Single-chamber Ventricular Pacemaker Research Articles

Transcatheter Non-Acute Retrieval of the Tines-Based Leadless Ventricular Pacemaker.

We report our single-center experience of mid-term to long-term retrieval and reimplantation of a tines-based leadless pacemaker (Micra transcatheter pacing system; TPS). The TPS is a clinically effective alternative to transvenous single-chamber ventricular pacemakers. Whereas it is currently recommended to abandon the TPS at the end of device life, catheter-based retrieval may be favorable in specific scenarios. We report on nine consecutive patients with the implanted TPS who subsequently underwent transcatheter retrieval attempts. The retrieval system consists of the original TPS delivery catheter and an off-the-shelf single-loop 7 mm snare. The procedure was guided by fluoroscopy and intracardiac echocardiography. After an implantation duration of 3.1 ± 2.8 years (range 0.4-9.0), the overall retrieval success rate was 88.9% (8 of 9 patients). The mean procedure time was 89 ± 16 minutes, and fluoroscopy time was 18.0 ± 6.6 min. No procedure-related adverse device events occurred. In the one unsuccessful retrieval, intracardiac echocardiography revealed that the TPS was partially embedded in the ventricular tissue surrounding the leadless pacemaker body in the right ventricle. After retrieval, three patients were reimplanted with a new TPS device. All implantations were successful without complications. A series of transvenous late retrievals of implanted TPS devices demonstrated safety and feasibility, followed by elective replacement with a new leadless pacing device or conventional transvenous pacing system. This provides a viable end-of-life management alternative to simple abandonment of this leadless pacemaker.

Chronic clinical performance of a novel subxiphoidal pacemaker system: Early feasibility study design.

Extravascular and leadless pacemakers are a new class of cardiac devices that may reduce the rate of complications common to traditional cardiac pacemakers with intracardiac leads. These devices also have the potential of expanding access to cardiac pacing therapy by simplifying the complexity and cost of implantation. The objective of this study is to evaluate the implantation, chronic safety, and performance of a novel subxiphoidal pacemaker. This study is an open-label, non-randomized, early feasibility study. Ten patients indicated for implantation of a single-chamber ventricular pacemaker will be enrolled and implanted with the investigational device. The pacemaker will be inserted underneath the ribcage and clipped to the xiphoid process, with stimulation electrodes positioned on the cardiac pericardium. Patients will be programmed to chronic pacing; pacing capture threshold, sensing amplitude, and lead impedance will be measured at implant and regularly scheduled follow-up visits. 24-h Holter ECG and cardiac troponin will also be periodically measured. Adverse events will be recorded throughout the study period. This study is designed to assess the feasibility, safety, and chronic performance of a novel extravascular pacemaker, and will provide valuable data on whether this device has the potential to be a viable alternative to conventional pacemakers.

Early real-world implant experience with a helix-fixation ventricular leadless pacemaker.

Roughly one in six patients receiving conventional transvenous pacemaker systems experience significant complications within 1year of implant, mainly due to the transvenous lead and subcutaneous pocket. A new helix-fixation single-chamber ventricular leadless pacemaker (LP) system capable of pre-deployment exploratory electrical mapping is commercially available. Such an LP may mitigate complications while streamlining the implantation. In this study, the initial real-world implant experience of the helix-fixation LP was evaluated following its commercial release. In patients indicated for single-chamber right ventricular pacing, helix-fixation Aveir VR LPs (Abbott, Abbott Park, IL) were implanted using the dedicated loading tool, introducer, and delivery catheter. Implant procedural characteristics, electrical parameters, and any 30-day procedure-related adverse events of consecutive implant attempts were retrospectively evaluated. A total of 167 patients with Class I indication for permanent pacing received implants in four North American centers (57% male, 70years old). Pre-fixation electrical mapping of potential sites allowed repositioning to be avoided in 95.7% of patients. Median [interquartile range] LP procedure and fluoroscopy durations were 25.5min [20.0, 35.0] and 5.7min [4.0, 9.2], respectively. Pacing capture threshold, sensed R-wave amplitude, and impedance were 0.8V [0.5, 1.3], 9.0mV [6.0, 12.0], and 705 Ω [550, 910], respectively. Implantation was successful in 98.8% of patients, with 98.2% free from acute adverse events. The initial, real-world experience of the helix-fixation ventricular leadless pacemaker demonstrated safe and efficient implantation with minimal repositioning, viable electrical metrics, and limited acute complications.

