Left bundle branch area pacing outcomes: the multicentre European MELOS study

AIMS

Permanent transseptal left bundle branch area pacing (LBBAP) is a promising new pacing method for both bradyarrhythmia and heart failure indications. However, data regarding safety, feasibility and capture type are limited to relatively small, usually single centre studies. In this large multicentre international collaboration, outcomes of LBBAP were evaluated.

METHODS AND RESULTS

This is a registry-based observational study that included patients in whom LBBAP device implantation was attempted at 14 European centres, for any indication. The study comprised 2533 patients (mean age 73.9 years, female 57.6%, heart failure 27.5%). LBBAP lead implantation success rate for bradyarrhythmia and heart failure indications was 92.4% and 82.2%, respectively. The learning curve was steepest for the initial 110 cases and plateaued after 250 cases. Independent predictors of LBBAP lead implantation failure were heart failure, broad baseline QRS and left ventricular end-diastolic diameter. The predominant LBBAP capture type was left bundle fascicular capture (69.5%), followed by left ventricular septal capture (21.5%) and proximal left bundle branch capture (9%). Capture threshold (0.77 V) and sensing (10.6 mV) were stable during mean follow-up of 6.4 months. The complication rate was 11.7%. Complications specific to the ventricular transseptal route of the pacing lead occurred in 209 patients (8.3%).

CONCLUSIONS

LBBAP is feasible as a primary pacing technique for both bradyarrhythmia and heart failure indications. Success rate in heart failure patients and safety need to be improved. For wider use of LBBAP, randomized trials are necessary to assess clinical outcomes.

EHRA clinical consensus statement on conduction system pacing implantation: endorsed by the Asia Pacific Heart Rhythm Society (APHRS), Canadian Heart Rhythm Society (CHRS), and Latin American Heart Rhythm Society (LAHRS)

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last five years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique.

Comparison of Left Bundle Branch Area Pacing and Biventricular Pacing in Candidates for Resynchronization Therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) is a well established therapy in patients with reduced left ventricular ejection fraction (LVEF), heart failure, and wide QRS or expected frequent ventricular pacing. Left bundle branch area pacing (LBBAP) has recently been shown to be a safe alternative to BVP.

OBJECTIVES

The aim of this study was to compare the clinical outcomes between BVP and LBBAP among patients undergoing CRT.

METHODS

This observational study included patients with LVEF ≤35% who underwent BVP or LBBAP for the first time for Class I or II indications for CRT from January 2018 to June 2022 at 15 international centers. The primary outcome was the composite endpoint of time to death or heart failure hospitalization (HFH). Secondary outcomes included endpoints of death, HFH, and echocardiographic changes.

RESULTS

A total of 1,778 patients met inclusion criteria: 981 BVP, 797 LBBAP. The mean age was 69 ± 12 years, 32% were female, 48% had coronary artery disease, and mean LVEF was 27% ± 6%. Paced QRS duration in LBBAP was significantly narrower than baseline (128 ± 19 ms vs 161 ± 28 ms; P < 0.001) and significantly narrower compared to BVP (144 ± 23 ms; P < 0.001). Following CRT, LVEF improved from 27% ± 6% to 41% ± 13% (P < 0.001) with LBBAP compared with an increase from 27% ± 7% to 37% ± 12% (P < 0.001) with BVP, with significantly greater change from baseline with LBBAP (13% ± 12% vs 10% ± 12%; P < 0.001). On multivariable regression analysis, the primary outcome was significantly reduced with LBBAP compared with BVP (20.8% vs 28%; HR: 1.495; 95% CI: 1.213-1.842; P < 0.001).

CONCLUSIONS

LBBAP improved clinical outcomes compared with BVP in patients with CRT indications and may be a reasonable alternative to BVP.

