Multipoint pacing is associated with improved prognosis and cardiac resynchronization therapy response. MORE-CRT MPP randomized study secondary analyses.

BACKGROUND AND AIMS: Cardiac resynchronization therapy (CRT) via biventricular (BIV) pacing is indicated in patients with heart failure (HF), reduced ejection fraction and prolonged QRS duration. Quadripolar leads and MultiPoint Pacing (MPP) allow multiple left ventricle (LV) sites pacing. We aimed to assess clinical benefit of MPP in patients who do not respond to standard BIV pacing. METHODS: Overall 3724 patients were treated with standard BIV pacing. After 6 months, 1639 patients were considered as CRT non-responders (echo-measured relative reduction in LV end-systolic volume (LVESV) < 15%) and randomized to MPP or BIV. RESULTS: We analysed 593 randomized patients (291 MPP, 302 BIV), who had BIV pacing >97% of time before randomization and complete 12-months clinical and echocardiographic data. The endpoint, composed by freedom from cardiac death and HF hospitalizations, and by LVESV relative reduction ≥15% between randomization and 12 months, occurred more frequently in MPP (96/291 (33.0%)) vs. BIV (71/302 (23.5%), p = 0.0103), also confirmed at multivariate analysis (hazard ratio = 1.55, 95% confidence interval = 1.02-2.34, p = 0.0402 vs. BIV). HF hospitalizations occurred less frequently in MPP (14/291 (4.81%)) vs. BIV (29/302 (9.60%), incidence rate ratio = 50%, p = 0.0245). Selecting patients with large (>30 ms) dispersion of interventricular electrical delay among the 4 LV lead dipoles, reverse remodeling was more frequent in MPP (18/51 (35.3%)) vs. BIV (11/62 (17.7%), p = 0.0335). CONCLUSION: In patients who do not respond to standard CRT, despite high BIV pacing percentage, MPP is associated with lower occurrence of HF hospitalizations and higher probability of reverse LV remodeling, compared with BIV pacing.

Performance of the quadripolar CRT-D system: Five-year results from the Quadripolar Pacing Post-Approval Study.

BACKGROUND: Cardiac resynchronization therapy (CRT) is associated with challenges such as elevated capture thresholds, diaphragmatic stimulation, and lead instability. OBJECTIVE: This study aimed to assess the long-term safety and efficacy of the quadripolar CRT-defibrillator (CRT-D) device system with the Quartet 1458Q left ventricular (LV) lead in a CRT-indicated population observed for 5 years and to evaluate all-cause mortality and impact of baseline characteristics on survival through 5 years. METHODS: Patients indicated for a CRT-D system were observed every 6 months after implantation for 5 years, and device performance and adverse events were assessed at each visit. The 3 primary end points were freedom from quadripolar CRT-D system-related complications through 5 years, freedom from Quartet 1458Q LV lead-related complications through 5 years, and mean programmed pacing capture threshold at 5 years. RESULTS: The study enrolled 1970 participants at 71 sites. The quadripolar CRT-D system was successfully implanted in 97.2% of participants. Freedom from quadripolar CRT-D device system-related complications through 5 years was 89.7%. Freedom from Quartet 1458Q LV lead-related complications through 5 years was 95.7%; 3.49% of participants had LV lead-related complications, and an overall LV lead complication rate was 0.0122 event per patient-year. The mean LV pacing capture threshold was 1.52 ± 1.01 V at 5 years. The 5-year survival rate was 67.4%. CONCLUSION: The quadripolar CRT-D system with the Quartet 1458Q LV lead exhibited low rates of complications and stable electrical performance through 5 years of follow-up and suggested a higher 5-year survival rate compared with traditional CRT systems.

Clinical Usefulness of the Active Fixation Quadripolar Left Ventricular Lead Compared With the Passive Fixation Quadripolar Lead in Cardiac Resynchronization Therapy.

