Right Ventricular Mid-septum Research Articles

Electrophysiological demonstration of nonselective His-Purkinje system capture with para-Hisian pacing.

The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited. We included 152 consecutive patients (mean age 61±24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n=54), para-Hisian region (n=66), or mid interventricular septum (n=17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12‑lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI). QRS duration was prolonged in all pacing sites: from 114±28 to 160±29 (RV apex), from 110±28 to 122±29 (para-Hisian), and from 121±24 to 154±30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48h after implantation but did not require repositioning. QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.

Optimizing diastolic filling by pacing in nonobstructive hypertrophic cardiomyopathy

Treatment options for symptomatic patients with nonobstructive hypertrophic cardiomyopathy (nHCM) are limited. The purpose of this study was to determine the effect of sequential atrioventricular (AV) pacing, from different right ventricular (RV) sites with varying AV delays, on the diastolic function and functional capacity of patients with nHCM. Twenty-one patients with symptomatic nHCM and normal left ventricular (LV) systolic function were prospectively enrolled. Inclusion criteria included PR interval >150 ms, E/e' ≥15, and an indication for implantable cardioverter-defibrillator (ICD) implantation. Doppler echocardiographic study was performed during dual-chamber pacing at various AV intervals. Pacing was performed at 3 RV sites: RV apex (RVA), RV midseptum (RVS), and RV outflow tract (RVO). The site and sensed AV delay (SAVD) at which optimal diastolic filling occurred were chosen based on diastolic filling period and E/e'. During ICD implantation, the RV lead was implanted at the site identified by the pacing study. Devices were programmed in DDD mode at the optimal SAVD. During follow-up, diastolic function and functional capacity were assessed. Among the 21 patients (age 47.8 ± 7.7 years; 81.0% male), baseline E/A and E/e' were 2.4 ± 0.6 and 17.2 ± 2.2, respectively. There was an improvement in diastolic function (E/e') in 18 patients (responders) when pacing from the RVA (12.9 ± 3.4; P <.001) than from the RVS (16.6 ± 2.3) and RVO (16.9 ± 2.2). Among responders, optimal diastolic filling occurred at SAVD of 130-160 ms with RVA pacing. Nonresponders had longer duration of symptoms (P = .006), lower LV ejection fraction (P = .037), and higher late gadolinium enhancement burden (P <.001). During 13.5 ± 1.5 months of follow-up, there was an improvement (Δ) in diastolic function (E/e' -4.1 ± 0.5), functional capacity (New York Heart Association functional class -1.5 ± 0.3), and reduction in N-terminal pro-brain natriuretic peptide level (-55.6 ± 12.3 pg/mL) compared to baseline. Pacing at an optimized AV delay from the RVA improves diastolic function and functional capacity in a subset of patients with nHCM.

Forecasting patient instability: Current advances & future opportunities

The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited.We included 152 consecutive patients (mean age 61 ± 24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n = 54), para-Hisian region (n = 66), or mid interventricular septum (n = 17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12‑lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI).QRS duration was prolonged in all pacing sites: from 114 ± 28 to 160 ± 29 (RV apex), from 110 ± 28 to 122 ± 29 (para-Hisian), and from 121 ± 24 to 154 ± 30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48 h after implantation but did not require repositioning.QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.

Right ventriculography improves the accuracy of leadless pacemaker implantation in right ventricular mid-septum

