One-Month Global Longitudinal Strain Identifies Patients Who Will Develop Pacing-Induced Left Ventricular Dysfunction over Time: The Pacing and Ventricular Dysfunction (PAVD) Study

New Insights into Pacing Induced Cardiomyopathy

Pacing induced cardiomyopathy (PICM) can occur as a complication due to pacing the right ventricle. Its precise definition varies across different studies, leading to uncertainty as to the best approach for managing this entity. More than 10% of patients who undergo chronic right ventricular pacing develop PICM. Risk factors associated with PICM include reduced left ventricular ejection fraction (LVEF), the proportion of right ventricular pacing, and paced QRS duration. The main approach to treating PICM has been upgrading to biventricular pacing cardiac resynchronization therapy when the LVEF decreases. However, emerging evidence suggest that conduction system pacing might provide an opportunity to manage PICM.

Pacing-induced cardiomyopathy in patients with preserved ejection fraction undergoing permanent cardiac pacemaker placement

BACKGROUND

Chronic right-ventricular (RV) pacing can worsen heart failure in patients with a low ejection fraction (EF), but little is known about pacing-induced cardiomyopathy (PICM) in patients with preserved EF. We aimed to investigate risk factors of PICM in these patients during long-term follow-up.

METHODS

The prospective registry at Chosun University Hospital, South Korea, included de novo patients with preserved EF undergoing transvenous permanent pacemaker (PPM) implantation for atrioventricular blockage from 2017 to 2021. Patients with EF ≥ 50% and expected ventricular pacing ≥ 40% were included. Composite outcomes were cardiac death (pump failure), hospitalization because of heart failure, PICM, and biventricular pacing (BVP) upgrade.

RESULTS

A total of 168 patients (69 men, 76.3 ± 10.4 years) were included. During three years of follow-up, one patient died, 14 were hospitalized, 16 suffered PICM, and two underwent BVP upgrade. PICM were associated with reduced global longitudinal strain (GLS), prolonged paced QRS duration (pQRSd) and diastolic variables (E/e', LAVI). Cox regression analysis identified pQRSd (hazard ratio [HR], 1.111; 95% confidence interval [CI], 1.011-1.222; P = 0.03) and reduced GLS (HR, 1.569; 95% CI, 1.163-2.118; P = 0.003) as independent predictors of PICM. GLS showed high predictive accuracy for PICM, with an area under the curve of 0.84 (95% CI 0.779-0.894; P < 0.001) [GLS -12.0, 62.5% sensitivity, and 86.1% specificity].

CONCLUSION

RV pacing increased the risk of PICM in patients with preserved EF. Reduced GLS and prolonged pQRSd could help identify individuals at high risk of PICM even with preserved EF.

Comparison of Global Longitudinal Strain in Dual-chamber versus Ventricular Pacemaker in Complete Heart Block

Context

Bradycardia caused by total atrioventricular block (TAVB) is treated by implantation of permanent pacemakers (PPMs) in either dual-chamber (DDD) versus ventricular (VVI) pacing modes. DDD is considered a more physiological pacing mode than VVI as it avoids atrioventricular dyssynchrony. However, previous trials have failed to demonstrate the superiority of DDD in improving quality of life and morbidity.

Aims

This study aims to provide postpacemaker function of the left ventricle (LV) measured with global longitudinal strain (GLS), in TAVB patients.

Settings and Design

This is a comparative study; samples included in the study are adult TAVB patients undergoing PPM implantation, without significant heart function, and structural abnormality. Echocardiographic parameters are obtained before, after 1 month, and after 3 months post-PPM.

Subjects and Methods

A total of 98 TAVB patients undergoes PPM implantation during the study period, 55 patients were excluded, and in the end, only 43 patients fulfill the inclusion criteria.

Statistical Analysis Used

Baseline data between DDD and VVI are compared using unpaired t-test. Statistical significance 1 month post-PPM and 3 months post-PPM is analyzed using paired t-test.

Results

There were no significant differences between both groups at baseline. However, significant GLS changes are observed 1 month after PPM in the VVI group (P = 0.002), but no significant change was observed in the DDD group even after 3 months (P = 0.055).