EHRA expert consensus statement and practical guide on optimal implantation technique for conventional pacemakers and implantable cardioverter-defibrillators: endorsed by the Heart Rhythm Society (HRS), the Asia Pacific Heart Rhythm Society (APHRS), and the Latin-American Heart Rhythm Society (LAHRS)

With the global increase in device implantations, there is a growing need to train physicians to implant pacemakers and implantable cardioverter-defibrillators. Although there are international recommendations for device indications and programming, there is no consensus to date regarding implantation technique. This document is founded on a systematic literature search and review, and on consensus from an international task force. It aims to fill the gap by setting standards for device implantation.

Multipoint pacing by a left ventricular quadripolar lead improves the acute hemodynamic response to CRT compared with conventional biventricular pacing at any site

BACKGROUND

Response to cardiac resynchronization therapy (CRT) remains challenging. Pacing from multiple sites of the left ventricle (LV) has shown promising results.

OBJECTIVE

The purpose of this study was to systematically compare the acute hemodynamic effects of multipoint pacing (MPP) by means of a quadripolar lead with conventional biventricular (BiV) pacing.

METHODS

Twenty-nine patients (23 men; mean age 72 ± 12 years; LV ejection fraction 29% ± 7%; 15 with ischemic cardiomyopathy, 17 with left bundle branch block; mean QRS 183 ± 23 ms) underwent CRT implantation. Per patient, 3.2 ± 1.2 different veins and 6.3 ± 2.4 pacing sites were tested. LV electrical delay (Q-LV) was measured at each location, along with the increase in LV dP/dtmax (maximum rate of rise of LV pressure) obtained by BiV and MPP. The effect of MPP, by means of simultaneous pacing from distal and proximal dipoles, was investigated at all available sites.

RESULTS

Overall, 3.2 ± 1.2 different MPP measurements were collected per patient. When all sites were considered, LV dP/dtmax increased from 951 ± 193 mm Hg/s at baseline to 1144 ± 255 and 1178 ± 259 mm Hg/s on BiV and MPP, respectively. When the best site was considered, LV dP/dtmax increased from a baseline value of 942 ± 202 mm Hg/s to 1200 ± 267 mm Hg/s (BiV) and 1231 ± 267 mm Hg/s (MPP). The mean QRS duration at any site during MPP and conventional CRT was 171 ± 18 and 175 ± 16 ms (P = .003), respectively.

CONCLUSION

Compared with BiV pacing at any LV site, MPP yielded a small but consistent increase in hemodynamic response. A correlation between the increase in hemodynamics and Q-LV on MPP was observed for all measurements, including those taken at the best and worst sites. The MPP-induced improvement in contractility was associated with significantly greater narrowing of the QRS complex than conventional BiV pacing.

Determination of the longest intrapatient left ventricular electrical delay may predict acute hemodynamic improvement in patients after cardiac resynchronization therapy

BACKGROUND

One of the reasons for patient nonresponse to cardiac resynchronization therapy is a suboptimal left ventricular (LV) pacing site. LV electric delay (Q-LV interval) has been indicated as a prognostic parameter of cardiac resynchronization therapy response. This study evaluates the LV delay for the optimization of the LV pacing site.

METHODS AND RESULTS

Thirty-two consecutive patients (23 men; mean age, 71±11 years; LV ejection fraction, 30±6%; 18 with ischemic cardiomyopathy; QRS, 181±25 ms; all mean±SD) underwent cardiac resynchronization therapy device implantation. All available tributary veins of the coronary sinus were tested, and the Q-LV interval was measured at each pacing site. The hemodynamic effects of pacing at different sites were evaluated by invasive measurement of LV dP/dtmax at baseline and during pacing. Overall, 2.9±0.8 different veins and 6.4±2.3 pacing sites were tested. In 31 of 32 (96.8%) patients, the highest LV dP/dtmax coincided with the maximum Q-LV interval. Q-LV interval correlated with the increase in LV dP/dtmax in all patients at each site (AR1 ρ=0.98; P<0.001). A Q-LV value >95 ms corresponded to a >10% in LV dP/dtmax. An inverse correlation between paced QRS duration and improvement in LV dP/dtmax was seen in 24 patients (75%).