BackgroundImplanting leadless pacemakers in the right ventricular (RV) apex is prone to causing pericardial tamponade and myocardial perforation.ObjectiveTo investigate the feasibility and safety of right ventriculography-guided implantation of Micra™ leadless pacemaker (Micra™, Medtronic, Minneapolis, MN, USA) in the RV mid-septum.MethodsOne hundred eight consecutive patients who underwent Micra™ implantation intended in the mid-septum were enrolled and randomized (3:1) into the radiography group (n = 81) with assistance of right ventriculography to illustrate the RV septum and the non-radiography group (n = 27). All subjects underwent a postoperative computed tomography (CT) scan to determine the Micra™ location. The Micra™ location assessed by CT image was compared between the two groups to confirm the accuracy of the intended pacing site. The duration of the procedure, X-ray radiation dose, and time were also compared between the two groups.ResultsReconstructed CT 3-D cardiac images found the Micra™ location in the intended mid-septum in 13 patients (48.1%, 13/27) in the non-radiography group and 76 patients (93.8%, 76/81) in the radiography group (P < 0.0001 between two groups). There was no significant difference in procedure interval between the two groups while the X-ray radiation dose (564.86 ± 112.44 vs. 825.85 ± 156.12 mGy, P < 0.0001), X-ray exposure time (7.79 ± 1.43 vs. 12.03 ± 2.86 min, P < 0.0001), and the number of fluoroscopy re-positioning (2.79 ± 1.03 vs. 6.41 ± 1.82, P < 0.0001) were significantly less in the radiography group than in the non-radiography group. No implantation-related complications were observed in both groups.ConclusionRight ventriculography increases the accuracy of Micra™ implantation in the mid-septum and reduces X-ray exposure.Trial registrationThe trial registration number (ChiCTR2100051374) and date (09/22/2021).

Key Role of Pacing Site as Determinant Factor of Exercise Testing Performance in Pediatric Patients with Chronic Ventricular Pacing.

Chronic right ventricular (RV) apical pacing has been associated with deterioration of functional capacity and chronotropic incompetence during exercise testing in children. The effects of alternative pacing site on exercise performance in pediatric population remain unknown. We evaluated the influence of ventricular pacing site on exercise capacity in pediatric patients with complete congenital atrioventricular block requiring permanent pacemaker therapy. Sixty-four children paced from RV apex (n=26), RV midseptum (n=15) and left ventricular (LV) apex (n=23) were studied cross-sectionally. Treadmill exercise stress testing was performed according to modified Bruce protocol. LV apical pacing was associated with greater exercise capacity. In comparison with the other study groups, children with RV apical pacing showed significantly lower VO2peak (37±4.11; p=0.003), O2 pulse (8.78±1.15; p=0.006), metabolic equivalents (7±0.15; p=0.001) and exercise time (6±3.28; p=0.03). Worse values in terms of maximum heart rate (139±8.83bpm; p=0.008) and chronotropic index (0.6±0.08; p=0.002) were detected in the RV apical pacing group although maximal effort (respiratory exchange ratio) did not differ among groups (p=0.216). Pacing from RV apex (odds ratio 9.4; confidence interval 2.5-18.32; Wald 4.91; p=0.0036) and low peak heart rate achieved (odds ratio 3.66; confidence interval 0.19-7.4; Wald 4.083; p=0.015) predicted significantly decrease in exercise capacity. Duration of pacing, gender, VVIR mode, baseline heart rate and QRS duration had not significant impact on exercise capacity. The site of ventricular pacing has the major impact on exercise capacity in children requiring permanent pacing. Among the sites assessed, LV apex is related to the better exercise performance.

The Short-Term Effect of Right Ventricular Mid-septal Pacing on Right Ventricular Function

Background: Right ventricular (RV) apical pacing is associated with left ventricular (LV) dyssynchrony and dysfunction. However, the effect of pacing on RV function, in particular with leads positioned in the RV mid-septum, remains unknown. We investigated the short-term effect of pacing on RV function Methods: We enrolled 24 patients with normal baseline LV and RV function requiring permanent pacemaker insertion. Echocardiography was performed prior to implantation (baseline) and at 1 month. We assessed RV tricuspid annular plane systolic excursion (TAPSE), tricuspid annular tissue Doppler-derived systolic velocity (S’), RV fractional area change (FAC) and RV global longitudinal strain (GLS) using speckle tracking Results: Mean age was 73.8 ± 9.5 years. 1-month percent ventricular pacing average was 32% (range 0-100%). 17 patients had atrioventricular nodal dysfunction and 7 had sick sinus syndrome. There was a small but statistically significant decline in RV GLS 1 month following pacemaker insertion(Table). There was also a trend towards decline of RV function on all other measured parameters. Conclusions: RV mid-septal pacing may be associated with a slight decline of RV function early after pacemaker insertion, which may be identified by strain analysis. Longer-term follow-up is under way to assess if this predicts long-term RV dysfunction.

