Optimization of right ventricular lead position in cardiac resynchronisation therapy

Apical or Septal Right Ventricular Location in Patients Receiving Defibrillation Leads: A Systematic Review and Meta-Analysis

This study reviews the published data comparing the efficacy and safety of apical and septal right ventricle defibrillator lead positioning at 1-year follow-up. Systemic research on Medline (PubMed), ClinicalTrials.gov , and Embase was performed using the keywords "septal defibrillation," "apical defibrillation," "site defibrillation," and "defibrillation lead placement," including implantable cardioverter-defibrillator and cardiac resynchronization therapy devices. Comparisons between apical and septal position were performed regarding R-wave amplitude, pacing threshold at a pulse width of 0.5 ms, pacing and shock lead impedance, suboptimal lead performance, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter, readmissions due to heart failure and mortality rates. A total of 5 studies comprising 1438 patients were included in the analysis. Mean age was 64.5 years, 76.9% were male, with a median LVEF of 27.8%, ischemic etiology in 51.1%, and a mean follow-up period of 26.5 months. The apical lead placement was performed in 743 patients and septal lead placement in 690 patients. Comparing the 2 placement sites, no significant differences were found regarding R-wave amplitude, lead impedance, suboptimal lead performance, LVEF, left ventricular end-diastolic diameter, and mortality rate at 1-year follow-up. Pacing threshold values favored septal defibrillator lead placement ( P = 0.003), as well as shock impedance ( P = 0.009) and readmissions due to heart failure ( P = 0.02). Among patients receiving a defibrillator lead, only pacing threshold, shock lead impedance, and readmission due to heart failure showed results favoring septal lead placement. Therefore, generally, the right ventricle lead placement does not appear to be of major importance.

Right ventricular lead location and outcomes among patients with cardiac resynchronization therapy: A meta-analysis

BACKGROUND

Cardiac resynchronization therapy (CRT) has been demonstrated to improve heart failure (HF) symptoms, reverse LV remodeling, and reduce mortality and HF hospitalization (HFH) in patients with a reduced left ventricular (LV) ejection fraction (LVEF). Prior studies examining outcomes based on right ventricular (RV) lead position among CRT patients have provided mixed results. We performed a systematic review and meta-analysis of randomized controlled trials and prospective observational studies comparing RV apical (RVA) and non-apical (RVNA) lead position in CRT.

METHODS

Our meta-analysis was constructed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews and meta-analyses. We searched EMBASE and MEDLINE. Eligible studies reported on at least one of the following outcomes of interest: all-cause mortality, the composite endpoint of death and first HFH hospitalization, change in LVEF, New York Heart Association (NYHA) class improvement, and change in LV end systolic volume (LVESV). We performed meta-analysis summaries using a DerSimonian-Laird random-effects model and conservatively used the Knapp-Hartung approach to adjust the standard errors of the estimated model coefficients.

RESULTS

We included nine studies representing a total of 1832 patients. Of those, 1318 (72%) patients had RVA lead placement and 514 (28%) had RVNA lead placement. The mean age of patients was 65.5 ± 4.4 years, and they were predominantly men (69%-97%). There was no statistically significant difference in all-cause mortality by RVA vs. RVNA (OR = 0.77, 95% CI 0.32-1.89; I2 = 16.7%, p = 0.31), or in the combined endpoint of all-cause mortality and first HFH (OR 0.88, 95% CI 0.62-1.25; I2 = 0%, p = 0.84). Also, there was no difference between RVA and RVNA for NYHA class improvement (OR = 1.03, 95% CI 0.9-1.17; I2 = 0%, p = 0.99), change in LVEF (mean difference (MD) = 1.33, 95% CI -1.45 to 4.10; I2 = 47%; p = 0.093), and change in LVESV (MD = -1.11, 95% CI -3.34 to 1.12; I2 = 0%; p = 0.92).

CONCLUSION

This meta-analysis shows that in CRT pacing, RV lead position does not appear to be associated with clinical outcomes or LV reverse remodeling. Further studies should focus on the relationship of RV lead vis-à-vis LV lead location, and its clinical importance.

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.

