Interlead Electrical Delay Research Articles

Long-term outcomes in a randomized controlled trial of multimodality imaging-guided left ventricular lead placement in cardiac resynchronization therapy.

This study aims to investigate the long-term occurrence of the composite endpoint of heart failure (HF) hospitalization or all-cause death (primary endpoint) in patients randomized to cardiac resynchronization therapy (CRT) using individualized multimodality imaging-guided left ventricular (LV) lead placement compared with a routine fluoroscopic approach. Furthermore, this study aims to evaluate whether inter-lead electrical delay (IED) is associated with improved response rate of this endpoint. We reviewed follow-up data until November 2020 for all 182 patients included in the ImagingCRT trial for the occurrence of HF hospitalization and all-cause death. During median (inter-quartile range) time to primary endpoint/censuring of 6.7 (3.3-7.9) years, the rate of the primary endpoint was 60% (n = 53) in the imaging group compared with 52% (n = 48) in the control group [hazard ratio (HR) 1.22, 95% confidence interval (CI) 0.83-1.81, P = 0.31]. Neither the risk of HF hospitalization (HR 1.11, 95% CI 0.62-1.99, P = 0.72) nor of all-cause death differed between treatment groups (HR 1.23, 95% CI 0.82-1.85, P = 0.32). The risk of the primary endpoint was significantly reduced among those with IED ≥100 ms when compared with those with IED <100 ms (HR 0.62, 95% CI 0.39-0.98, P = 0.04). In this study, an individualized multimodality imaging-guided strategy targeting LV lead placement towards the latest mechanically activated non-scarred myocardial segment during CRT implantation did not reduce HF hospitalization or all-cause death when compared with routine LV lead placement during long-term follow-up. Targeting the latest electrical activation should be studied as an alternative individualized strategy for optimizing LV lead placement in CRT recipients.

Evaluation of relationship between interlead electrical delay time and reverse remodeling of left ventricle in patients with quadripolar cardiac resynchronization therapy for long-term follow-up

Abstract Background Cardiac resynchronization therapy (CRT) has undoubtedly shown a high role in the treatment of advanced heart failure (HF). The effectiveness of CRT is individual and variable in each case. It is associated with the functional and structural features of heart as well as the dynamics of these features over time. Despite the quadripolar left ventricle (LV) lead widespread use, the problem of low response to CRT in the early and long-term remains actual. The search for predictors of the CRT response is an important scientific and practical issue. Purpose To determine the relationship between the interlead electrical delay time and the CRT response during 24 month postoperative period. Materials and methods We evaluated the clinical status, the quality of life and echocardiographic response of 37 patients with HF treated for 2 years with quadripolar LV lead CRT devices implanted according to guidelines: 25 males/12 females with age 62±10 years, 25 pts with history of ischemic cardiac disease, LVEF 26±7%; QRS duration 184±31 ms. The response to CRT was defined as 15% decrease of LV end-systolic volume (ESV). Interlead electrical delay time (EDT) was calculated automatically during CRT implantation, and subsequent 3–6-12–18–24 month follow-up. Results The dynamic changes EDT and ESV were assessed for 24 months after CRT. There was a significantly higher average percentage of decrease of ESV in patients (n=18), in whom the stimulation of the LV lead was carried out from a pole having a maximum EDT, in 3 months (12±8% versus 10±6% p=0.021) and in 6 months (23±9% versus 18±9% p=0.003) after CRT. That was the dynamic of reverse remodeling is significantly higher in such patients for the first 6 months. Using logistic regression, it was shown that the relative decrease EDT in the first 3 months after CRT can be a predictor of outcomes in18 and 24 months after CRT with an accuracy of 71% and 77%, respectively. The greater the relative decrease EDT between 0 and 3 months, the greater the probability of a respond in 18 and 24 months after CRT. The cut-off threshold for determining the outcomes in 18 months was 18% on the balance of specificity and sensitivity equal to 80% and in 24 months was 15% on the balance of specificity and sensitivity equal to 90%. There were no differences between the HF etiology (ischemic/ non-ischemic) and baseline rhythm. Conclusion The relationship between EDT and LV reverse remodeling have been investigated for 24 months. The rate of reverse remodeling is higher in patients in whom the stimulation of the LV lead was carried out from a pole having a maximum EDT. Relative decrease EDT in early period after CRT may be a predictor of the CRT outcomes in longtime period. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Russian Science Foundation

