Clinical response with adaptive CRT algorithm compared with CRT with echocardiography-optimized atrioventricular delay: a retrospective analysis of multicentre trials

Cardiac resynchronization therapy in heart failure based on Strauss criteria for left bundle branch block

AIMS

The left bundle branch block (LBBB) is a strong predictor of response to cardiac resynchronization therapy (CRT). However, a significant number of patients do not respond to the treatment. The study sought to evaluate the impact of the stricter Strauss criteria for left bundle branch block (St-LBBB) on CRT response, hospitalizations, ventricular arrhythmia (VA) events and mortality.

METHODS

This study is a retrospective analysis of prospectively collected data on heart failure (HF) patients with LBBB admitted for CRT implantation. Patients were divided into two groups according to the fulfilment or not of St-LBBB criteria.

RESULTS

The study included 82 patients with ischaemic (ICM) and non-ischaemic (NICM) cardiomyopathy [46 (56%) with St-LBBB and 36 (44%) with non-St-LBBB]. Patients with St-LBBB showed higher CRT response rates compared with those with non-St-LBBB (P < 0.01), while the group with NICM exhibited the greatest benefit (P < 0.01). St-LBBB CRT responders displayed significantly lower rates of HF hospitalization (P < 0.0001) compared with the non-St-LBBB group. According to Kaplan-Meier time curves, this was primarily evident in patients with NICM (P < 0.0001). CRT responders displayed significantly fewer VA events (P < 0.001) and lower mortality rates (P < 0.0001) than non-responders. Kaplan-Meier estimates demonstrated a significantly lower incidence of VAs in NICM patients with St-LBBB (P = 0.049) compared with ICM patients with St-LBBB (P = 0.25). Lower mortality rates were observed in CRT responders than non-responders (P < 0.0001), with the group of NICM with St-LBBB criteria exhibiting the greatest benefit (P = 0.0238).

CONCLUSIONS

Patients with NICM and St-LBBB present the greatest benefit concerning CRT response, HF hospitalizations, VA events and mortality. Although St-LBBB criteria seem to improve patient selection for CRT, more data are needed to elucidate the role of St-LBBB criteria in this setting.

Electrical dyssynchrony mapping and optimization of nonresponders in patients programmed with the adaptive cardiac resynchronization therapy algorithm

BACKGROUND

The adaptive cardiac resynchronization therapy (CRT) (aCRT) algorithm provides an important clinical benefit. However, a significant number of patients are nonresponders.

OBJECTIVES

The goals of this study were to quantify electrical synchrony in patients programmed with aCRT and to assess the echocardiographic effects of optimization in CRT nonresponders and incomplete responders.

METHODS

We studied 125 patients programmed with aCRT and measured electrical synchrony at multiple device settings using novel electrical dyssynchrony mapping (EDM) technology. Electrical synchrony was quantified as cardiac resynchronization index (CRI), a measure that analyzes areas between multiple pairs of anterior and posterior electrograms and calculates synchrony normalized to native rhythm.

RESULTS

CRI improved from baseline aCRT settings to optimal settings on the basis of EDM (56%±29% vs 92%±12%; P<.001). Patients programmed with left ventricle (LV)-only aCRT (group 1, n=68 [54%]) had a higher CRI (62%±25% vs 48%±31%; P=.014) than did patients programmed with biventricular aCRT (group 2, n=57 [46%]). In group 1 and group 2, optimal CRI during sequential biventricular (92%±13% and 93%±9%, respectively) and LV-only (92%±6% and 91%±7%, respectively) pacing was significantly (P<.001) higher than CRI at baseline aCRT setting. In a subset of 53 nonresponders optimized using EDM, there were significant improvements in CRI (37%±25%; P<.0001), LV ejection fraction (6.2%±6.6%; P<.0001), end-diastolic volume (9.5±28.2 mL; P=.015), end-systolic volume (13.4±24.9 mL; P<.001), and transverse (1.5%±4.4%; P=.014), longitudinal (1.0%±2.5%; P=.003), and circumferential (2.6%±8.5%; P=.047) strain.

CONCLUSION

Electrical synchrony improves 56% with CRT using aCRT programming and 92% with EDM optimization. Optimization of aCRT-programmed nonresponders results in significant improvements in LV size and systolic function, offering the possibility of converting CRT nonresponders into responders.

Emergent role of dynamic optimization in cardiac resynchronization therapy: Systematic review and network meta-analysis

AIMS

Suboptimal device programming is frequent in non-responders to cardiac resynchronization therapy (CRT). However, the role of device optimization and the most appropriate technique are still unknown. The aim of our study was to analyse the effect of different CRT optimization techniques within a network meta-analysis.

METHODS

A systematic search was conducted on MEDLINE, Embase and CENTRAL for studies comparing outcomes with empirical device settings or optimization using echocardiography, static algorithms or dynamic algorithms. Studies investigating the effect of optimization in non-responders were also analysed.

