Percentage Of Right Ventricular Pacing Research Articles

AV WENCKEBACH POINT AS A LONG-TERM PREDICTOR OF RIGHT VENTRICULAR PACING DEPENDENCE

Patients presenting symptomatic sick sinus syndrome with preserved AV node function with indication for permanent pacemaker implantation theoretically benefit form single chamber device (AAI) as it represents a more physiologic pacing mode and it reduces complication rates. The incidence of high degree AV block in patients with sick sinus syndrome was reported to be between 0.6 and 3 % annually. We hypothesized that the baseline AV wenckebach point (WP) at the time of AAI pacemaker implantation represent a valid predictor of the futur need for a ventricular lead implantation. We retrospectively analyzed 211 patients who underwent double chamber pacemaker (DDD) implantation who had more than one AV WP measure over a follow-up of up to 7 years. The primary outcome was the percentage of right ventricular pacing at follow-up stratified for the baseline WP. Secondary outcomes included the evolution of the mean WP and right ventricular pacing percentage over time. There is a linear relationship between baseline WP and right ventricular pacing at follow-up (correlation coefficient -0.68) With a baseline value greater than 120 bpm, patients have 9% RV pacing burden at follow-up while an initial value ≤ 100 bpm will result in a 54% RV pacing burden at follow-up. Also, there was no significant difference in the mean WP and percentage of right ventricular pacing at 6 years of follow-up. Routine measurement of the WP should be part of the assessment of patients with sick sinus syndrome in order to better determine if they are candidate for single chamber AAI pacemaker implantation. If the WB is > than 120 bpm, implantation of an AAI pacemaker seems reasonable as suggested by a low burden of ventricular pacing at follow-up and a stable WP measure over time.

Effectiveness of Ventricular Intrinsic Preference (VIP™) and Ventricular AutoCapture (VAC) algorithms in pacemaker patients: Results of the validate study

BackgroundSeveral past clinical studies have demonstrated that frequent and unnecessary right ventricular pacing in patients with sick sinus syndrome and compromised atrio-ventricular conduction (AVC) produces long-term adverse effects. The safety and efficacy of two pacemaker algorithms, Ventricular Intrinsic Preference™ (VIP) and Ventricular AutoCapture (VAC), were evaluated in a multi-center study in pacemaker patients. MethodsWe evaluated 80 patients across 10 centers in India. Patients were enrolled within 15 days of dual chamber pacemaker (DDDR) implantation, and within 45 days thereafter were classified to either a compromised AVC (cAVC) arm or an intact AVC (iAVC) arm based on intrinsic paced/sensed (AV/PV) delays. In each arm, patients were then randomized (1:1) into the following groups: VIP OFF and VAC OFF (Control group; CG), or VIP ON and VAC ON (Treatment Group; TG). Subsequently, the AV/PV delays in the CG groups were mandatorily programmed at 180/150ms, and to up to 350ms in the TG groups. The percentage of right ventricular pacing (%RVp) evaluated at 12-month post-implantation follow-ups were compared between the two groups in each arm. Additionally, in-clinic time required for collecting device data was compared between patients programmed with the automated AutoCapture algorithm activated (VAC ON) vs. the manually programmed method (VAC OFF). ResultsPatients randomized to the TG with the VIP algorithm activated exhibited a significantly lower %RVp at 12 months than those in the CG in both the cAVC arm (39±41% vs. 97±3%; p=0.0004) and the iAVC arm (15±25% vs. 68±39%; p=0.0067). In-clinic time required to collect device data was less in patients with the VAC algorithm activated. No device-related adverse events were reported during the year-long study period. ConclusionsIn our study cohort, the use of the VIP algorithm significantly reduced the %RVp, while the VAC algorithm reduced in-clinic time needed to collect device data.