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

P1173Interlead electrical delay time as early predictor of the reverse myocardial remodeling in modern CRT devices

Abstract Funding Acknowledgements Russian Science Foundation Grant №19-14-00134 Background Cardiac resynchronization therapy (CRT) has undoubtedly shown a high role in the treatment of advanced heart failure (HF). Despite the quadripolar left ventricle (LV) lead widespread use, the problem of low response to CRT remains actual. The search for predictors of the CRT response is an important scientific and practical task. The aim To determine the relationship between the interlead electrical delay time and the CRT response during 12 month observational period. Materials and methods We evaluated the clinical status, the quality of life and echocardiographic response of 50 patients with HF treated for 1 year with quadripolar LV lead CRT devices implanted according to guidelines: 35 males/15 females with age 62.78 ± 11.58 years, 28 pts with history of ischemic cardiac disease, LVEF 27.42 ± 9.56%; QRS duration 157.34 ± 19.76 ms. The response to CRT was defined as 15% decrease of end-systolic left ventricle (LV) volume (LVESV), 10% relative increase of LV ejection fraction (LVEF), an improvement of at least 1 NYHA HF functional class. Interlead electrical delay time (EDT) was calculated automatically during CRT implantation, and subsequent 3-6-12 month FU. EDT values from 4 LV lead poles were evaluated according to LV sizes, volumes and LVEF. Results It was shown that the greater EDT value, the more pronounced was response to CRT. The first difference in EDT is observed after 6-month observational period. The EDT difference was determined using the delta formula for equalize. In 21 patients in whom the stimulation of the LV lead was carried out from a pole having a maximum EDT value, the response to CRT was observed earlier - at 6 months FU (24 pts with maximum EDT value vs. other 26 pts). In addition, the echocardiographic data of reverse myocardial remodeling (LVESD, LVEDD, LVESV, LVEDV and LVEF) correlated with a gradual decrease in the EDT values, r = 0.49, P = 0.008. There were no differences between the HF etiology (ischemic/ non-ischemic) and baseline rhythm. The mean EDT was initially 104.94 ± 44.22 ms, 6 month FU 98.91 ± 34.28 ms, 12 month FU 91.84 ± 32.78 ms. Conclusion The interlead electrical delay time in quadripolar CRT devices depends on reverse myocardial remodeling. EDT gradual decrease may be a predictor of the response to CRT. Abstract Figure. Interlead Delay Time 12M Follow Up

Clinical impact of left ventricular paced conduction disturbance in cardiac resynchronization therapy

Myocardial scarring is associated with nonresponse to cardiac resynchronization therapy (CRT) and conduction delay. Little is known about the significance and cause of left ventricular (LV) paced conduction disturbance (LPCD). The purpose of this study was to investigate the clinical impact of paced interlead electrical delay and the difference in eachconduction time from LV pace to right ventricular (RV) sense (LVp-RVs) and from RV pace to LV sense (RVp-LVs) [(LVp-RVs) - (RVp-LVs)], in CRT. Among 137 patients who underwent CRT implantation, LVp-RVs and RVp-LVs were measured intraoperatively. The relationships between [(LVp-RVs) - (RVp-LVs)] and perfusion defects on myocardial perfusion single photon emission computed tomography (SPECT) imaging or [(LVp-RVs) - (RVp-LVs)] and clinical outcomes were assessed. After CRT implantation, 81 patients (59%) responded to CRT. [(LVp-RVs) - (RVp-LVs)] was significantly longer in nonresponders than in responders (9.7 ± 47.3 ms vs -4.5 ± 33.2 ms; P= .041). Patients with LPCD [(LVp-RVs) > (RVp-LVs)] had higher perfusion defects in the anterolateral region (2.7 ± 2.7 vs 1.1±1.6; P = .0015) on SPECT. Multivariate analysis showed that LPCD was the independent predictor of nonresponse to CRT (odds ratio 0.40; 95% confidence interval [CI] 0.17-0.90; P=.026). During median follow-up of 2.3 years (interquartile range 1.3-5.5), LPCD was the independent predictor of cardiac death and/or heart failure hospitalization in multivariate analysis (hazard ratio 2.04; 95% CI 1.19-3.55; P = .010). LPCD could predict nonresponse to CRT and poor outcome. Further intervention, such as adjustment of pacing timing or multipoint/site pacing, may be needed in such patients.

