Left Ventricular Lead Location Research Articles

Variation in optimal hemodynamic atrio-ventricular delay of biventricular pacing with different endocardial left ventricular lead locations using precision hemodynamics.

It is not known whether the optimal atrioventricular (AVopt ) delay varies between left ventricular (LV) pacing site during endocardial biventricular pacing (BiVP) and may therefore needs consideration. We assessed the hemodynamic AVopt in patients with chronic heart failure undergoing endocardial LV lead implantation. AVopt was assessed during atrio-BiVPwith a "roving LV lead."Up to four locations were studied: mid-lateral wall, mid-septum (or a close alternative), site of greatest hemodynamic improvement, and LV lead implant site. The AVopt was compared to a fixed AV delay of 180 ms. Seventeen patients were included (12 male, aged 66.5 ± 12.8 years, ejection fraction 26 ± 7%, 16 left bundle branch block or high percentage of right ventricular pacing [RVP], QRS duration 167 ± 27 ms). In most locations (62/63), AVopt increased systolic blood pressure during BiVP compared with RVP (relative improvement 6 mmHg,interquartile range [IQR] 4-9 mmHg). Compared to a fixed AV delay, the hemodynamic improvement at AVopt was higher (1 mmHg, IQR 0.2-2.6 mmHg, p < .001). Within most patients (16/17), we observed a difference in AVopt between pacing sites (median paced AVopt 209 ms, IQR 117-250). Within this range, the hemodynamic impact of these differences was small (median loss 0.6 mmHg, IQR 0.1-2.6 mmHg). Within a patient, different endocardial LV lead locations have slightly different hemodynamic AVopt which are superior to a fixed AV delay. The hemodynamic consequence of applying an optimum from a different lead location is small.

Lateral left ventricular lead position is superior to posterior position in long-term outcome of patients underwent cardiac resynchronization therapy

Abstract Background Preferring side branch of coronary sinus during cardiac resynchronization therapy (CRT) implantation is empirical due to the limited data on the association of left ventricular (LV) lead position and long-term clinical outcome. Purpose We evaluated the long-term all-cause mortality by LV lead non-apical positions and further characterized them by interlead electrical delay (IED). Methods In our retrospective database 2087 patients were registered between 2000 and 2018. Those with non-apical LV lead locations were classified into anterior (n=108), posterior (n=643), and lateral (n=1336) groups. All-cause mortality was assessed by Kaplan-Meier and Cox analyses. Echocardiographic response was measured 6 months after CRT implantation. Results During the median follow-up time of 3.7 years, 1150 (55.1%) patients died, 710 (53.1%) with lateral, 78 (72.2%) with anterior and 362 (56.3%) with posterior positions. Patients with lateral position had significantly better outcome in all-cause mortality compared to others (HR 0.80; 95% CI: 0.71–0.90; p&amp;lt;0.0001), which was also confirmed by multivariate analysis after adjusting for relevant clinical covariates (HR 0.81; 95% CI: 0.72–0.91; p&amp;lt;0.0001). When echocardiographic response was evaluated in the lateral group, patients with an IED longer than 110 ms (ROC AUC 0.63; 95% CI: 0.53–0.73; p=0.012) showed 2.1 times higher odds of improvement in echocardiographic response 6 months after the implantation. Conclusions In this study we proved that after CRT implantation only the lateral LV lead location was associated with long-term mortality benefit. Moreover, patients with this position showed the greatest echocardiographic response over 110 ms IED. Survival of total patient cohort Funding Acknowledgement Type of funding source: None

Lateral left ventricular lead position is superior to posterior position in long-term outcome of patients who underwent cardiac resynchronization therapy.