Radial left ventricular dyssynchrony by speckle tracking in apical versus non apical right ventricular pacing- evidence of dyssynchrony on medium term follow up.

Introduction: To study effects of various sites of right ventricular pacing lead implantation on left ventricular function by 2-dimensional (2D) speckle tracking for radial strain and LV dyssynchrony. Methods: This was retrospective prospective study. Fifteen patients each with right ventricular (RV) apical (RV apex and apical septum) and non-apical (mid septal and low right ventricular outflow tract [RVOT]) were programmed to obtain 100% ventricular pacing for evaluation by echo. Location and orientation of lead tip was noted and archived by fluoroscopy. Electrocardiography (ECG) was archived and 2D echo radial dyssynchrony was calculated. Results: The baseline data was similar between two groups. Intraventricular dyssynchrony was significantly more in apical location as compared to non-apical location (radial dyssynchrony: 108.2 ± 50.2 vs. 50.5 ± 24, P < 0.001; septal to posterior wall delay [SLWD] 63.5 ± 27.5 vs. 34 ± 10.7, P < 0.001, SPWD 112.5 ± 58.1 vs. 62.7 ± 12.1, P = 0.003). The left ventricular ejection fraction was decreased more in apical location than non apical location. Interventricular dyssynchrony was more in apical group but was not statistically significant. The QRS duration, QTc and lead thresholds were higher in apical group but not statistically significant. Conclusion: Pacing in non apical location (RV mid septum or low RVOT) is associated with less dyssynchrony by specific measures like 2D radial strain and correlates with better ventricular function in long term.

Abstract 13951: Right Anterior Oblique in Addition to Left Anterior Oblique Projections Are Useful to Implant Right Ventricular Pacemaker Lead Into Mid-Septum and Achieve More Physiological Pacing

Introduction: It has been reported that it is difficult to implant right ventricular (RV) leads to the true mid-septum using conventional fluoroscopic criteria. Thus, we investigated which is the best method to achieve the true RV mid-septum using 3 dimensions (3D) reconstruction of 64-slice multidetector computed tomography (64 MDCT). Methods and Results: We retrospectively analyzed 33 patients in whom we intended to place RV lead into the septum using conventional fluoroscopic criteria, 40 degree left anterior oblique (LAO40), and performed 64 MDCT later. 3D reconstruction of 64 MDCT revealed that the right ventricular lead was anchored on the true mid-septum in 10 patients (only 30%; MS group, n=10), anterior wall in 19 patients, and free wall in 4 patients (non-MS group, n=23). After implantation of the pacemaker, we evaluated the predictive value of MS group when we used electrocardiography criteria (q wave or negative QRS complex in lead I), 90 degree left lateral (LL90) view and 30 degree right anterior oblique (RAO30) view using 3D reconstruction of 64 MDCT in addition to LAO view. As shown in a table, the method using both LAO and RAO views was the best to achieve the true RV mid-septum among these methods. MS group had significantly shorter paced QRS duration and ΔQRS (paced QRS-own QRS) than non-MS group (139±21.9ms vs. 155.3±10.9ms, p=0.03 and 24.2±21.2ms vs. 55.5±9.1ms, p=0.0001). Conclusions: The true mid-septum RV pacing could achieve more physiological pacing. Not only confirming rightward orientation in LAO view but also aiming the middle of the cardiac silhouette in the RAO view may be a simple and accurate way to achieve the true RV mid-septum positioning.