0446: Septal right ventricular lead positioning and optimized DDD pacing versus intrinsic conduction in sinus node disease: an echocardiographic study. The optimist trial

Preserved intrinsic conduction in paced sinus node disease (SND) patients seems to be associated with a better outcome when compared with apical right ventricular (RV) DDD pacing.The prospective, multicenter, randomized OPTIMIST study was designed to compare RV lead positioning in the septum to preserved intrinsic conduction in chronically paced SND patients. SND patients with a class I indication were implanted with a DDD pacemaker (St. Jude medical), the RV lead being located in the midseptum. The algorithm VIP™ (Ventricular Intrinsic Preference) was programmed « on » in all patients at hospital discharge. After a 6 weeks observational period, patients with a ventricular pacing percentage inferior to 10% were randomized in 2 parallel groups: VIP « on » (preserved natural conduction - group 1) or « off » with AV delay optimization (RV pacing - group 2). Patients were followed every 6 months with echocardiography through 18 months. The primary endpoint was the left ventricular end-systolic diameter (LVESD) (Corelab analysis), with a non inferiority hypothesis. 216 patients mean age 76.07±9.45 were included and 167 randomized. The baseline characteristics were comparable in group 1 and 2 including left ventricular ejection fraction, LVEF (62.4±12.6 vs 64.4±8.7%), LVESD (32.7±8.5 vs 32.5±9.3mm) and 6 weeks RV pacing percentage (1.81±1.92 vs 2.15±2.07%). At the end of FU, as expected the percentage of RV pacing was significantly higher in group 2 (78.9±31.6 vs 7.9±17.4%). The LVEF was 62.3±10.1% in group 1 and 60.9±10.9% in group 2 (NS) and the LVESD was 31.9±7.23mm in group 1 and 31.26±7.21mm in group 2 (NS).The non-inferiority hypothesis was validated (p=2.572e-06 for a delta = 4.785). AF burden was not different between the 2 groups. When implanting the RV lead in the midseptum, DDD pacing with high percentage of RV capture was not associated with LV echocardiographic deterioration as compared to preserved intrinsic conduction pacing mode. January 17 th , Saturday 2015

The changing landscape of cardiac pacing.

A number of trials have shown that irrespective of baseline QRS duration, left ventricular (LV) dysfunction and heart failure are more common in patients with right ventricular (RV) than in those with biventricular (BiV) pacing. By contrast, preliminary results of the BIOPACE trial (follow-up 5.6years) yielded a disappointing comparison of RV vs. BiV pacing. Pacemaker-induced cardiomyopathy (PIC) may occur in patients with normal and abnormal LV ejection fractions (LVEF) and tends to occur if there is RV pacing more than 40 % of the time. Yet, some pacemaker-dependent patients do not develop LV dysfunction. PIC can be improved in about two thirds of patients by upgrading to a BiV system and the results are comparable to de novo BiV pacing in patients with a wide QRS complex. The findings of the BLOCK HF trial (2013) suggested that patients requiring pacing virtually 100 % of the time might benefit from BiV pacing irrespective of the LVEF (< 50 %), manifestations of heart failure, QRS duration, or functional class. These characteristics would generate many patients for BiV pacing. However, these recommendations should now be weighed against a more conservative approach based on the recently announced results of the BIOPACE trial. Organizational guidelines recommend BiV pacing for bradycardia irrespective of QRS duration for patients with LVEF < 35 %. At this time, BiV pacing for antibradycardia therapy (irrespective of QRS duration) has to be individualized in the setting of a normal or decreased LVEF (> 35 %) and according to the expected percentage of RV pacing. The benefit of BiV pacing should be considered against procedural complications, which are more frequent than with traditional RV pacing.

Does a high percentage of right ventricular pacing influence the incidence of paroxysmal atrial fibrillation in myotonic dystrophy type 1 patients?

Paroxysmal atrial tachyarrhythmias occur frequently in myotonic dystrophy type 1 (MD1) patients. Pacemakers, implanted for the treatment of bradyarrhythmias and including detailed diagnostic functions, may facilitate the diagnosis and management of frequent paroxysmal atrial fibrillation (AF) that may remain undetected during a conventional clinical follow-up. The effect of right ventricular pacing on AF incidence is still controversial. To evaluate the influence of a high percentage of right ventricular pacing on AF in MD1 patients during a 12-month follow-up period. We enrolled in the present study 70 MD1 patients (age 51.3 ± 5 years; 32 females) who underwent dual chamber pacemaker implantation. At 12 months of follow-up, the study population was divided into three groups according to the percentage of atrial and ventricular stimulation: Group 1, the atrial sensing ventricular sensing group (ASVS; n = 22; age 52 ± 7.7; eight female) with a percentage of atrial and ventricular stimulation lower than 50%; Group 2, the atrial sensing ventricular pacing group (ASVP; n = 24; age 50.5 ± 7.6; 13 female) with a percentage of atrial stimulation lower than 50% and percentage of ventricular stimulation higher than 80%; and Group 3, the atrial pacing ventricular pacing group (APVP; n = 24; age 56 ± 4.3; 11 female) with a percentage of atrial and ventricular stimulation higher than 80%. We counted the number of episodes of atrial arrhythmia that occurred during the observation period and the duration of each episode. We found a statistically significant difference in the number and duration of AF episodes between the three groups at the 12-month follow-up. In particular, there were more episodes (253 ± 30 vs. 80 ± 27 vs. 53 ± 32; p < 0.03) and longer durations of AF (8,700 ± 630 vs. 4,480 ± 975 vs. 3,853 ± 870 min; p < 0.03) in the ASVP group than in the ASVS group and the APVP group. Lead parameters remained stable over time and there were no displacements of the electrodes after implantation. In a 12-month follow-up comparison, we showed a statistically significant increase in paroxysmal AF episodes in MD1 patients with a high percentage of right ventricular pacing and a lower percentage of atrial stimulation.