AimsPreferring side branch of coronary sinus during cardiac resynchronization therapy (CRT) implantation has been empirical due to the limited data on the association of left ventricular (LV) lead position and long‐term clinical outcome. We evaluated the long‐term all‐cause mortality by LV lead non‐apical positions and further characterized them by interlead electrical delay (IED).Methods and resultsIn our retrospective database, 2087 patients who underwent CRT implantation were registered between 2000 and 2018. Those with non‐apical LV lead locations were classified into anterior (n = 108), posterior (n = 643), and lateral (n = 1336) groups. All‐cause mortality was assessed by Kaplan–Meier and Cox analyses. Echocardiographic response was measured 6 months after CRT implantation. During the median follow‐up time of 3.7 years, 1150 (55.1%) patients died—710 (53.1%) with lateral, 78 (72.2%) with anterior, and 362 (56.3%) with posterior positions. When we investigated the risk of all‐cause mortality, there was a significantly lower rate of death in patients with lateral LV lead location when compared with those with an anterior (P < 0.01) or posterior (P < 0.01) position. Multivariate analysis after adjustment for relevant clinical covariates such as age, sex, ischaemic aetiology, left bundle branch block morphology, atrial fibrillation, and device type revealed consistent results that lateral position is associated with a significant risk reduction of all‐cause mortality when compared with anterior [hazard ratio 0.69; 95% confidence interval (CI) 0.55–0.87; P < 0.01] or posterior (hazard ratio 0.84; 95% CI 0.74–0.96; P < 0.01) position. When echocardiographic response was evaluated within the lateral group, patients with an IED longer than 110 ms (area under the receiver operating characteristic curve, 0.63; 95% CI 0.53–0.73; P = 0.012) showed 2.1 times higher odds of improvement in echocardiographic response 6 months after the implantation.ConclusionsIn this study, we proved in a real‐world patient population that after CRT implantation, lateral LV lead location was associated with long‐term mortality benefit and is superior to both anterior and posterior positions. Moreover, patients with this position showed the greatest echocardiographic response over 110 ms IED.

40Lateral left ventricular lead position and long interlead electrical delay predict long-term all-cause mortality in cardiac resynchronization therapy patients

Abstract Background There is limited data on the association of left ventricular (LV) lead position and long-term clinical outcome in patients after cardiac resynchronization therapy (CRT). Purpose We evaluated the mid-term echocardiographic response and long-term all-cause mortality of patients who underwent CRT implantation by LV lead non-apical positions and further characterized them by right to left ventricular, interlead electrical delay (IED). Methods In our retrospective registry patients after CRT implantation between 2000 and 2018 were registered. Those with non-apical LV lead location were classified into anterior (n = 111), posterior (n = 652), and lateral (n = 1373) positions. Primary endpoint was all-cause mortality assessed by univariate- and Cox multivariate analyses. Secondary endpoint was echocardiographic response within 6 months after CRT implantation. Results From 2136 patients 1180 (55.2%) reached the primary endpoint during the mean follow up time of 4.5 years. Univariate analysis showed patients with lateral position had significantly better outcome compared to others (HR 0.80; 95% CI: 0.71-0.90; p &amp;lt; 0.01), which was also confirmed by Cox multivariate analysis (HR 0.69; 95% CI: 0.50-0.93; p = 0.02) after adjusting for relevant clinical covariates such as IED and LBBB. The median value of IED was 106 (89/124) ms in the total patient cohort, which was significantly longer in the lateral group [anterior 80 (60/100) ms vs. lateral 110 (91/128) ms vs. posterior 100 (85/120) ms; p&amp;lt; 0.01]. When echocardiographic response was further evaluated in patients with lateral position, those with an IED longer than 110 ms (ROC AUC 0.64, 95% CI: 0.54-0.74; p = 0.01) showed the greatest benefit within 6 months. Conclusions After CRT implantation the most beneficial outcome was associated with lateral left ventricular lead location, moreover the greatest echocardiographic response was found when interlead electrical delay was longer than 110 ms in this group. Abstract Figure. All-cause mortality of total cohort

A new method to recommend left ventricular lead positions for improved CRT volumetric response and long-term prognosis

ObjectivesUsing ECG-gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), we sought to develop and validate a new method to recommend left ventricular (LV) lead positions in order to improve volumetric response and long-term prognosis after cardiac resynchronization therapy (CRT). MethodsSeventy-nine patients received gated SPECT MPI at baseline, and echocardiography at baseline and follow-up. The volumetric response referred to a reduction of ≥ 15% in LV end-systolic volume 6 months after CRT. After excluding apical, septal, and scarred segments, there were three levels of recommended segments: (1) the optimal recommendation: the latest contracting viable segment; (2) the 2nd recommendation: the late contracting viable segments whose contraction delays were within 10° of the optimal recommendation; and (3) the 3rd recommendation: the viable segments adjacent to the optimal recommendation when there was no late contracting viable segment. ResultsAfter excluding 11 patients whose LV lead was placed in apical or scarred segments, 75.6% of the patients concordant to recommended LV segments (n = 41) responded to CRT while 51.9% of those with non-recommended LV lead locations (n = 27) were responders (P = .043). Response rates were 76.9%, 76.9%, and 73.3% (P = .967), respectively, when LV lead was implanted in the optimal recommendation (n = 13), the 2nd recommendation (n = 13), and the 3rd recommendation (n = 15). LV leads placed at recommended segments reduced composite events of all-cause mortality or heart failure (HF) rehospitalization compared with pacing at non-recommended segments (log-rank χ2 = 5.623, P = .018). ConclusionsPacing in the recommended LV lead segments identified on gated SPECT MPI was associated with improved volumetric response to CRT and long-term prognosis.