The therapeutic benefit of upgrade to cardiac resynchronization therapy in patients with pacing-induced cardiomyopathy.

Pacing-induced cardiomyopathy (PICM) is an important cause of heart failure in patients with a right ventricular pacing burden. Recent evidence suggests that an upgrade to cardiac resynchronization therapy (CRT) may confer benefit in PICM. To assess the extent and identify predictors of improvement following upgrade to CRT in patients with PICM. We retrospectively analyzed 43 patients undergoing CRT upgrade for PICM over the 10-year period of 2011 to 2021 at our center. All patients with PICM who underwent device upgrade from a dual- or single-chamber ventricular pacemaker to CRT were included. PICM was defined as a decrease of ≥10% in left ventricular ejection fraction (LVEF), resulting in an LVEF <50% among patients with ≥20% Right ventricular pacing burden without an alternative cause for cardiomyopathy. LVEF significantly improved from 28.7% preupgrade to 44.3% post-CRT upgrade (P < .01). Of 37 patients with severe LV dysfunction, 34 (91.9%) improved to an LVEF >35% and 13 (35.1%) improved to an LVEF >50%. The LV end-diastolic diameter decreased from 5.9 cm preupgrade to 5.4 cm postupgrade (P < .01). Using linear regression, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use was associated with significant LVEF improvement (+7.21%, P = .05). We observed a low rate of complications, and 1 in 4 CRT upgrades required venoplasty (n = 10 of 43, 23.3%). We provide further evidence for the benefit of CRT upgrade in the management of patients with PICM.

Leadless versus transvenous single-chamber ventricular pacemakers: 3 year follow-up of the Micra CED study.

The Micra Coverage with Evidence Development (CED) Study is a novel comparative analysis of Micra (leadless VVI) and transvenous single-chamber ventricular pacemakers (transvenous VVI) using administrative claims data. To compare chronic complications, device reinterventions, heart failure hospitalizations, and all-cause mortality after 3 years of follow-up. USMedicare claims data linked to manufacturer device registration information were used to identify Medicare beneficiaries with a de novo implant of either a Micra VR leadless VVI or transvenous VVI pacemaker from March 9, 2017 to December 31, 2018. Unadjusted and propensity score overlap-weight adjusted Fine-Gray competing risk models were used to compare outcomes at 3 years. Leadless VVI patients (N = 6219) had a 32% lower rate of chronic complications and a 41% lower rate of reintervention compared with transvenous VVI patients (N = 10 212) (chronic complication hazard ratio [HR] 0.68; 95% confidence interval [CI], 0.59-0.78; reintervention HR 0.59; 95% CI 0.44-0.78). Infections rates were significantly lower among patients with a leadless VVI (<0.2% vs. 0.7%, p < .0001). Patients with a leadless VVI also had slightly lower rates of heart failure hospitalization (HR 0.90; 95% CI 0.84-0.97). There was no difference in the adjusted 3-year all-cause mortality rate (HR 0.97; 95% CI, 0.92-1.03). This nationwide comparative evaluation of leadless VVI versus transvenous VVI de novo pacemaker implants demonstrated that the leadless group had significantly fewer complications, reinterventions, heart failure hospitalizations, and infections than the transvenous group at 3 years, confirming that the previously reported shorter-term advantages associated with leadless pacing persist and continue to accrue in the medium-to-long-term.

Chronic outcomes of leadless vs transvenous single chamber ventricular pacemakers in high-risk subgroups