Hemodynamic Impact and Outcome of Permanent Pacemaker Implantation Following Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation (TAVI) frequently requires postprocedural permanent pacemaker (PPM) implantation. We evaluated clinical and hemodynamic impact of PPM after TAVI. Clinical and echocardiographic data were retrospectively analyzed in 230 consecutive patients who underwent TAVI and echocardiography at baseline and after 6 months. Echocardiographic parameters included left ventricular ejection fraction (LVEF), left ventricular (LV) stroke volume, early mitral velocity/annulus velocity ratio (E/e'), right ventricular index of myocardial performance, systolic pulmonary artery pressure (SPAP), and aortic, mitral, and tricuspid regurgitation grades. Clinical outcomes included 2-year survival and cardiovascular and PPM-related event-free survival. The Medtronic CoreValve and Edwards Sapien prosthesis were used in 201 and 29 patients, respectively. PPM was required in 58 patients (25.4%). Two-year and event-free survival rates were similar between patients with and without PPM. At 6 months, patients with PPM demonstrated attenuated improvement in LVEF (-0.9 ± 8.7% vs 2.3 ± 10.8%, respectively, p = 0.03) and LV stroke volume (-2 ± 16 vs 4 ± 10 ml/m(2), respectively, p = 0.015), a trend toward smaller reduction in systolic pulmonary artery pressure (-1 ± 12 vs -6 ± 10 mm Hg, respectively, p = 0.09), and deterioration of right ventricular index of myocardial performance (-3 ± 17% vs 5 ± 26%, respectively, p = 0.05). The differences in post-TAVI aortic, mitral, and tricuspid regurgitation grades were insignificant. In conclusion, PPM implantation after TAVI is associated with reduced LVEF and impaired LV unloading. However, this unfavorable hemodynamic response does not affect the 2-year clinical outcome. The maintenance of clinical benefit appears to be driven by TAVI-related recovery of LV and right ventricular performance that mitigates unfavorable impact of PPM.

Potential Prevention of Pacing‐Induced Heart Failure Using Simple Pacemaker Programming Algorithm

Right ventricular pacing (RVP) causes ventricular desynchronization and may lead to the development of heart failure (HF). Prolongation of atrioventricular delay (AVD) in DDDR pacemakers reduces unnecessary RV stimulation. The aim of the study was to verify the influence of RVP reduction on HF symptoms. The study comprised 31 patients (17 men, mean age: 71.6 ± 8 yrs) with DDDR pacemaker implanted due to sinus node dysfunction (SND). At baseline, 28 patients did not present any symptoms of HF. Three patients were in NYHA class II. Patients were randomized either to 150 ms AVD or to minimizing right ventricular pacing (MRVP). Crossing over to the alternate mode took place after 4 months. Cardiopulmonary exercise test (CPX), echocardiography (ECHO) and BNP measurements were done before pacemaker implantation, after 4 and 8 months. The percentage of RVP was significantly higher in 150 ms AVD than in MRVP: 81.7 ± 22.6 versus 14.2±20.5%, P < 0.0001. Patients with 150 ms mode had worse CPX parameters than those with MRVP mode: peak oxygen uptake was 14.2±4.3 versus 19.9±6.3 ml/kgper min, P = 0.0001, higher BNP concentrations: 72.3±48.3 versus 49.4±43.9 pg/ml, P = 0.001 and worse left ventricle [LV] function: ejection fraction: 53.2±6.7 versus 57.3±5.5%, P < 0.0001; LV diastolic diameter: 4.86±0.52 versus 4.66±0.5 cm, P < 0.01. Predominant RVP in patients without symptoms of HF at baseline may be responsible for worse performance in cardiopulmonary exercise test, higher BNP concentrations and impairment of LV function. Specific DDDR pacemaker programming promotes intrinsic AV conduction and may prevent the development of pacing-induced HF.