Clinical and echocardiographic response of apical vs nonapical right ventricular lead position in CRT: A meta-analysis

Background

Traditionally the right ventricular (RV) pacing lead is placed in the RV apex in cardiac resynchronization therapy (CRT). It is not clear whether nonapical placement of the RV lead is associated with a better response to CRT. We aimed to perform a meta‐analysis of all randomized controlled trials (RCTs) that compared apical and nonapical RV lead placement in CRT.

Methods

We searched PubMed, EMBASE, Cochrane, Scopus, and relevant references for studies and performed meta‐analysis using random effects model. Our main outcome measures were all‐cause mortality, composite of death and heart failure hospitalization, improvement in ejection fraction (EF), left ventricle end‐diastolic volume (LVEDV), left ventricle end‐systolic volume (LVESV), and adverse events.

Results

Seven RCTs with a total population of 1641 patients (1199 apical and 492 nonapical) were included in our meta‐analysis. There was no difference in all‐cause mortality (5% vs 4.3%, odds ratio (OR) = 0.86; 95% confidence interval (CI) 0.45‐1.64; P = .65; I² = 11%) and a composite of death and heart failure hospitalization (14.2% vs 12.9%, OR = 0.92; 95% CI: 0.61‐1.38; P = .68; I² = 0) between apical and nonapical groups. No difference in improvement in EF (Weighted mean difference (WMD) = 0.37; 95% CI: −2.75‐3.48; P = .82; I² = 68%), change in LVEDV (WMD = 3.67; 95% CI: −4.86‐12.20; P = .40; I² = 89%) and LVESV (WMD = −1.20; 95% CI: −4.32‐1.91; P = .45; I² = 0) were noted between apical and nonapical groups. Proportion of patients achieving >15% improvement in EF was similar in both groups (OR = 0.85; 95% CI: 0.62‐1.16; P = .31; I² = 0).

Conclusion

In patients with CRT, nonapical RV pacing is not associated with improved clinical and echocardiographic outcomes compared with RV apical pacing.

Comparison of right ventricular septal pacing and right ventricular apical pacing in patients receiving cardiac resynchronization therapy defibrillators: the SEPTAL CRT Study

AIMS

Cardiac resynchronization therapy (CRT) is a recommended treatment of heart failure (HF) patients with depressed left ventricular ejection fraction and wide QRS. The optimal right ventricular (RV) lead position being a matter of debate, we sought to examine whether RV septal (RVS) pacing was not inferior to RV apical (RVA) pacing on left ventricular reverse remodelling in patients receiving a CRT-defibrillator.

METHODS AND RESULTS

Patients (n = 263, age = 63.4 ± 9.5 years) were randomly assigned in a 1:1 ratio to RVS (n = 131) vs. RVA (n = 132) pacing. Left ventricular end-systolic volume (LVESV) reduction between baseline and 6 months was not different between the two groups (-25.3 ± 39.4 mL in RVS group vs. -29.3 ± 44.5 mL in RVA group, P = 0.79). Right ventricular septal pacing was not non-inferior (primary endpoint) to RVA pacing with regard to LVESV reduction (average difference = -4.06 mL; P = 0.006 with a -20 mL non-inferiority margin). The percentage of 'echo-responders' defined by LVESV reduction >15% between baseline and 6 months was similar in both groups (50%) with no difference in the time to first HF hospitalization or death (P = 0.532). Procedural or device-related serious adverse events occurred in 68 patients (RVS = 37) with no difference between the two groups (P = 0.401).

CONCLUSION

This study demonstrates that septal RV pacing in CRT is non-inferior to apical RV pacing for LV reverse remodelling at 6 months with no difference in the clinical outcome. No recommendation for optimal RV lead position can hence be drawn from this study.

CLINICALTRIALS GOV NUMBER

NCT 00833352.

Apical vs. non-apical right ventricular pacing in cardiac resynchronization therapy: a meta-analysis

AIMS

Cardiac resynchronization therapy (CRT) has been shown to improve outcomes in patients with heart failure. The optimal site of right ventricular (RV) stimulation in CRT has not been established. We aimed to conduct a meta-analysis of randomized-controlled trials and observational studies comparing the mid- and long-term effects of RV apical (RVA) and non-apical (RVNA) pacing on CRT outcomes.