Abstract Background The Micra leadless pacemaker (LP-VVI) has been shown to have lower chronic complications and device-related reinterventions compared to transvenous ventricular pacemakers (TV-VVI) in a large, real-world population. This study compares the complication and reintervention rate in subgroups with comorbidities associated with higher risk of pacemaker complications and hypothesized to benefit from leadless pacing. Methods The longitudinal Micra Coverage with Evidence Development (CED) Study compared the outcomes of Medicare patients receiving LP-VVI to those receiving a TV-VVI in the US. Patients in the Micra CED study were included in this study if they had a diagnosis of chronic kidney disease Stages 4–5 (CKD45), end-stage renal disease (ESRD), malignancy, diabetes, tricuspid valve disease (TVD), or chronic obstructive pulmonary disease (COPD) on any administrative claim in the 12 months prior to pacemaker implant. A pre-specified set of complications and system reinterventions were identified using the relevant diagnosis and procedure codes. Adjusted and unadjusted Fine-Gray competing risks models were used to compare reinterventions and complications between LP-VVI and TV-VVI patients within each subgroup. All results were adjusted for multiple comparisons using a Bonferroni correction. An ad-hoc comparison of a composite endpoint of select reinterventions (system replacement, removal, revision, and lead reinterventions) and device complications was also conducted. Results The sample size of patients in each subgroup ranged from 2,032 patients with ESRD to 11,936 patients with diabetes. The percent of LP-VVI patients in each subgroup ranged from 44.0 in the TVD subgroup to 74.9 in the ESRD subgroup. Compared to patients implanted with a TV-VVI, patients with a LP-VVI with malignancy, diabetes, TVD, and COPD had significantly fewer complications (Table 1; Malignancy, HR 0.68, [0.48–0.95]; Diabetes, HR 0.69, [0.53–0.89]; TVD, HR 0.60 [0.44–0.82]; COPD, HR 0.73, [0.55–0.98]). LP-VVI patients with diabetes, TVD, and COPD also had lower rates of reintervention (Table; Diabetes, HR 0.58, [0.37–0.89]; TVD, HR 0.46 [0.28–0.76]; COPD, HR 0.51, [0.29–0.90]). LP-VVI patients with malignancy, diabetes, TVD, and COPD had lower rates of the combined endpoint of device complications and select reinterventions (Table; Malignancy, HR 0.52, [0.32–0.83]; Diabetes, HR 0.52, [0.35–0.77]; TVD, HR 0.44 [0.28–0.70]; COPD, HR 0.55, [0.34–0.89]). Conclusions In a real-world study of US Medicare patients, the leadless pacemaker was associated with lower rates of chronic complications and reinterventions at 2 years compared with TV-VVI pacing in several high-risk subgroups. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Medtronic

Micra pacemaker in adult congenital heart disease patients: A case series.

Implantation of transvenous endocardial or epicardial pacemakers presents specific challenges in adult congenital heart disease (ACHD) patients. Micra leadless permanent pacemakers (Micra PPM) may overcome some of these difficulties. FifteenACHD patients who underwent Micra PPM insertion were retrospectively evaluated. Males 53.3%. Mean age at study: 37.5 ± 10.7 years. Mean age at Micra PPM insertion: 35.5 ± 11.0 years. Mean follow-up so far: 2.0 ± 0.3 years. Concerning the ACHD patients, 6.7% had a simple defect, 66.6% had a moderately complex defect, 26.7% were complex. Four patients (26.7%) had a previous PPM implantation. Three patients (20%) had a systemic right ventricle. Two patients (13.3%) had a single ventricle physiology. Five (33.3%) had Trisomy 21. The most commonly used Micra PPM modality was single chamber ventricular pacemaker (73.3%). Mean threshold post implantation was 0.48 V [range: 0.25-1.13 V], while mean threshold at 6 months control was 0.60 V [range: 0.38-1.13 V] (p = ns). Mean R wave postimplantation was 10.3 V [range: 3.25-19.4 V], whilst mean R wave at 6 months follow-up was 10.1 V [range: 3.5-19.0 V] (p = ns). No major peri and postprocedural complications were encountered. since ACHD patients are living longer and surviving into adulthood, the incidence of conduction disorders continues to increase, as part of the natural history of some lesions or as early or late complication of surgery. The Micra leadless PPM can be successfully implanted in ACHD patients and have significant theoretical advantages. They should be considered when transvenous and epicardial pacing are either contraindicated or represent an otherwise suboptimal approach.

PO-707-06 THE THERAPEUTIC BENEFIT OF UPGRADE TO CARDIAC RESYNCHRONIZATION THERAPY IN PATIENTS WITH PACING INDUCED CARDIOMYOPATHY

Pacing induced cardiomyopathy (PICM) is an important cause of heart failure in patients with a high right ventricle (RV) pacing burden. Recent evidence suggests upgrade to cardiac resynchronization therapy (CRT) may reverse PICM. To assess the extent and identify predictors of improvement following upgrade to CRT in patients with PICM. We retrospectively analysed 38 patients undergoing CRT upgrade for PICM over a ten-year period 2011-2021 at our tertiary referral centre. All patients who underwent device upgrade from a dual or single chamber ventricular pacemaker to CRT were included. PICM was defined as a decrease of ≥10% in left ventricular ejection fraction (LVEF), resulting in LVEF <50% among patients experiencing ≥ 20% RV pacing without an alternative cause for cardiomyopathy. LVEF significantly improved from 29.7% pre-upgrade to 44.0% post CRT upgrade (p < 0.01). Of 24 patients with severe LV dysfunction, 21 (87.5%) improved to a LVEF >35% and 8 (33%) improved to a LVEF > 50%. The LV end diastolic diameter improved from 5.8 cm pre-upgrade to 5.3 cm post upgrade which was statistically significant (p < 0.05). The percentage RV pacing did not correlate with the severity of LV dysfunction (Pearson’s r = 0.33, p > 0.05) or predict CRT response (Pearson’s r = 0.16, p > 0.05). We observed a low rate of complications and one in four CRT upgrades required venoplasty (9/36). Upgrade to CRT has a significant therapeutic role in the management of patients with PICM. Our data shows that 88% of patients with severe PICM will see recovery of the LV function to an EF >35%.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