Influence of the Right Ventricular Lead Location on Ventricular Arrhythmias in Cardiac Resynchronization Therapy.

Background:The influence of different right ventricular lead locations on ventricular arrhythmias (VTA) in patients with a cardiac resynchronization therapy (CRT) is not clear. This study aimed to evaluate the influence on VTA in patients with a CRT when right ventricular lead was positioned at the right ventricular middle septum (RVMS) and the right ventricular apical (RVA).Methods:A total of 352 patients implanted with a CRT-defibrillator (CRT-D) between May 2012 and July 2016 in the Department of Cardiology of Anhui Provincial Hospital were included. Two-year clinical and pacemaker follow-up data were collected to evaluate the influence of the right ventricular lead location on VTA. Patients were divided into the RVMS group (n = 155) and the RVA group (n = 197) based on the right ventricular lead position. The VTA were compared between these two groups using a Kaplan-Meier curve and Cox multivariate analysis.Results:When the left ventricular lead location was not considered, RVMS and RVA locations did not affect VTA. However, the subgroup analysis results showed that when the left ventricular lead was positioned at the anterolateral cardiac vein (ALCV), the RVMS group had an increased risk of ventricular arrhythmias and appropriate defibrillation (hazard ratio [HR] = 3.29, P = 0.01 and HR = 4.33, P < 0.01, respectively); when the left ventricular lead was at the posterolateral cardiac vein (PLCV), these risks in the RVMS group decreased (HR = 0.45, P = 0.02 and HR = 0.33, P < 0.01, respectively), and when the left ventricular lead was at the lateral cardiac vein, there was no difference between the two groups. In regard to inappropriate defibrillation, there was no significant difference among all these groups.Conclusions:When the left ventricular lead was positioned at ALCV or PLCV, the right ventricular lead location was associated with VTA and appropriate defibrillation after CRT. Greater distances between leads not only improved cardiac function but also may reduce the risk of VTA.

Left Ventricular Lead Location and Long-Term Outcomes in Cardiac Resynchronization Therapy Patients.

The authors aimed to evaluate the association of left ventricular (LV) lead location and long-term outcomesin MADIT-CRT (Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy). There is limited data on the association of lead location with long-term clinical outcomes in patients with cardiac resynchronization therapy with defibrillator (CRT-D). The LV lead location was classified in 797 patients with CRT-D, in 569 patients with left bundle branch block (LBBB), in 228 patients with non-LBBB, and in 505 patients with an implantable cardioverter-defibrillator (ICD) only. Leads were classified into apical (n= 83) and non-apical (n= 486); with the non-apical LV leads further categorized into anterior (n= 99) and posterior/lateral (n= 387) within LBBB. All-cause mortality and heart failure (HF) events were assessed using Kaplan-Meier and Cox analyses. In CRT-D patients with LBBB and posterior/lateral LV lead location, there was an association with a significant reduction in long-term all-cause mortality (hazard ratio [HR]: 0.54, 95% confidence interval [CI]: 0.37 to 0.79; p=0.001), and HF events (HR: 0.44, 95% CI: 0.33 to 0.60; p< 0.001) compared to an ICD only, accompanied withbetter LV reverse remodeling. CRT-D patients with LBBB and an anterior LV lead location were shown to be associated with a significant reduction in HF events compared to an ICD only (anterior HR: 0.50, 95% CI: 0.30 to 0.82; p= 0.006); however, no association with mortality reduction was observed from CRT-D versus an ICD only. CRT-D wasnot associated with improved outcomes in non-LBBB patients, regardless of LV lead location. In mild HF patients with LBBB and an implanted CRT-D, lateral/posterior, and anterior LV lead locations are similarly associated with reduction in the risk of HF or death events compared to ICD alone. Mortality benefit derived from CRT-D is associated only with patients with lateral/posterior LV lead location. An apical LV lead location should be avoided due to the early risk of death whenever possible. (Multicenter Automatic Defibrillator Implantation With Cardiac Resynchronization Therapy [MADIT-CRT], NCT00180271; Multicenter Automatic Defibrillator Implantation Trial WithCardiac Resynchronization Therapy Post Approval Registry [MADIT-CRT-PAR], NCT01294449; and MADIT-CRT Long-Term International Follow-Up Registry - Europe, NCT02060110).