Conclusions

In our study, we conclude that DDD is superior in maintaining LV function in the short term in TAVB patients after PPM implantation.

Evolution of ventricular and valve function in patients with right ventricular pacing - A randomized controlled trial comparing leadless and conventional pacing

BACKGROUND

Leadless pacemakers (PMs) were recently introduced to overcome lead-related complications. They showed high safety and efficacy profiles. Prospective studies assessing long-term safety on cardiac structures are still missing.

OBJECTIVE

The purpose of this study was to compare the mechanical impact of Micra with conventional PM on heart function.

METHODS

We conducted a non-inferiority trial in patients with an indication for single chamber ventricular pacing. Patients were 1:1 randomized to undergo implantation of either Micra or conventional monochamber ventricular pacemaker (PM). Patients underwent echocardiography at baseline, 6 and 12 months after implantation. Analysis included left ventricular ejection fraction (LVEF), global longitudinal strain (GLS) and valve function. N-terminal-pro hormone B-type natriuretic peptide (NT-pro-BNP) levels were measured at baseline and 12 months.

RESULTS

Fifty-one patients (27 in Micra group and 24 in conventional group) were included. Baseline characteristics were similar for both groups. At 12 months, (1) the left ventricular function as assessed by LVEF and GLS worsened similarly in both groups (∆LVEF -10 ± 7.3% and ∆GLS +5.7 ± 6.4 in Micra group vs. -13.4 ± 9.9% and +5.2 ± 3.2 in conventional group) (p = 0.218 and 0.778, respectively), (2) the severity of tricuspid valve regurgitation was significantly lower with Micra than conventional pacing (p = 0.009) and (3) median NT-pro-BNP was lower in Micra group (970 pg/dL in Micra group versus 1394 pg/dL in conventional group, p = 0.041).

CONCLUSION

Micra is non inferior to conventional PMs concerning the evolution of left ventricular function at 12-month follow-up. Our data suggest that Micra has a comparable mechanical impact on the ventricular systolic function but resulted in less valvular dysfunction.

Left Ventricular Mass Index Predicts Pacemaker-Induced Cardiomyopathy in Patients with Dual Chamber Permanent Pacemakers Implanted Due to Complete Atrioventricular Block

Background

Pacing-induced cardiomyopathy (PICM) occurs as a result of high-burden right ventricular (RV) pacing, which usually develops in patients with complete atrioventricular (AV) block. There is a paucity of data on the association between PICM and pre-implantation left ventricular mass index (LVMI). Thus, the purpose of this study was to analyze the influence of LVMI on PICM in patients who had dual chamber permanent pacemakers (PPMs) implanted secondary to complete AV block.

Methods

Overall, 577 patients with dual chamber permanent pacemakers (PPMs) were classified into three tertiles according to their pre- implantation LVMI. The average follow-up period was 57 ± 38 months. The baseline characteristics, laboratory and echocardiographic variables were compared between the tertiles. PICM was defined as a ≥ 10% drop in left ventricular ejection fraction (LVEF) from pre-implantation with a resultant LVEF < 50%. PICM occurred in 42 (7.2%) patients. The independent predictors of PICM development, as well as the impact of LVMI on PICM, were investigated.

Results

After controlling for confounding baseline variables, the tertile with the greatest LVMI had a 1.8 times higher risk for the development of long-term PICM compared with the tertile with the lowest LVMI, which was accepted as the reference group. A receiver operating characteristic curve analysis revealed that the best LVMI cut- off value for predicting long-term PICM was 109.8 g/m2 with 71% sensitivity and 62% specificity (area under curve: 0.68; 95% confidence interval: 0.60-0.76; p < 0.001).

Conclusions

This investigation revealed that pre-implantation LVMI had a prognostic role in predicting PICM in patients with an implanted dual chamber PPM due to complete AV block.

Reduction of left ventricular global longitudinal strain in patients with permanent pacemakers as a predictor of heart failure and mortality outcomes

INTRODUCTION

Frequent right ventricular (RV) pacing is associated with cardiomyopathy. The impact of RV pacing on left ventricular (LV) global longitudinal strain (GLS) and clinical outcomes is unclear.

