Atrioventricular Delay Programming Research Articles

Electrocardiographic imaging demonstrates electrical synchrony improvement by dynamic atrioventricular delays in patients with left bundle branch block and preserved atrioventricular conduction.

Cardiac resynchronization therapy programmed to dynamically fuse pacing with intrinsic conduction using atrioventricular (AV) timing algorithms (e.g. SyncAV) has shown promise; however, mechanistic data are lacking. This study assessed the impact of SyncAV on electrical dyssynchrony across various pacing modalities using non-invasive epicardial electrocardiographic imaging (ECGi). Twenty-five patients with left bundle-branch block (median QRS duration (QRSd) 162.7 ms) and intact AV conduction (PR interval 174.0 ms) were prospectively enrolled. ECGi was performed acutely during biventricular pacing with fixed nominal AV delays (BiV) and using SyncAV (optimized for the narrowest QRSd) during: BiV + SyncAV, LV-only single-site (LVSS + SyncAV), MultiPoint pacing (MPP + SyncAV), and LV-only MPP (LVMPP + SyncAV). Dyssynchrony was quantified via ECGi (LV activation time, LVAT; RV activation time, RVAT; LV electrical dispersion index, LVEDi; ventricular electrical uncoupling index, VEU; and biventricular total activation time, VVtat). Intrinsic conduction LVAT (124 ms) was significantly reduced by BiV pacing (109 ms) (P = 0.001) and further reduced by LVSS + SyncAV (103 ms), BiV + SyncAV (103 ms), LVMPP + SyncAV (95 ms), and MPP + SyncAV (90 ms). Intrinsic RVAT (93 ms), VVtat (130 ms), LVEDi (36 ms), VEU (50 ms), and QRSd (163 ms) were reduced by SyncAV across all pacing modes. More patients exhibited minimal LVAT, VVtat, LVEDi, and QRSd with MPP + SyncAV than any other modality. Dynamic AV delay programming targeting fusion with intrinsic conduction significantly reduced dyssynchrony, as quantified by ECGi and QRSd for all evaluated pacing modes. MPP + SyncAV achieved the greatest synchrony overall but not for all patients, highlighting the value of pacing mode individualization during fusion optimization.

Acute hemodynamic impact of atrioventricular delay and left ventricular pacing vector programming in MultiPoint Pacing.

The benefits of cardiac resynchronization therapy (CRT) in heart failure patients have been shown to depend on device programming, particularly atrioventricular delay (AVD) and left ventricular (LV) pacing site selection. This study compared the hemodynamic AVD optimization for commonly used biventricular (BiV) and MultiPoint Pacing(MPP, Abbott) LV vector selection strategies. After de novo CRT-D (Abbott Quadra Assura MP) and quadripolar LV lead (Abbott Quartet) implant, acute LV pressure was measured across a range of AVDs (60-225 ms) in four pacing modes: BiV with most proximal cathode, BiV with most distal cathode, MPP using two cathodes with earliest and latest right ventricle (RV)-LV activation times, and MPP using two cathodes with maximal anatomical separation. Hemodynamic improvement was evaluated by changes in maximum LV pressure first-derivative versus RV pacing (ΔdP/dt). Twenty patients (64 years old, 68% male) completed the acute pacing protocol at six centers in China. Hemodynamic improvement versus RV pacing for BiV (proximal), BiV (Distal), MPP (electrical), and MPP (anatomical) was 22.1% ± 13.6%, 23.7% ± 13.4%, 24.5% ± 13.4%, and 25.1% ± 13.9%, respectively. The best MPP setting was marginally superior to the best BiV across all patients (25.8% ± 13.4% vs. 24.5% ± 13.1%, p = .040) and in the majority of patients (75.0% vs. 25.0%, p = .004). AVD programmed as little as 20 ms from optimum significantly reduced the ΔdP/dt benefit for all modes. The maximal hemodynamic improvement across AV delays in this population was greater with MPP than BiV. Furthermore, patient-specific AVD programming was critical in achieving the full hemodynamic response for all BiV and MPP modes.

Dynamic atrioventricular delay programming improves ventricular electrical synchronization as evaluated by 3D vectorcardiography