P5490Impact of Left Ventricular lead location and QRS morphology on clinical outcomes with a quadripolar CRT-D system in the MultiPoint Pacing (MPP) IDE study

P5490Impact of Left Ventricular lead location and QRS morphology on clinical outcomes with a quadripolar CRT-D system in the MultiPoint Pacing (MPP) IDE study

Biventricular paced QRS predictors of left ventricular lead locations in relation to mortality in cardiac resynchronization therapy

BackgroundLeft ventricular (LV) lead location during cardiac resynchronization therapy (CRT) has influenced mortality and heart failure events; however the biventricular paced QRS morphology has not been established as a predictor of LV lead location or mortality. MethodsWe evaluated the biventricular paced QRS morphology in 306 patients undergoing CRT in relation to specific anatomic locations. A logistic regression model and Kaplan–Meier survival estimates were used to determine predictors of LV lead location and survival. ResultsThe mean age was 68±13years. Predictors of LV lead location from anterior, lateral, and posterior segments were: absence of R in V1, QS in aVL; and R in aVL, respectively. Absence of an R in II, III, or aVF predicted an inferior site. A QS in V4–V6 differentiated apical from basal sites (p=0.01). LV pacing from sites along the middle cardiac vein revealed a higher mortality (34%), than lateral sites (20%, p=0.02). ConclusionsBiventricular paced QRS criteria were predictive of LV lead locations. The proposed algorithm enhanced the predictive accuracy of these criteria. LV pacing sites along the middle cardiac vein were associated with increased mortality.

Impact of Myocardial Viability and Left Ventricular Lead Location on Clinical Outcome in Cardiac Resynchronization Therapy Recipients with Ischemic Cardiomyopathy

Cardiac resynchronization therapy (CRT) recipients with ischemic cardiomyopathy (ICM) have scar segments that may limit ventricular resynchronization and clinical response. The impact of myocardial viability at the left ventricular (LV) pacing site on CRT response is poorly elucidated. A retrospective cohort of 160 ICM patients with single photon emission computed tomography-myocardial perfusion imaging before device implantation were included. Coronary venous angiography and chest radiographs helped classify segmental location of LV lead (LVL). The primary outcome was a composite of heart failure (HF) hospitalization and mortality at 3 years, and secondary outcome was change in systolic function at 6 months. The patients were divided into groups based on the myocardial substrate at the site of LVL: LVL on or adjacent to (1) normal myocardium (LVL-N, n = 64), (2) segmental scar (LVL-S, n = 62), and (3) scar and ischemia (LVL-SI, n = 34). Upon follow-up, 75 (47%) patients reached primary endpoint with a higher incidence noted in LVL-S (60%), and LVL-SI (53%), compared to 31% in LVL-N (P = 0.004). Kaplan Meier method demonstrated poor event free survival for primary outcome in LVL-S (P = 0.002), and LVL-SI (P = 0.03). In Cox proportional hazard model, LVL-S (HR: 2.26, P = 0.004), and LVL-SI (1.9, P = 0.047) were independent predictors of primary outcome. In CRT recipients with ICM, scar and reversible ischemia in or adjacent to LV pacing site were independent predictors of HF hospitalization and death.