Eff ects of right ventricular pacing on left ventricular ejection fraction in a pacemaker clinic

Background The aim of this study was to evaluate whether a change of left ventricular ejection fraction (LVEF) depending on percentage of right ventricular pacing is found in a real-life setting of a pacemaker clinic.Methods and results 269 patients with either a pacemaker or an ICD and who are regularly followed at the pacemaker clinic of the Luzerner Kantonsspital participated in the study. We tested whether LVEF measured by echocardiography between the fi rst measurement at the time of the pacemaker implantation and the last measurement at the time of the last pacemaker control is dependent on the extent of ventricular pacing. Mean follow-up was 3.9 ± 2.9 years. Mean LVEF most signifi cantly decreased in the group of patients with baseline LVEF ≥ 45% and an extent of right ventricular pacing ≥ 66% (from 57.6 ± 7.2% to 53.1 ± 10.2%, P< 0.001). In patients with an extent of right ventricular pacing < 66% no decrease of LVEF was observed. Analysis of variance showed that LVEF decrease between the fi rst measurement at the time of the pacemaker implantation and the last measurement at the time of the last pacemaker control was dependent on the extent of right ventricular pacing, even if other factors such as age, gender and previous myocardial infarction are incorporated in the analysis.Conclusion In a real-life population of a pacemaker clinic right ventricular pacing was associated with a decrease in LVEF.

Atrial lead placement at the lower atrial septum: a potential strategy to reduce unnecessary right ventricular pacing

Right ventricular (RV) pacing has been shown to be potentially detrimental to left ventricular function. In conventional dual-chamber pacing the position of the atrial lead could influence duration of the atrio-ventricular (AV) intervals, which is one of the variables that could be associated with an increased percentage of RV pacing. We wanted to see if lead placement at selected atrial septal sites could reduce AV intervals in patients receiving a dual-chamber pacemaker or implantable cardioverter defibrillator. This was a prospective, acute, randomized single centre study that enrolled 57 patients. The atrial lead was placed in both the right atrial appendage (RAA) and the lower atrial septum (LAS) in each patient in random order. The P-wave durations, PR intervals, A sense-V sense (As-Vs), and A pace-V sense (Ap-Vs) intervals were measured at both atrial lead locations in each patient during device implant. The P-wave durations during sinus rhythm (SR), RAA pacing, and LAS pacing were 113 ± 19, 144 ± 27, and 84 ± 12 ms (RAA vs. LAS, P < 0.001), respectively. The PR intervals during SR, RAA pacing, and LAS pacing were 195 ± 47, 230 ± 61, and 167 ± 44 ms (RAA vs. LAS, P < 0.001), respectively. The As-Vs interval was 31% shorter in LAS pacing than in RAA pacing (134 ± 44 ms vs. 194 ± 52 ms, P < 0.001). The Ap-Vs interval was 24% shorter during LAS pacing than during RAA pacing (195 ± 45 ms vs. 257 ± 63 ms, P < 0.001). When compared with RAA pacing, LAS pacing was associated with a shorter P wave duration, PR interval, As-Vs, and Ap-Vs intervals. The potential long-term impact of the strategy of pacing from LAS in reducing unnecessary RV pacing needs to be explored in future studies.