METHODS

We systematically searched the Cochrane library, EMBASE, and MEDLINE databases for studies evaluating RVA vs. RVNA pacing in CRT with regards to left ventricular end-systolic volume (LVESV) reduction, functional status improvement (defined as ≥1 New York Heart Association class improvement), and the clinical outcome of mortality or cardiovascular hospitalization. Effect estimates [standardized mean difference (SMD) and odds ratio (OR) with 95% confidence intervals (CI)] were pooled using random-effect models.

RESULTS

Twelve studies comprising 2670 patients (1655 with an apical and 1015 with a non-apical RV lead position) were included. In meta-analyses, LVESV reduction and functional status improvement were similar in patients with RVA and RVNA pacing (SMD 0.13, 95% CI: -0.24 to 0.50, P = 0.48; OR 1.08, 95% CI: 0.81 to 1.45, P = 0.60, respectively). Data regarding mortality and hospitalizations could not be pooled due to a small number of relevant studies with significant heterogeneity.

CONCLUSION

Our meta-analysis suggests that in CRT patients the effects of RVA or RVNA pacing on LV remodelling and functional status are similar. Mortality and morbidity outcomes with different RV lead positions should be further assessed in randomized clinical trials.

Is cardiac resynchronization therapy for right ventricular failure in pulmonary arterial hypertension of benefit?

Pulmonary arterial hypertension is a manifestation of a group of disorders leading to pulmonary vascular remodeling and increased pulmonary pressures. The right ventricular (RV) response to chronic pressure overload consists of myocardial remodeling, which is in many ways similar to that seen in left ventricular (LV) failure. Maladaptive myocardial remodeling often leads to intraventricular and interventricular dyssychrony, an observation that has led to cardiac resynchronization therapy (CRT) for LV failure. CRT has proven to be an effective treatment strategy in subsets of patients with LV failure resulting in improvement in LV function, heart failure symptoms, and survival. Current therapy for pulmonary arterial hypertension is based on decreasing pulmonary vascular resistance, and there is currently no effective therapy targeting the right ventricle or maladaptive ventricular remodeling in these patients. This review focuses on the RV response to chronic pressure overload, its effect on electromechanical coupling and synchrony, and how lessons learned from left ventricular cardiac resynchronization might be applied as therapy for RV dysfunction in the context of pulmonary arterial hypertension.

Assessment of cardiac stroke volume in patients with implanted cardiac pacemaker using parametric electrical impedance tomography: a theoretical 2D study

The present theoretical study examines the ability to estimate cardiac stroke volume (CSV) in patients with implanted cardiac pacemaker using parametric electrical impedance tomography (pEIT) in a 2D computerized model of the thorax. CSV is a direct indicator of the cardiac pumping efficiency. The commonly used methods for measuring CSV require the invasive procedure of right heart catheterization or use expensive imaging techniques (i.e., MRI). Hence, experience with these techniques for diagnosis and monitoring has been limited to hospitalized patients. In the present study, pEIT scheme was applied in a computerized 2D model of the human thorax with implanted cardiac device to determine the left ventricular (LV) volume at different cardiac cycle phases. The LV was simulated as a prolate ellipse with its axes' lengths as the reconstruction parameters while all other geometries and conductivity values remained constant. An optimization was carried out in order to ensure that the ellipse is the appropriate model for the LV at each cardiac cycle phase. LV volumes calculated by both the pEIT algorithm and the ellipsoid model are consistent. A high correlation (ρ = 0.99) between the true and reconstructed volumes was found. The SV calculation error was ∼1%. The results suggest that the LV volume can be estimated using the pEIT method in a 2D computerized model, and that the method has the potential to be used for monitoring patients with implanted cardiac pacemaker.