CONCLUSIONS

Pacing the LV at the latest activated site is highly predictive of the maximum increase in contractility, expressed as LV dP/dtmax. A positive correlation between Q-LV interval and hemodynamic improvement was found in all patients at every pacing site, a value of 95 ms corresponding to an increase in LV dP/dtmax of ≥10%.

Safety and performance of a system specifically designed for selective site pacing

INTRODUCTION

In the right ventricle, selective site pacing (SSP) has been shown to avoid detrimental hemodynamic effects induced by right ventricular apical pacing and, in the right atrium, to prevent the onset of atrial fibrillation and to slow down disease progression. The purpose of our multicenter observational study was to describe the use of a transvenous 4-French catheter-delivered lead for SSP in the clinical practice of a large number of centers.

METHODS

We enrolled 574 patients in whom an implantable device was indicated. In all patients, SSP was achieved by using the Select Secure System™ (Medtronic Inc., Minneapolis, MN, USA).

RESULTS

In 570 patients, the lead was successfully implanted. In 125 patients, atrial SSP was performed: in 75 (60%) the lead was placed in the interatrial septum, in 31 (25%) in the coronary sinus ostium, and in 19 (15%) in the Bachman bundle. Ventricular SSP was undertaken in 138 patients: in 105 (76%) the high septal right ventricular outflow tract (RVOT) position was paced, in seven (5%) the high free-wall RVOT, in 25 (18%) the low septal RVOT, and in one (1%) the low free-wall RVOT. In the remaining 307 patients, the His zone was paced: in 87 (28%) patients, direct His-bundle pacing and in 220 (72%) patients para-hisian pacing was achieved. Adequate pacing parameters and a lead-related complication rate of 2.6% were recorded during a follow-up of 20 ± 10 months.

CONCLUSIONS

Our results demonstrated that many sites, in the right atrium, in the right ventricle, and in His-bundle region, can be paced using the Select Secure System™.

EHRA clinical consensus statement on conduction system pacing implantation: executive summary. Endorsed by the Asia-Pacific Heart Rhythm Society (APHRS), Canadian Heart Rhythm Society (CHRS) and Latin-American Heart Rhythm Society (LAHRS)

Conduction system pacing (CSP) has emerged as a more physiological alternative to right ventricular pacing and is also being used in selected cases for cardiac resynchronization therapy. His bundle pacing was first introduced over two decades ago and its use has risen over the last years with the advent of tools which have facilitated implantation. Left bundle branch area pacing is more recent but its adoption is growing fast due to a wider target area and excellent electrical parameters. Nevertheless, as with any intervention, proper technique is a prerequisite for safe and effective delivery of therapy. This document aims to standardize the procedure and to provide a framework for physicians who wish to start CSP implantation, or who wish to improve their technique. A synopsis is provided in this print edition of EP-Europace. The full document may be consulted online, and a 'Key Messages' App can be downloaded from the EHRA website.

Device Programming for His Bundle Pacing

Although permanent His bundle pacing was first reported almost 2 decades ago, it is only recently gaining wider adoption, following facilitation of the implant procedure by dedicated tools. An additional challenge is programming the system, as His bundle pacing may have specific configurations and require special considerations which current implantable pulse generators are not designed for. The aim of this article is to provide practical recommendations for programming His bundle pacing, to deliver optimal therapy and ensure patient safety.

Effect of biventricular pacing on metabolism and perfusion in patients affected by dilated cardiomyopathy and left bundle branch block: evaluation by positron emission tomography

AIMS

Evaluate the possible changes in myocardial metabolism and perfusion induced by biventricular pacing (BIVP) in patients affected by dilated cardiomyopathy (DC) and left bundle branch block (LBBB).

