.16-4.75], P<0.0001). After a median follow-up of 3.1 years, mortality was not different in patients who received PPM compared with patients who did not (hazard ratio [HR], 1.02 [95% CI, 0.93-1.12], P=0.7). PPM placement was not associated with a higher risk of endocarditis but was associated with a higher risk of heart failure readmission (HR, 1.28 [95% CI, 1.14-1.43], P<0.001).

PPM implantation frequently occurs after TVS, notably in female patients and patients undergoing TV replacement. Although mortality is not increased, it is associated with higher rates of heart failure rehospitalization.

Pacing-induced cardiomyopathy is a potential complication of right ventricular pacing. Definition varies between studies and the optimal management approach is uncertain. We aimed to characterize definition, prevalence, risk factors, and treatment strategies of pacing-induced cardiomyopathy (PiCM). We performed a systematic review and meta-analysis of studies that evaluated PiCM after pacemaker implantation identified through a literature search of PubMed and EMBASE up to March 2022. We collected data on the study definition of PiCM and calculated pooled prevalence across studies. Meta-analysis with random effects modeling was used to assess the association between potential risk factors and PiCM, reported as odds ratio with 95% confidence interval. Twenty-six studies (6 prospective studies) with a total of 57,993 patients (mean/median age range was 51-78 years; female 45%) were included in the final analysis. Fifteen unique definitions of PiCM were reported. The pooled prevalence of PiCM was 12% (95% confidence interval 11%-14%). In meta-analysis, risk factors included male sex, history of myocardial infarction, chronic kidney disease, atrial fibrillation, baseline left ventricular ejection fraction, native QRS duration, right ventricular pacing percentage, and paced QRS duration. Treatment strategies identified included biventricular cardiac resynchronization therapy (6 studies) and His-bundle pacing (3 studies). Definition of PiCM varied significantly between studies. More than 1 in 10 patients with chronic right ventricular pacing developed PiCM. Key risk factors included baseline left ventricular ejection fraction, native QRS duration, RV pacing percentage, and paced QRS duration. The optimal management strategy has yet to be defined. Further research is needed to define and treat this understated complication.

Patients with preserved left ventricular (LV) ejection function (EF) and atrioventricular block (AVB) who are anticipated for high-burden of right ventricular (RV) pacing possess a risk to develop pacing-induced cardiomyopathy (PIC) and adverse clinical outcomes. Hence, the aim of the study is to evaluate the incidence, predictors, and clinical outcomes of RV PIC in patients with preserved LVEF, AVB, and high-burden of RV pacing. One thousand and thirteen patients with second or third-degree AVB underwent first time pacemaker implantation between January 2002 and August 2016. A total of 203 patients with a newly implanted pacemaker, normal baseline LVEF, and high burden of RV pacing were included in the present study. Follow-up echocardiography was examined for a new decrease in LVEF of 10% or higher. Alternative causes for cardiomyopathy were ruled out. Patient characteristics, echocardiographic measurements, device clinic data, mortality, and hospitalizations for heart failure were collected and compared between the PIC and the non-PIC groups. Fifty-one patients (25%) developed LV dysfunction with 22 patients (11%), showing LVEF < 40%. During a mean follow-up of 49.2 months, the risk of heart failure hospitalization or all-cause mortality was significantly higher in the PIC group versus non-PIC group (35.3% vs 19.1%, p = 0.009). In conclusion the incidence of PIC in patients with normal LVEF and AVB, who are anticipated for high-burden of RV pacing is high. PIC in patients with a previously normal LV function is associated with unfavorable long-term clinical outcomes, including higher rates of heart failure hospitalizations and all-cause mortality.

We investigated the clinical features, predictors, and long-term prognosis of pacing-induced cardiomyopathy (PiCM).

From a retrospective analysis of 1418 consecutive pacemaker patients, 618 were found to have a preserved baseline left ventricular ejection fraction (LVEF), follow-up echocardiographic data, and no history of heart failure (HF). PiCM was defined as a reduction in LVEF (< 50%) along with either (i) a ≥ 10% decrease in LVEF, or (ii) new-onset regional wall motion abnormality unrelated to coronary artery disease. PiCM occurred in 87 of 618 patients (14.1%), with a decrease in mean LVEF from 60.5% to 40.1%. The median time to PiCM was 4.7 years. Baseline left bundle branch block, wider paced QRS duration (≥ 155 ms), and higher ventricular pacing percentage (≥ 86%) were identified as independent predictors of PiCM in multivariate logistic regression analysis. The risk of PiCM increased gradually with the number of identified predictors, becoming more significant in the presence of two or more predictors (P < 0.001). During the entire follow-up (median 7.2 years), the risk of all-cause death or HF admission was significantly higher in patients with PiCM compared to those without PiCM (38.3% vs. 54.0%, adjusted hazard ratio 2.93; 95% confidence interval 1.82-4.72; P < 0.001).

Pacing-induced cardiomyopathy patients showed a worse long-term prognosis than those without PiCM. Therefore, patients with multiple risk factors of PiCM should be monitored carefully even if their left ventricular systolic function is preserved initially. A timely upgrade to a biventricular or His-bundle pacing device needs to be considered in patients with PiCM.

It is now well recognized that heart failure (HF) patients with left bundle branch block (LBBB) derive substantial clinical benefits from cardiac resynchronization therapy (CRT), and LBBB has become one of the important predictors for CRT response. The conventional tachypacing-induced HF model has several major limitations, including absence of stable LBBB and rapid reversal of left ventricular (LV) dysfunction after cessation of pacing. Hence, it is essential to establish an optimal model of chronic HF with isolated LBBB for studying CRT benefits. In the present study, a canine model of asynchronous HF induced by left bundle branch (LBB) ablation and 4 weeks of rapid right ventricular (RV) pacing is established. The RV and right atrial (RA) pacing electrodes via the jugular vein approach, together with an epicardial LV pacing electrode, were implanted for CRT performance. Presented here are the detailed protocols of radiofrequency (RF) catheter ablation, pacing leads implantation, and rapid pacing strategy. Intracardiac and surface electrograms during operation were also provided for a better understanding of LBB ablation. Two-dimensional speckle tracking imaging and aortic velocity time integral (aVTI) were acquired to validate the chronic stable HF model with LV asynchrony and CRT benefits. By coordinating ventricular activation and contraction, CRT uniformed the LV mechanical work and restored LV pump function, which was followed by reversal of LV dilation. Moreover, the histopathological study revealed a significant restoration of cardiomyocyte diameter and collagen volume fraction (CVF) after CRT performance, indicating a histologic and cellular reverse remodeling elicited by CRT. In this report, we described a feasible and valid method to develop a chronic asynchronous HF model, which was suitable for studying structural and biologic reverse remodeling following CRT.

Long-term right ventricular pacing has deleterious effects on the left ventricle (LV). The risk of pacemaker-induced cardiomyopathy (PICM) seems to be lower in patients with a normal LV ejection fraction (LVEF). Patients developing PICM respond favorably to a cardiac resynchronization therapy upgrade, suggesting that the dysfunction is partially reversible. Biventricular pacing has emerged as a treatment and/or prevention of PICM. Cumulative pacing greater than 40% of the time is considered the most important risk factor for PICM. No organizational guidelines exist for preventive biventricular pacing. The decision to pursue biventricular pacing should be individualized.