BACKGROUND: This study compared the stability of the Medtronic Attain Stability Quad (ASQ), a novel quadripolar active fixation left ventricular (LV) lead with a side helix, to that of conventional quadripolar leads with passive fixation (non-ASQ) and evaluated their LV lead performance. METHODS AND RESULTS: In all, 183 consecutive patients (69 ASQ, 114 non-ASQ) who underwent cardiac resynchronization therapy (CRT) between January 2018 and June 2021 were enrolled. Complications, including elevated pacing capture threshold (PCT) levels, phrenic nerve stimulation (PNS), and LV lead dislodgement, were analyzed during the postimplantation period until the first outpatient visit after discharge. The frequency of LV lead-related complications was significantly lower in the ASQ than non-ASQ group (14% vs. 30%, respectively; P=0.019). Specifically, LV lead dislodgement occurred only in the non-ASQ group, and elevated PCT levels were significantly lower in the ASQ group (7% vs. 23%; P=0.007). Kaplan-Meier analysis confirmed a significantly lower incidence of LV lead-related complications in the ASQ group (log-rank P=0.005). Cox multivariable regression analysis showed a significant reduction in lead-related complications associated with ASQ (hazard ratio 0.44; 95% confidence interval 0.23-0.83; P=0.011). CONCLUSIONS: The ASQ group exhibited fewer LV lead-related complications requiring reintervention and setting changes than the non-ASQ group. Thus, the ASQ may be a favorable choice for CRT device implantation.

Cardiac resynchronization therapy non-responder to responder conversion rate in the MORE-CRT MPP trial.

AIMS: To assess the impact of MultiPoint™ Pacing (MPP) in cardiac resynchronization therapy (CRT) non-responders after 6 months of standard biventricular pacing (BiVP). METHODS AND RESULTS: The trial enrolled 5850 patients who planned to receive a CRT device. The echocardiography core laboratory assessed CRT response before implant and after 6 months of BiVP; non-response to BiVP was defined as <15% relative reduction in left ventricular end-systolic volume (LVESV). Echocardiographic non-responders were randomized in a 1:1 ratio to receive MPP (541 patients) or continued BiVP (570 patients) for an additional 6 months and evaluated the conversion rate to the echocardiographic response. The characteristics of both groups at randomization were comparable. The percentage of non-responder patients who became responders to CRT therapy was 29.4% in the MPP arm and 30.4% in the BIVP arm (P = 0.743). In patients with ≥30 mm spacing between the two left ventricular pacing sites (MPP-AS), identified during the first phase as a potential beneficial subgroup, no significant difference in the conversion rate was observed. CONCLUSION: Our trial shows that ∼30% of patients, who do not respond to CRT in the first 6 months, experience significant reverse remodelling in the following 6 months. This finding suggests that CRT benefit may be delayed or slowly incremental in a relevant proportion of patients and that the percentage of CRT responders may be higher than what has been described in short-/middle-term studies. MultiPoint™ Pacing does not improve CRT response in non-responders to BiVP, even with MPP-AS.

Transcranial MEP threshold voltages and current densities simulated with finite element modelling.

OBJECTIVE: The aim of this study was to compare stimulation thresholds and current densities in the brain for transcranial motor evoked potentials (tcMEPs) from the hands and feet with linked quadripolar (LQP), M3-M4 and C1-C2 electrode montages. METHODS: Twenty-five patients underwent cerebral vascular surgery with tcMEP monitoring. tcMEP voltage thresholds were compared between LQP (C1, M3, C2, M4), C1-C2, and M3-M4 montages. In a finite element model (FEM), hand, arm, and leg regions of interest (ROIs) on the cortical motor homunculus were segmented. Current densities in these ROIs at tcMEP thresholds were compared across tcMEP electrode montages. RESULTS: LQP tcMEP thresholds were 61.5 volts for hands and 95.2 volts for feet. Thresholds were higher for M3-M4 (hands, 89.4 V; feet, 141.3 V) and C1-C2 (hands: 137.3 V; feet: 194.7 V). Total current at threshold voltage was greater for LQP (hands, 210.9 mA; feet, 311.3 mA) compared to M3-M4 (hands, 166.8 mA; feet, 256.6 mA), but similar to C1-C2 (hands, 246.7 mA; feet, 341.1 mA). In FEM simulations, current density and local current density topography in the hand ROI at threshold were very similar for LQP, M3-M4 and C1-C2. CONCLUSIONS: TcMEP voltage thresholds were least for LQP, and lesser for M3-M4 compared to C1-C2. In FEM simulations, resistance to current to hand ROI was ordered the same (LQP < M3-M4 < C1-C2). The local distribution of current density in motor cortex with tcMEP was mainly determined by cortical geometry. SIGNIFICANCE: Current densities and resistance to current simulated with FEM may explain threshold requirements for tcMEP electrode montages.