The acute and chronic effects of different right ventricular site pacing on left ventricular mechanical synchrony as assessed by phase analysis of SPECT myocardial perfusion imaging

BackgroundThis study aimed to assess acute and chronic effects of right ventricular mid-septum (RVS) versus right ventricular apex (RVA) pacing on left ventricular (LV) mechanical dyssynchrony using phase analysis of gated single photon emission computed tomography myocardial perfusion imaging (MPI). MethodsThirty-nine patients with complete atrioventricular (AV) block, who were indicated for permanent pacing, were recruited and randomized to receive RVA (n = 20) or RVS (n = 19) pacing. All patients underwent MPI at 1 week and 6 months after pacemaker implantation. LV dyssynchrony and cardiac function were assessed by MPI and compared between the two groups. ResultsThere were no significant differences in baseline characteristics between the RVS and RVA groups. The paced QRS duration was significantly longer in the RVA group than in the RVS group. LV dyssynchrony parameters were not significantly different between the groups at the 1-week follow-up, but they were significantly smaller in the RVS group than in the RVA group at the 6-month follow-up. LV dyssynchrony parameters significantly decreased in the RVS group from the 1-week follow-up to the 6-month follow-up, but were unchanged in the RVA group. No differences in LV function parameters were observed between the groups at the 1-week and 6-month follow-ups. ConclusionsRVS pacing produces better electrical and mechanical synchrony than RVA pacing for patients with complete AV block.

Safety of mid-septal electrode placement in implantable cardioverter defibrillator recipients — Results of the SPICE (Septal Positioning of ventricular ICD Electrodes) study

BackgroundDetrimental effects of right ventricular (RV) apical pacing have directed the interest toward alternative pacing sites such as the RV mid-septum. As safety data are scarce for implantable cardioverter defibrillator (ICD) recipients the study aims to evaluate ICD lead performance in the mid-septal position. Methods and resultsA total of 299 ICD recipients (79% male, aged 65.2±12.1years, 83% primary prevention of sudden cardiac death) were randomized to receive the RV ICD electrode either in a mid-septal (n=145) or apical (n=154) location. Event-free survival was evaluated at 3 (primary endpoint) and 12months (secondary endpoint). Events included a composite of lead revision, suboptimal right ventricular electrode performance (including defibrillation thresholds (DFT)>25J) or lead position not in accordance with randomized location. Event-free survival at 3 (12) months was observed in 80.6% (72.3%) of patients randomized to a mid-septal and in 82.2% (72.1%) of patients randomized to an apical lead position, p=0.726 (p=0.969). Pre-defined margins for non-inferiority were not reached at 3 or 12months. High DFT was found in 7 patients (5.0%) of the mid-septal and in 3 (2.2%) patients of the apical group (p=0.209). ConclusionIn ICD recipients electrode positioning to the RV mid-septum or the RV apex results in slightly different rates concerning the survival free of lead revision, suboptimal right ventricular electrode performance or non-randomized lead position. Non-inferiority of the mid-septal lead location cannot be concluded. This should be taken into consideration when a mid-septal lead position is pursued. Clinical trial registrationClinicalTrials.gov identifier NCT00745745.

A Randomized Study of Defibrillator Lead Implantations in the Right Ventricular Mid‐Septum versus the Apex: The SEPTAL Studyτ

The study was designed to evaluate the feasibility and performance of right ventricular (RV) mid-septal versus apical implantable defibrillator (ICD) lead placement. SEPTAL is a randomized, noninferiority trial, which randomly assigned patients to implantation of ICD leads in the RV mid-septum versus apex, with a primary objective of comparing the implant success rate of implant at each site, based on strict electrical predefined criteria. We also compared the (1) pacing lead characteristics, (2) rates of appropriate and inappropriate ICD therapies, and (3) all-cause mortality between the 2 sites at 1 year. The trial enrolled 215 patients (mean age = 59.7 ± 12.4 years, mean LVEF = 34.0 ± 14.2%, 84.2% men), of whom 148 (68.8%) presented with ischemic heart disease. The ICD indication was primary prevention in 117 patients (54.4%). The lead was successfully implanted in 96/107 patients (89.7%) assigned to the RV mid-septum, and in 99/108 (91.7%) assigned to the apex (ns). The 1-year rate of lead-related adverse events was similar in both groups. A total of 8 first inappropriate ICD therapies (7.9%) were delivered in the RV mid-septal group, versus 8 (7.8%) in the apical group (ns), while first appropriate therapies were delivered to 22 (21.4%) and 24 patients (23.8%), respectively (ns). All-cause mortality was 7.9% in the RV mid-septal versus 2.9% in the RV apical group (ns). This study confirmed the technical feasibility and noninferior performance of ICD leads implanted in the RV mid-septum versus the apex.