Left axis deviation in patients with left bundle branch block is a marker of myocardial disease associated with poor response to cardiac resynchronization therapy

AimsPatients with left axis deviation (LAD) and left bundle branch block (LBBB) show less benefit from cardiac resynchronization therapy (CRT) compared to other LBBB-patients. This study investigates the reasons for this. MethodsSixty-eight patients eligible for CRT were included. Patients were divided into groups according to QRS-axis; normal axis (NA), left axis deviation (LAD) and right axis deviation (RAD). Before CRT implantation CMR imaging was performed to evaluate scar tissue. Echocardiography was performed before and after implantation. The electrical substrate was assessed by measuring interlead electrical delays. Response was evaluated after 8 months by left ventricular (LV) remodelling and clinical response. ResultsForty-four (65%) patients were responders in terms of LV remodelling. The presence of LAD was found to be independently associated with a poor LV remodelling non-response OR 0.21 [95% CI 0.06–0.77] (p = 0.02). Patients with axis deviation had more myocardial scar tissue (1.3 ± 0.6 vs. 0.9 ± 0.6, P = 0.04), more severe LV hypertrophy (14 (64%) and 6 (60%) vs. 7 (29%), P = 0.05) and tended to have a shorter interlead electrical delay than patients with NA (79 ± 40 ms vs. 92 ± 48 ms, P = 0.07). A high scar tissue burden was more pronounced in non-responders (1.4 ± 0.6 vs. 1.0 ± 0.5, P = 0.01). ConclusionsLAD in the presence of LBBB is a predictor of poor outcome after CRT. Patients with LBBB and LAD have more scar tissue, hypertrophy and less activation delay.

P331Ventricular paced interlead electrical delay and response to cardiac resynchronization therapy

P331Ventricular paced interlead electrical delay and response to cardiac resynchronization therapy

Longer inter-lead electrical delay is associated with response to cardiac resynchronization therapy in patients with presumed optimal left ventricular lead position.

In a randomized trial of cardiac resynchronization therapy (CRT), a presumed optimal left ventricular (LV) lead position close to the latest mechanically activated non-scarred myocardium was achieved in 98% of patients by standard implantation. We evaluated whether inter-lead electrical delay (IED) was associated with response to CRT in these patients. We prospectively included 160 consecutive patients undergoing CRT. Pre-implant speckle-tracking echocardiography radial strain and 99mTc myocardial perfusion imaging determined the latest mechanically activated non-scarred myocardial segment. We measured procedural IED as the time interval between sensed signals in right ventricular and LV lead electrograms. All patients had LV pacing site concordant or adjacent to the latest mechanically activated non-scarred segment verified by cardiac computed tomography. Response to CRT was defined as ≥15% reduction in LV end-systolic volume at 6 months follow-up. Selecting a practical IED cut-off value of 100 ms, more patients with long IED than patients with short IED responded to CRT (87 vs. 68%; P = 0.004). In multivariate logistic regression analysis, IED ≥100 ms remained associated with CRT response after adjusting for baseline characteristics, including QRS duration and scar burden [odds ratio 3.19 (1.24-8.17); P = 0.01]. Categorizing IED by tertiles, CRT response improved with longer IED (P = 0.03). Comparable response rates were observed in patients with a concordant and adjacent LV lead position. A longer IED was associated with more pronounced LV reverse remodelling response in CRT recipients with a presumed optimal LV lead position concordant or adjacent to the latest mechanically activated non-scarred segment.

139-06: Impact of mechanical activation and right-to-left ventricular interlead electrical delay on response to cardiac resynchronization therapy