A Retrospective analysis of four cases of pacemaker exit block

Abstract Introduction: Exit block has been defined as a delay or failure of a pacemaker impulse to discharge the surrounding myocardium, including atrial and ventricular pacemaker exit blocks. The present report analyzed the etiology and electrocardiogram characteristics of pacemaker exit blocks, providing ideas for its diagnosis and treatment. Patient concerns: The patients in cases 1 and 2 sought medical advice for symptoms such as palpitations, chest tightness and shortness of breath. Both the patients had a dual-chamber pacemaker implant due to sick sinus syndrome Patients in cases 3 and 4 sought medical advice for symptoms such as chest tightness, chest pain, and dizziness. Both patients had a single-chamber ventricular pacemaker implant due to third-degree atrioventricular block. Diagnosis: Considering the symptoms and prolonged latency of atrial pacing, Cases 1 and 2 were diagnosed as first-degree atrial pacemaker exit blocks. Case 3 presented prolonged ventricular pacing latency, diagnosed as first-degree ventricular pacemaker exit block. Case 4 presented prolonged ventricular pacing latency and partial loss of capture diagnosed as second-degree ventricular pacemaker exit block. Interventions: In case 1, the patient required no treatment. In case 2, the AV interval was adjusted to ensure sequential pacing of the atrioventricular. In case 3, the serum potassium level was lowered. In case 4, the patient refused further treatment. Outcomes: In case 1, the patient had no discomfort, and the follow-up electrocardiogram was unchanged. The symptoms improved after treatment in case 2. After 1 year, the patient had no discomfort, and the follow-up electrocardiogram was similar to that before. In case 3, the exit block disappeared after lowering the serum potassium level. The pacemaker worked normally after 1 year of follow-up. In case 4, the exit block disappeared half an hour after the chest pain was relieved. The patient was lost to follow-up. Conclusion: A first-degree atrial pacemaker exit block may be misdiagnosed as atrial pacing dysfunction. This can be identified using the programming control of a pacemaker. For exit block of ventricular pacing, eliminating the cause of the disease is usually the most effective measure, and if necessary, a temporary pacemaker should be implanted.

Contemporaneous Comparison of Outcomes Among Patients Implanted With a Leadless vs Transvenous Single-Chamber Ventricular Pacemaker

The safety and efficacy of leadless VVI pacemakers have been demonstrated in multiple clinical trials, but the comparative performance of the device in a large, real-world population has not been examined. To compare patient characteristics and complications among patients implanted with leadless VVI and transvenous VVI pacemakers. The Longitudinal Coverage With Evidence Development Study on Micra Leadless Pacemakers (Micra CED) is a continuously enrolling observational cohort study evaluating complications, utilization, and outcomes of leadless VVI pacemakers in the US Medicare fee-for-service population. Patients implanted between March 9, 2017, and December 1, 2018, were identified and included. All Medicare patients implanted with leadless VVI and transvenous VVI pacemakers during the study period were enrolled. Patients with less than 12 months of continuous enrollment in Medicare prior to leadless VVI or transvenous VVI implant and with evidence of a prior cardiovascular implantable electronic device were excluded, leaving 5746 patients with leadless VVI pacemakers and 9662 patients with transvenous VVI pacemakers. Data were analyzed from May 2018 to April 2021. Medicare patients implanted with leadless VVI pacemakers or transvenous VVI pacemakers. The main outcomes were acute (30-day) complications and 6-month complications. Of 15 408 patients, 6701 (43.5%) were female, and the mean (SD) age was 81.0 (8.7) years. Compared with patients with transvenous VVI pacemakers, patients with leadless VVI pacemakers were more likely to have end-stage kidney disease (690 [12.0%] vs 226 [2.3%]; P < .001) and a higher mean (SD) Charlson Comorbidity Index score (5.1 [3.4] vs 4.6 [3.0]; P < .001). The unadjusted acute complication rate was higher in patients with leadless VVI pacemakers relative to transvenous VVI pacemakers (484 of 5746 [8.4%] vs 707 of 9662 [7.3%]; P = .02). However, there was no significant difference in overall acute complication rates following adjustment for patient characteristics (7.7% vs 7.4%; risk difference, 0.3; 95% CI, -0.6 to 1.3; P = .49). Pericardial effusion and/or perforation within 30 days was significantly higher among patients with leadless VVI pacemakers compared with patients with transvenous VVI pacemakers in both unadjusted and adjusted models (unadjusted, 47 of 5746 [0.8%] vs 38 of 9662 [0.4%]; P < .001; adjusted, 0.8% vs 0.4%; risk difference, 0.4; 95% CI, 0.1 to 0.7; P = .004). Patients implanted with leadless VVI pacemakers had a lower rate of 6-month complications compared with patients implanted with transvenous VVI pacemakers (unadjusted hazard ratio, 0.84; 95% CI, 0.68-1.03; P = .10; adjusted hazard ratio, 0.77; 95% CI, 0.62-0.96; P = .02). In this study, despite significant differences in patient characteristics, patients in whom a leadless pacemaker was implanted were observed to have higher rates of pericardial effusion and/or perforation but lower rates of other device-related complications and requirements for device revision at 6 months. Understanding the benefits and risks associated with leadless VVI pacemakers compared with transvenous VVI pacemakers can help clinicians and patients make informed treatment decisions.

