Left Ventricular Enlargement, Cardiac Resynchronization Therapy Efficacy, and Impact of MultiPoint Pacing

Predictors for Super-Responders in Cardiac Resynchronization Therapy

BACKGROUND

Prediction of cardiac resynchronization therapy (CRT) response, particularly a super-response, is of great importance.

STUDY QUESTION

The aim of our study was to assess the predictors for super-responders in CRT.

STUDY DESIGN

We conducted a retrospective, observational study, which finally included 622 patients with heart failure treated with CRT between January 2008 and May 2020 who had a minimal follow-up of 6 months after CRT.

MEASURES AND OUTCOMES

A total of 192 super-responders, defined by a left ventricular ejection fraction (LVEF) of at least 45%, and/or minimum 15% increase in LVEF and an improvement of the New York Heart Association functional class by at least 2 degrees at the last follow-up, and the rest of 430 patients who did not fulfill the super-responder criteria.

RESULTS

The highest rate of super-responders (41.91%, n = 171) was at patients with left ventricle-only pacing with optimal fusion (OPT) compared with patients with biventricular (BiV) pacing (9.81%, n = 21, P < 0.000). In the OPT group, univariable analysis showed that nonischemic cardiomyopathy, a smaller degree of mitral regurgitation, and better left ventricle function at enrollment were predictors for super-response compared with the BiV group where a narrower QRS after implantation, nonischemic cardiomyopathy, and a better baseline LVEF were predictors for super-responders. In the multivariable analysis, both narrower QRS after implantation and nonischemic cardiomyopathy were independent predictors for super-response in the BiV group compared with OPT where nonischemic cardiomyopathy remained the only independent predictor for super-response.

CONCLUSIONS

In this retrospective study, OPT CRT programing was an additional predictor of super-response to CRT besides nonischemic cardiomyopathy.

Acute Hemodynamic Effect of a Novel Dual-Vein, Multisite Biventricular Pacing Configuration

BACKGROUND

Biventricular pacing (BVP) from multiple left ventricular (LV) sites could enhance the efficacy of cardiac resynchronization therapy (CRT) by engaging a greater myocardial mass.

OBJECTIVES

The goal of this study was to evaluate the acute hemodynamic effect of various multisite pacing (MSP) configurations against conventional BVP.

METHODS

Twenty patients with nonischemic dilated cardiomyopathy and left bundle branch block (mean age: 59 ± 14 years; LV ejection fraction: 27% ± 6%; native QRS: 171 ± 16 milliseconds) were investigated during a routine CRT implant procedure. In addition to conventional right atrial and right ventricular leads, 2 quadripolar leads were placed in the distant coronary venous branches. LV hemodynamics was evaluated by using a micromanometer-tipped catheter during atrioventricular BVP with 4 LV lead configurations: single-lead conventional BVP; single-lead multipoint pacing; triventricular pacing from distal dipoles of 2 LV leads; and maximum MSP (MSP-Max) from 4 dipoles of 2 LV leads.

RESULTS

Compared with right atrial pacing, any BVP configuration produced a significant increase in the maximal LV diastolic pressure rise (LVdP/dTMax) (a median relative increase of 28% [IQR: 8%-45%], 25% [IQR: 18%-46%], 36% [IQR: 18%-54%], and 38% [IQR: 28%-58%], respectively; all, P < 0.001). MSP-Max but no other multisite BVP generated a significant increase of the maximal LVdP/dTMax than conventional BVP (P = 0.041). Increased LVdP/dTMax during MSP-Max was associated with greater LV diameter and lower LV ejection fraction, independently of the QRS width.

CONCLUSIONS

The study shows the hemodynamic advantage of a novel dual-vein MSP-Max configuration that could be useful for CRT in patients with advanced LV remodeling.

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.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Programming Algorithms for Cardiac Resynchronization Therapy

Current cardiac resynchronization therapy (CRT) implant guidelines emphasize the presence of electrical dyssynchrony (left bundle branch block (LBBB) and QRS > 150 ms) yet have modest predictive value for response and have not reduced the 30% nonresponse rate. Optimized programming to optimize CRT delivery has promised much but to date has largely been ineffective. What is missing is the understanding of LV paced effects (which are unpredictable) and optimal paced AV interval (that can be conserved during physiologic variations) that then can be incorporated into an individualized programming prescription. Automatic device-based algorithms that deliver electrical optimization and maintain this during ambulatory fluctuations in AV interval are discussed.