BackgroundOptimal timing of the atrioventricular delay in cardiac resynchronization therapy (CRT) can improve synchrony in patients suffering from heart failure. The purpose of this study was to evaluate the impact of SyncAV™ on electrical synchrony as measured by vectorcardiography (VCG) derived QRS metrics during bi-ventricular (BiV) pacing. MethodsPatients implanted with a cardiac resynchronization therapy (CRT) device and quadripolar left ventricular (LV) lead underwent 12‑lead ECG recordings. VCG metrics, including QRS duration (QRSd) and area, were derived from the ECG by a blinded observer during: intrinsic conduction, BiV with nominal atrioventricular delays (BiV Nominal), and BiV with SyncAV programmed to the optimal offset achieving maximal synchronization (BiV + SyncAV Opt). ResultsOne hundred patients (71% male, 40% ischemic, 65% LBBB, 32 ± 9% ejection fraction) completed VCG assessment. QRSd during intrinsic conduction (166 ± 25 ms) was narrowed successively by BiV Nominal (137 ± 23 ms, p < .05 vs. intrinsic) and BiV + SyncAV Opt (122 ± 22 ms, p < .05 vs. BiV Nominal). Likewise, 3D QRS area during intrinsic conduction (90 ± 42 mV ∗ ms) was reduced by BiV Nominal (65 ± 39 mV ∗ ms, p < .05 vs. intrinsic) and further by BiV + SyncAV Opt (53 ± 30 mV ∗ ms, p = .06 vs. BiV Nominal). ConclusionWith VCG-based, patient-specific optimization of the programmable offset, SyncAV reduced electrical dyssynchrony beyond conventional CRT.

Badanie EKG metodą Holtera u chorego z urządzeniem wszczepialnym — przykłady algorytmów ograniczających stymulację prawej komory

High percentage of right ventricular pacing is associated with an increased risk of adverse clinical events such as worsening of heart failure symptoms or atrial fibrillation. Right ventricular pacing should be minimized especially in patients with heart failure and reduced left ventricular ejection fraction after implantation of one- or two-chamber cardioverter-defibrillator. Adequate atrioventricular delay programming or appropriate pacing mode programming that promotes patients own rhythm for example AAI/DDD or DDD/ADI helps in avoiding right ventricular pacing. There are special algorithms, different between pacemaker-producing companies, basing on the above methods that spare right ventricular pacing. Some of those algorithms can mimic pacemaker dysfunction and can be a challenge during Holter electrocardiogram (ECG) interpretations. In this article Holter ECG examples of different algorithms to reduce right ventricle pacing are presented and discussed.

Young Investigator Award session: Basic Science311Intraventricular flow patterns after percutaneous mitral valve repair with MitraClip implantation312Papillary muscles contribute significantly to shortening of dilated left ventricles313Relationship between cardiac uptake by 99mTc-DPD scintigraphy and left ventricular longitudinal strain in patients with transthyretin-related cardiac amyloidosis314Premature ventricular contraction in resynchronized patients with short atrio-ventricular delay: hemodynamic impact beyond A-wave truncation

Young Investigator Award session: Basic Science311Intraventricular flow patterns after percutaneous mitral valve repair with MitraClip implantation312Papillary muscles contribute significantly to shortening of dilated left ventricles313Relationship between cardiac uptake by 99mTc-DPD scintigraphy and left ventricular longitudinal strain in patients with transthyretin-related cardiac amyloidosis314Premature ventricular contraction in resynchronized patients with short atrio-ventricular delay: hemodynamic impact beyond A-wave truncation

Atrioventricular delay programming and the benefit of cardiac resynchronization therapy in MADIT-CRT

The optimal atrioventricular pacing delay (AVD) in cardiac resynchronization therapy (CRT) remains to be determined. To determine whether programming CRT devices to short AVD (S-AVD) will improve clinical response secondary to greater reductions in dyssynchrony. The study population comprised 1235 patients with left bundle branch block enrolled in Multicenter Automatic Defibrillator Implantation Trial in Cardiac Resynchronization Therapy (MADIT-CRT). We assessed the relationship between AVD and outcomes. Patients programmed to S-AVD (median value of <120 ms; n = 337) vs long AVD (L-AVD; ≥120 ms; n = 390) were assessed for the end points of heart failure (HF) or death, death alone, and echocardiographic response to the CRT at 1-year follow-up. Outcomes were also compared to the left bundle branch block implantable cardioverter-defibrillator-only group (n = 508). Multivariate analysis showed that patients programmed to S-AVD experienced a significant 33% (hazard ratio [HR] 0.67; 95% confidence interval [CI] 0.44-0.85; P = .037) reduction in the risk of HF or death and a 47% (HR 0.53; 95% CI 0.29-0.94; P = .031) reduction in death alone as compared with those programmed to L-AVD. Patients with CRT-programmed S-AVD and L-AVD experienced 63% (HR 0.37; 95% CI 0.26-0.53; P < .001) and 46% (HR 0.54; 95% CI 0.31-0.96; P < .001) reduction, respectively, in the risk of HF or death compared to patients with implantable cardioverter-defibrillator alone. At 1 year of follow-up, S-AVD vs L-AVD was associated with a greater reduction in left ventricular end-systolic volume (34.2% vs 30.8%; P = .002) along with a significantly greater improvement in dyssynchrony (22.3% vs 9.4%; P = .036). Our findings indicate that in MADIT-CRT programming, the CRT AVD <120 ms was associated with a greater clinical and echocardiographic response to CRT.

