Left Ventricular Pacing Threshold Research Articles

Efficacy and safety of novel left ventricular pacing leads: 1-year analysis of the NAVIGATOR trial.

Assess safety and performance of novel quadripolar preshaped left ventricular (LV) leads: NAVIGO 4LV 2D ('S shaped') and NAVIGO 4LV ARC ('U shaped'). Patients indicated for cardiac resynchronisation therapy were enrolled in a multicentre, prospective, controlled study (NAVIGATOR, NCT03279484). Patients were implanted with either a NAVIGO 4LV 2D or ARC lead, and assessed at 10 weeks, 6, 12 and 24 months post-implant. Co-primary safety and performance endpoints were assessed at 10 weeks. Safety endpoint was the patients' rate free from lead-related complications. Performance endpoint was the rate of patients with successful lead performance, defined as LV pacing threshold ≤2.5 V at 0.5 ms on at least one pacing vector, and the absence of phrenic nerve stimulation at the final programmed configuration. Lead-related complications and electrical parameters were monitored throughout study. A NAVIGO 4LV lead was successfully implanted in 211 out of 217 patients (97.2%). The safety endpoint was met, with 100% and 96.1% of patients free from complications for NAVIGO 4LV 2D and ARC, respectively. The performance endpoint was met with 98.1% and 98.9% of patients with a successful lead performance for NAVIGO 4LV 2D and ARC, respectively. Over 12 months, the global complication-free rate for both leads was 97.1% (95% CI: 93.71% to 98.70%), with a mean pacing capture threshold of 1.23 V±0.73 V and a mean impedance of 951 Ω±300.1 Ω. A high implantation success rate and low complication rate was reported for the novel NAVIGO 4LV 2D and ARC leads, along with successful performance up to 12 months.

Safety and efficacy of His-Purkinje system pacing in the treatment of patients with atrial fibrillation and heart failure: a systematic review and meta-analysis.

To evaluate the safety and efficacy of the His-Purkinje system pacing (HPCSP) in the treatment of individuals with atrial fibrillation (AF) complicated by heart failure (HF). The PubMed, Cochrane Library, Web of Science, and Embase databases were searched through September 1, 2022. The literature was initially screened based on the inclusion and exclusion criteria. The baseline characteristics of the subjects, implantation success rate, New York Heart Association (NYHA) classification, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDd), QRS duration, pacing threshold, and impedance were extracted and summarized; statistical analysis was performed using RevMan 5.3 software. In all, 22 articles were included, involving 1,445 patients. Compared to biventricular pacing (BiVP), HPCSP resulted in improved cardiac function, including increased ejection fraction (MD = 5.69, 95% CI: 0.78-10.60, P = 0.02) and decreased LVEDd (MD = -3.50, 95% CI: -7.05-0.05, P = 0.05). It was also correlated with shorter QRS duration (MD = -38.30, 95% CI: -60.71--15.88, P < 0.01) and reduced all-cause mortality and rehospitalization events (RR = 0.72, 95% CI: 0.57-0.91, P < 0.01) in patients. Left bundle branch pacing (LBBP) lowered the pacing threshold (MD = 0.47; 95% CI: 0.25-0.69; P < 0.01), and there was no statistical difference in the rate of endpoint events when comparing these two physiologic pacing modalities (RR = 1.56, 95% CI: 0.87-2.80, P = 0.14). The safety and efficacy of HPCSP in patients with AF and HF were verified in this meta-analysis. HPCSP can reverse cardiac remodeling and has great clinical application value. Relatively speaking, His-bundle pacing (HBP) can maintain better ventricular electro-mechanical synchronization, and the pacing parameters of LBBP are more stable. PROSPERO (CRD42022336109).

Thoracoscopic Implantation of Epicardial Left Ventricular Lead for Cardiac Resynchronization Therapy.