Myocardial viability at the left ventricular lead location and the occurrence of ventricular tachyarrhythmias in cardiac resynchronization therapy

Purpose: There is some conflicting data regarding the potential arrhythmic effect of left ventricular (LV) pacing in cardiac resynchronization therapy (CRT). In heart failure (HF) patients scar-related anisotropy and dispersion of refractoriness provide conditions for re-entry ventricular tachyarrhythmias (VTs). The aim of our study was to analyse the association between myocardial viability at the LV lead location and the occurrence of VTs in patients undergoing CRT. Methods: Before CRT defibrillator device implantation 57 patients with advanced HF [age 62.3±10.2; NYHA II-IV; 38 men (66%); 24 ischaemic aetiology (42%); 48 sinus rhythm (84.2%); QRS duration 165±24 ms] were evaluated using single-photon emission computed tomography (SPECT) myocardial perfusion imaging (20-segment model). LV lead position was determined at implant venography using 2 projections (LAO 30° and RAO 30°) of coronary sinus tributaries. Myocardial viability was calculated as the mean tracer activity in the corresponding segments at left ventricular (LV) lead location. Results: In median follow-up 30 (24-34) months, VTs were registered in 18 patients (31.6%). Patients without VTs had higher myocardial viability at the LV lead position (66.1±10.3% vs. 54.8±11.4% of tracer activity; P = 0.001) than those with VTs. In addition, among patients with registered VTs the extent of regional viability was also related to the number of malignant tachyarrhythmias. In multivariante logistic regression model LV lead viability (OR = 0.90; 95% CI 0.85-0.97; P = 0.003) was the only independent predictor of VT occurrence. After receiver-operating curve analysis cut-off value of 59.63% of mean tracer activity had a sensitivity of 72% and a specificity of 77% for predicting VTs. Conclusion: Myocardial viability at the LV lead position is independently related to the occurrence of VTs in CRT patients. Segments with decreased viability in the potential LV pacing site should be identified before implantation to avoid possible enhancement of electrical instability.

Impact of the left ventricular lead position for long-term prognosis after cardiac resynchronization therapy in heart failure patients

Background: An important determinant of successful cardiac resynchronization therapy for heart failure is the position of the left ventricular (LV) pacing lead. The aim of this study was to analyze the impact of the LV lead position on outcome in patients with cardiac resynchronization therapy (CRT). Objective; We assessed the relationship between anatomic LV lead position and long-term mortality and morbidity in CRT patients. Methods: The location of the LV lead was assessed by means of coronary venograms and chest x-rays recorded at the time of device implantation. The LV lead location was classified along the short axis into an anterior, lateral, or posterior position and along the long axis into a basal, midventricular, or apical region. Echocardiographic reduction of LV end-systolic volume, increase of LV ejection fraction and clinical outcomes were evaluated with respect to the LV lead position. Results: Totally 91 patients implanted with CRT from July 2004 to July 2011 were included in this analysis, and median follow-up period was 34 months. The LV lead was placed in the LV apex in 3 (3%) patients, in the midventricular position in 64 (70%), in the basal position in 19 (21%), in the anterior position in 8 (9%), in the lateral position in 75 (82%), and in the posterior position in 1 (1%) patients. The lateral lead location compared with leads located in the nonlateral position was associated with a significantly decreased risk for death (hazard ratio (HR)=0.347; 95% confidence interval (CI), 0.165 to 0.727; P=0.014). The midventriculer lead position was also associated with a decreased risk for death (HR=0.441; 95% CI, 0.226 to 0.862; P=0.002). Survival salvage analysis showed that cumulative hazards were significantly lower in those with lateral lead position (log-rank P=0.003), and mid ventricular lead position (log-rank P=0.014). Cox multivariate analysis showed lateral LV lead position was an independent positive factor of mortality (HR=0.346; 95% CI, 0.146 to 0.820; P=0.016). All 3 patients that a LV lead was placed in the LV apex were dead with heart failure. There was no significant difference in echocardiographic results among the positions of the LV lead. Conclusion: CRT with the lateral and the midventricular LV lead positions are associated with decreased risk of death in comparison with other LV lead positions.

Abstract 259: The Role of Gender in Cardiac Resynchronization Therapy Response in Patients with Optimal Anatomical and Electrical Left Ventricular Lead Location.