Prevalence and predictors of pacing-induced cardiomyopathy in young adult patients (

Clinical trials and observational studies of pacing-induced cardiomyopathy (PICM) have largely included elderly patients with mean age >70 years. The prevalence and predictors of PICM in younger patients (age < 60 years) after pacemaker implantation are not known. Adults (18-59 years) who received single-chamber ventricular or dual-chamber pacemakers at Vanderbilt University Medical Center from 1986 to 2015 were included. Patients without documented ventricular pacing burden and patients with baseline left ventricular ejection fraction (LVEF) <35% were excluded. PICM was defined as LVEF decrease of ≥ 10% and LVEF < 50% during follow-up with right ventricular pacing ≥20%, and without alternative explanations for cardiomyopathy. A total of 325 patients were included in the study. During a median follow-up duration of 11.5 (Interquartile range 7-17) years, 38 patients (11.7%) developed PICM (1.3 per 100 patient-year). Older age (HR 2.5 for age ≥50 years, p = .013), reduced baseline LVEF (HR 2.4, p = .022), and preimplant AVB (HR 2.7, p = .007) were associated with an increased risk of PICM in the multivariate analysis. Furthermore, baseline AF conferred an increased risk of PICM only in patients without preimplant AVB but not patients with pre-implant AVB. The incidence of PICM in young patients was low, but PICM could occur more than a decade after pacemaker implantation. Older age, baseline reduced LVEF, and preimplant AVB were associated with an increased risk of PICM in the young patient cohort.

Caractéristiques et évolution des complications de la stimulation cardiaque dans un centre de cardiologie de l’Afrique de Subsaharienne

Aim of the studyThe working environment and the low rate of pacemaker insertions increase the risk of complications in sub-Saharan Africa. The objective of our work was to assess the impact of specific preventive measures on these complications over the long term. Patient and MethodsWe conducted a retrospective study of all pacemaker implantations from June 2006 to June 2016 at the Abidjan Heart Institute. We evaluated the incidence of pacemaker complications, their risks factors and their impact on the overall prognosis of patients. ResultsThree hundred and two procedures were performed in 286 patients (49% male, mean age: 67±12 years), with a predominance of primary implantation (82.8%) of single-chamber ventricular pacemakers (66.6%). Twenty-five major complications (8.27%) and 14 minor (4.6%) occurred with a predominance of lead displacements (3.64%). The major complications were favored by the subclavian approach (P=0.018; OR=2.34; 95% CI [1.16–4.75]) and intraoperative incidents (P=0.02; OR=2.17; 95% CI [1.16–4.75]. The preventive measures taken made it possible to achieve a significant (P=0.017) and linear (P=0.009) reduction of these complications, with no effect the patients prognosis (Log-Rank=0.217; P=0.64). ConclusionQuality cardiac stimulation is possible in Sub-Saharan Africa with preventive measures adapted to the environment.