METHODS

We analyzed GLS via two-dimensional speckle tracking and LV ejection fraction (EF) on pre- and post-implantation transthoracic echocardiograms of patients undergoing dual chamber pacemaker implantation. We collected long-term data on strain, LVEF, and clinical outcomes.

RESULTS

One hundred and ten patients (mean age 76 ± 12 years; 59 [54%] female) were followed for mean 23 ± 17 months. Mean baseline LVEF was 58 ± 11% and mean GLS was -17 ± 4%. Twenty-four (22%) patients had an absolute decrease in LVEF > 10% and 43 (39%) patients had a relative reduction of GLS > 15%. Among patients with a reduction of GLS, a larger proportion of patients had RV pacing burden ≥20% (67% vs. 46%; p = .048). Compared to patients without GLS reduction, more patients with a reduction in GLS reached a composite endpoint of HF hospitalization, CRT upgrade or death (47% vs. 16%; p = .001).

CONCLUSION

Reduction in LV GLS was seen in nearly four in 10 patients undergoing pacemaker implantation and was significantly associated with increased RV pacing burden. LV GLS reduction was associated with increased risk of adverse outcomes. LV GLS may have utility in predicting outcomes among patients with RV pacing.

Ventricular Dyssynchrony and Pacing-induced Cardiomyopathy in Patients with Pacemakers, the Utility of Ultra-high-frequency ECG and Other Dyssynchrony Assessment Tools

The majority of patients tolerate right ventricular pacing well; however, some patients manifest signs of heart failure after pacemaker implantation and develop pacing-induced cardiomyopathy. This is a consequence of non-physiological ventricular activation bypassing the conduction system. Ventricular dyssynchrony was identified as one of the main factors responsible for pacing-induced cardiomyopathy development. Currently, methods that would allow rapid and reliable ventricular dyssynchrony assessment, ideally during the implant procedure, are lacking. Paced QRS duration is an imperfect marker of dyssynchrony, and methods based on body surface mapping, electrocardiographic imaging or echocardiography are laborious and time-consuming, and can be difficult to use during the implantation procedure. However, the ventricular activation sequence can be readily displayed from the chest leads using an ultra-high-frequency ECG. It can be performed during the implantation procedure to visualise ventricular depolarisation and resultant ventricular dyssynchrony during pacing. This information can assist the electrophysiologist in selecting a pacing location that avoids dyssynchronous ventricular activation.

Clinical impact of left bundle branch area pacing in heart failure with preserved ejection fraction and mid-range ejection fraction

BACKGROUND

Recently, conduction system pacing, including His bundle and left bundle branch area pacing (LBBAP), has emerged as an alternative pacing procedure for right ventricular (RV) pacing. The current study aimed to compare the clinical outcomes of LBBAP and conventional RV mid-septal pacing (RVMSP) in patients with heart failure (HF) with preserved ejection fraction (HFpEF) and HF with mid-range ejection (HFmrEF) requiring frequency RV pacing due to atrioventricular block (AVB).

METHODS

A total of 89 patients with HFpEF and HFmrEF requiring RV pacing due to symptomatic AVB were enrolled between September 2018 and April 2021, among whom 43 and 46 underwent LBBAP and RVMSP, respectively.

RESULTS

No significant differences in baseline characteristics were observed between the two groups. The LBBAP group had a significantly shorter paced-QRS duration and paced left ventricular activation time (LVAT) compared to the RVMSP group (123.4 ± 10.4 ms vs. 152.3 ± 12.3 ms, p < 0.001 and 68.3 ± 10.0 ms vs. 95.2 ± 12.3 ms, p < 0.001, respectively). The LBBAP group had significantly lower N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels at the 6-month follow-up compared to the RVMSP group [459.6 pg/mL (240.4-678.7) vs. 972.7 pg/mL (629.5-1315.9), p = 0.01]. More patients in the LBBAP group exhibited a significant improvement in NT-proBNP, defined as a >50% decreased from baseline levels.