METHODS AND RESULTS

Eight male patients (aged 60-79 years, mean 69) affected by DC (NYHA functional class III and ejection fraction <40%) were submitted to cardiac PET in basal condition and 3 weeks after the implantation of a biventricular device. Metabolism was evaluated using F18-fluorodeoxyglucose (FDG), by the glucose load-insulin technique, and perfusion by N13-ammonia (NH3), injected at rest. Visual and a semi quantitative analyses were performed, calculating by ROIs the septum to lateral uptake ratio (SLR). The myocardial blood flow (MBF) was also calculated in ml/min/g using a dynamic acquisition and a modified Patlak method. In all 8 patients a selective defect in FDG uptake in the septum was present in basal condition (mean SLR 0.59+/-0.17) with a 'reverse mismatch' effect with respect to NH3 (mean SLR 1.07+/-0.18). During BIVP the distribution of FDG in the septal area significatively improved (mean SLR 0.86+/-0.15 P=0.011 with respect to basal); on the contrary, no significant changes were found in NH3 uptake (mean SLR 1.02+/-0.23, P=ns). On quantitative analysis the mean MBF in the septum was 1.05+/-0.37 in basal condition and did not significantly change during BIVP (0.95+/-0.34, P=0.06).

CONCLUSIONS

Our results suggest that, in patients affected by DC and LBBB, BIVP improves the septal glucose metabolism without significant changes in myocardial perfusion.

Cardiac resynchronization therapy-defibrillator improves long-term survival compared with cardiac resynchronization therapy-pacemaker in patients with a class IA indication for cardiac resynchronization therapy: data from the Contak Italian Registry

AIMS

In candidates for cardiac resynchronization therapy (CRT), the choice between pacemaker (CRT-P) and defibrillator (CRT-D) implantation is still debated. We compared the long-term prognosis of patients who received CRT-D or CRT-P according to class IA recommendations of the European Society of Cardiology (ESC) and who were enrolled in a multicentre prospective registry.

METHODS AND RESULTS

A total of 620 heart failure patients underwent successful implantation of a CRT device and were enrolled in the Contak Italian Registry. This analysis included 266 patients who received a CRT-D and 108 who received a CRT-P according to class IA ESC indications. Their survival status was verified after a median follow-up of 55 months. During follow-up, 73 CRT-D and 44 CRT-P patients died (rate 6.6 vs. 10.4%/year; log-rank test, P = 0.020). Patients receiving CRT-P were predominantly older, female, had no history of life-threatening ventricular arrhythmias, and more frequently presented non-ischaemic aetiology of heart failure, longer QRS durations, and worse renal function. However, the only independent predictor of death from any cause was the use of CRT-P (hazard ratio, 1.97; 95% confidence interval, 1.21-3.16; P = 0.007).

CONCLUSION

The implantation of CRT-D, rather than CRT-P, may be preferable in patients presenting with current class IA ESC indications for CRT. Indeed, CRT-D resulted in greater long-term survival and was independently associated with a better prognosis.

Hisian area and right ventricular apical pacing differently affect left atrial function: an intra-patients evaluation

AIMS

Right ventricular apex (RVA) pacing has adverse effects on left atrial (LA) function and may contribute to atrial arrhythmias. The effects of Hisian area (HA) pacing on LA function are still lacking. The objective of this study is to assess the left ventricular (LV) electromechanical activation/relaxation, systolic (S), diastolic (D) phases, and their effects on LA function during pacing from HA and RVA.