(1) Background: Limited data exist on the safety and efficacy of epicardial left ventricular (LV) lead placement using video-assisted thoracoscopic surgery (VATS) for cardiac resynchronization therapy (CRT). (2) Methods: Acute and post-discharge outcomes of CRT were compared between patients with epicardial LV leads (Epicardial-LV group, n = 13) and those with endocardial LV leads (Endocardial-LV group, n = 243). (3) Results: Epicardial LV leads were implanted via VATS alone (n = 8) or along with mini-thoracotomy (n = 5), for failed endocardial implantation (n = 11) or recurrent lead dislodgement (n = 2). All epicardial procedures under general anesthesia with one-lung ventilation were successfully completed in 1.0 ± 0.4 h without phrenic nerve stimulation. LV pacing thresholds in the epicardial-LV (1.5 ± 1.0 V) and endocardial-LV (1.3 ± 0.8 V) were comparable (p = 0.651). All patients were discharged alive post-VATS 8.8 ± 3.9 days. During the follow-up (34.3 ± 28.6 months), all patients with epicardial LV leads stayed alive except for one cardiac death post-CRT 14 months and one heart transplantation post-CRT 30 months. All epicardial LV leads maintained stable performance without dislodgement/significant changes in pacing threshold/impedance. LV lead dislodgement occurred only in endocardial-LV (7/243, 2.9%). Efficacy in both groups was comparable in terms of QRS narrowing, increase in LV ejection fraction, and survival free of cardiac death, or heart-failure-related hospitalization. (4) Conclusions: Epicardial LV lead placement using VATS can be a safe and effective alternative to endocardial implantation, with comparable acute and post-discharge outcomes achieved by both approaches.

Long-term performance of left ventricular leads in cardiac resynchronisation therapy.

Cardiac resynchronisation therapy (CRT) confers symptomatic and survival benefits in chronic heart failure with reduced ejection fraction (HFrEF). There remains a paucity of data on long-term performance of left ventricular (LV) leads, particularly with newer quadripolar lead designs. This single-centre study utilised an electronic, outpatient HFrEF database to identify CRT recipients (2008-2014). The primary endpoint was temporal trend in LV pacing thresholds during follow-up. Secondary outcomes were complications relating to acute or chronic lead failure and device-related infections. Two hundred eighty patients were included, with mean (±SD) age of 74.2 years (±9.0) and median follow-up of 7.6 years (interquartile range 4-9). Mean LV threshold was 1.37 V (±0.73) at implant and remained stable over the study period. No differences were observed based upon lead manufacturer. Compared to non-quadripolar leads (n=216), those of quadripolar designs (n=64) had a lower threshold at 6 months (1.20 vs 1.37 V; P=.04) and at the end of the study period (1.32 vs 1.46 V; P=.04). Patients with HFrEF of ischaemic aetiology had higher thresholds at implant (1.46 vs 1.34 V; P=.05), and this persisted until the end of follow-up (1.49 vs 1.34 V; P=.03). There was low incidence of acute (0.71%; 2/280) and chronic lead failure (1.79%; 5/280), with four cases (1.43%) of device infection. LV leads in the context of CRT have excellent chronic stability and low rates of adverse events. Those with newer quadripolar lead designs have lower thresholds at initial follow-up and in the longer term.