Canadian Cardiovascular Society guidelines on the use of cardiac resynchronization therapy: evidence and patient selection

Recent landmark trials provided the impetus to update the recommendations for cardiac resynchronization therapy (CRT). This article provides guidance on the prescription of CRT within the confines of published data. A future article will explore the implementation of these guidelines. These guidelines are intended to serve as a framework for the prescription of CRT within the Canadian health care system and beyond. They were developed through a critical evaluation of the existing literature, and expert consensus. The panel unanimously adopted each recommendation. The 8 recommendations relate to ensuring the adequacy of medical therapy before the initiation of CRT, the use of symptom severity to select candidates for CRT, differing recommendations based on the presence or absence of sinus rhythm, the presence of left bundle branch block vs other conduction patterns, and QRS duration. The use of CRT in the setting of chronic right ventricular pacing, left ventricular lead placement, and the routine assessment of dyssynchrony to guide the prescription of CRT are also included. The strength of evidence was weighed, taking full consideration of any risks of bias, as well as any imprecision, inconsistency, and indirectness of the available data. The strength of each recommendation and the quality of evidence were adjudicated. Trade-offs between desirable and undesirable consequences of alternative management strategies were considered, as were values, preferences, and resource availability. These guidelines were externally reviewed by experts, modified based on those reviews, and will be updated as new knowledge is acquired.

Right ventricular pacing and sensing function in high posterior septal and apical lead placement in cardiac resynchronization therapy

BACKGROUND

The conventional right ventricular (RV) lead position in cardiac resynchronization therapy pacemakers (CRT-P) is the RV apex (RV-A). Little is known about electrophysiological stability and associated complications of pacing leads in RV high posterior septal (RV-HS) position in CRT-P.

METHODS

Two hundred and thirty-five consecutive CRT-P patients were included from 1999-2010. Pacing thresholds at 0.5ms and 2.5V, sensing electrograms and lead impedances were measured at implant and repeated 1,3,6,12,18 and 24 months after CRT-P. Electrophysiological measurements of leads located in RV-A and RV-HS were analyzed retrospectively. Bipolar RV leads were used, including high impedance leads, passive fixation and active fixation.

RESULTS

RV pacing leads were implanted in RV-A (n=79) and RV-HS (n=156). Average RV pacing thresholds from CRT implant procedure to 24-month follow-up at 0.5ms were 0.77±0.69V in RV-A and 0.71±0.35V in RV-HS (P=0.31), and at 2.5V were 0.06±0.08ms in RV-A and 0.07±0.05ms in RV-HS (P=0.12). Average RV electrogram amplitudes from baseline to 24 months after CRT were 15.3±6.9mV in RV-A and 12.1±6.0mV in RV-HS (P=0.55). Average RV impedances during follow-up were 850±286Ω in RV-A and 618±147Ω in RV-HS (P=0.57). Similar RV lead revisions between RV-A and RV-HS were observed after 2-year follow-up (P=0.55).

CONCLUSION

The RV-HS lead position demonstrated stable and acceptable long-term pacing and sensing function, with rates of complications comparable to conventional RV-A lead position in CRT. The RV-HS lead position is feasible in CRT-P.

Adverse response to cardiac resynchronisation therapy in patients with septal scar on cardiac MRI preventing a septal right ventricular lead position

PURPOSE

Myocardial scar is an adverse factor when considering which patients are likely to respond to cardiac resynchronisation therapy (CRT). We hypothesized that septal scarring on magnetic resonance imaging (MRI) may be associated with a poor outcome from CRT, which may relate to the inability to place the right ventricular (RV) lead in the septum.

METHODS

Fifty patients (ejection fractions, 25 ± 8%; 45 men, 62.8 ± 14 years; 26 dilated cardiomyopathy; and 24 ischaemic cardiomyopathy (ICM)) receiving CRT underwent delayed enhancement cardiac MRI to assess location and burden of myocardial scar. Acute hemodynamic response (AHR) was evaluated at implant with a pressure wire in the left ventricular (LV) cavity. LV remodelling was determined by reduction in LV end-systolic volume at 6 months.

RESULTS

The presence of ICM with septal scar was associated with a poor acute and chronic response to CRT. This was predominantly due to a worse response in patients with septal scar. Patients without septal scar had a better AHR with a 26.7 ± 28.9% rise in LV dP/dt (max) from baseline vs. -2.8 ± 14.5% for patients with septal scar (P = 0.01) with Biventricular (BIV) pacing. A greater proportion remodelled (56% vs. 20% (P = 0.02)). Furthermore, only 33% of patients with septal scar had an RV septal lead compared with 66% with no septal scar (P = 0.03).

CONCLUSIONS

The presence of septal scar was associated with a poor acute and chronic response to CRT. This may relate to the inability to achieve a RV septal lead placement.