Capture threshold of bipolar and unipolar pacing of left ventricle via coronary sinus branch: longitudinal study.

Introduction: The aim of this paper is to first monitor the changes in the capture threshold of endovascularly placed leads for left ventricle pacing, second to compare the pacing configurations, and third to verify the effect of Steroid elution for endovascular leads. Sample and Method: The study included 202 consecutive single centre patients implanted with the Quartet™ lead (St. Jude Medical). The capture threshold and related lead parameters were tested during implantation, on the day of the patient's discharge, and 3, 9, and 15 months after implantation. The electrical energy corresponding to the threshold values for inducing ventricular contraction was recorded for subgroups of patients with bipolar and pseudo-unipolar pacing vectors and electrodes equipped with and without a slow-eluting steroids. The best setting for the resynchronization effect was generally chosen. Capture threshold was taken as a selection criterion only if there were multiple options with (expected) similar resynchronization effect. Results and Discussion: The measurements showed that the ratio of threshold energies of UNI vs. BI was 5× higher (p < 0.001) at implantation. At the end of the follow-up, it dropped to 2.6 (p = 0.012). The steroid effect in BI vectors was caused by a double capture threshold in the NSE group compared to the SE group (p < 0.001), increased by approximately 2.5 times (p < 0.001). The study concludes that after a larger initial increase in the capture threshold, the leads showed a gradual increase in the entire set. As a result, the bipolar threshold energies increase, and the pseudo-unipolar energies decrease. Since bipolar vectors require a significantly lower pacing energy, battery life of the implanted device would improve. When evaluating the steroid elution of bipolar vectors, we observe a significant positive effect of a gradual increase of the threshold energy.

Association of interventricular activation delay with clinical outcomes in cardiac resynchronization therapy.

BACKGROUND: Pacing at sites of longest interventricular delay has been associated with greater reverse remodeling in cardiac resynchronization therapy (CRT). However, the effects of pacing at such sites on clinical outcomes is less well studied. OBJECTIVE: The purpose of this study was to assess the association between interventricular delay and clinical outcomes in CRT patients implanted with quadripolar left ventricular (LV) leads. METHODS: RALLY-X4 was a registry study of the Acuity X4 quadripolar LV leads. Interventricular delay was measured during unpaced basal rhythm from the right ventricular (RV) lead to the LV lead electrode (E1 to E4) chosen for CRT pacing. Patients were stratified by median RV-LV delay (80 ms) into short and long delay groups; they also were analyzed by multivariable modeling. The primary composite outcome measure was all-cause mortality and heart failure hospitalization (HFH) at 18 months. RESULTS: A total of 581 patients had complete RV-LV delay data. Mean LV ejection fraction was 27%, and 73% had typical left bundle branch block. Predictors of long RV-LV delay included female sex, left bundle branch block, and QRS duration >150 ms. Survival free of the primary outcome at 18-month follow-up was 87% in the long activation delay group compared with 77% in the short delay group (P = .0042). Multivariate analysis showed that RV-LV delay was an independent predictor of survival free of HFH (P = .028). CONCLUSION: Among CRT patients with quadripolar LV pacing leads, longer baseline interventricular activation delay was significantly associated with the composite endpoint of all-cause mortality and HFH.