Comparative study between effects of single and dual chamber pacemaker on stroke volume, cardiac output and strain using 3D echocardiography, pulsed Doppler method and global longitudinal strain (GLS)

Abstract Background Dual-chamber cardiac pacing is thought to deliver higher clinical benefits as compared with single-chamber ventricular pacing. During the last two decades, 3D-echocardiography developed from a sophisticated, time-consuming method preferably used as a scientific tool towards a routine clinical approach. At present, available evidence suggested that 3D echocardiography provided improved accuracy and reproducibility over 2D methods for LV volume and function calculation. It was also more useful for early detection of volumetric changes associated with changes in cardiac hemodynamics. Methods This was an observational study of fifty consecutive patients without structural heart disease and preserved ejection fraction (EF&amp;gt;50%) presented with high grade atrioventricular block for permanent pacemaker implantation. They were assigned to receive a single-chamber ventricular pacemaker (23patients) or a dual-chamber pacemaker (27 patients). Stroke volume and cardiac output was assessed by full volume 3D echo and pulsed wave Doppler before implantation, at one-week and 6-months after implantation. For the Doppler method, LVOT diameter was measured for each patient at baseline and same value was used at follow up to avoid any confounding factors. GLS was measured at all visits. Results At one-week post pacing, both groups showed a significant decrease in SV due to a drop in EDV while ESV did not change significantly. There was a significant increase in cardiac output (COP) more in dual-chamber pacing group than in the group with single-chamber pacing. However, there were no significant differences between both groups regarding stroke volume (SV), end-systolic volume (ESV), end-diastolic volume (EDV) or ejection fraction (EF) during all time intervals (pre-pacing, at one-week and 6-months post pacing). GLS showed equal decrease in both groups. At 6 months, SV continued to decrease, and COP showed significant decrease. This drop in SV and COP was due to a significant increase in ESV while EDV did not show significant change at 6-month follow up. There was no significant difference between full volume 3D and Doppler methods regarding SV and COP values at all time intervals in both groups. GLS showed additional equal decrease in both groups. Conclusion Dual chamber pacing provided higher COP than single chamber pacing. This is due to pacing at higher heart rates, not due to increase in SV by maintaining atrioventricular synchrony. It was shown in both experimental and clinical studies that RV pacing leads to ventricular dyssynchrony, similar to that of left bundle branch block with subsequent electrical, mechanical and anatomical changes leading to detrimental effects on left ventricular structure and function. Both groups showed significant drop in GLS plus SV, COP and EF at 6-months due to significant increase in ESV. 2D echocardiography and Doppler method were not inferior to 3D echocardiography regarding calculation of SV and COP. Haemodynamics of single &amp; dual pacing Funding Acknowledgement Type of funding source: None

Spanish Pacemaker Registry. 17th Official Report of the Section on Cardiac Pacing of the Spanish Society of Cardiology (2019)

Introduction and objectivesThis report describes Spanish cardiac pacing activity during 2019: quantities and types of devices and demographic and clinical factors. MethodsThe analysis is based on data obtained from the European Pacemaker Patient Identification Card, data submitted to the online platform cardiodispositivos.es, and supplier-reported data on the total number of implanted pacemakers. ResultsInformation was received on 15 833 procedures from 102 implantation centers, representing 39% of the estimated total activity. The implantation rates of conventional and resynchronization pacemakers were 832 and 32 units per million population, respectively. A total of 431 leadless pacemakers were implanted. Most implantations were performed in elderly patients (mean age, 78.7 years). Most electrodes were bipolar and with active fixation and 34.1% were magnetic resonance imaging-compatible. Atrioventricular block was the most common electrocardiographic abnormality. Dual-chamber sequential pacing predominated; nonetheless, up to 20% of patients in sinus rhythm received a single-chamber ventricular pacemaker, mainly those older than 80 years of age and women. Remote monitoring capability was present in 41% of cardiac resynchronization therapy pacemakers and in 14.8% of conventional pacemakers. ConclusionsConsumption of pacing generators increased by 1.6%, mainly due to a 15.1% increase in cardiac resynchronization therapy pacemakers. Sequential pacing predominates; its use is influenced by age and sex. Remote monitoring increased by 20.6% in cardiac resynchronization therapy pacemakers and continues to be scarce in conventional pacemakers.