Potential efficacy of multipoint pacing in the reduction of mitral regurgitation volume: a case report

A 70‐year‐old woman who had cardiac sarcoidosis and severe tethering mitral regurgitation (MR) and had been implanted with a biventricular pacemaker experienced recurrent hospitalisation due to decompensated heart failure (HF). Application of MultiPoint™ pacing reduced the MR volume and maintained the symptoms under control; however, the predicted longevity of the device significantly decreased because of the very high threshold of the added pacing site. Transcatheter mitral valve repair (TMVR) using MitraClip® was performed to further diminish the severe MR, thereby enabling the switch from highly consumptive multipoint pacing (MPP) to energy‐saving single‐point pacing. MPP could further reduce MR compared to the conventional single‐point pacing, and this could be a bridging therapy to TMVR in some patients implanted with a biventricular pacemaker. This is the first case to report that switching from conventional single‐point pacing to MPP decreased the MR, to some extent, resulting in the improvement of HF symptoms.

Usefulness of Multisite Ventricular Pacing in Nonresponders to Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) is an established treatment for heart failure patients with myocardial dysfunction and delayed ventricular activation, but approximately 25% to 40% of patients do not respond to CRT. Left ventricular (LV) multisite pacing (MSP) has been proposed as a tool to improve CRT response. The goal of this study is to examine the safety and efficacy of LV MSP in CRT nonresponders. Between January 2018, and September 2019, the Strategic Management to Improve CRT Using Multi-Site Pacing trial prospectively enrolled 584 CRT-defibrillator recipients for established indications at 52 sites across the United States and evaluated their response at 6 months using the clinical composite score (CCS). Of the nonresponders, 102 patients had the LV MSP feature turned on and 78 patients completed the 12-month CCS evaluation. The LV MSP feature-related complication-free rate was 99.0% with a lower 95% confidence interval limit of 94.9%, which was higher than the performance goal of 90%. The proportion of nonresponders with an improved CCS from 6 to 12 months was 51.3% with a lower 95% confidence interval limit of 41.4%, which was higher than the performance goal of 5%. The estimated mean reduction in battery longevity with the LV MSP feature was about 3.6 months (estimated battery longevity of 8.87 ± 2.08 years at 6 months and 8.07 ± 2.23 years at 12 months). In conclusion, in CRT nonresponders, the use of the LV MSP feature is safe and associated with a ∼50% conversion rate with a small projected reduction in CRT-defibrillator battery longevity. LV MSP should be considered in the management of CRT nonresponders.

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.

Impact of anatomical reverse remodelling in the design of optimal quadripolar pacing leads: A computational study

Lead position is an important factor in determining response to Cardiac Resynchronization Therapy (CRT) in dyssynchronous heart failure (HF) patients. Multipoint pacing (MPP) enables pacing from multiple electrodes within the same lead, improving the potential outcome for patients. Virtual quadripolar lead designs were evaluated by simulating pacing from all combinations of 1 and 2 electrodes along the lead in each virtual patient from cohorts of HF (n = 24) and simulated reverse remodelled (RR, n = 20) patients. Electrical synchrony was assessed by the time 90% of the ventricular myocardium is activated (AT090). Optimal 1 and 2 electrode pacing configurations for AT090 were combined to identify the 4-electrode lead design that maximised benefits across all patients. LV pacing in the HF cohort in all possible single and double electrode locations reduced AT090 by 14.48 ± 5.01 ms (11.92 ± 3.51%). The major determinant of reduction in activation time was patient anatomy. Pacing with a single optimal lead design reduced AT090 more in the HF cohort than the RR cohort (12.68 ± 3.29% vs 10.81 ± 2.34%). Pacing with a single combined HF and RR population-optimised lead design achieves electrical resynchronization with near equivalence to personalised lead designs both in HF and RR anatomies. These findings suggest that although lead configurations have to be tailored to each patient, a single optimal lead design is sufficient to obtain near-optimal results across most patients. This study shows the potential of virtual clinical trials as tools to compare existing and explore new lead designs.

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 outcome 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.

CRT Efficacy in "Mid-Range" QRS Duration Among Asians Contrasted to Non-Asians, and Influence of Height

OBJECTIVES

The purpose of this study was to test the hypotheses that cardiac resynchronization therapy (CRT) efficacy differed among Asians compared with non-Asian populations, differed between QRS duration (QRSd) ranges 120-149 and ≥150 ms, and was influenced by height in the multinational ADVANCE CRT trial.