Background: While optimal left ventricular (LV) lead location and the female sex are known to predict a favorable response to cardiac resynchronization therapy (CRT), the role of gender differences affecting CRT outcomes in patients with optimal LV lead location remains uncertain. Methods: We analyzed a prospective cohort of 180 CRT patients. Anatomical lead location was confirmed by coronary venograms and chest radiographs. LV lead electrical delay (LVLED) was measured from QRS onset on surface ECG to the first sensed signal of the LV lead, and standardized based on native QRS width. Echocardiographic response was evaluated at baseline and 6 months. Time to first heart failure hospitalization or death was assessed over 3 years. Results: 100 patients (Age 68.2 ± 12.3 years; Baseline LVEF 23.2 ± 6.8 %, NYHA 3.0 ± 0.3) with optimal LV lead location defined as ‘long’ LVLED (LVLED&gt;50%) with non-apical and anterolateral, lateral or posterolateral lead position were selected from the original cohort. They were further divided into the female (n=26) and male (n=74) groups. Baseline clinical characteristics were similar between groups except for a higher incidence of ischemic cardiomyopathy in males (72.4% vs. 47.1%, p=0.01) and longer QRS duration in females (171.3 ± 29.9 vs. 153.6 ± 26.9, p=0.008). Baseline echocardiographic characteristics revealed a smaller LV internal dimension in systole (LVIDs) and diastole (LVIDd) in females (51.7 ± 10.2 vs. 57.1 ± 8.9, p=0.02; 58.5% ± 10.1 vs. 64.5 ± 8.3, p=0.007 respectively). Survival with respect to first heart failure hospitalization (Figure 1A) and a composite of mortality and heart failure (Figure 1B) were comparable. Echocardiographic response, defined as an increase in mean LVEF by 10% was significant in females (+11.6 ± 11.0 % vs. +5.3 ± 9.0 %, p=0.01). Conclusion: In CRT patients with optimal lead location, females have superior outcomes with respect to reverse remodeling but gender differences donot appear to predict clinical outcomes.

Abstract 272: The Role of Diabetes Mellitus in Cardiac Resynchronization Therapy Response in Patients with Optimal Anatomical and Electrical Left Ventricular Lead Location.

Background: While optimal left ventricular (LV) lead location is known to predict a favorable response to cardiac resynchronization therapy (CRT) therole of underlying Diabetes Mellitus (DM) in this patient population remains uncertain. Methods: We analyzed a prospective cohort of 180 CRT patients. Anatomical lead location was confirmed by coronary venograms and chest radiographs. LV lead electrical delay (LVLED) was measured from QRS onset on surface ECG to the first sensed signal of the LV lead, and standardized based on native QRS width. Echocardiographic response was evaluated at baseline and 6 months. Time to first heart failure hospitalization or death was assessed over 3 years. Results: 100 patients (Age 68.2 ± 12.3 years; Baseline LVEF 23.2 ± 6.8 %, NYHA 3.0 ± 0.3) with optimal LV lead location defined as ‘long’ LVLED(LVLED&gt;50%) with non-apical and anterolateral, lateral or posterolateral lead position were selected from the original cohort. They were further categorized by the presence (n=38) or absence (n=62) of DM. Baseline clinical and echocardiographic characteristics were similar between groups except for a higher incidence of hypertension in diabetics (94.7% vs. 58.1%, p &lt;0.001) and longer LVLED in non-diabetics (81.7 ± 16.5 vs. 74.8 ± 14.8, p=0.03). DM was significantly associated with time to first heart failure hospitalizations (Fig 1A) and a composite of all-cause mortality and heart failure (Fig1B) by the Kaplan-Meir method. However on multivariate cox regression Diabetes was not an independent predictor of response. Echocardiographic response was similar across both groups. Conclusion: In CRT patients with optimal lead location and Diabetes, there is a trend towards worse outcomes. This could be the setting of Diabetes related cardiomyopathy and the higher incidence of ischemic heart disease in diabetics.

QRS morphology, left ventricular lead location, and clinical outcome in patients receiving cardiac resynchronization therapy