P1236Revealing cardiac mechanics with CMR whilst CRT is active: the first step

Abstract Introduction Cardiac resynchronisation therapy (CRT) is a routine treatment for heart failure with reduced ejection fraction and conduction delay to improve symptoms and prognosis. Technological advancements both in cardiac magnetic resonance (CMR) and devices (MRI-conditional modes) now enable investigation of the haemodynamic response to CRT over a range of heart rates. Methods Patients with a CRT-D device were enrolled from heart failure clinics at a single tertiary centre. A complete device system assessment and baseline device check was conducted to ensure MRI compatibility and suitability. Left ventricular (LV) volumes and systolic blood pressure were measured at baseline and heart rates of 75, 90, 100, 115, 125, and 140 bpm (randomised order) with CRT active and intrinsic conduction (AOO). MRI conditional mode parameters were replicated through standard parameter modification to ensure biventricular pacing during CRT active scans. All scans were conducted using a 3.0 T Siemens Prisma MRI scanner with analysis on commercially available software. Contractility was derived from the systolic blood pressure and left ventricular end systolic volume. A post scan device and lead assessment was conducted to assess for scanning safety. Results Scanning was conducted in 22 patients (safety cohort). Post scan battery voltage reduced by 2.9±1.0%. Mean change in atrial, right ventricular and left ventricular lead impedance was 0.5±0.06%, 3.0±0.04% and −1.7±0.05% respectively. Mean change in atrial, right ventricular and left ventricular pacing threshold was 0.0±0.3%, 8.3±0.3% and 5.6±0.3%. No patient experienced symptoms related to scanning or device failure. Preliminary data for patients with CRT on and off have been analysed (paired analysis cohort, n=8, 6 men). Mean age was 71.1±8.2, aetiology was primarily ischaemic (62.5%) with the remainder dilated cardiomyopathy. The mean LV ejection fraction at baseline was 29.4±12.9%. Biventricular pacing led to acute improvements in ejection fraction (p=0.005), left ventricular cardiac output (p&lt;0.0001) and contractility (p=0.05) over the entire range of heart rates studied. We also noted an improvement in the force frequency relationship during biventricular pacing with a higher peak contractility (p=0.05), a higher heart rate at which this occurred (HR=130) and a generally up sloping relationship when compared with intrinsic conduction. Conclusion We have demonstrated for the first time, the mechanistic improvements in cardiac contractility consequent to CRT using CMR and also that MRI scans of conditional devices can be safe with CRT active. Acknowledgement/Funding Dr A Koshy is conducting a PhD supported by grant from Medtronic. Dr Klaus Witte has received honoraria from Medtronic

Impact of left ventricular pacing threshold on ventricular arrhythmia occurrence in cardiac resynchronization therapy

BackgroundCardiac resynchronization therapy (CRT) is an established heart failure (HF) treatment option, however its effect on ventricular arrhythmias (VAs) is controversial. Regional scar burden and high left ventricular (LV) pacing threshold (PT) are associated with poor outcome in CRT patients. The aim of our study was to analyze the impact of intraoperative LVPT on VA occurrence. MethodsEighty consecutive patients with advanced HF scheduled for a CRT defibrillator device [aged 63.3±10.9 years; New York Heart Association II–III 86.2%; 52 males (65%); 34 ischemic etiology (42.5%); 71 sinus rhythm (88.7%); QRS duration 168±25.7ms] were evaluated using single-photon emission computed tomography myocardial perfusion imaging. Regional myocardial viability was calculated as the mean tracer activity in the corresponding segments at the LV lead pacing site. Fluoroscopic position and intraoperative LVPT were determined at implant after the final LV lead position was determined. ResultsLVPT was inversely associated with regional myocardial viability (ρ −0.785, p<0.001). After a median follow-up of 36 months (24–57) months VAs were registered in 27 patients (33.7%). Patients with VAs had higher median intraoperative LVPT compared to those without VAs [2.2V (1.9–2.8) vs. 0.8V (0.6–1.2), p<0.001]. In a multivariate logistic regression model intraoperative LVPT was identified as a strong independent predictor of VAs. ConclusionIncreased intraoperative LVPT during CRT could be associated with lower regional myocardial viability at LV lead location. CRT patients with higher LVPT could have an increased risk of VA occurrence.

Bipolar active fixation left ventricular lead or quadripolar passive fixation lead? An Italian multicenter experience.