CONCLUSION

LBBAP maintains physiological ventricular activation and contributes to greater improvement in NT-proBNP value 6 months after implantation in patients with HFpEF and HFmrEF compared to RVMSP. This article is protected by copyright. All rights reserved.

Shenfu Injection: A Famous Chinese Prescription That Promotes HCN4 Activity in Bone Marrow Mesenchymal Stem Cells

We investigated the effects of Shenfu Injection (SFI) on HCN4 activity in bone marrow mesenchymal stem cells (BMSCs). The sample of BMSCs was divided into six groups: a control group, a high-dose SFI group (0.25 ml/ml), a middle-dose SFI group (0.1 ml/ml), a low-dose SFI group (0.05 ml/ml), an adenovirus-encoded control vector group, and an adenovirus-encoded HCN4 group. Cell ultrastructure was observed using a transmission electron microscope. Quantitative reverse transcription PCR (RT-qPCR) was performed to detect HCN4 expression, and HCN4 activity was detected using the whole-cell patch clamp technique. An enzyme-linked immunosorbent assay was performed to detect cAMP content. Application of flow cytometry confirmed that the isolated cells showed BMSC-like phenotypes. Differentiation of BMSCs in both the SFI and the adenovirus-encoding HCN4 groups occurred according to the cellular ultrastructure. Application of the whole-cell patch clamp technique revealed that SFI could activate the inward pacing current of BMSCs in a concentration-dependent manner. The RT-qPCR results showed that HCN4 expression was significantly higher in the high-dose SFI group than in the medium- and low-dose groups, whereas the cAMP content in the overexpressed HCN4 group decreased significantly; this content in the high-dose SFI group increased significantly. In conclusion, SFI promotes HCN4 activity in BMSCs, which could explain its treatment effect when administered to patients with cardiovascular diseases.

Left Ventricular Global Longitudinal Strain Is Associated With Cardiovascular Outcomes in Patients Who Underwent Permanent Pacemaker Implantation

Background: Patients who underwent permanent pacemaker (PM) implantation have a potential risk of left ventricular (LV) systolic dysfunction. However, assessment of LV ejection fraction (LVEF) shows a limited role in identifying subclinical LV systolic dysfunction and predicting cardiovascular (CV) outcomes.

Methods: We reviewed 1,103 patients who underwent permanent PM implantation between January 2007 and December 2017. After excluding patients who did not undergo echocardiograms before or after PM implantation and those with LV ejection fraction (LVEF) <50%, significant valve dysfunction, and history of cardiac surgery before PM implantation, 300 (67 ± 13 years, 119 men) were finally analyzed. LV mechanical function was assessed with LV global longitudinal strain (LV-GLS) using 2-dimensional speckle-tracking echocardiography. CV outcomes were defined as a composite of CV death and hospitalization for heart failure.

Results: At 44 ± 28 months after post-PM echocardiogram, 23 patients (7.7%) had experienced CV outcomes. Patients with CV outcomes were older and had more comorbidities and a lower baseline |LV-GLS| than those without CV outcomes. LV mechanical function worsened after PM implantation in patients with CV outcomes. The cut-off value of 11.2% in |LV-GLS| on post-PM echocardiogram had a better predictive value for CV outcomes (AUC; 0.784 vs. 0.647, p = 0.012). CV outcome in patients with |LV-GLS| <11.2% was worse than that in those with |LV-GLS| ≥ 11.2% (log-rank p < 0.001). Multivariate Cox model revealed that reduced |LV-GLS| was independently associated with CV outcomes.

Conclusions: Pacing deteriorates LV mechanical function. Impaired LV-GLS is associated with poor CV outcomes in patients who underwent PM implantation.

Clinical symptoms of limited exercise capacity linked to AAI-DDD functionality: An in silico and in vivo approach

BACKGROUND

Exercise capacity is an important aspect of quality of life in patients undergoing pacemaker implantation. Device algorithms for ventricular pacing avoidance have been developed to avoid unnecessary and potentially harmful effects of right ventricular pacing. However, little data exists on the immediate response of these algorithms to sudden AV block during exercise.