METHODS AND RESULTS

Thirty-seven patients with normal cardiac function underwent permanent HA pacing. In all patients, a RVA backup lead was added. The patients first underwent 3 months of HA pacing, followed by 3 months of RVA pacing. After each 3-month period, we compared by echocardiography: S-D LV electromechanical delay (S-D EMD), S-D intra-LV dyssynchrony, LV S-D phases, and their function evaluated by myocardial performance index (MPI) and mitral annular tissue Doppler early diastolic velocity (E'), pulmonary arterial systolic pressure (PASP), and LA function (LA phasic volumes and their emptying fraction). Right ventricular apex compared with HA pacing increased S-D EMD (P < 0.001) and intra-LV dyssynchrony (P < 0.001). As a consequence, a significant longer LV isovolumetric contraction time (P < 0.001) and LV isovolumetric relaxation time (P = 0.05) were measured during RVA compared with HA pacing, whereas LV ejection time was shorter (P = 0.033). Moreover, HA pacing resulted in significantly better MPI (P = 0.039), higher value of E' (P = 0.049), and lower PASP (P < 0.001). Finally, RVA compared with HA pacing was associated to higher LA volumes pre-atrial contraction (P = 0.001) and minimal volume (P = 0.003) with reduction in passive emptying fraction (P < 0.001) and total emptying fraction (P = 0.005).

CONCLUSION

Hisian area compared with RVA pacing resulted in a more physiological LV electromechanical activation/relaxation and consequently better LA function.

A feasible approach for direct his-bundle pacing using a new steerable catheter to facilitate precise lead placement

INTRODUCTION

Much clinical evidence has shown that right ventricular (RV) apical pacing is detrimental to left ventricular function. Preservation of the use of the His-Purkinje (H-P) system may be ideal in heart block that is restricted to the AV node, but may be of no benefit when H-P disease exists.

AIM

To investigate the feasibility of direct His-bundle pacing (DHBP) using a new system consisting of a steerable catheter and a new 4.1 F screw-in lead.

METHOD

Between May and December 2004, 26 patients (19 male, mean age: 77 +/- 5 years) with a standard pacemaker (PM) indication and preserved His-bundle conduction were enrolled and DHBP was attempted.

RESULTS

DHBP was achieved in 24 patients (92%); two patients were paced in the His area, but the paced QRS morphology and duration were different from the native QRS. The mean time for lead positioning was 19 +/- 17 minutes, the mean fluoroscopy time was 11 +/- 8 minutes, and the total procedure time (skin-to-skin including positioning of a quadripolar diagnostic catheter for His recording) was 75 +/- 18 minutes. In DHBP pacing, the acute pacing threshold was 2.3 +/- 1.0 V at a pulse duration of 0.5 msec, and the sensed potentials were 2.9 +/- 2.0 mV. At a 3-month follow-up examination, the same QRS duration and morphology recorded on implantation were observed in all patients. The pacing threshold was 2.8 +/- 1.4 V, and sensed potentials were 2.5 +/- 1.8 mV; the sensing configuration was changed from bipolar to unipolar in 6 patients to resolve undersensing issues. No major complications were observed.

CONCLUSIONS

This feasibility study shows that DHBP can be accomplished with a new system consisting of a steerable catheter and an active fixation lead in 92% of the patients in whom it was attempted.

Multicentre experience with the second-generation subcutaneous implantable cardioverter defibrillator and the intermuscular two-incision implantation technique

INTRODUCTION

The recently developed second-generation subcutaneous implantable cardioverter defibrillator (S-ICD) and the intermuscular two-incision implantation technique demonstrate potential favorable features that reduce inappropriate shocks and complications. However, data concerning large patient populations are lacking. The aim of this multicentre prospective study was to evaluate the safety and outcome of second-generation S-ICD using the intermuscular two-incision technique in a large population study.