BACKGROUND

CRT guidelines, derived from trials among U.S./European patients, assign weaker recommendations to those with midrange QRSd (QRSd <150 ms). Patient height may modulate CRT efficacy. Together, these may affect CRT prescription and efficacy in Asia.

METHODS

CRT response was assessed using the Clinical Composite Score 6 months postimplant (n = 934). Heart failure events and cardiac deaths were reported until 12 months. Asian and non-Asian patients were compared overall, by QRSd <150 ms (Asian n = 71 vs non-Asian n = 248), and QRSd ≥150 ms (Asian n = 180 vs non-Asian n = 435) and by height.

RESULTS

Asians comprised 27% (251 of 934) of the primary study population. More Asians had QRSd ≥150 ms (72% [180 of 251] vs 64% [435 of 683] in non-Asian patients; P = 0.022). Overall CRT response was better in Asians vs non-Asians (Clinical Composite Score 85% vs 65%; P <0.001), and following QRSd dichotomization (QRSd <150 ms: 80% vs 59%; P <0.001; QRS ≥150 ms: 86% vs 69%; P < 0.001). HF events and cardiac deaths were fewer in Asians irrespective of QRSd (P < 0.001). Stepwise multivariable analysis indicated that in group QRSd <150 ms, nonischemic cardiomyopathy, number of other comorbidities (0-1 vs ≥4), and atrial fibrillation influenced CRT response. The trend favoring Asian race (OR: 1.46; 95% CI: 0.72-2.95) was eliminated (OR: 1.00; 95% CI: 0.47-2.11) when height or QRSd/height were included (QRSd/height P = 0.006; OR: 1.64; 95% CI: 1.15-2.35). In QRSd <150 ms, probability of CRT response diminished as height increased, but increased with QRSd/height, in both Asians and non-Asians. In QRSd ≥150 ms, height or QRSd/height had minimal effect in Asians or non-Asians.

CONCLUSIONS

Height modulates CRT efficacy among patients with QRSd <150 ms and contributes to high probability of benefit from CRT among Asians. CRT should be encouraged among Asian patients with midrange QRSd. (Advance Cardiac Resynchronization Therapy [CRT] Registry; NCT01805154).

Optimal CRT Implantation-Where and How To Place the Left-Ventricular Lead?

Purpose of Review

Cardiac resynchronization therapy (CRT) represents a well-established and effective non-pharmaceutical heart failure (HF) treatment in selected patients. Still, a significant number of patients remain CRT non-responders. An optimal placement of the left ventricular (LV) lead appears crucial for the intended hemodynamic and hence clinical improvement. A well-localized target area and tools that help to achieve successful lead implantation seem to be of utmost importance to reach an optimal CRT effect.

Recent Findings

Recent studies suggest previous multimodal imaging (CT/cMRI/ECG torso) to guide intraprocedural LV lead placement. Relevant benefit compared to empirical lead optimization is still a matter of debate. Technical improvements in leads and algorithms (e.g., multipoint pacing (MPP), adaptive algorithms) promise higher procedural success. Recently emerging alternatives for ventricular synchronization such as conduction system pacing (CSP), LV endocardial pacing, or leadless pacing challenge classical biventricular pacing.

Summary

This article reviews current strategies for a successful planning, implementation, and validation of the optimal CRT implantation. Pre-implant imaging modalities offer promising assistance for complex cases; empirical lead positioning and intraoperative testing remain the cornerstone in most cases and ensure a successful CRT effect.

Fusion Pacing with Biventricular, Left Ventricular-only and Multipoint Pacing in Cardiac Resynchronisation Therapy: Latest Evidence and Strategies for Use

Despite advances in the field of cardiac resynchronisation therapy (CRT), response rates and durability of therapy remain relatively static. Optimising device timing intervals may be the most common modifiable factor influencing CRT efficacy after implantation. This review addresses the concept of fusion pacing as a method for improving patient outcomes with CRT. Fusion pacing describes the delivery of CRT pacing with a programming strategy to preserve intrinsic atrioventricular (AV) conduction and ventricular activation via the right bundle branch. Several methods have been assessed to achieve fusion pacing. QRS complex duration (QRSd) shortening with CRT is associated with improved clinical response. Dynamic algorithm-based optimisation targeting narrowest QRSd in patients with intact AV conduction has shown promise in people with heart failure with left bundle branch block. Individualised dynamic programming achieving fusion may achieve the greatest magnitude of electrical synchrony, measured by QRSd narrowing.