Registro Español de Marcapasos. XVII Informe Oficial de la Sección de Estimulación Cardiaca de la Sociedad Española de Cardiología (2019)

Introduction and objectivesThis report describes Spanish cardiac pacing activity during 2019: quantities and types of devices and demographic and clinical factors. MethodsThe analysis is based on data obtained from the European Pacemaker Patient Identification Card, data submitted to the online platform cardiodispositivos.es, and supplier-reported data on the total number of implanted pacemakers. ResultsInformation was received on 15 833 procedures from 102 implantation centers, representing 39% of the estimated total activity. The implantation rates of conventional and resynchronization pacemakers were 832 and 32 units per million population, respectively. A total of 431 leadless pacemakers were implanted. Most implantations were performed in elderly patients (mean age, 78.7 years). Most electrodes were bipolar and with active fixation and 34.1% were magnetic resonance imaging-compatible. Atrioventricular block was the most common electrocardiographic abnormality. Dual-chamber sequential pacing predominated; nonetheless, up to 20% of patients in sinus rhythm received a single-chamber ventricular pacemaker, mainly those older than 80 years of age and women. Remote monitoring capability was present in 41% of cardiac resynchronization therapy pacemakers and in 14.8% of conventional pacemakers. ConclusionsConsumption of pacing generators increased by 1.6%, mainly due to a 15.1% increase in cardiac resynchronization therapy pacemakers. Sequential pacing predominates; its use is influenced by age and sex. Remote monitoring increased by 20.6% in cardiac resynchronization therapy pacemakers and continues to be scarce in conventional pacemakers.

Leadless cardiac pacing in resource limited settings: A Groote Schuur hospital experience with the Micra leadless pacemaker

Background: Cardiac pacemakers improve survival and quality of life in patients with atrioventricular (AV) block. However, conventional pacemakers carry a small risk of both acute and chronic lead and pacemaker generator complications. Leadless pacemakers negate these risks by not having a pacing lead and a subcutaneous generator. We report our Groote Schuur Hospital experience with the Medtronic Micra transcatheter pacing system (TPS). Methods: We report a consecutive case series of patients that received the Micra leadless pacemaker. The Micra transcatheter pacemaker, a single chamber ventricular pacemaker, is inserted using a TPS via the femoral vein into the right ventricle. Implantation data were obtained, and medical records were reviewed for the 6 weeks and 1-year follow-up visits. Results: A total of 5 patients were implanted with a Micra leadless pacemaker from 11 March 2015 - 2 November 2016. Four patients were male and 1 female, with an average age of 64 years. Four patients received the pacemaker for a second- or third-degree AV block and 1 patient received the pacemaker for unexplained syncope and right bundle branch block. The Micra leadless pacemaker was successfully implanted in all patients with no acute implantationrelated complications. One-year follow-up was available for 4 patients with good pacing thresholds, sensitivity and impedance. One patient demised after 9 months post Micra implantation due to unrelated causes (acute myeloid leukaemia). Conclusion: The Micra leadless pacing system is safe and effective and shows good short-term results in a real-world, resource-limited setting. This form of pacing offers a viable option for patients who require pacing for AV block, especially in patients with vascular access problems or who are at high risk of lead or pacemaker generator complications.

Reversal of Pacing-Induced Cardiomyopathy Following CardiacResynchronization Therapy.

This study sought to determine the extent, time course, and predictors of improvement following cardiac resynchronization therapy (CRT) upgrade among pacing-induced cardiomyopathy (PICM) patients. PICM is an important cause of heart failure in patients exposed to frequent right ventricular (RV) pacing. CRT may reverse PICM. We retrospectively studied 1,279 consecutive patients undergoing CRT procedures between 2003 and 2016.Patients undergoing CRT upgrade from a dual-chamber or single-chamber ventricular pacemaker for PICM wereincluded. PICM was defined as decrease of≥10% in left ventricular ejection fraction (LVEF), resulting in LVEF <50% among patients experiencing≥20% RV pacing without an alternative cause of cardiomyopathy. Severe PICM was defined as pre-upgrade LVEF ≤35%. Clinical, electrocardiographic, and echocardiographic characteristics associated withboth the extent of LVEF recovery and with post-upgrade LVEF of >35% among those with severe PICM were identified. Of 69 PICM patients, LVEF improved from 29.3% to 45.3% over a median 7.0 months. Of 54 patients with severe PICM, 39 (72.2%) improved to LVEF >35% over a median 7.0 months. Most improvement occurred within thefirst3 months, although improvement continued over the remainder of the first year. In linear regression, narrowernative QRS was associated with greater LVEF improvement following CRT upgrade (+2.00% per 10-ms decrease; p=0.05). CRT is highly efficacious in reversing PICM, with 72% of severe PICM patients achieving LVEF>35%and most of the improvement occurring within 1 year. These data support initial upgrade to a CRT pacemakerwithconsideration of further upgrade to CRT defibrillator after 1 year if LVEF remains ≤35%.