154 Patients receiving standard pacemaker generator replacements frequently have impaired left ventricular function and exercise intolerance, related to the percentage of right ventricular pacing

<h3>Background</h3> Right ventricular (RV) pacing is an accepted treatment for symptomatic bradycardia. However, long-term RV pacing is increasingly recognised to be detrimental to left ventricular (LV) systolic function. We wanted to establish the prevalence, associated features and predictors of LV systolic dysfunction (LVSD) and outcome in a contemporary group of patients with long–term RV pacemakers. <h3>Methods</h3> We prospectively recruited consecutive patients listed for PGR between 2008 and 2010 at Leeds General Infirmary. We performed echocardiography, exercise testing and recorded indications for pacing, pacing variables and duration of pacing, co-morbidities, current medication and renal function. <h3>Results</h3> Of 399 PGR procedures 342 subjects (86%), 184 men, attended. Non-attendees had similar pacing variables and were of similar age as attendees. Mean age (SE) was 76 (1), and mean duration of pacing was 10 (0.3) years. Comorbidites were common: diabetes mellitus in 11%, previous myocardial infarction in 15%, previous cardiac surgery in 26% and atrial fibrillation (AF) in 26%. Medical therapy included β-blockers in 60% and ACE inhibitors in 70%. Dual chamber devices were implanted in 77% (45% of all patients had rate responsive (RR) pacing programmed). Mean percentage of ventricular pacing (%VP) was 61 (2)%. Mean left ventricular ejection fraction (LVEF) was 49 (1)%, (44% had an LVEF &lt;50%). Mean peak oxygen uptake (pVo₂) (in 107 subjects) was 17 (1) ml/kg/min and mean creatinine was 108 (3) μmol/l. There was an inverse relationship between LVEF and %VP (0.42; p&lt;0.0001), and years since first implanted (p=0.09) but there was no effect on LVEF of age, the presence of AF and the pacing mode. In single chamber devices, RR pacing was associated with higher %VP (p=0.01), and a trend to worse LVEF (p=0.09). These differences were not seen in RR programmed dual chamber devices. There was a negative relationship between pVo₂ and %VP (r=0.21; p&lt;0.03). Even with a short follow-up period of 16 (0.5) months, 23 (7%) patients are dead. Patients dead at the censor date were older at the time of the assessment (p&lt;0.005), had a higher %VP (p&lt;0.03) and worse renal function (p&lt;0.001), but did not have significantly worse LVEF or pVo₂. The presence of a single chamber device was associated with a poorer outcome (p&lt;0.002) despite patients with a single chamber device being of similar age as those with a dual chamber device. <h3>Conclusions</h3> Patients receiving standard pacemaker generator replacements frequently have cardiovascular comorbidities, left ventricular dysfunction and impaired pVo₂ and suffer a high mortality rate. In an unselected population of patients with pacemakers, we have established that the amount of RV pacing is related not only to important surrogate measures of outcome such as exercise tolerance and LVEF but also mortality. Whether an aggressive policy of limiting RV pacing in patients at risk reduces mortality is unknown.

Reduction of Right Ventricular Pacing with Advanced Atrioventricular Search Hysteresis: Results of the PREVENT Study

Right ventricular pacing predisposes to the development of heart failure and atrial fibrillation. Automatic atrioventricular search hysteresis (AVSH) is a commonly used strategy to decrease the percentage of right ventricular pacing (%VP) in patients without permanent AV block, but the results have not been optimal. The randomized, crossover PREVENT study evaluated whether an enhanced AVSH with two new features can reduce %VP compared with standard AVSH. The new features are the repetitive hysteresis [switch from extended to basic AV delay after a consistent loss of intrinsic AV conduction (IAVC) lasting for six consecutive atrial cycles] and the scan hysteresis (periodic IAVC search extension over six consecutive atrial cycles). Both standard AVSH and enhanced AVSH performed a periodic IAVC search every 180 cardiac cycles and operated with a basic AV-delay of 225 ms and a rate-independent maximum AV-delay of 300 ms for paced and sensed atrial events. Among 178 patients, 53.4% had no evidence of AV block at enrollment and 46.6% had history of intermittent AV block. The median %VP was decreased by enhanced AVSH compared to standard AVSH (4.0% vs 5.5%, P < 0.001), particularly in patients with a history of AV block (21.4% vs 25.5%, P < 0.001). The primary study hypothesis that 25% of all patients would experience > 20% relative %VP reduction was not met as 46 (25.8%) patients (95% confidence interval, 20.5-31.8%) presented such relative reduction. The enhanced AVSH algorithm reduces %VP compared with standard AVSH in patients with intermittent AV block.

Prevention of atrial fibrillation by prevention of ventricular pacing?