Atrioventricular delay programming in cardiac resynchronization therapy devices: fixed or adaptive?: A randomized monocenter trial

IntroductionCardiac resynchronization therapy devices are routinely programmed on fixed atrioventricular delays (AVD) under resting conditions based on echocardiographic techniques. Whether this AVD also ensures optimal exercise hemodynamics, is unclear. MethodsIn order to compare fixed-AVD with rate-adaptive AVD, 100 patients with cardiac resynchronization therapy systems and sinus rhythm were randomized to fixed-AVD or adaptive-AVD. The patients then underwent bicycle ergometry with noninvasive hemodynamic monitoring. At rest and at peak exercise, stroke volume, cardiac output, and cardiac index were determined using “electrical velocimetry.” ResultsThere were no significant differences in clinical characteristics and baseline hemodynamic parameters between fixed or adaptive AVD. In patients randomized to adaptive AVD, a trend towards higher stroke volume, cardiac output, and cardiac index at peak exercise was encountered. ConclusionsBased on the trend towards better exercise hemodynamics demonstrated by this pilot study, a randomized follow-up study with clinical end points appears to be justified to clarify this issue.

Contemporary and future trends in cardiac resynchronization therapy to enhance response

The rationale for cardiac resynchronization therapy (CRT), expectations in terms of patient benefit, patient selection for CRT, selection of a CRT pacemaker (CRT-P) vs CRT plus implantable cardioverter-defibrillator (CRT-D) platform, and studies evaluating device programming to enhance benefit from CRT are reviewed. The notion of an "optimal" left ventricular (LV) pacing site, the rationale for identifying and avoiding LV pacing in regions of scar, the use of anatomic, hemodynamic, and electrical parameters to identify an optimal LV pacing site, and the potential utility of multisite LV pacing to enhance benefit from CRT are discussed. Finally, the advantages and disadvantages of the various methods for LV lead delivery are reviewed.

Response to Letter Regarding Article, “Primary Results From the SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial: A Randomized Trial Comparing Empirical, Echocardiography-Guided and Algorithmic Atrioventricular Delay Programming in Cardiac Resynchronization Therapy”

We appreciate the authors' careful review of our manuscript and prepared the following response to their comments. The first comment is that the SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) trial was underpowered to detect the additional response to atrioventricular (AV) optimization. Importantly, the authors performed a post hoc power calculation, basing their calculations on the observed fixed-group response. These calculations do not have the same validity as prospective power calculations and must be interpreted with great caution.1 Second, the noninferiority margin of 15 mL for a left ventricular end-systolic volume difference from baseline to 6 months post–cardiac resynchronization therapy was …

Letter by Shanmugam et al Regarding Article, “Primary Results From the SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial: A Randomized Trial Comparing Empirical, Echocardiography-Guided, and Algorithmic Atrioventricular Delay Programming in Cardiac Resynchronization Therapy”

To the Editor: We read with great interest the recent article by Ellenbogen et al,1 who compare atrioventricular optimization (AVOpt) in cardiac resynchronization therapy (CRT) with a fixed atrioventricular (AV) delay. Using improvement in left ventricular end-systolic volume (LVESV) at 6 months as the primary end point, the authors conclude that the routine use of AV optimization is no longer warranted. We believe that the study was underpowered to detect the additional response to AVOpt. In the sample size calculation the authors assumed a standard deviation of 60 mL and an expected response to CRT of a 30-mL reduction in LVESV. They then assumed a …

Echocardiographic Effects of Changing Atrioventricular Delay in Cardiac Resynchronization Therapy Based on Displacement

In studies showing benefits of cardiac resynchronization therapy (CRT), individual atrioventricular (AV) delays have been optimized using echocardiography. However, the method for AV delay optimization remains controversial. In 100 consecutive patients with CRT device implantation, AV delay was optimized using echocardiography. The optimal AV delay was determined by changing the interval in 20-ms increments while measuring displacement in 6 basal left ventricular segments (averaged and reported as left ventricular displacement [D(LV)]) and other echocardiographic measures. A single optimal AV delay existed for each patient, and the associated highest D(LV) corresponded with the maximal velocity-time integral (VTI) in the left ventricular outflow tract (VTI(LVOT)) and the E/e' ratio. Significant increases in D(LV) and the VTI(LVOT) from before to after implantation with standard settings and from standard to optimal AV delay by displacement were found. Diastolic filling time corresponded poorly with D(LV) and the VTI(LVOT). Individual optimal AV delay programming provides significant improvement in left ventricular performance and hemodynamics. Displacement analysis and the VTI(LVOT) are interchangeable, whereas diastolic filling time cannot be recommended.