Longer Paced QRS Duration is Associated With Increased Prevalence of Right Ventricular Pacing-Induced Cardiomyopathy.

Pacing-induced cardiomyopathy (PICM) is an important cause of heart failure in patients exposed to frequent right ventricular (RV) pacing. While echocardiography is diagnostic, the optimal surveillance strategy remains unknown. We sought to identify clinical and electrocardiographic factors associated with the presence of PICM to guide further testing. We retrospectively studied 1,750 consecutive patients undergoing pacemaker implantation 2003-2012. Patients were included if baseline LVEF was normal, single chamber ventricular or dual chamber pacemaker (but not ICD or cardiac resynchronization therapy device) was implanted, frequent (≥20%) RV pacing was present and repeat echocardiogram was available following implantation. PICM was defined as ≥10% decrease in LVEF, resulting in LVEF <50%. Patients with alternative causes of cardiomyopathy were excluded. Clinical and electrocardiographic indicators of PICM were identified using multivariate logistic regression. Of 184 patients meeting study criteria, 42 (22.8%) developed PICM, with decrease in mean LVEF from 62.1% to 35.3% over mean follow-up 2.5 years. Longer follow-up paced QRS duration was associated with the presence of PICM (multivariate odds ratio 1.34 per 10 millisecond increase, 95% CI 1.06-1.63, p = 0.01). Paced QRS duration ≥150 milliseconds was 95% sensitive for PICM. Only half of patients with PICM had heart failure signs or symptoms at the time of echocardiographic diagnosis. Patients with frequent RV pacing and paced QRS duration ≥150 milliseconds should be screened by echocardiogram to assess for PICM. Patients with paced QRS duration <150 milliseconds likely do not require screening, in the absence of heart failure signs or symptoms.

Twenty-Seven Years Experience With Transvenous Pacemaker Implantation in Children Weighing

Epicardial pacemaker implantation is the favored approach in children weighing <10 kg in many units. The high incidence of premature failure and fractures with earlier epicardial leads led our unit to undertake transvenous pacemaker implantation in neonates and infants from 1987. To date there have been no long-term follow-up reports of what is for many a controversial strategy. Between 1987 and 2003, 37 neonates and infants-median age 6.7 months (1 day to 3 years) and median weight 4.6 kg (2.7-10 kg)-had a permanent transvenous pacing system implanted. Pacing leads were placed into the right ventricular apex/outflow tract through a subclavian vein puncture with a redundant loop in the atrium. Three patients were lost to follow-up, 4 patients died from complications of cardiac surgery, and 2 patients had their system removed. At long-term follow-up in 28 patients at a median of 17.2 (range, 11.2-27.4) years, 10 patients have a single chamber ventricular pacemaker, 14 a dual chamber pacemaker, 3 a biventricular pacemaker, and 1 has a single chamber implantable cardioverter defibrillator. Subclavian vein patency was assessed in 26 patients. The overall subclavian vein occlusion rate was 10 of 13 (77%) <5 kg and 2 of 13 (15%) >5 kg during long-term follow-up. After a median of 14.3 (range, 13.4-17.6) years of pacing, 7 patients continue with their original lead. Transvenous pacing in infants <10 kg results in encouraging short- and long-term clinical outcomes. Subclavian vein occlusion remains an important complication, occurring predominantly in those weighing <5 kg.

Efficacy of rate modulators in children with single-chamber pacemakers

Background: Pacemaker implantation is a well-approved method for certain bradyarrhythmias. In children with single-chamber pacemakers, and in those with sinus node dysfunctions, there are no intrinsic mechanisms for rate modulation. Rather, rate modulators serve to provide the required rate. Objectives: The aim of this study was to assess the efficacy of pacemaker rate modulators in children. Patients and Methods: Twenty pacemaker-dependent children with single-chamber ventricular pacemakers were compared with the same number of children of the same age range without pacemakers. Efficacy of the rate modulators was assessed with treadmill exercise testing and compared with controls. Basal heart rates, exercise tolerance, maximal heart rates, and rate change slopes were studied. Results: Basal heart rates, maximal heart rates, and exercise tolerance were significantly lower in the children with pacemakers. Age, sex, and body mass index had no effect on the heart rate slope during the exercise test. There was no significant difference between epicardial and endocardial pacemakers. Conclusions: In the children in this study, pacemaker accelerometers failed to meet physiological demands.