METHODS

The ventricular pacing avoidance algorithms of four pacemaker manufacturers were tested in an ex-vivo model. The RSIM-1500-USB Device-Interactive Heart Simulator (Rivertek Medical Systems, Inc.) was used to simulate three different scenarios: the first one starting with an initially conducted atrial pacing rate of 60 min^-1 , the second one starting with an atrial rate of 120 min^-1 and finally a scenario starting with an atrial rate of 150 min^-1 . In all three scenarios, the initially conducted atrial rate was followed by a sudden, long lasting episode of third-degree AV-block. The response to those scenarios was recorded for each of the (brand-specific) ventricular pacing avoidance algorithms.

RESULTS

In the first scenario, the simulation resulted in a ventricular pause of 1333 ms (Boston Scientific), 2000 ms (Medtronic and Microport), and 2340 ms (Biotronik). In the second and third scenario, different results were observed across devices. All simulations of the second and third scenario resulted in repetitive 2:1 block response (during eight cycles) in Boston Scientific and Biotronik devices. These scenarios were confirmed in patient cases.

CONCLUSION

Simulator based observations of unanticipated pacemaker-induced 2:1 block response during exercise may explain clinical symptoms experienced by some patients having a two-chamber pacemaker.

Progressive QRS Duration and Ventricular Dysfunction in Pediatric Patients with Chronic Ventricular Pacing

Pacemakers are a mainstay of therapy for patients with congenital and acquired heart block, but ventricular pacing is related to ventricular dysfunction. We sought to evaluate patient and device characteristics associated with ventricular dysfunction in pediatric patients with chronic ventricular pacing. This was a retrospective cohort of pediatric patients with heart block and chronic ventricular pacing. Patient, ECG, and device characteristics were analyzed to determine factors associated with ventricular dysfunction. Longitudinal ECG and echocardiogram parameters were obtained to track changes in QRS and systemic ventricular systolic function over time. In total, 82 patients were included (median age at implant 0.81 years). Over a follow-up time of 6.1 years, 18% developed ventricular dysfunction. Patients with dysfunction had greater current QRS duration (p = 0.002) compared to those with preserved function with a similar time from device implantation. There was no difference between lead location or age at device implantation. QRS duration increased with time from implant and the resultant ΔQRS was associated with ventricular dysfunction (p = 0.01). QRS duration >162 ms was associated with a 5.8 (2-9)-fold increased risk for dysfunction. Transvenous leads were associated with longer QRS duration with no difference compared to epicardial leads in development of ventricular dysfunction. This study demonstrated that the absolute paced QRS duration and Δpaced QRS were association with long-term ventricular dysfunction independent of how long a given patient was paced. Patients in high-risk categories may benefit from close echocardiographic monitoring. Whether permissive junctional rhythm or His bundle/biventricular pacing decreases the rate of dysfunction needs further study.

Predictors of pacing induced left ventricular dysfunction and cardiomyopathy assessed by three-dimensional echocardiography and speckle tracking strain

Background

Long-term RV pacing leads to ventricular dyssynchrony, in the form of LBBB-like morphology, with subsequent detrimental effects on LV structure and function. Three-dimensional echocardiography allowed early detection of volumetric changes associated with PICMP and provided more accurate assessment of mechanical dyssynchrony. Speckle tracking strain is able to identify LV dysfunction even before any reduction in LVEF. Our aim was to study pacing effects on LV function and hemodynamics using 3D echo and speckle tracking strain.

Results

This was a prospective study of 175 consecutive patients without structural heart disease (LVEF > 50%) presented for permanent pacing. Full-volume 3D echocardiography done before implantation, 1 week, and 6 months together with GLS. Patients were followed for 6 months to detect incidence of PIVD (defined as reduction in LVEF > 10% but still above 50%) and PICMP (defined as decrease in LVEF by 10% from baseline in absence of other known causes of cardiomyopathy resulting in EF< 50%). PIVD and PICMP predictors and risk factors were analyzed. Only 50 patients met study criteria. Twenty-five (50%) patients developed LV systolic dysfunction; of these, 19 (38%) developed PIVD and 6 (12%) developed PICMP. Pre-implantation GLS was significantly lower in the 6 patients who subsequently developed PICMP, compared to those who developed PIVD and the preserved EF group (mean GLS − 15.50 vs. − 21.0, − 20.0 respectively; p = 0.005, 0.033, respectively). At 1 week, GLS was significantly lower in the 25 patients who subsequently developed PIVD, compared to those who did not (GLS − 13.0 vs. − 18.0, respectively; p = 0.002). A reduction of baseline GLS by 15% or more at 1 week was associated with the development of PIVD and PICMP (p = < 0.001). A wider native QRS complex was associated with PIVD and PICMP (p = 0.008, 0.018, respectively). The other predictors were found non-significant.