Purpose: Prior studies suggest that a LV lead position in the latest mechanically activated segment (mechanically concordant) and a long right-to-left interlead sensed electrical delay (RL-IED) improves cardiac resynchronization therapy (CRT) outcome. We compared the effect of a mechanically concordant LV lead and a long RL-IED on clinical and echocardiographic outcome in patients receiving a CRT device. Methods: We prospectively included 161 patients in NYHA class II-IV and an ECG with a left bundle branch block (age 70 ± 9 years, 39 (24%) female, QRS width 173 ± 21 ms, LV EF 25 ± 6 %, end-systolic (ESV) volume 197 ± 71 ml). The LV lead position was verified by postimplant cardiac CT. The segment with the latest mechanical activation segment was determined by preimplant speckle tracking radial strain echocardiography. The RL-IED was measured during CRT implant and expressed as a percentage of preimplant QRS width. Follow-up was performed after six months. Results: The LV lead was positioned mechanically concordant in 75 (47%) patients, while 82 (51%) and 4 (2%) had the lead in an adjacent or remote segment, respectively. The median RL_IED was 63 (range 1–84) %. The proportion of patients improving in NYHA class, the increase in LV EF, and reduction in ESV was similar in patients with or without a mechanically concordant LV lead (51 vs. 68 %, P = 0.12; 13 ± 9 vs. 11 ± 9 %, P = 0.11; 74 ± 56 vs. 66 ± 53 ml, P = 0.39, respectively). Separated by the median RL-IED, 69 % with a long RL-IED improved in NYHA class compared to 46 % with a short RL-IED (P < 0.01). Patients with a long RL-EID had a larger increase in LVEF and reduction in ESV (13 ± 10 vs. 11 ± 7 %, P = 0.04; 86 ± 54 vs. 54 ± 50 ml, P < 0.001, respectively). Conclusion: A long RL-IED, but not a mechanically concordant LV lead position, is associated with improved clinical and echocardiographic CRT outcome in patients with a high degree of mechanically optimal LV lead positions concordant or adjacent to the segment with latest mechanical activation.

The Left Ventricular Lead Electrical Delay Predicts Response to Cardiac Resynchronisation Therapy

Up to one-third of patients who undergo cardiac resynchronisation therapy (CRT) are not responders. To identify potential responders to CRT may be sometimes difficult and time-consuming. Forty-five patients who had undergone CRT implantation for standard indications were evaluated. Electrical left ventricular (LV) lead location was assessed by left ventricular activation time (LVAT), LV lead electrical delay (LVLED), and RV-LV interlead electrical delay (RVsense-LVsense). Anatomic LV pacing location was assessed as basal or mid-ventricular between 3:00 to 5:00 (traditionally optimal site), and all the other positions (traditionally non-optimal site). CRT response was defined as a decrease in LV end-systolic volume (LVESV) exceeding 15% at six months. LVLED was larger in the responder group than that in the non-responder group (67.3 ± 8.5% vs. 55.3 ± 8.1%, P< 0.001). In the multivariate analysis, LVLED and cLBBB morphology were the two independent predictors of positive echocardiographic response to CRT (OR=1.180, P=0.003; OR=7.497, P=0.04, respectively). A cutoff value of LVLED> 54.82% predicted responders with 96.3% sensitivity and 75.2% specificity and the area under the receiver operating characteristic (ROC) curve was 0.844 for LVLED (P=0.002). No relationship was found between the anatomic LV pacing sites and response to CRT (P=0.188). The larger left ventricular lead electrical delay may predict response to cardiac resynchronisation therapy.

High value of right ventricular to left ventricular interlead electrical delay during right ventricular pacing predict favorable response in patients with cardiac resynchronization therapy

Introduction: Anatomical and electrical separation of left ventricular (LV) and right ventricular (RV) electrodes is significant for successful cardiac resynchronization therapy (CRT). During bi-ventricular pacing, the electrical activation was composed by RV and LV pacing wavefronts. So the region with latest activation during intrinsic rhythm might not correspond to the optimal pacing site during CRT. Hypothesis: We assess the hypothesis that interlead electrical delay measurements during RV and LV pacing besides intrinsic rhythm could predict favorable response to CRT. Methods and results: We evaluated 51 heart failure patients (age 64±13 years, LV ejection fraction 28±12%, QRS duration 155±37ms) who had successfully implanted CRT. The LV-RV interlead electrical delay (IED) during intrinsic rhythm, RV pacing (RV pacing-LV sensing: RVp-LVs) and LV pacing (LV pacing-RV sensing: LVp-RVs) were measured intraoperatively by utilizing intracardiac electrograms. After CRT implantation, 33 (65%) patients responded to CRT. The responders showed a significantly higher value of RVp-LVs compared with non-responders (166±42 vs. 141±36ms, respectively, p=0.04) and the absolute value of the difference between RVp-LVs and LVp-RVs was lower in responders than in non-responders (16±19 vs. 28±22ms, respectively, p=0.04). The IED during intrinsic rhythm (71±53 vs. 40±44ms, p=0.07) and LVp-RVs (170±47 vs. 146±35, p=0.06) showed higher tendency in responders, however they couldn't predict responders. Moreover, among narrow QRS patients (n=21; median QRS duration 118ms, 95 to 140ms), RVp-LVs was significantly higher in responders than in non-responders (159±32 vs. 121±32ms, p=0.01). Same as the entire cohort, the IED during intrinsic rhythm couldn't predict responders (59±24 vs. 35±36ms, p=0.11). At multivariate analysis, RVp-LVs was the only independent predictor of reverse remodeling in narrow QRS subgroup (p=0.03). Conclusion: Interlead electrical delay during intrinsic rhythm couldn't predict LV reverse remodeling after CRT. However high value of RVp-LVs measured intraoperatively was associated with favorable response irrespective of QRS width, which implies an optimal LV lead position during CRT implantation.