Selective Site Pacing From the Right Ventricular Mid-Septum

Pacing from the right ventricular (RV) apex is associated with adverse effects such as heart failure and atrial fibrillation. We attempted pacing from the RV mid-septum, which is theoretically a more physiological pacing site. A total of 172 consecutive patients with indications for permanent pacemaker implantation were studied. A screw-in lead and a curved stylet were used for lead positioning on the RV mid-septum. Pacemaker indices were evaluated at implantation and one year later. As an electrocardiographic parameter, QRS duration was measured in lead II. These data were compared to those of 66 patients subjected to conventional RV apical pacing. Lead placement was successful in all patients of RV mid-septal pacing. There were no technical problems during or after the procedure. The cumulative percentage of ventricular pacing at one year postimplantation was 85 ± 24 % in the SSP group. Sensing, pacing threshold, and lead impedance in the SSP group remained clinically stable over one year. When these measurements were compared between the SSP and AP groups, the pacing threshold and the lead impedance at one year postimplantation in the SSP group were higher (P < 0.05) and lower (P < 0.01), respectively, than those of the AP group. The mean QRS duration was markedly shorter (123 ± 16 versus 150 ± 18 msec, P < 0.0001). Selective site pacing from the RV mid-septum is feasible and results in less conduction delay compared to conventional RV apical pacing, and its procedure seems to be more physiological in permanent pacemaker implantation.

Impact of temporary right ventricular pacing from different sites on echocardiographic indices of cardiac function

To assess the impact of pacing from different right ventricular (RV) pacing sites on left ventricular (LV) function. Chronic apical RV pacing may induce heart failure. To reduce this RV, mid-septum and outflow tract are suggested as alternative pacing sites. We therefore assessed cardiac performance during temporary RV pacing from apical vs. mid-septum or outflow tract sites, using echocardiography and electrocardiography. Patients scheduled for a permanent pacemaker underwent temporary pacing in dual-chamber mode (DDD) and with atrio-ventricular delay optimized. The ventricular lead was moved to either the RV apex, mid-septum or outflow tract. Comprehensive echocardiography was performed in each position. Twenty-two patients completed the study. The baseline data was collected at atrial pacing mode (AAI). QRS duration lengthened with RV apical pacing (97 ± 22 ms AAI vs. 154 ± 18 ms RV apical, P < 0.001) and shortened with mid-septum or outflow tract pacing (147 ± 14 ms RV mid-septum and 136 ± 16 ms RV outflow tract, P = 0.001 and P < 0.001, respectively, vs. RV apical). Right ventricular apical pacing was associated with reductions in stroke volume and LV ejection fraction (54 ± 6% AAI vs. 48 ± 5% RV apical, P = 0.001). Right ventricular mid-septum (52 ± 5%) and outflow tract (54 ± 6%) pacing improved LV ejection fraction in comparison with apical pacing (P < 0.01 for both). Pacing at all sites induced dyssynchrony. In comparison with RV apical pacing dyssynchrony was reduced by mid-septum or outflow tract pacing. Right ventricular pacing at the mid-septum or outflow tract results in narrower QRS complexes, less dyssynchrony, and better LV systolic function than RV apical pacing.