Acute Hemodynamic Effects of Simultaneous and Sequential Multi-Point Pacing in Heart Failure Patients With an Expected Higher Rate of Sub-response to Cardiac Resynchronization Therapy: Results of Multicenter SYNSEQ Study.

The aim of the SYNSEQ (Left Ventricular Synchronous vs. Sequential MultiSpot Pacing for CRT) study was to evaluate the acute hemodynamic response (AHR) of simultaneous (3P-MPP syn) or sequential (3P-MPP seq) multi-3-point-left-ventricular (LV) pacing vs. single point pacing (SPP) in a group of patients at risk of a suboptimal response to cardiac resynchronization therapy (CRT). Twenty five patients with myocardial scar or QRS ≤ 150 or the absence of LBBB (age: 66 ± 12 years, QRS: 159 ± 12 ms, NYHA class II/III, LVEF ≤ 35%) underwent acute hemodynamic assessment by LV + dP/dtmax with a variety of LV pacing configurations at an optimized AV delay. The change in LV + dP/dt max (%ΔLV + dP/dt max) with 3P-MPP syn (15.6%, 95% CI: 8.8%-22.5%) was neither statistically significantly different to 3P-MPP seq (11.8%, 95% CI: 7.6-16.0%) nor to SPP basal (11.5%, 95% CI:7.1-15.9%) or SPP mid (12.2%, 95% CI:7.9-16.5%), but higher than SPP apical (10.6%, 95% CI:5.3-15.9%, p = 0.03). AHR (defined as a %ΔLV + dP/dt max ≥ 10%) varied between pacing configurations: 36% (9/25) for SPP apical, 44% (11/25) for SPP basal, 54% (13/24) for SPP mid, 56% (14/25) for 3P-MPP syn and 48% (11/23) for 3P-MPP seq.Fifteen patients (15/25, 60%) had an AHR in at least one pacing configuration. AHR was observed in 10/13 (77%) patients with a LBBB but only in 5/12 (42%) patients with a non-LBBB (p = 0.11). To conclude, simultaneous or sequential multipoint pacing compared to single point pacing did not improve the acute hemodynamic effect in a suboptimal CRT response population. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT02914457.

Long-term follow-up of patients with a quadripolar active fixation left ventricular lead: An Italian multicenter experience.

INTRODUCTION: Left ventricular (LV) lead optimal positioning is one of the most important determinants of cardiac resynchronization therapy (CRT) success. LV quadripolar active fixation (QAF) leads have been designed to ensure stable LV pacing in the target area and reduce the likelihood of phrenic nerve stimulation (PNS). The aim of this analysis is to compare performances, safety, and clinical outcomes of QAF with those of quadripolar passive fixation leads (QPL) and bipolar active fixation (BAF) leads in a real-world cohort of CRT patients. METHODS AND RESULTS: This retrospective analysis compared the procedure and follow-up data of 117 QAF included in the One Hospital ClinicalService project from nine Italian hospitals with two historical cohorts of 261 BAF and 124 QPL. QAF enabled basal pacing more frequently than QPL (24.1% vs. 6.5%, p < .001) but not differently from BAF (p = .981). At implant, mean QAF LV myocardial threshold (LVMT) was 1.21 ± 0.8 V at 0.4 ms, not different from that of BAF (p = .346) and QPL (p = .333). At a median follow-up of 22 months, LVMT was 1.37 ± 0.90 V (p = .036 vs. implant). Acute LV lead dislodgment occurrence was low in all cohorts: 1 (0.9%) in QAF, 4 in BAF (1.5%), and none (0.0%) in QPL. During follow-up, total LV-related complication rate was lower in QAF (0.5/100 patient-years) than in BAF (4.2/100 patient-years, p = .014) and QPL (3.6/100 patient-years, p = .055). QAF, BAF, and QPL annual rate of heart failure hospitalization were respectively 6.1/100 patient-years, 2.5/100 patient-years (p = .081), and 3.6/100 patient-years (p = .346). CRT responders' rate in QAF was 69.9%, with no difference in comparison to BAF (p = .998) and QPL (p = .509). During follow-up, mean left ventricular ejection fraction (LVEF) of QAF increased from 31.8 ± 10.1% to 40.3 ± 10.7% (p < .001). The average degree of echocardiographic response (ΔLVEF) did not differ between QAF and other cohorts; however, LVEF CRT responder's distribution of QAF differs from those of BAF (p = .003) and QPL (p = .022), due to a higher percentage of super-responders. CONCLUSIONS: QAF with short interelectrode spacing resulted in non-inferior clinical outcomes and CRT responders' rate in comparison to BAF and QPL, while reducing complication rate during follow-up and increasing the possibilities of electronic repositioning to manage PNS or to optimize resynchronization therapy.