This editorial refers to ‘The relationship between right ventricular pacing and atrial fibrillation burden and disease progression in patients with paroxysmal atrial fibrillation: the long-MinVPACE study’ by R.A. Veasey et al., on page 815. Atrial fibrillation (AF) is a frequent problem after pacemaker implantation. It is likely that paroxysmal AF had occurred in many patients before pacemaker insertion but was documented for the first time by stored atrial electrograms of dual-chamber devices. On the other hand, pacing from the right atrial appendage may promote the development of AF by mechanisms such as increased dispersion of atrial refractoriness, or scar tissue formation around the implanted atrial lead. The development of permanent AF after pacemaker implantation for sinus node disease even raises the question whether the device is still needed in this situation. 1 Randomized controlled trials have demonstrated that the incidence of AF is higher with asynchronous right ventricular pacing in the VVI(R) mode compared with dual-chamber pacing. 2 A post hoc analysis of the Mode Selection Trial (MOST) suggested that right ventricular pacing may be responsible for the development of AF, at least in patients with sinus node disease and narrow QRS. 3 In this analysis, a linear association between the percentage of right ventricular pacing and the risk of developing AF was observed especially for dual-chamber pacing. Reports on the development of heart failure with right ventricular pacing confirm and extend these concerns on the risks of unnecessary right ventricular pacing. Can this ‘proarrhythmic’ effect of pacing be prevented? It has been suggested that biventricular pacing might reduce the risk of developing AF with pacing. 4 Post hoc analyses 5 and small studies, 6 however, did not find a reduction in the incidence of AF with cardiac resynchronization therapy compared with right ventricular pacing or standard medical care. In contrast, the systematic prevention of unnecessary right ventricular pacing, facilitated by the use of dedicated pacing algorithms, seems to be associated with a reduction in the occurrence of AF. In the randomized Search AV Extension and managed ventricular Pacing for Promoting Atrioventricular Conduction (SAVE-PACe) trial, prevention of unnecessary right ventricular pacing (present during an average of 99% of the time in the conventional pacing group) was associated with a 40% relative risk reduction for the development of persistent AF. 3 Pacing used to prevent AF has been disappointing in most randomized trials. 7 – 9 In retrospect, this may have been caused by right ventricular pacing that may increase the risk of developing AF. Also biventricular pacing does not seem promising in the prevention of AF. 10 It raises the question: can pacing be more effective in the prevention of AFn if right ventricular pacing is prevented? Some analyses suggest that the reduction in right ventricular pacing may enhance the ability of atrial pacing to prevent AF. In the Pacing In Prevention of Atrial Fibrillation (PIPAF) trial, patients paced in the right ventricle for ,42% of the time had a significant reduction of the cumulative time in AF during atrial preventive pacing, while this effect was absent in patients paced in the ventricle for more than this. 11 In a single-centre experience in 153 patients, right ventricular pacing for ,40% of the time after 1 month was associated with a significantly lower mean AF burden during the following 5 years. 12 In fact, in these patients, AF burden was 6–11% compared with 22– 32% in patients who were paced in the right ventricle for .40% of the time. Other studies did not find this association. In a post hoc analysis in 331 patients from the Atrial Fibrillation Therapy (AFT) trial, AF burden was weakly associated with the percentage of right ventricular pacing with a 0.03% increase in AF burden for every 10% of right ventricular pacing. 13 However, the median percentage of right ventricular pacing in this trial was 97%, rendering any extrapolation questionable. In the same report, data from 79 patients of the Pacemaker Atrial Fibrillation Suppression (PAFS) trial showed no association between the percentage of right ventricular pacing and AF burden. However, the PAFS study consisted of four short (4 weeks each) cross-over study periods with different pacing modalities. Likely, these periods were too short, and there might have been significant carry-over effects. An

Left ventricular dysfunction due to right ventricular stimulation: is biventricular upgrade really necessary?

Left ventricular (LV) dysfunction can occur due to chronic right ventricular apical pacing. Upgrading of the pacemaker to biventricular pacing is an option to reverse LV dysfunction but reprogramming of the atrioventricular (AV) timing can also be favourable. In this case report we describe the effect of AV-time reprogramming in a patient with LV function deterioration that emerged two years after implantation of a dual chamber system for sick sinus syndrome. Echocardiographc studies demonstrated a tremendous improvement in LV function during two years follow-up whereas the percentage of right ventricular pacing diminished dramatically. Careful analysis of the cause of LV deterioration can avoid unnecessary upgrading to biventricular pacing. (Neth Heart J 2010;18:604-5.).