Delayed Success Following Radiofrequency Catheter Ablation of Ventricular Premature Contractions Originating from Right Ventricular Mid Septum

There were few reports about delayed success following radiofrequency catheter ablation of ventricular premature contractions (VPCs). A 72-year-old female was admitted to our hospital to treat frequent VPCs. The electrocardiogram (ECG) showed sinus rhythm at 75 bpm and VPCs with the inferior axis and left bundle branch block. QRS morphology of VPCs was Q wave in V1 and RSR pattern in aVL. We expected that the origin of VPCs was right ventricular (RV) mid septum. In holter ECG recording, the number of VPCs was 25000 beats/day. Catheter ablation was performed to eliminate VPCs. Ablation catheter was positioned at RV mid septum with ventricular electrogram preceded 22 ms from the onset of QRS of VPCs. VPCs were disappeared during radio frequency current delivery, but VPCs were recurred just after RF application. However total RF time was 26 minutes, VPCs were not eliminated finally. For eight hours just after ablation, VPCs were occurred 30 beats/min and increased in comparison with preablation period. After eight hours from ablation, VPCs decreased gradually, and 48 hour later VPC was disappeared. Conclusion: These observations demonstrate that continued evolution of RF lesions may result in the eventual success of an initially unsuccessful ablation session.

Similar Long‐Term Benefits Conferred by Apical Versus Mid‐Septal Implantation of the Right Ventricular Lead in Recipients of Cardiac Resynchronization Therapy Systems

The benefits conferred by cardiac resynchronization therapy (CRT) are markedly influenced by the left ventricular (LV) lead placement. Little is known regarding the optimal right ventricular (RV) stimulation site. To compare the long-term outcomes of CRT in patients with RV leads placed in the mid-septal region versus the apex. This nonrandomized, observational study included 117 patients with standard indications for CRT. The LV lead was implanted on the postero-lateral or lateral LV wall, while the RV lead was implanted at the apex (n = 82) or in the mid-septum (n = 35). Both groups were similar with respect to baseline clinical, demographic, and echocardiographic characteristics. After 12 months of CRT, the rates of clinical response to CRT were similar in both groups (63% vs. 66%), and similar degrees of reverse LV remodeling and LV resynchronization were observed on echocardiography and color tissue Doppler imaging. A > or =30% relative increase in LV ejection fraction (EF) occurred in 76% of patients in the RV apex group, versus 49% of patients in the RV mid-septum group (P = 0.05). A > or =45% left ventricular ejection fraction (LVEF) was measured at 12 months in 40% of patients in the RV apex group, versus 31% in the RV mid-septum group (ns). RV mid-septal stimulation was not associated with a higher rate of response to CRT or greater improvement in LV function compared to RV apical stimulation.

Effect of Pacing the Right Ventricular Mid‐Septum Tract in Patients with Permanent Atrial Fibrillation and Low Ejection Fraction

Permanent right ventricular (RV) pacing leads have been traditionally implanted in the right ventricular apex (RVA). Nowadays, some deleterious effects of RVA pacing have been recognized. The aim of this study was to evaluate the effect of different sites of RV pacing in patients with permanent atrial fibrillation (AF) and low ejection fraction (LEF) needing a pacemaker (PM) implantation. Two hundred seventy-three patients with permanent AF and EF <30% underwent a one-chamber rate responsive (VVIR) PM implant procedure. Patients were divided into two groups: Group A, including 113 patients with the pacing lead tip placed in the RV mid-septum, and Group B of 120 patients with the pacing lead tip placed at the apex of RV. All patients had clinical and Echo control after 1, 3, 6, 12, and 18 months after PM implantation to assess New York Heart Association (NYHA) class and EF. After 18 months, NYHA class changed in Group A from 2.9 +/- 0.4 at implant to 1.7 +/- 0.3 at 18 months (P = 0.01), and in Group B from 3.0 +/- 0.5 at implant to 3.3 +/- 0.6 at 18 months (P = n.s.). EF increased in Group A: 28 +/- 2% at implant, 33 +/- 1% at 18 months (P = 0.0125), while no significant changes were observed in Group B: at implant 27 +/- 2%, 26 +/- 2% at 18 months (P = n.s.). The present study suggests that more physiological pacing from the RV sept can improve EF and quality of life (QoL) in patients with permanent AF and low EF needing a PM.