Novel lead anchor technique using an active fixation quadripolar left ventricular lead in cardiac resynchronization therapy.

In this report, we present a case of successful advancement of a LV lead into tortuous vessels. This was achieved by deep engagement of the coronary sinus with a cannulation catheter by applying the anchor technique using the Medtronic Attain Stability Quad lead.

Quantitative sodium magnetic resonance imaging in food: Addressing sensitivity issues using single quantum chemical shift imaging at high field.

According to various health organizations, the global consumption of salt is higher than recommended and needs to be reduced. Ideally, this would be achieved without losing the taste of the salt itself. In order to accomplish this goal, both at the industrial and domestic levels, we need to understand the mechanisms that govern the final distribution of salt in food. The in-silico solutions in use today greatly over-simplify the real food structure. Measuring the quantity of sodium at the local level is key to understanding sodium distribution. Sodium magnetic resonance imaging (MRI), a non-destructive approach, is the ideal choice for salt mapping along transformational process. However, the low sensitivity of the sodium nucleus and its short relaxation times make this imaging difficult. In this paper, we show how sodium MRI can be used to highlight salt heterogeneities in food products, provided that the temporal decay is modeled, thus correcting for differences in relaxation speeds. We then propose an abacus which shows the relationship between the signal-to-noise ratio of the sodium MRI, the salt concentration, the B0 field, and the spatial and temporal resolutions. This abacus simplifies making the right choices when implementing sodium MRI.

Bipolar versus quadripolar left ventricular leads for cardiac resynchronization therapy: evidence to date.

INTRODUCTION: In cardiac resynchronization therapy (CRT) devices, transvenous left ventricular (LV) leads are more prone to instability, high pacing thresholds, and phrenic nerve stimulation (PNS) that may necessitate lead revision, replacement in a suboptimal position, or deactivation of the lead. To overcome some of these challenges, quadripolar (QP) LV leads have been developed and accounted for over 90% of implanted LV leads 5 years after they were introduced. AREAS COVERED: This review provides an overview of the current evidence of implanting QP leads in CRT as compared with traditional bipolar (BP) leads including details about feasibility, safety and lead performance, clinical outcomes and cost-effectiveness. EXPERT OPINION: Based on the current literature, implantation with a QP lead decreases revision rates but does not affect any clinical outcomes including mortality, hospitalization, symptoms, or echocardiographic parameters. Feasibility and stability do not differ between QP and BP leads. A QP lead should be preferred as first choice over a BP lead due to lower rates of PNS and lower pacing thresholds leading to less frequent lead revisions and battery replacements. In addition, this strategy may be cost saving despite a higher price of QP leads.

Development, Validation, and Comparison of Two Mass Spectrometry Methods (LC-MS/HRMS and LC-MS/MS) for the Quantification of Rituximab in Human Plasma.