Conclusion

PICMP may be more common than previously reported and it may occur shortly after implantation. Pre-implantation GLS is a sensitive parameter for PICMP. One-week GLS, pre-implantation QRS complex width are early predictors for PICMP and PIVD before any reduction in EF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43044-021-00136-x.

Pre-implant global longitudinal strain as an early sign of pacing-induced cardiomyopathy in patients with complete atrioventricular block

Introduction

Long‐term right ventricular pacing is the only treatment for patients with a complete atrioventricular block (CAVB); however, it frequently triggers ventricular dys‐synchrony with left ventricular (LV) dysfunction. Previous studies showed that an early decline of LV global longitudinal strain (GLS) predicts pacing‐induced LV dysfunction. We aimed to investigate the potential ability of the initial LV strain to predict pacing‐induced cardiomyopathy (PICM) through long‐term follow‐ups.

Methods

We retrospectively enrolled 80 patients with CAVB with normal LV function who were implanted with dual‐chamber pacemakers between 2008 and 2018. Echocardiographic data and parameters (including longitudinal, radial, and circumferential strain based on speckle‐tracking) were analyzed for the pre‐implant (≤6 months) and post‐implant periods. PICM was defined as a ≥10% reduction in the left ventricular ejection fraction (LVEF) resulting in an LVEF of <50% during the post‐implant period. Predictors of PICM were identified using Cox proportional hazard models.

Results

Patients who developed PICM were more likely to exhibit lower baseline LV GLS, as well as wider native and pacing QRS durations, than those who did not develop PICM (P = .016, P = .011, and P = .026, respectively). In the multivariate analysis, pre‐implant LV GLS (hazard ratio: 1.27; 95% confidence interval 1.009–1.492; P = .004) was independently associated with the development of PICM.

Conclusion

A lower baseline LV GLS predicts an increased risk of PICM. Patients with CAVB exhibiting low GLS are at increased risk of PICM. More frequent follow‐up visits are warranted in these patients, who may also require de novo His‐bundle pacing or an upgrade to biventricular pacing.

His bundle pacing–is it the final frontier of physiological pacing ?–A single centre experience from the Indian sub–Continent

Background

Long term right ventricular pacing can have deleterious effects on left ventricular (LV) function. His bundle pacing (HBP), a novel procedure can probably circumvent this setback. We investigated if (1) HBP is associated with pacing induced LV dysfunction by using LV global longitudinal strain (GLS) and (2) intermediate term performance of the Select Secure (3830) lead in the His bundle location. This report is probably the first on HBP in the Indian population.

Methods

61 patients, with normal LV ejection fraction (EF) with a guideline based indication for permanent pacing underwent a HBP pacemaker implantation using the His Select Secure 3830 lead; with lead guided mapping for locating the His bundle. The patients underwent GLS assessment; evaluation of the His lead parameters - sensing, impedance and capture thresholds immediately after implantation and at 6 months in addition to the standard follow up.

Results

At 6 month follow up, the average GLS did not show significant variation from baseline in patients requiring ventricular pacing more than 40% and was similar, irrespective of selective or non selective His bundle pacing. All the patients had stable pacemaker parameters - with little change in capture threshold, lead impedance or sensing of the His bundle lead - implying electrical and mechanical stability on intermediate term follow-up.

Conclusion

HBP is a feasible procedure in the hands of an experienced operator, with stable lead performance. It does not appear to be associated with pacing mediated left ventricular dysfunction at intermediate term follow up. It should probably become the default method of permanent pacing.