The cost of non-response to cardiac resynchronization therapy: characterizing heart failure events following cardiac resynchronization therapy

AIMS

The aim of this study is to quantify healthcare resource utilization among non-responders to cardiac resynchronization therapy (CRT-NR) by heart failure (HF) events and influence of comorbidities.

METHODS AND RESULTS

The ADVANCE CRT registry (2013-2015) prospectively identified responders/CRT-NRs 6 months post-implant using the clinical composite score. Heart failure event rates and associated cost, both overall and separated for inpatient hospitalizations, office visits, emergency room visits, and observational stays, were quantified. Costs of events were imputed from payments for similar real-world encounters in subjects with CRT-D/P devices in the MarketScan™ commercial and Medicare Supplemental insurance claims databases. Effects of patient demographics and comorbidities on event rates and cost were evaluated. Of 879 US patients (age 69 ± 11 years, 29% female, ischaemic disease 52%), 310 (35%) were CRT-NR. Among CRT-NRs vs. responders, more patients developed HF (41% vs. 11%, P < 0.001), HF event rate was higher (67.0 ± 21.7 vs. 11.4 ± 3.7/100 pt-year, P < 0.001), and HF readmission within 30 days was more common [hazard ratio 7.06, 95% confidence interval (2.1-43.7)]. Inpatient hospitalization was the most common and most expensive event type in CRT-NR. Comorbid HF was increased by diabetes, hypertension, and pulmonary disorders. Over 2 years, compared to CRT responders, each CRT-NR resulted in excess cost of $6388 ($3859-$10 483) to Medicare (P = 0.015) or $10 197 ($6161-$17 394) to private insurances (P = 0.014).

CONCLUSION

Healthcare expenditures associated with contemporary CRT non-response management are among the highest for any HF patient group. This illustrates an unmet need for interventions to improve HF outcomes and reduce costs among some CRT recipients.

Optimizing lead placement for pacing in dyssynchronous heart failure: The patient in the lead

Cardiac resynchronization therapy (CRT) greatly reduces morbidity and mortality in patients with dyssynchronous heart failure. However, despite tremendous efforts, response has been variable and can be further improved. Although optimizing left ventricular lead placement (LVLP) is arguably the cornerstone of CRT, the procedure of LVLP using the transvenous approach has remained largely unchanged for more than 2 decades. Improvements have been developed using scar location and electrical and/or mechanical mapping, and interest in conduction system pacing as an alternative to biventricular pacing has emerged recently. Conduction system pacing is promising but may not be suitable for all patients with dyssynchronous heart failure. This review underscores the importance of a patient-tailored approach and discusses the potential applications of both conduction system pacing and targeted biventricular CRT.

Optimized single-point left ventricular pacing leads to improved resynchronization compared with multipoint pacing

BACKGROUND

Multipoint pacing (MPP) in cardiac resynchronization therapy (CRT) activates the left ventricle from two locations, thereby shortening the QRS duration and enabling better resynchronization; however, compared with conventional CRT, MPP reduces battery longevity. On the other hand, electrocardiogram-based optimization using the fusion-optimized intervals (FOI) method achieves more significant reverse remodeling than nominal CRT programming. Our study aimed to determine whether MPP could attain better resynchronization than single-point pacing (SPP) optimized by FOI.

METHODS

This prospective study included 32 consecutive patients who successfully received CRT devices with MPP capabilities. After implantation, the QRS duration was measured during intrinsic rhythm and with three pacing configurations: MPP, SPP-FOI, and MPP-FOI. In 14 patients, biventricular activation times (by electrocardiographic imaging, ECGI) were obtained during intrinsic rhythm and for each pacing configuration to validate the findings. Device battery longevity was estimated at the 45-day follow-up.

RESULTS

The SPP-FOI method achieved greater QRS shortening than MPP (-56 ± 16 vs. -42 ± 17 ms, p < .001). Adding MPP to the best FOI programming did not result in further shortening (MPP-FOI: -58 ± 14 ms, p = .69). Although biventricular activation times did not differ significantly among the three pacing configurations, only the two FOI configurations achieved significant shortening compared with intrinsic rhythm. The estimated battery longevity was longer with SPP than with MPP (8.1 ± 2.3 vs. 6.3 ± 2.0 years, p = .03).

CONCLUSIONS

SPP optimized by FOI resulted in better resynchronization and longer battery duration than MPP.