Rituximab is a chimeric immunoglobulin G1-kappa (IgG1κ) antibody targeting the CD20 antigen on B-lymphocytes. Its applications are various, such as for the treatment of chronic lymphoid leukemia or non-Hodgkin's lymphoma in oncology, and it can also be used in the treatment of certain autoimmune diseases. Several studies support the interest in therapeutic drug monitoring to optimize dosing regimens of rituximab. Thus, two different laboratories have developed accurate and reproductive methods to quantify rituximab in human plasma: one using liquid chromatography quadripolar tandem mass spectrometer (LC-MS/MS) and the other, liquid chromatography orbitrap tandem mass spectrometer (LC-MS/HRMS). For both assays, quantification was based on albumin depletion or IgG-immunocapture, surrogate peptide analysis, and full-length stable isotope-labeled rituximab. With LC-MS/MS, the concentration range was from 5 to 500 µg/mL, the within- and between-run precisions were <8.5%, and the limit of quantitation was 5 µg/mL. With LC-MS/HRMS, the concentration range was from 10 to 200 µg/mL, the within- and between-run accuracy were <11.5%, and the limit of quantitation was 2 µg/mL. Rituximab plasma concentrations from 63 patients treated for vasculitis were compared. Bland-Altman analysis and Passing-Bablok regression showed the interchangeability between these two methods. Overall, these methods were robust and reliable and could be applied to routine clinical samples.

Removal of sacral neuromodulation quadripolar tined-lead using a straight stylet: description of a surgical technique.

BACKGROUND: Up to 7.5% of tined-lead removals in patients having sacral neuromodulation (SNM) therapy are associated with a lead breakage. It is still unclear what adverse effects can be caused by unretrieved fragments. The aim of our study was to describe the lead removal technique we have been using for the last 2 years in our centre. METHODS: We retrospectively enrolled patients who had lead removal between January 2018 and January 2020 using our standardized technique. The novelty of the technique is in the use of the straight stylet, which is available in the quadripolar tined-lead kit. The stylet gives the electrode greater stiffness, reducing interactions with surrounding tissues and probability of damage or breakage during removal. RESULTS: In 59 patients (42 women, mean age 57.2 years [range 40-79 years]) the lead was removed using our standardized technique. In 44 of 59 patients, the tined-lead was removed within 2 months from the SNM-test, due to lack of beneficial effects. In 15 patients the electrode was removed because of failure of definitive implantation. Meantime from definitive implantable pulse generator (IPG) implantation to lead removal was 67.9 months. We recorded only 1 case of lead-breakage during removal: a female patient with a non-tined lead fixed on sacral bone, placed 18 years previously using an open technique. CONCLUSIONS: Lead breakage during removal is not uncommon and adverse effects of retained fragments may occur. Our technique has been safely used for the last 2 years in our centre, with no episodes of lead breakage or retained fragments, except for one non-tined electrode.

Six months clinical outcome comparison between quadripolar and bipolar left ventricular leads in cardiac resynchronization therapy: A prospective, non-randomized, single-centre observational study.

BACKGROUND AND OBJECTIVES: Quadripolar left ventricular (LV) leads in cardiac resynchronization therapy (CRT) offer multi-vector pacing with different pacing configurations and hence enabling LV pacing at most suitable site with better lead stability. We aim to compare the outcomes between quadripolar and bipolar LV lead in patients receiving CRT. METHODS: In this prospective, non-randomized, single-center observational study, we enrolled 93 patients receiving CRT with bipolar (BiP) (n = 31) and quadripolar (Quad) (n = 62) LV lead between August 2016 to August 2019. Patients were followed for six months, and outcomes were compared with respect to CRT response (defined as ≥5% absolute increase in left ventricle ejection fraction), electrocardiographic, echocardiographic parameters, NYHA functional class improvement, and incidence of LV lead-related complication. RESULTS: At the end of six months follow up, CRT with quadripolar lead was associated with better response rate as compared to bipolar pacing (85.48% vs 64.51%; p = 0.03), lesser heart failure (HF) hospitalization events (1.5 vs 2; p = 0.04) and better improvement in HF symptoms (patients with ≥1 NYHA improvement 87.09% vs 67.74%; p = 0.04). There were fewer deaths per 100 patient-year (6.45 vs 9.37; p = 0.04) and more narrowing of QRS duration (Δ12.56 ± 3.11 ms vs Δ7.29 ± 1.87 ms; p = 0.04) with quadripolar lead use. Lead related complications were significantly more with the use of bipolar lead (74.19% vs 41.94%; p = 0.02). CONCLUSIONS: Our prospective, non-randomized, single-center observational study reveals that patients receiving CRT with quadripolar leads have a better response to therapy, lesser heart failure hospitalizations, lower all-cause mortality, and fewer lead-related complications, proving its superiority over the bipolar lead.