About one-third of patients receiving cardiac resynchronization therapy (CRT) are not responders, due to either patient selection or technical issues. Left ventricular quadripolar passive fixation leads (QPL) and bipolar active fixation (BAF) leads have been designed to ensure a targeted left ventricular stimulation area, minimizing lead dislodgments and phrenic nerve stimulation (PNS). The aim was to compare real-world safety and efficacy of BAF (Attain Stability, Medtronic Plc.) and QPL (Attain Performa, Medtronic Plc.). We performed a retrospective analysis examining procedural and follow-up data of 261 BAF and 124 QPL (programmed to single-site left ventricular pacing), included in the ClinicalService project from 16 Italian hospitals. At median follow-up of 12 months, no difference in left ventricular pacing threshold was recorded between BAF and QPL (1.3 ± 0.9 V @0.4 ms vs. 1.3 ± 1.0 V @0.4 ms; P = 0.749). Total left ventricular lead dislodgement rate was 1.43/100 patient-years in BAF vs. 2.9/100 patient-years in QPL (P = 0.583). However, no dislodgements occurred among BAF after hospital discharge. Events requiring repeated surgery or permanently turning CRT off occurred in 0.8% of BAF, as compared with 4.0% of QPL (P = 0.025). There was no difference between groups in the echo CRT responders' rate (70% of BAF and 66% of QPL; P = 0.589) or in the annual rate of heart failure hospitalization (P = 0.513). BAF resulted in noninferior clinical outcome and CRT responders' rate in comparison to QPL. Moreover, BAF ensured more precise and stable placement in cardiac veins, with comparable electrical performance and less than 1% patients with unsolved PNS.

Myocardial viability as shown by left ventricular lead pacing threshold and improved dyssynchrony by QRS narrowing predicts the response to cardiac resynchronization therapy.

Patients with advanced heart failure and dyssynchrony can benefit from cardiac resynchronization therapy (CRT). To predict the response to CRT, myocardial viability and improved dyssynchrony are suggested to be important. We retrospectively investigated 93 patients who underwent CRT implantation in Nagoya University Hospital. We assessed QRS narrowing the day after implantation to measure the improvement in dyssynchrony and measured the left ventricular pacing threshold (LVPT) to determine the local myocardial viability in all patients. Responders to CRT were defined as those having a greater than or equal to 15% decrease in left ventricular end-systolic volume by echocardiography at their 6-month follow-up. Sixty-two patients (67%) were classified as responders. The QRS width before CRT implantation, QRS narrowing after implantation, left atrial diameter, septal-to-posterior wall motion delay, left ventricular end-diastolic diameter, radial strain, and LVPT were significantly different between the responder and nonresponder groups. On multivariate analysis, QRS narrowing (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.01-1.05; P = 0.005) and LVPT (OR, 0.42; 95% CI, 0.22-0.82; P = 0.011) were independent predictors of a response to CRT. We calculated the cutoff values from the receiver operating characteristic curves as 22.5 milliseconds of QRS narrowing and 1.55 V of LVPT. The response rates in patients with both predictive factors (QRS narrowing ≥ 22.5 milliseconds and LVPT ≤ 1.55 V), one factor, and no factors were 91%, 61%, and 25%, respectively (P < 0.001). Both myocardial viability and improved electrical dyssynchrony may be essential to predict a good response to CRT.

Utility of Novel Vectors in a Quadripolar Left Ventricular Lead

Background Two complications which frequently arise with the use of cardiac resynchronization therapy (CRT) are phrenic nerve stimulation (PNS) and/or high pacing thresholds. These complications often result in costly and invasive surgical procedures required to revise an existing left ventricular (LV) lead in order to provide safe and optimal therapy. Quadripolar (QP) left ventricular leads include four electrically active rings which provide redundancy and allow the prescriber to change pacing configurations and optimize CRT delivery. This capability can also be used to resolve PNS or high pacing threshold by programming a new pacing vector, and thus provides a low-risk alternative to traditional invasive procedures. Objective The goal of this study is to evaluate the utility of seven programmable novel LV pacing vectors which utilize one or both distal rings that are unique to quadripolar LV leads. Methods The analysis was part of a multi-center, prospective, non-randomized study. Novel pacing vector data was collected during a clinic follow-up visit at 3 months post implant for subjects implanted with a BIOTRONIK Sentus QP lead in combination with a BIOTRONIK CRT-D implantable device. Novel vectors contained one or both distal LV rings (LV3 and LV4) and were evaluated via a threshold test at a pulse width of 0.4 ms. LV pacing thresholds ≤ 2.5 V at 0.4 ms were considered acceptable. Results A total of 930 subjects were successfully implanted at 76 U.S. and international sites. Of 662 subjects with available novel data at 3 months post implant, there were 509 subjects who underwent threshold testing of at least four of the seven novel pacing vectors. The percentage of subjects in this group with at least one novel vector with an acceptable LV pacing threshold was 89.2% (N=454). Table 1 provides the number and percentage of subjects for the total novel vectors with an acceptable threshold. Conclusion The results demonstrate an ability to provide alternate novel vector pacing configurations for subjects who may otherwise require an invasive procedure to resolve PNS or high pacing threshold.