Novel insights on effect of atrioventricular programming of biventricular pacemaker in heart failure – a case series

BackgroundEchocardiography plays an integral role in the diagnosis of congestive heart failure including measurement of left heart pressure as well as mechanical dyssynchrony.MethodsIn this report we describe novel therapeutic uses of echo pulsed wave Doppler in atrioventricular pacemaker optimization in patients who had either not derived significant symptomatic benefit post biventricular pacemaker implantation or deteriorated after deriving initial benefit. In these patients atrioventricular optimization showed novel findings and improved cardiac output and symptoms.ResultsIn 3 patients with Cheyne Stokes pattern of respiration echo Doppler showed worsening of mitral regurgitation during hyperpneac phase in one patient, marked E and A fusion in another patient and exaggerated ventricular interdependence in a third patient thus highlighting mechanisms of adverse effects of Cheyne Stokes respiration in patients with heart failure. All 3 patients required a very short atrioventricular delay programming for best cardiac output. In one patient with recurrent congestive heart failure post cardiac resynchronization, mitral inflow pulse wave Doppler showed no A wave until a sensed atrioventricular delay of 190 ms was reached and showed progressive improvement in mitral inflow pattern until an atrioventricular delay of 290 ms. In 2 patients atrioventricular delay as short as 50 ms was required to allow E and A separation and prevent diastolic mitral regurgitation. All patients developed marked improvement in congestive heart failure symptoms post echo-guided biv pacemaker optimization.ConclusionThese findings highlight the value of echo-guided pacemaker optimization in symptomatic patients post cardiac resynchronization treatment.

Randomized prospective trial of atrioventricular delay programming for cardiac resynchronization therapy

The purpose of this study was to determine if AV delay optimization with continuous-wave Doppler aortic velocity-time integral (VTI) is clinically superior to an empiric program in patients treated with cardiac resynchronization therapy (CRT) for severe heart failure. The impact of AV delay programming on clinical outcomes associated with CRT is unknown. A randomized, prospective, single-blind clinical trial was performed to compare two methods of AV delay programming in 40 patients with severe heart failure referred for CRT. Patients were randomized to either an optimized AV delay determined by Doppler echocardiography (group 1, n = 20) or an empiric AV delay of 120 ms (group 2, n = 20) with both groups programmed in the atriosynchronous biventricular pacing (VDD) mode. Optimal AV delay was defined as the AV delay that yielded the largest aortic VTI at one of eight tested AV intervals (between 60 and 200 ms). New York Heart Association (NYHA) functional classification and quality-of-life (QOL) score were compared 3 months after randomization. Immediately after CRT initiation with AV delay programming, VTI improved by 4.0 +/- 1.7 cm vs 1.8 +/- 3.6 cm (P < .02), and ejection fraction (EF) increased by 7.8 +/- 6.2% vs 3.4 +/- 4.4% (P < .02) in group 1 vs group 2, respectively. After 3 months, NYHA classification improved by 1.0 +/- 0.5 vs 0.4 +/- 0.6 class points (P < .01), and QOL score improved by 23 +/- 13 versus 13 +/- 11 points (P < .03) for group 1 vs group 2, respectively. Echocardiography-guided AV delay optimization using the aortic Doppler VTI improves clinical outcomes at 3 months compared to an empiric AV delay program of 120 ms.

Intrinsic Conduction Maximizes Cardiopulmonary Performance in Patients with Dual Chamber Pacemakers

Dual chamber pacemaker programmability allows the possibility of atrially-tracked ventricular pacing in patients who would otherwise have intrinsic atrioventricular (AV) conduction. Thirteen patients with permanent AV sequential pacemakers (ages 50-79) were evaluated with paired exercise tests to determine the cardiopulmonary effects of pacemaker induced right ventricular activation compared with normal AV and intraventricular conduction. Peak oxygen uptake (VO2), oxygen pulse (O2P), respiratory rate (RR), and respiratory exchange ratio (RER) were determined using breath-by-breath analysis of expired gases. Patients exercised to fatigue and exercise tests were performed in random sequence. For patients with intrinsic AV conduction (group I, n = 8) the AV delay was programmed to preserve intrinsic conduction during one study; the alternate test used AV delay programming to produce ventricular pacing. Five patients with chronic AV block (group II) acted as a control for the effects of a rate adaptive AV delay compared to a fixed AV delay. Paired t-testing showed a significantly lower peak VO2 (P less than 0.015) and O2P (P less than 0.01) in patients with atrially-tracked ventricular pacing compared to intrinsic conduction. In contrast, group II showed a significant improvement in peak VO2 with rate adaptive AV delay compared to fixed AV delay programming (P less than 0.05). In conclusion, intrinsic conduction should be preserved in patients with dual chamber pacemakers whenever possible.