Intracardiac conduction time as a predictor of cardiac resynchronization therapy response: Results of the BIO|SELECT pilot study.

BACKGROUND: Quadripolar left ventricular (LV) leads are capable of sensing and pacing the left ventricle from 4 different electrodes, which may potentially improve patient response to cardiac resynchronization therapy (CRT). OBJECTIVE: We measured 3 different time intervals: right ventricular (RV)-sensed to LV-sensed during intrinsic rhythm (RVs-LVs), RV-paced to LV-sensed (RVp-LVs), and LV-paced to LV-sensed (LVp-LVs, between distal [LV1] and proximal pole on a quadripolar LV lead), and assessed their association with CRT response in terms of LV end-systolic volume (LVESV) and a composite benefit index (CBI) comprising LVESV, LV ejection fraction (LVEF), brain natriuretic peptide level, and NYHA class. METHODS: A CRT-defibrillator system with quadripolar LV lead was implanted in 196 patients (mean age 69 years, mean LVEF 30%, left bundle-branch block [LBBB] 58%). Conduction intervals were measured before hospital discharge. At baseline and 7-month follow-up, echocardiographic and other components of CBI were determined. RESULTS: The mean RVs-LV1s, RVp-LV1s, and LVp-LVs delays were 68 ± 38 ms, 132 ± 34 ms, and 99 ± 31 ms, respectively. From baseline to 7 months, LVESV decreased by 17.3% ± 28.6%. The RVs-LV1s interval correlated stronger with CBI (R2 = 0.12, P < .00001) than with LVESV change (R2 = 0.05, P = .006). In contrast, RVp-LV1s did not correlate and LVp-LVs correlated only weakly with CRT response. The subgroup of patients (44%) with LBBB and RVs-LV1s above the lower quartile (≥34 ms) showed the greatest response to CRT. CONCLUSION: The RVs-LVs interval during intrinsic rhythm is relevant for CRT success, whereas RVp-LVs and LVp-LVs intervals did not predict CRT response.

Cardiac resynchronization therapy with multipoint pacing via quadripolar lead versus traditional biventricular pacing: A systematic review and meta-analysis of clinical studies on hemodynamic, clinical, and prognostic parameters.

BACKGROUND: Cardiac resynchronization therapy (CRT) is one of the cornerstones of heart failure (HF) therapy, as it has reduced mortality and morbidity and has shown improvement in functional capacity. Multipoint pacing (MPP) is a way of configuring CRT with the aim to improve the percentage of patients who respond to CRT. OBJECTIVE: To demonstrate the effectiveness of the MPP compared to traditional biventricular pacing (BiV). METHODS: We performed a systematic review and meta-analysis according to PRISMA guidelines of studies in which MPP vs BiV strategy were compared. RESULTS: MPP use is associated with a higher rate of patients experiencing functional improvement (odds ratio: 2.51, 95% confidence interval [CI], 1.56-4.06; P = .0002) and with higher delta LV dP/dtmax (mean difference, 1.82; 95% CI, 0.24-3.39; P = .0240) with respect to BiV. MPP and BiV have no significantly different effect on left ventricular end-systolic volume (LVESV) (mean difference, 0.39; 95% CI, -11.12 to 11.89; P = .9475); moreover, there is no significant difference between the 2 treatments regarding hospitalization for HF (odds ratio, 0.70; 95% CI, 0.32 to 1.54; P = .3816) and all-cause death (odds ratio, 0.81; 95% CI, 0.40 to 1.62; P = .5460). MPP is associated with a significantly lower projected battery longevity (mean difference -8.66 months; 95% CI, -13.67 to -3.66; P = .00007) with respect to BiV. CONCLUSION: MPP significantly improves functional class and acute hemodynamic parameters with respect to BiV. Prognostic indices and LVESV are not significantly influenced by MPP. MPP is associated with a significant reduction in projected battery longevity.