Adverse Consequences of Right Ventricular Apical Pacing and Novel Strategies to Optimize Left Ventricular Systolic and Diastolic Function

Several studies have focused on the deleterious consequences of Right Ventricular Apical (RVA) pacing on Left Ventricular (LV) function, mediated by pacing-induced ventricular dyssyn-chrony. Therapeutic strategies to reduce the detrimental consequences of RVA pacing have been pro-posed, that includes upgrading of RVA pacing to Cardiac Resynchronization Therapy (CRT), alterna-tive Right Ventricular (RV) pacing sites, minimal ventricular pacing strategies, as well as atrial-based pacing. In developing countries, single chamber RV pacing still constitutes a majority of cases of permanent pacing, and assessment of the optimal RV pacing site is of paramount importance. In chronically-paced patients, it is crucial to maintain as close and normal LV physiological function as possible, by minimizing ventricular dyssynchrony, reducing the chances for heart failure and other complications to develop. This review provides an analysis of the deleterious immediate and long-term consequences of RVA pacing, and the most recent available evidence regarding improvements in pacing options and strategies to optimize LV diastolic and systolic function. Furthermore, the place of advanced echocardiography in the identification of patients with pacing-induced LV dysfunction, the potential role of a new predictor of LV dysfunction in RV-paced subjects, and the long- term out-comes of patients with RV septal pacing will be explored

Clinical features, predictors, and long-term prognosis of pacing-induced cardiomyopathy

AIMS

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

METHODS AND RESULTS

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).

CONCLUSION

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.

Next-generation pacemakers: from small devices to biological pacemakers

Electrogenesis in the heart begins in the sinoatrial node and proceeds down the conduction system to originate the heartbeat. Conduction system disorders lead to slow heart rates that are insufficient to support the circulation, necessitating implantation of electronic pacemakers. The typical electronic pacemaker consists of a subcutaneous generator and battery module attached to one or more endocardial leads. New leadless pacemakers can be implanted directly into the right ventricular apex, providing single-chamber pacing without a subcutaneous generator. Modern pacemakers are generally reliable, and their programmability provides options for different pacing modes tailored to specific clinical needs. Advances in device technology will probably include alternative energy sources and dual-chamber leadless pacing in the not-too-distant future. Although effective, current electronic devices have limitations related to lead or generator malfunction, lack of autonomic responsiveness, undesirable interactions with strong magnetic fields, and device-related infections. Biological pacemakers, generated by somatic gene transfer, cell fusion, or cell transplantation, provide an alternative to electronic devices. Somatic reprogramming strategies, which involve transfer of genes encoding transcription factors to transform working myocardium into a surrogate sinoatrial node, are furthest along in the translational pipeline. Even as electronic pacemakers become smaller and less invasive, biological pacemakers might expand the therapeutic armamentarium for conduction system disorders.

Early Right Ventricular Apical Pacing-Induced Gene Expression Alterations Are Associated with Deterioration of Left Ventricular Systolic Function

The chronic high-dose right ventricular apical (RVA) pacing may have deleterious effects on left ventricular (LV) systolic function. We hypothesized that the expression changes of genes regulating cardiomyocyte energy metabolism and contractility were associated with deterioration of LV function in patients who underwent chronic RVA pacing. Sixty patients with complete atrioventricular block and preserved ejection fraction (EF) who underwent pacemaker implantation were randomly assigned to either RVA pacing (n = 30) group or right ventricular outflow tract (RVOT) pacing (n = 30) group. The mRNA levels of OPA1 and SERCA2a were significantly lower in the RVA pacing group at 1 month's follow-up (both p < 0.001). Early changes in the expression of selected genes OPA1 and SERCA2a were associated with deterioration in global longitudinal strain (GLS) that became apparent months later (p = 0.002 and p = 0.026, resp.) The altered expressions of genes that regulate cardiomyocyte energy metabolism and contractility measured in the peripheral blood at one month following pacemaker implantation were associated with subsequent deterioration in LV dyssynchrony and function in patients with preserved LVEF, who underwent RVA pacing.