Performance and clinical comparison between left ventricular quadripolar and bipolar leads in cardiac resynchronization therapy: Observational research

AimTo evaluate Attain Performa (Medtronic, Dublin, Ireland) quadripolar lead performance in clinical practice and, secondarily, to compare its long term clinical outcomes vs bipolar leads for left ventricular (LV) pacing. Methods and resultsWe retrospectively analyzed clinical, procedural and follow-up data of 215 patients implanted with a quadripolar lead. One hundred and twenty one patients implanted with bipolar lead were selected to compare long-term clinical outcomes. The quadripolar lead was implanted in the target vein in 196 patients (91%) without acute dislodgements. In 50% of patients the chosen final pacing configuration at implant would not have been available with bipolar leads. A dedicated quadripolar pacing vector was chosen more frequently when the LV tip location was apical than otherwise (65.6% vs 42.7%, p=0.003). After a median follow-up of 14 months, the LV pacing threshold was less than 2.5V at 0.4ms in 98 patients (90%) with a safety margin between phrenic nerve and LV pacing threshold >3V in 97 patients (89%). We observed a slight trend toward a lower risk of heart failure worsening and a lower incidence of ventricular arrhythmias and pulmonary congestion in patients implanted with quadripolar leads compared with the control group. ConclusionQuadripolar leads improve the management of phrenic nerve stimulation at no trade-off with pacing threshold and lead stability. Quadripolar leads seems to be associated with a lower incidence of VT/VF and pulmonary congestion, when compared with bipolar leads, but further investigations are necessary to confirm that this positive effect is associated with better LV reverse remodeling.

Transvenous versus open chest lead placement for resynchronization therapy in patients with heart failure: comparison of ventricular electromechanical synchronicity.

BackgroundTransvenous lead placement is the standard approach for left ventricular (LV) pacing in cardiac resynchronization therapy (CRT), while the open chest access epicardial lead placement is currently the most frequently used second choice. Our study aimed to compare the ventricular electromechanical synchronicity in patients with heart failure after CRT with these two different LV pacing techniques.MethodsWe enrolled 33 consecutive patients with refractory heart failure secondly to dilated cardiomyopathy who were eligible for CRT in this study. Nineteen patients received transvenous (TV group) while 14 received open chest (OP group) LV lead pacing. Intra- and inter-ventricular electromechanical synchronicity was assessed by tissue Doppler imaging (TDI) before and one year after CRT procedure.ResultsBefore CRT procedure, the mean QRS-duration, maximum time difference to systolic peak velocity among 12 left ventricle segments (LV Ts-12), standard deviation of time difference to systolic peak velocity of 12 left ventricle segments (LV Ts-SD), and inter-ventricular mechanical delay (IVMD) in OP and TV group were 166 ± 17 ms and 170 ± 21 ms, 391 ± 42 ms and 397 ± 36 ms, 144 ± 30 ms and 148 ± 22 ms, 58 ± 25 ms and 60 ± 36 ms, respectively (all P > 0.05). At one year after the CRT, the mean QRS-duration, LV Ts-12, LV Ts-SD, and IVMD in TV and OP group were 128 ± 14 ms and 141 ± 22 ms (P = 0.031), 136 ± 37 ms and 294 ± 119 ms (P = 0.023), 50 ± 22 ms and 96 ± 34 ms (P = 0.015), 27 ± 11 ms and 27 ± 26 ms (P = 0.86), respectively. The LV lead implantation procedure time was 53.4 ± 16.3 min for OP group and 136 ± 35.1 min for TV group (P = 0.016). The mean LV pacing threshold increased significantly from 1.7 ± 0.6 V/0.5 ms to 2.3 ± 1.6 V/0.5 ms (P < 0.05) in TV group while it remained stable in the OP group.ConclusionsCompared to conventional endovascular approach, open chest access of LV pacing for CRT leads to better improvement of the intraventricular synchronization.