Several studies have reported a poor outcome with cardiac resynchronization therapy (CRT) in non-left bundle branch block (LBBB) patients. Although the left ventricular (LV) lead location is an important determinant of the clinical outcome, there is scant information regarding its role in non-LBBB patients. This study sought to examine the impact of electrical and anatomical location of the LV lead in relation to baseline QRS morphology on the CRT outcome. A left ventricular lead electrical delay (LVLED) was measured intra-procedurally as an interval between QRS onset on the surface electrocardiogram (ECG) to the peak of sensed electrogram on LV lead and corrected for QRS width. The impact of the LVLED on time to first heart failure hospitalization (HFH), and composite outcome of all-cause mortality, HFH, LVAD implantation, and cardiac transplantation at 3 years was assessed. Among 144 patients (age 67 ± 12 years, QRS duration 156 ± 28 ms, non-LBBB 43%), HFH was higher in non-LBBB compared with LBBB (43.5 vs. 24%, P = 0.015). Within LBBB, patients with the long LVLED (≥50%) had 17% HFH vs. 53% in the short LVLED (<50%), P = 0.002. Likewise in non-LBBB, patients with the long LVLED compared with the short LVLED had a lower HFH (36 vs. 61%, P = 0.026). In adjusted Cox proportional hazards model, the long LVLED in LBBB and non-LBBB was associated with an improved outcome. Specifically, in non-LBBB, LVLED ≥50% was associated with improved event-free survival with respect to time to first HFH (HR: 0.34; P = 0.011) and composite outcome (HR: 0.41; P = 0.019). Cardiac resynchronization therapy delivered from an LV pacing site characterized by the long LVLED was associated with the favourable outcome in LBBB and non-LBBB patients.

The anatomic and electrical location of the left ventricular lead predicts ventricular arrhythmia in cardiac resynchronization therapy

Both anatomic and electrical locations of the left ventricular (LV) lead have been identified as important predictors of clinical outcomes in cardiac resynchronization therapy (CRT). The impact of LV lead location on incident device-treated ventricular arrhythmia (VA), however, is not well understood. To assess the relationship between electrical and anatomic LV lead location and device treated VAs in CRT. Sixty-nine patients undergoing CRT implantation for standard indications were evaluated. Anatomic LV lead location was assessed by means of coronary venography and chest radiography and categorized as apical or nonapical. Electrical LV lead location was assessed by LV electrical delay (LVLED) and was calculated as the time between the onset of the native QRS on the surface electrocardiogram and sensed signal on the LV lead during implantation and corrected for native QRS. Incident appropriate device-treated VA was assessed via device interrogation. Apical lead placement was an independent predictor of VAs (hazard ratio 5.29; 95% confidence interval 1.69-16.5; P = .004). Among patients with a nonapical lead, LVLED<50% native QRS was an independent predictor of VAs (hazard ratio 6.90; 95% confidence interval 1.53-31.1; P = .012). Those with a nonapical lead and LVLED ≥ 50% native QRS were at substantially lower risk for first incident and recurrent VAs when compared to all other patients. The apical lead position is associated with an increased risk of VAs in CRT patients. Among patients with a nonapical lead position, an LVLED of<50% of the native QRS is associated with an increased risk of VAs.

Left ventricular lead location and the risk of ventricular arrhythmias in the MADIT-CRT trial

We aimed to evaluate the influence of left ventricular (LV) lead position on the risk of ventricular tachyarrhythmias in cardiac resynchronization therapy (CRT) patients. Left ventricular (LV) lead position was evaluated by biplane coronary venograms and anterior/posterior, lateral chest X-rays in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial - Cardiac Resynchronization Therapy (MADIT-CRT). The LV lead location could be defined in 797 of 1089 patients (73%). The LV lead was placed at the LV apex in 110 (14%) patients, in the anterior position in 146 (18%), in the lateral position in 448 (56%), and in the posterior position in 93 (12%) patients. After adjustment for clinical covariates, lateral or posterior lead location was associated with significantly lower risk of ventricular tachycardia (VT)/ventricular fibrillation (VF) [hazard ratio (HR) = 0.57, 95% confidence interval (CI): 0.38-0.85; P = 0.006] when compared with an anterior lead location. Patients with anterior lead position had similar risk of VT/VF as patients with implantable cardioverter defibrillator (ICD)-only (HR = 1.04, 95% CI: 0.72-1.81; P = 0.837). There was no difference in the risk of mortality between posterior or lateral and anterior LV lead locations. Cardiac resynchronization therapy with posterior or lateral LV lead position is associated with decreased risk of arrhythmic events in comparison with anterior lead location and ICD-only patients. There is no evidence for increased risk of VT/VF episodes associated with CRT.