Response to Letters Regarding Article, “Heart Rate Predicts Outcomes in an Implantable Cardioverter-Defibrillator Population”

On the basis of our findings,1 Drs Fazio and Carlomagno and Dr Lin and colleagues considered that a J-shaped relationship may exist between heart rate and outcomes. Like the U-shaped relationship we saw with an increasing percentage of right ventricular pacing and outcomes,2 we suspected that a J- or U-shaped relationship may exist between heart rate and outcomes. However, we could not discern with certainty that the slowest heart rates were associated with worse outcomes even though a trend in that direction appeared. Dr Lin and colleagues also suspected that a J-shaped relationship may …

Catheter Ablation versus Standard Conventional Treatment in Patients with Left Ventricular Dysfunction and Atrial Fibrillation (CASTLE‐AF) ‐ Study Design

Electrical isolation of the pulmonary veins by catheter ablation is an emerging treatment modality for the treatment of atrial fibrillation (AF) and is increasingly used in patients with heart failure. The catheter ablation versus standard conventional treatment in patients with left ventricular dysfunction and atrial fibrillation trial (CASTLE-AF) is a randomized evaluation of ablative treatment of atrial fibrillation in patients with left ventricular dysfunction. The primary endpoint is the composite of all-cause mortality or worsening of heart failure requiring unplanned hospitalization using a time to first event analysis. Secondary endpoints are all-cause mortality, cardiovascular mortality, cerebrovascular accidents, worsening of heart failure requiring unplanned hospitalization, unplanned hospitalization due to cardiovascular reason, all-cause hospitalization, quality of life, number of therapies (shock and antitachycardia pacing) delivered by the implantable cardioverter-defibrillator (ICD), time to first ICD therapy, number of device-detected ventricular tachycardia and ventricular fibrillation episodes, AF burden, AF free interval, left ventricular function, exercise tolerance, and percentage of right ventricular pacing. CASTLE-AF will randomize 420 patients for a minimum of 3 years at 48 sites in the United States, Europe, Australia, and South America.

Are We Overestimating Percentage of Right Ventricular Pacing in Patients with Implantable Cardioverter Defibrillators?

Are We Overestimating Percentage of Right Ventricular Pacing in Patients with Implantable Cardioverter Defibrillators?

AB7-3: CPAP therapy causes a reduction in atrial fibrillation burden, due to a decrease in the percentage of right ventricular pacing in patients with congestive heart failure and obstructive sleep apnea

AB7-3: CPAP therapy causes a reduction in atrial fibrillation burden, due to a decrease in the percentage of right ventricular pacing in patients with congestive heart failure and obstructive sleep apnea

Reduction of Right Ventricular Pacing in Patients with Dual‐Chamber ICDs

Unnecessary right ventricular (RV) pacing in patients with implantable cardioverter defibrillators (ICD) may adversely affect heart failure morbidity and total mortality. Inhibition of Unnecessary RV Pacing with AV Search Hysteresis in ICDs (INTRINSIC RV) is a prospective, multicenter, randomized trial evaluating outcomes in ICD recipients programmed to single-chamber pacing (VVI) versus dual-chamber (DDDR) pacing with AV search hysteresis (AVSH). Patients underwent ICD implant (for standard indications). The ICD was programmed to DDDR with AVSH regardless of any need for pacing. Rate-adaptive pacing was set at 60-130 ppm with dynamic AV delay from 200 to 90 ms. AVSH was programmed to search every 32 intervals and extend the AV delay by 50%. One week post-implant patients with ICDs were interrogated to assess the percentage of RV pacing with the expectation that most would have <20% RV pacing and would be randomized into INTRINSIC RV. Early analysis showed that targets for randomization were not met. AVSH parameters were modified under a protocol amendment to increase AV delay extension to 100%. We report findings related to this programming change based upon analyses of (nonrandomized) data pre- and post-amendment. Twenty-one percent of patients (n = 314) were enrolled pre-amendment and 79% (n = 1,216) were enrolled post-amendment. The mean percentage of RV pacing at the 1-week visit was 41.4 +/- 29.6% pre-amendment and 14.7 +/- 22.6% post-amendment (P < 0.0001). The proportion of patients eligible for randomization (RV pacing <20% at the 1-week visit) was 31.2% pre-amendment and 76.8% post-amendment (P < 0.0001). AVSH can dramatically reduce the percentage of RV pacing among ICD recipients.