96-66: Intraoperative left ventricular pacing threshold could be associated with regional myocardial viability and the occurrence of ventricular tachyarrhythmias in cardiac resynchronization therapy

96-66: Intraoperative left ventricular pacing threshold could be associated with regional myocardial viability and the occurrence of ventricular tachyarrhythmias in cardiac resynchronization therapy

Active fixation of a thin transvenous left-ventricular lead by a side helix facilitates targeted and stable placement in cardiac resynchronization therapy.

Suboptimal placement, phrenic nerve stimulation, and dislodgements of left-ventricular (LV) leads are main challenges in cardiac resynchronization therapy. We investigated the handling, performance, safety, and stability for a novel 4Fr LV lead with a small side helix located proximal to the ring electrode for active fixation of the LV lead. The novel LV lead was successfully implanted in 103 of 106 patients. Patients with dislodged LV leads and with demanding coronary vein anatomies were included. The lead body was rotated clockwise to engage the active fixation side helix in the vein wall. The stimulating electrode was located in basal LV segment and middle LV segment in 54 and 46% of the patients, respectively. The lead was targeted to a vein concordant to the LV segment with latest mechanical activation. Concordant LV lead placement was achieved in 73% of the patients and in adjacent segment in 24%. The average pacing capture threshold (PCT) at implantation was 1.04 ± 0.6 V (n = 103) and at an average follow-up at 7 months, the PCT remained low and no dislodgements have been observed. During follow-up, four leads have been explanted without complications. Active fixation of this 4Fr LV lead by using a side helix, offers flexibility to place the lead precisely in targeted vein segments over a wide range of vein anatomies. The average LV pacing threshold was low at implantation and follow-ups. The lead seems to be extractable and no late dislodgements have been observed.

Effectiveness and Reliability of Selected Site Pacing for Avoidance of Phrenic Nerve Stimulation in CRT Patients with Quadripolar LV Leads: The EffaceQ Study.

Cardiac resynchronization therapy (CRT) relies on sufficient left ventricular (LV) pacing with safety margin to phrenic nerve stimulation (PNS). Previous studies introduced LV vector reprogramming in bipolar coronary sinus leads to optimize LV pacing and avoid PNS. We investigated the efficacy and reliability of quadripolar leads in CRT. The EffaceQ study enrolled 344 patients with de novo CRT implantation with a quadripolar LV lead in an observational, prospective multicenter study. The study was powered to demonstrate that in at least 90% of patients with an implanted quadripolar LV lead, a viable LV pacing configuration (LVPC) is available (primary end point: LV pacing threshold ≤2.5 V/0.5 ms, sufficient PNS margin). Quadripolar leads were successfully implanted in 96% of patients. A total of 278 of 299 (93.0%) patients with complete data met the criteria for viable LVPC. With the use of traditional LVPCs, a viable LVPC would have been available (268 of 299 patients; P = 0.002) in significantly fewer patients (89.6%). In any LVPC, PNS was inducible in 65.0% of patients and 22.6% of patients reported PNS during ambulatory 3-month follow-up. LVPC reprogramming was performed in 49.8% of patients. PNS inducibility decreased from distal to proximal electrodes, whereas LV pacing thresholds increased from distal to proximal. At prehospital discharge, 5.9 ± 2.8 viable LVPCs were observed, stable during follow-up. The quadripolar electrode offered significantly more LVPC for LV optimization and PNS avoidance. Quadripolar LV leads yield high numbers of patients with viable LVPCs and alternatives for noninvasive repositioning of LV pacing.