Clinical implication of right ventricular to left ventricular interlead sensed electrical delay in cardiac resynchronization therapy

AIMS

To evaluate the clinical implication of right ventricular (RV) to left ventricular (LV) interlead sensed electrical delay (RV-LVs) and the relation to ventricular lead position in cardiac resynchronization therapy (CRT).

METHODS AND RESULTS

Eighty-five consecutive CRT patients (mean age 66 ± 11 years) received LV lead prospectively targeted to the latest mechanical activated segment (concordant), assessed by two-dimensional speckle tracking radial strain (ST-RS) echocardiography. The RV lead was randomized to RV apex (n= 43) or RV high posterior septum (n= 42). Right ventricular to left ventricular interlead sensed electrical delay was obtained during the CRT implant procedure. Intraventricular dyssynchrony was evaluated by ST-RS echocardiography. Interventricular mechanical delay (IVMD) was measured by using pulse-wave Doppler. Separated by the median RV-LVs (82 ms), a long RV-LVs demonstrated more LV end-systolic volume (LVESV) reduction than a short RV-LVs (-27 ± 20 vs. -16 ± 22%; P= 0.02), 6 months after CRT (6FU). Right ventricular to left ventricular interlead sensed electrical delay correlated to IVMD (r = 0.50; P< 0.001) and intraventricular dyssynchrony (r = 0.25; P= 0.02) at baseline. Concordant LV leads (n= 61) demonstrated superior reduction of LVESV (P= 0.005) 6 months after CRT; however, both RV lead positions had similar effects. Right ventricular to left ventricular interlead sensed electrical delay was irrespective to LV lead concordance and RV lead position (P= ns). Independent predictors to reverse remodelling (reduction of LVESV ≥ 15%) at 6FU were concordant LV lead (odds ratio, 3.210; P= 0.029) and IVMD (odds ratio, 1.028; P= 0.026).

CONCLUSION

Right ventricular to left ventricular interlead sensed electrical delay was not predictive to LV reverse remodelling affected by CRT at 6FU. Concordant LV leads demonstrated superior LV reverse remodelling at 6FU. Right ventricular to left ventricular interlead sensed electrical delay was irrespective of ventricular lead position and might be insufficient to target optimal LV lead position in CRT.

TRIAL REGISTRATION

http://clinicaltrials.gov. Unique identifier: NCT01035489.

Midterm 'super-response' to cardiac resynchronization therapy by biventricular pacing with fusion: insights from electro-anatomical mapping

Aims

Some authors recommend avoiding fusion with left ventricular (LV) intrinsic depolarization during cardiac resynchronization therapy (CRT). If fusion is still present during optimized biventricular (Biv) pacing and its long-term effects on the response to CRT are currently unknown. The aim of the study was to analyse the endocardial LV activation pattern induced by echocardiographically optimized Biv pacing and its influence on LV reverse remodelling.

Methods and results

Contact electro-anatomical mapping was performed in 15 heart failure (HF) patients with left bundle branch block and echocardiographically optimized CRT (seven ischaemic aetiology, 64 ± 8 years, three women, New York Heart Association class 3 ± 0.4, LV ejection fraction 25 ± 5%). Left ventricular activation maps were performed in sinus rhythm (SR), during DDD right ventricular apical (RVA) and optimized Biv pacing. Fusion with intrinsic rhythm during pacing was considered when LV septal activation was produced at least partially by intrinsic depolarization, when compared with LV activation map during SR. Patients were considered responders to CRT if they had ≥10% reduction in LV end-systolic volume (LVESV) after 6 months of CRT. During SR, the LV breakthrough was mid-septal (n = 12), basal septum (n = 2), and apical (n = 1). During RVA pacing, LV breakthrough shifted apical in all patients. Right ventricular apical/Biv pacing proved fusion with intrinsic depolarization in 8 of 15 patients. The PR interval was shorter in patients with fusion RVA/Biv pacing (164 ± 24 vs. 234 ± 55 ms, P = 0.006). There was a trend for shorter LV activation time (LV_at) in patients with fusion during RVA pacing (87 ± 33 vs. 113 ± 21 ms, P = 0.08) as well as during optimized Biv pacing (83 ± 18 vs. 104 ± 24 ms, P = 0.07), although LV_at was similar in SR (100 ± 22 vs. 106 ± 20, P = NS). In patients with fusion, 6 months responder rate was significantly higher (100 vs. 28.5%, P < 0.007) as was the degree of LVESV reduction (39 ± 17 vs. 1.0 ± 14%, P < 0.001).