Single- and multi-site pacing strategies for optimal cardiac resynchronization therapy: impact on device longevity and therapy cost.

BACKGROUND: Multiple left ventricular pacing strategies have been suggested for improving response to cardiac resynchronization therapy (CRT). However, these programming strategies may sometimes entail accepting configurations with high pacing threshold and accelerated battery drain. We assessed the feasibility of predefined pacing programming protocols, and we evaluated their impact on device longevity and their cost-impact. METHODS: We estimated battery longevity in 167 CRT-D patients based on measured pacing parameters according to multiple alternative programming strategies: single-site pacing associated with lowest threshold, non-apical location, longest interventricular delay, and pacing from two electrodes. To determine the economic impact of each programming strategy, we applied the results of a model-based cost analysis using a 15-year time horizon. RESULTS: Selecting the electrode with the lowest threshold resulted in a median device longevity of 11.5 years. Non-apical pacing and interventricular delay maximization were feasible in most patients and were obtained at the price of a few months of battery life. Device longevity of > 10 years was preserved in 87% of cases of non-apical pacing and in 77% on pacing at the longest interventricular delay. The mean reduction in battery life when the second electrode was activated was 1.5 years. Single-site pacing strategies increased the therapy cost by 4-6%, and multi-site pacing by 12-13%, in comparison with the lowest-cost scenario. CONCLUSIONS: Modern CRT-D systems ensure effective pacing and allow multiple optimization strategies for maximizing service life or for enhancing effectiveness. Single- or multi-site pacing strategies can be implemented without compromising device service life and at an acceptable increase in therapy cost.

Safety of magnetic resonance imaging scanning in patients with cardiac resynchronization therapy-defibrillators incorporating quadripolar left ventricular leads.

BACKGROUND: Magnetic resonance imaging (MRI) scanning of magnetic resonance (MR)-conditional cardiac implantable cardioverter-defibrillators (ICDs) can be performed safely following specific protocols. MRI safety with cardiac resynchronization therapy-defibrillators (CRT-Ds) incorporating quadripolar left ventricular (LV) leads is less clear. OBJECTIVE: The purpose of this study was to evaluate the safety and effectiveness of ICDs and CRT-D systems with quadripolar LV leads after an MRI scan. METHODS: The ENABLE MRI Study included 230 subjects implanted with a Boston Scientific ImageReady ICD (n = 39) or CRT-D (n = 191) incorporating quadripolar LV leads undergoing nondiagnostic 1.5-T MRI scans (lumbar and thoracic spine imaging) a minimum of 6 weeks postimplant. Pacing capture thresholds (PCTs), sensing amplitudes (SAs), and impedances were measured before and 1 month post-MRI using the same programmed LV pacing vectors. The ability to sense/treat ventricular fibrillation (VF) was assessed in a subset of patients. RESULTS: A total of 159 patients completed a protocol-required MRI scan (MRI Protection Mode turned on) with no scan-related complications. All right ventricular (RV) and left LV PCT and SA effectiveness endpoints were met: RV PCT 99% (145/146 patients), LV PCT 100% (120/120), RV SA 99% (145/146), and LV SA 98% (116/118). In no instances did MRI result in a change in pacing vector or lead revision. All episodes of VF were appropriately sensed and treated. CONCLUSION: This first evaluation of predominantly CRT-D systems with quadripolar LV leads undergoing 1.5-T MRI confirmed that scanning was safe with no significant changes in RV/LV PCT, SA, programmed vectors, and VF treatment, thus suggesting that MRI in patients having a device with quadripolar leads can be performed without negative impact on CRT delivery.