Effect of Smaller Left Ventricular Capture Threshold Safety Margins to Improve Device Longevity in Recipients of Cardiac Resynchronization-Defibrillation Therapy

Device longevity in cardiac resynchronization therapy (CRT) is affected by the pacing capture threshold (PCT) and programmed pacing amplitude of the left ventricular (LV) pacing lead. The aims of this study were to evaluate the stability of LV pacing thresholds in a nationwide sample of CRT defibrillator recipients and to determine potential longevity improvements associated with a decrease in the LV safety margin while maintaining effective delivery of CRT. CRT defibrillator patients in the Medtronic CareLink database were eligible for inclusion. LV PCT stability was evaluated using ≥2 measurements over a 14-day period. Separately, a random sample of 7,250 patients with programmed right atrial and right ventricular amplitudes ≤2.5 V, LV thresholds ≤ 2.5 V, and LV pacing ≥90% were evaluated to estimate theoretical battery longevity improvement using LV safety margins of 0.5 and 1.5 V. Threshold stability analysis in 43,256 patients demonstrated LV PCT stability of <0.5 V in 77% of patients and <1 V in 95%. Device longevity analysis showed that the use of a 0.5-V safety margin increased average battery longevity by 0.62 years (95% confidence interval 0.61 to 0.63) compared with a safety margin of 1.5 V. Patients with LV PCTs >1 V had the greatest increases in battery life (mean increase 0.86 years, 95% confidence interval 0.85 to 0.87). In conclusion, nearly all CRT defibrillator patients had LV PCT stability <1.0 V. Decreasing the LV safety margin from 1.5 to 0.5 V provided consistent delivery of CRT for most patients and significantly improved battery longevity.

Epicardial leads in adult cardiac resynchronization therapy recipients: a study on lead performance, durability, and safety.

Transvenous left ventricular (LV) lead placement for cardiac resynchronization therapy-defibrillator (CRT-D) delivery is unsuccessful in 8% to 10% of cases. These patients might benefit from an epicardial lead. However, data on long-term epicardial lead performance are scarce. Furthermore, extracting an epicardial lead requires a rethoracotomy. The purpose of this study was to determine data on almost a decade of experience with epicardial leads and investigate the safety of partially leaving this lead in place after device infection. All adult patients receiving an epicardial lead (Medtronic CapSure Epi, model 4968) for CRT-D in the Leiden University Medical Center were included. Leads were implanted during a standalone procedure or in combination with other cardiothoracic procedures. Electrical lead parameters were assessed at implantation and every 6 months thereafter. In case of device infection the epicardial lead was cut off parasternal, just outside the thoracic cavity, leaving the distal part of the lead in place. Two-hundred sixteen patients were included with a median follow-up of 3 years (25th-75th percentile 1.0-5.5). LV pacing threshold decreased within 6 months after implantation [1.1 V (95% confidence interval [CI] 0.9-1.2) vs 0.8 V (95% CI 0.7-0.9), P = .01] and stabilized thereafter. Mean LV electrogram was 15.2 ± 7.5 mV, and average lead impedance was 633.5 ± 174.0 Ω. Five-year cumulative incidence was 1.6% for lead failure and 9.6% for device infection. The retained epicardial lead caused skin erosion in 3 patients and fistula formation in 1. This study demonstrates that epicardial LV leads have an excellent long-term performance. Partially retaining the lead after device infection was associated with a risk of reinfection with limited long-term clinical implications for the patient.

Left ventricular pacing threshold and outcome in MADIT-CRT.

High left ventricular (LV) pacing threshold (PT) may in some cases indicate the presence of scarred myocardium, a predictor of poor outcome in cardiac resynchronization therapy (CRT) treated patients. We hypothesized that intraoperative LVPT can be used to determine echocardiographic and clinical responses to CRT. The study comprised 975 patients enrolled in the CRT-D arm of the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT). Multivariate regression analysis was performed to evaluate the relationship between LVPT and percent reduction in LV end-systolic volume (ESV) and left atrial volume (LAV) 1 year after CRT. Cox proportional hazards analysis was used to evaluate the relationship between LVPT and heart failure (HF) events or death (primary endpoint) and all-cause death (secondary endpoint). An increasing LVPT was inversely related to percent reduction in both LVESV (P = 0.02) and LAV (P<0.01). Patients with LVPT in the highest quartile (>1.8 V) were less likely to achieve reverse LV remodeling (≥15% LVESV reduction from baseline) than those with LVPT in the lower quartiles (hazard ratios [HR] OR 0.56, P = 0.02). Mean percent reduction in LAV and LVESV was also significantly greater among those with lowest quartile LVPT. Multivariate analysis showed borderline significant 13% (P = 0.06) and significant 22% (P = 0.03) increase in the risk of HF/death and death alone, respectively, per 1 volt increase in LVPT. High intraoperative LVPT is associated with significantly lower echocardiographic and clinical response to CRT-D.