METHODS AND RESULTS

The study population included 101 consecutive patients (75% male; mean age, 45 ± 13 years) who received second-generation S-ICD (EMBLEM; Boston Scientific, Marlborough, MA) implantation using the intermuscular two-incision technique as an alternative to the standard implantation technique. Twenty nine (29%) patients were implanted for secondary prevention. Twenty four (24%) patients had a previously implanted transvenous ICD. All patients were implanted without any procedure-related complications. Defibrillation testing was performed in 80 (79%) patients, and ventricular tachycardia was successfully converted at less than or equal to 65 J in 98.75% (79/80) of patients without pulse generator adjustments. During a median follow-up of 21 ± 10 months, no complications requiring surgical revision or local or systemic device-related infections were observed. Ten patients (9.9%) received appropriate and successful shocks for ventricular arrhythmias. Three (2.9%) patients experienced inappropriate shocks due to oversensing the cardiac signal (n = 1), noncardiac signal (n = 1), and a combination of both cardiac and noncardiac signals (n = 1), with one patient requiring device explantation. No patients required device explantation due to antitachycardia pacing indications.

CONCLUSIONS

According to our multicentre study, second-generation S-ICD implanted with the intermuscular two-incision technique is an available safe combination and appears to be associated with a low risk of complications, such as inappropriate shocks.

Pre-existing atrial fibrillation is associated with increased mortality in COVID-19 Patients

PURPOSE

The impacts of pre-existing atrial fibrillation (AF) on COVID-19-associated outcomes are unclear. We conducted a systematic review and meta-analysis to investigate the pooled prevalence of pre-existing AF and its short-term mortality risk in COVID-19 patients.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in abstracting data and assessing validity. We searched MEDLINE and Scopus to locate all the articles published up to January 31, 2021, reporting data on pre-existing AF among COVID-19 survivors and non-survivors. The pooled prevalence of pre-existing AF was calculated using a random effects model and presenting the related 95% confidence interval (CI), while the mortality risk was estimated using the Mantel-Haenszel random effects models with odds ratio (OR) and related 95% CI. Statistical heterogeneity was measured using the Higgins I2 statistic.

RESULTS

Twelve studies, enrolling 15.562 COVID-19 patients (mean age 71.6 years), met the inclusion criteria and were included in the final analysis. The pooled prevalence of pre-existing AF was 11.0% of cases (95% CI: 7.8-15.2%, p < 0.0001) with high heterogeneity (I2 = 95.2%). Pre-existing AF was associated with higher risk of short-term death (OR 2.22, 95% CI 1.47-3.36, p < 0.0001), with high heterogeneity (I2 = 79.1%).

CONCLUSION

Pre-existing AF is present in about 11% of COVID-19 cases but results associated with an increased risk of short-term mortality.

Device Longevity in a Contemporary Cohort of ICD/CRT-D Patients Undergoing Device Replacement

INTRODUCTION

The longevity of defibrillators (ICD) is extremely important from both a clinical and economic perspective. We studied the reasons for device replacement, the longevity of removed ICD, and the existence of possible factors associated with shorter service life.

METHODS AND RESULTS

Consecutive patients who underwent ICD replacement from March 2013 to May 2015 in 36 Italian centers were included in this analysis. Data on replaced devices were collected. A total of 953 patients were included in this analysis. In 813 (85%) patients the reason for replacement was battery depletion, while 88 (9%) devices were removed for clinical reasons and the remaining 52 because of system failure (i.e., lead or ICD generator failure or a safety advisory indication). The median service life was 5.9 years (25th-75th percentile, 4.9-6.9) for single- and dual-chamber ICD and 4.9 years (25th-75th percentile, 4.0-5.7) for CRT-D. On multivariate analysis, the factors CRT-D device, SC/DC ICD generator from Biotronik, percentage of ventricular pacing, and the occurrence of a system failure were positively associated with a replacement procedure. By contrast, the device from Boston Scientific was an independent protective factor against replacement. Considerable differences were seen in battery duration in both ICD and CRT-D. Specifically, Biotronik devices showed the shortest longevity among ICD and Boston Scientific showed the longest longevity among CRT-D (log-rank test, P < 0.001 for pairwise comparisons).

CONCLUSION

Several factors were associated with shorter service life of ICD devices: CRT-D, occurrence of system failure and percentage of ventricular pacing. Our results confirmed significant differences among manufacturers.