Intraoperative right to left ventricular interlead delay predicts outcome in CRT recipients

Background: Prior studies suggested that right to left ventricular interlead sensed electrical delay (RL-IED) is predictive of echocardiographic response to cardiac resynchronization therapy (CRT). There is limited data on the effect of RL-IED on all-cause mortality in patients receiving a CRT device. Methods: We evaluated patients with RL-IED data available measured during the implantation procedure. Data on all-cause mortality was assessed using follow-up data and the Hungarian National Healthcare Fund Death Registry. Kaplan-Meier survival analyses and multivariate Cox proportional hazards regression models were used to analyze mortality in patients stratified by the median RL-IED (106.5 ms). Results: From 2000 to 2011, 494 patients (44%) of 1122 CRT implantation had RL-IED measurements available. Patients with RL-IED >106.5 ms were younger, had wider QRS complexes, less often atrial fibrillation and more dilated left ventricles. Left ventricular ejection fraction was similar in both groups (RL-IED ≤ 106.5 ms 28.1±7.5% vs. RL-IED > 106.5 ms 27.7±6.8%, p>0.5). During the median follow-up of 28 months, 145 (29%) patients died, 80 patients (16%) with RL-IED > 106.5 ms, and 65 patients (13%) with RL-IED ≤ 106.5 ms. RL-IED > 106.5 ms was associated with a significant, 48% risk reduction in all-cause mortality (HR= 0.52, 95% CI: 0.31-0.88, p= 0.01) after adjustment for clinical covariates (Fig. 1). ![Figure][1] Figure 1 Conclusions: In CRT patients, a longer right to left ventricular interlead electrical delay at the time of device implantation is associated with a significant mortality benefit as compared to those with shorter interlead delay. Right to left ventricular interlead electrical delay is an independent predictor of all-cause mortality in CRT patients. [1]: pending:yes

Value of right ventricular-left ventricular interlead electrical delay to predict reverse remodelling in cardiac resynchronization therapy: the INTER-V pilot study

Few studies have systematically evaluated the value of intra-procedural parameters in predicting response to cardiac resynchronization therapy (CRT). We investigated whether intracardiac (electrogram) measurements of electrical delays between the positioned right ventricular (RV) and left ventricular (LV) leads at implantation could predict the mid-term CRT response. Fifty-two patients underwent CRT implantation according to standard techniques and clinical indications. The RV-LV interlead electrical delay measured during spontaneous rhythm and the difference between the pacing-induced (Deltap) RV-LV interlead electrical delays measured during RV and LV pacing were defined intraoperatively using the electrical depolarizations registered at the ventricular leads on the device programmer. At 6 months, a reduction of LV end-systolic volume > or = 15% was used to define CRT responders. Responders (62%), when compared with non-responders, showed a higher proportion of ischaemic aetiology (P = 0.007) and a lower value of DeltapRV-LV interlead electrical delay (22.1 +/- 18.4 vs. 46.3 +/- 15.0 ms, P = 0.0001). At multivariate analysis, the DeltapRV-LV interlead electrical delay was the only independent predictor of response to CRT (P = 0.001). For such a parameter, the receiving operating characteristic curve analysis identified a cut-off value of 42 ms corresponding with the highest accuracy: sensitivity 90.6%; specificity 70%; positive and negative predictive value 83% and 82%, respectively. Conversely, no difference was ascertained between responders and non-responders when RV-LV interlead electrical delay was measured during spontaneous rhythm (76.1 +/- 28.5 vs. 89.6 +/- 21.2, P = 0.078). Intraprocedural measuring of paced RV-LV interlead electrical delay obtained during RV and LV pacing predicts mid-term CRT response.