Conclusion

Biventricular pacing with fusion may substantially increase the structural responder rate probably by shortening LV_at.

Evolution of paced QRS and QTc intervals in children with epicardial pacing leads

AIMS

Permanent ventricular pacing in children is associated with ventricular dysfunction due to asynchronous activation. It is unclear whether paced QRS intervals increase disproportionately over time, which could potentially cause ventricular dysfunction.

METHODS

A total of 52 children, with bipolar steroideluting epicardial leads implanted at a median age of 5.6 years (0.0-17.4), was analyzed and followed up to 12.2 years (median 3.7). Patients were subdivided in two groups: right (RV, n = 21) and left (LV, n = 31) ventricular pacing. To correct for age, standard deviation scores (Z-scores) for paced QRS and QTc intervals were calculated from published standard-ECG norm-values. As a measure for individual paced QRS and QTc interval changes, a regression slope coefficient (incline(i)) was calculated for each patient's course.

RESULTS

Mean Z-scores for paced QRS intervals at first and last follow-up were 4.7 +/- 1.2 and 4.9 +/- 0.9 for group RV, 4.4 +/- 1.1 and 4.8 +/- 1.1 for group LV. Incline(i) of paced QRS (group RV: 0.038 [-0.27-0.12], group LV: 0.147 [-0.05-0.30]; p = 0.07) and QTc intervals (group RV: 0.026 [-0.08-0.06], group LV: 0.023 [-0.04-0.09]; p = 0.63) did not differ between both groups and indicated limited interval changes over time.

CONCLUSION

Neither epicardial pacing of the right nor left ventricle caused disproportionate paced QRS or QTc interval increases over time. An age-related prolongation of the electrical activation unlikely causes ventricular dysfunction.

Identification of the Right Ventricular Pacing Site for Cardiac Resynchronization Therapy (CRT) Guided by Electroanatomical Mapping (CARTO)

BACKGROUND

The optimal left ventricle (LV) pacing site for cardiac resynchronization therapy (CRT) has been investigated, but less is known about the optimal site in the right ventricle (RV). The present study examined whether electrical resynchronization guided by electroanatomical mapping (CARTO) results in mechanical resynchronization.

METHODS AND RESULTS

The study group included 13 patients indicated for CRT: 10 with nonischemic cardiomyopathy, 2 with ischemic cardiomyopathy and 1 with cardiac sarcoidosis, (mean LV ejection fraction: 32+/-10%). CARTO of the RV septum was performed to identify the site with the most delayed conduction time during LV pacing. Hemodynamic measurements were performed during conventional biventricular pacing with the RV apex and LV (C-BVP) and during biventricular pacing with the most delayed site of the RV (d-RV) and LV (D-BVP). Lead placement at 15 coronary sinus veins was examined in the 13 patients. During pacing from anterolateral veins (n=2), the d-RV was the RV apex (RVA) in 1 patient and the mid-septum in the other. During pacing from lateral veins (n=9), the d-RV comprised the RVA (n=3), the mid-septum (n=5), and the right ventricular outflow tract (RVOT) (n=1). During pacing from the posterolateral veins (n=3), the d-RV was the RVOT in all cases. In 11 of 15 sites, d-RV differed from conventional RVA. Compared with C-BVP, D-BVP produced a significant improvement in LV dp/dt. Furthermore, RV mid-septum and LV pacing markedly increased LV dp/dt and pulse pressure (PP), but RVOT and LV pacing did not. D-BVP vs C-BVP: %LV dp/dt 30+/-20 and 15+/-15%, p<0.05; RV mid-septum and LV pacing vs C-BVP: %LV dp/dt 35+/-20 and 10+/-15%, p<0.02, and vs PP 33+/-20 and 10+/-29 mmHg, p<0.02.

CONCLUSIONS

For pacing from the LV lateral vein, potential improvement of cardiac performance compared with that by conventional RVA placement may be realized with concomitant pacing from the d-RV (mid-septum).