Immunoaffinity Column Cleanup with Liquid Chromatography for Determination of Aflatoxin B1 in Corn Samples: Interlaboratory Study

An interlaboratory study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for the determination of aflatoxin B1 levels in corn samples, enforced by European Union legislation. A test portion was extracted with methanolwater (80 + 20); the extract was filtered, diluted with phosphate-buffered saline solution, filtered on a microfiber glass filter, and applied to an immunoaffinity column. The column was washed with deionized water to remove interfering compounds, and the purified aflatoxin B1 was eluted with methanol. Aflatoxin B1 was separated and determined by reversed-phase LC with fluorescence detection after either pre- or postcolumn derivatization. Precolumn derivatization was achieved by generating the trifluoroacetic acid derivative, used by 8 laboratories. The postcolumn derivatization was achieved either with pyridinium hydrobromide perbromide, used by 16 laboratories, or with an electrochemical cell by the addition of bromide to the mobile phase, used by 5 laboratories. The derivatization techniques used were not significantly different when compared by the Student's t-test; the method was statistically evaluated for all the laboratories. Five corn sample materials, both spiked and naturally contaminated, were sent to 29 laboratories (22 Italian and 7 European). Test portions were spiked with aflatoxin B1 at levels of 2.00 and 5.00 ng/g. The mean values for recovery were 82% for the low level and 84% for the high contamination level. Based on results for spiked samples (blind pairs at 2 levels) as well as naturally contaminated samples (blind pairs at 3 levels), the values for relative standard deviation for repeatability (RSDr) ranged from 9.9 to 28.7%. The values for relative standard deviation for reproducibility (RSDR) ranged from 18.6 to 36.8%. The method demonstrated acceptable within- and between-laboratory precision for this matrix, as evidenced by the HorRat values.

Multipoint pacing via a quadripolar left-ventricular lead: preliminary results from the Italian registry on multipoint left-ventricular pacing in cardiac resynchronization therapy (IRON-MPP)

Aims

This registry was created to describe the experience of 76 Italian centres with a large cohort of recipients of multipoint pacing (MPP) capable cardiac resynchronization therapy (CRT) devices.

Methods and results

A total of 507 patients in whom these devices had been successfully implanted were enrolled between August 2013 and May 2015. We analysed: (i) current clinical practices for the management of such patients, and (ii) the impact of MPP on heart failure clinical composite response and on the absolute change in ejection fraction (EF) at 6 months. Multipoint pacing was programmed to ‘ON’ in 46% of patients before discharge. Methods of optimizing MPP programming were most commonly based on either the greatest narrowing of the QRS complex (38%) or the electrical delays between the electrodes (34%). Clinical and echocardiographic follow-up data were evaluated in 232 patients. These patients were divided into two groups according to whether MPP was programmed to ‘ON’ (n = 94) or ‘OFF’ (n = 138) at the time of discharge. At 6 months, EF was significantly higher in the MPP group than in the biventricular-pacing group (39.1 ± 9.6 vs. 34.7 ± 7.6%; P < 0.001). Even after adjustments, early MPP activation remained an independent predictor of absolute increase in LVEF of ≥5% (odds ratio 2.5; P = 0.001). At 6 months, an improvement in clinical composite score was recorded in a greater proportion of patients with MPP-ON than in controls (56 vs. 38%; P = 0.009). On comparing optimal MPP and conventional vectors, QRS was also seen to have decreased significantly (P < 0.001).

Conclusion

This study provides information that is essential in order to deal with the expected increase in the number of patients receiving MPP devices in the coming years. The results revealed different practices among centres, and establishing the optimal programming that can maximize the benefit of MPP remains a challenging issue. Compared with conventional CRT, MPP improved clinical status and resulted in an additional increase in EF.

Clinical Trial Registration

http://www.clinicaltrial.gov/. Unique identifier: NCT02606071.