GW24-e1773 Application of a novel pacing guide wire in cardiac resynchronisation therapy

ObjectivesThe implantation of left ventricular (LV) lead was the most complicated process in the cardiac resynchronisation therapy (CRT), the aim of this study was to investigate the availability of a...

Short-spaced dipole for managing phrenic nerve stimulation in patients with CRT: The “phrenic nerve mapping and stimulation EP” catheter study

Phrenic nerve stimulation (PNS), occurring in 33%-37% of the patients with cardiac resynchronization therapy (CRT), is a limiting factor when implanting left ventricular (LV) leads from coronary veins. To test the hypothesis that PNS occurrence is related to bipolar electrode spacing. During standard CRT defibrillator implant procedures, a 5-F diagnostic electrophysiology catheter with 10 electrodes, spaced 2-5-2 mm, was positioned in a cardiac vein suitable for permanent LV lead placement. Pacing in the unipolar configuration identified the site with the lowest PNS threshold. PNS and left ventricular pacing (LVP) thresholds were then measured in different configurations at 0.5 ms: unipolar, each LV electrode served as the cathode in turn; and bipolar with different electrode spacing, cathode being the electrode with the lowest unipolar PNS threshold. From February to September 2010, 40 patients undergoing CRT implantation were enrolled in 4 centers in Italy. It was possible to identify PNS and perform a complete set of measurements in 23 patients. A bipolar electrode spacing of 2 mm resulted in higher PNS thresholds in bipolar configurations han did a bipolar electrode spacing of ≥ 5 mm. However, no significant increase in the LVP threshold was observed (P = ns). This experience suggests that LVP with a bipolar electrode spacing of 2 mm significantly increases the PNS threshold without affecting the LVP threshold, thereby increasing the possibility of delivering CRT when the LV lead is placed in proximity to the phrenic nerve.

Determining the Risks of Magnetic Resonance Imaging at 1.5 Tesla for Patients With Pacemakers and Implantable Cardioverter Defibrillators

Conventional pacemaker and implantable cardioverter-defibrillator product labeling currently cautions against exposure to magnetic resonance imaging (MRI). However, there is a growing clinical need for MRI, without an acceptable alternative imaging modality in many patients with cardiac devices. The purpose of this study was to determine the risk of MRI at 1.5 T for patients with cardiac devices by measuring the frequency of device failures and clinically relevant device parameter changes. Data from a single-center retrospective review of 109 patients with pacemakers and implantable cardioverter-defibrillators (the MRI group) who underwent 125 clinically indicated MRI studies were compared to data from a prospective cohort of 50 patients with cardiac devices who did not undergo MRI (the control group). In the MRI group, there were no deaths, device failures requiring generator or lead replacement, induced arrhythmias, losses of capture, or electrical reset episodes. Decreases in battery voltage of ≥0.04 V occurred in 4%, pacing threshold increases of ≥0.5 V in 3%, and pacing lead impedance changes of ≥50 Ω in 6%. Although there were statistically significant differences between the MRI and control groups for the mean change in pacing lead impedance (-6.2 ± 23.9 vs 3.0 ± 22.1 Ω) and left ventricular pacing threshold (-0.1 ± 0.3 vs 0.1 ± 0.2 V), these differences were not clinically important. In conclusion, MRI in patients with cardiac devices resulted in no device or lead failures. A small number of clinically relevant changes in device parameter measurements were noted. However, these changes were similar to those in a control group of patients who did not undergo MRI.