Optimizing benefit from CRT: role of speckle tracking echocardiography, the importance of LV lead position and scar

Cardiac resynchronization therapy is demonstrated to be effective in patients with advanced heart failure. Correcting mechanical dyssynchrony is proposed as the predominant mechanism of response. Achieving optimum left ventricular lead position, at the site of maximal mechanical dyssynchrony but away from transmural scar, is identified as one of the main determinants of both symptomatic and prognostic benefit. Strategies employing multimodality cardiac imaging techniques have been used to identify this optimal pacing site, in addition to any potential anatomical limitations to successful implantation. Speckle tracking echocardiography offers prospective lead targeting, incorporating pathophysiological determinants of cardiac resynchronization therapy response. This review considers the key factors in defining optimum left ventricular lead location, emphasizing the role of myocardial scar. The use of speckle tracking echocardiography and the potential for this technique to be incorporated into routine practice to guide the implant strategy in an individual patient is discussed.

Occurrence of phrenic nerve stimulation in cardiac resynchronization therapy patients: the role of left ventricular lead type and placement site

Unwanted phrenic nerve stimulation (PNS) has been reported in ∼1 in 4 patients undergoing left ventricular (LV) pacing. The occurrence of PNS over mid-term follow-up and the significance of PNS are less certain. Data from 1307 patients enrolled in pre-market studies of LV leads manufactured by Medtronic (models 4193 and 4195 unipolar, 4194, 4196, 4296, and 4396 bipolar) were pooled. Left ventricular lead location was recorded at implant using a common classification scheme. Phrenic nerve stimulation symptoms were either spontaneously reported or identified at scheduled follow-up visits. A PNS-related complication was defined as PNS resulting in invasive intervention or the termination of LV pacing. Average follow-up was 14.9 months (range 0.0-46.6). Phrenic nerve stimulation symptoms occurred in 169 patients (12.9%). Phrenic nerve stimulation-related complications occurred in 21 of 1307 patients (1.6%); 16 of 738 (2.2%) in the unipolar lead studies, and 5 of 569 (0.9%) in the bipolar lead studies (P = 0.08). Phrenic nerve stimulation was more frequent at middle-lateral/posterior, and apical LV sites (139/1010) vs. basal-posterior/lateral/anterior, and middle-anterior sites (20/297; P= 0.01). As compared with an anterior LV lead position, a lateral LV pacing site was associated with over a four-fold higher risk of PNS (P= 0.005) and an apical LV pacing site was associated with over six-fold higher risk of PNS (P= 0.001). Phrenic nerve stimulation occurred in 13% of patients undergoing LV lead placement and was more common at mid-lateral/posterior, and LV apical sites. Most cases (123/139; 88%) of PNS were mitigated via electrical reprogramming, without the need for invasive intervention.

Standard chest radiograph predicts left ventricular lead location in chronic resynchronization therapy patients more accurately than intraoperative fluoroscopy

Targeting the proper left ventricular lead site is important in cardiac resynchronization therapy (CRT) procedures, as suboptimal lead locations may result in a lack of clinical response. Left ventricular lead locations are typically confirmed using fluoroscopy (fluoro) with AP, RAO, and LAO orientations. However, standard fluoro may inadequately delineate true left ventricular lead locations, due to insufficient angulation or extreme cardiac rotation. Posteroanterior and lateral chest radiograph (CXRPAL), performed routinely to verify lead stability and freedom from complication, may better confirm left ventricular lead location due to utilization of a straight lateral view. Compared to fluoro, lead localization using CXRPAL will be more predictive of true left ventricular lead location in CRT patients. Of 252 medically optimized CHF patients who underwent CRT implantation by multiple operators from October 2001 to August 2011, 46 (mean age, 58.9 ± 13.2 years; 10 female; 19 ICM; 19 LBBB; mean ejection fraction, 26.6 ± 8.9 %; mean QRS width, 144.4 ms) had CT scanning performed as part of routine medical care and comprise this study. Operative reports of left ventricular lead location by fluoro were reviewed. Left ventricular lead location was identified on CXRPAL by three independent observers blinded to operative results. Left ventricular lead locations according to fluoro and CXRPAL were correlated with CT scan at a mean follow-up of 57.6 ± 28.8 months (Tables 1 and 2). Compared to standard fluoro, CXRPAL agreed better with CT scan (κ = 0.413 fluoro vs. κ = 0.864 CXRPAL on the vertical axis, and κ = 0.086 fluoro vs. κ = 0.864 CXRPAL on the horizontal axis) for identification of left ventricular lead location. In this small study of 46 CRT patients, interpretation of left ventricular lead location using CXRPAL correlated better with true lead location identified on CT scan, compared to standard fluoroscopy. Use of a steep lateral view during CRT implantation may be necessary to accurately identify left ventricular lead locations.