RESULTS

A total of 17 studies with 4346 patients were included in the quantitative analysis. Of the treatments and outcomes examined, a significant difference was found only between dynamic algorithms and echocardiography, with the former leading to a higher echocardiographic response rate [odds ratio (OR): 2.02, 95% confidence interval (CI) 1.21-3.35], lower heart failure hospitalization rate (OR: 0.75, 95% CI 0.57-0.99) and greater improvement in 6-minute walk test [mean difference (MD): 45.52 m, 95% credible interval (CrI) 3.91-82.44 m]. We found no significant difference between empirical settings, static algorithms and dynamic algorithms. Seven studies with 228 patients reported response rates after optimization in non-responders. Altogether, 34.3%-66.7% of initial non-responders showed improvement after optimization, depending on response criteria.

CONCLUSIONS

At the time of CRT implantation, dynamic algorithms may serve as a resource-friendly alternative to echocardiographic optimization, with similar or better mid-term outcomes. However, their superiority over empirical device settings needs to be investigated in further trials. For non-responders, CRT optimization should be considered, as the majority of patients experience improvement.

Computational electrophysiology of the coronary sinus branches based on electro-anatomical mapping for the prediction of the latest activated region

This work dealt with the assessment of a computational tool to estimate the electrical activation in the left ventricle focusing on the latest electrically activated segment (LEAS) in patients with left bundle branch block and possible myocardial fibrosis. We considered the Eikonal-diffusion equation and to recover the electrical activation maps in the myocardium. The model was calibrated by using activation times acquired in the coronary sinus (CS) branches or in the CS solely with an electroanatomic mapping system (EAMS) during cardiac resynchronization therapy (CRT). We applied our computational tool to ten patients founding an excellent accordance with EAMS measures; in particular, the error for LEAS location was less than 4 mm. We also calibrated our model using only information in the CS, still obtaining an excellent agreement with the measured LEAS. The proposed tool was able to accurately reproduce the electrical activation maps and in particular LEAS location in the CS branches, with an almost real-time computational effort, regardless of the presence of myocardial fibrosis, even when information only at CS was used to calibrate the model. This could be useful in the clinical practice since LEAS is often used as a target site for the left lead placement during CRT.

Device treatment of heart failure

Background: The incidence of heart failure (HF) is rapidly increasing, introducing a significant burden and challenges in clinical practice. Non-pharmacological cardiac device therapy has been established as an essential component of optimal HF management, particularly for the prevention of sudden cardiac death and the improvement of HF symptoms, left ventricular (LV) systolic function, quality of life, and eventually survival.Current Concepts: Cardiac resynchronization therapy (CRT) can correct atrioventricular or inter/intraventricular dyssynchrony, thereby improving LV systolic function. Recently, the concept of CRT is being expanded, including His bundle (HB), HB-optimized LV, left bundle branch (LBB), and LBB optimized LV pacing CRTs. Newly introduced CRT approaches by stimulating the cardiac conduction system are expected to correct dyssynchrony better and consequently exhibit better CRT outcomes than the conventional biventricular pacing CRT. The current versions of implantable cardioverter-defibrillators (ICDs) or CRT devices can continuously monitor multiple biosignals. CRT/ICD can calculate a single index by combining these multiple bio-signal data for early detection of HF aggravation. Recently, subcutaneous and transvenous ICDs showed comparable safety and efficacy in HF patients. In drug-refractory HF patients without LV dyssynchrony, cardiac contractility modulation therapy provides some promising results.Discussion and Conclusion: Recent technological advancements have improved the efficacy and safety of cardiac device therapy. Therefore, cardiac device therapy should be used more actively to manage HF patients better.

Cost-effective analysis of automated programming optimization in cardiac resynchronization therapy: Holistic Markov modelling

BACKGROUND

Automated optimization algorithm (AdaptivCRT; Medtronic, Mounds View, MN, USA) allowing automated optimization of cardiac resynchronization therapy (CRT), has been introduced. However, little is known concerning its cost-effectiveness. This study aims to evaluate the potential economic benefits of AdaptivCRT of CRT.

METHODS

Markov modelling was informed by empirical data sourced from the AdaptivCRT Clinical Trial. Published meta-analyses were used to derive the impact of increasing response to hospitalization and mortality risks. Response was assessed via the clinical composite score.

RESULTS

Deterministic results suggested a mean survival of 10.97 years with adaptive algorithms against 10.5 years without (+0.47 in favour of novel algorithms). Heart failure hospitalization costs were modelled to ¥1,382,753 (US $12,686) with novel devices against ¥1,524,747 (US $13,989) with previous technology models. Sensitivity analyses show CRT with Adaptive algorithm was projected to provide cost savings in all scenarios.

CONCLUSIONS

The use of AdaptivCRT was projected to improve average patient survival and avoid costs in a Japanese healthcare setting.

Impact of adaptive cardiac resynchronization therapy in patients with systolic heart failure: Beyond QRS duration and morphology

BACKGROUND

Mechanical and electrical restoration by cardiac resynchronization therapy (CRT) with adaptive pacing algorithm (aCRT) in heart failure patients with a moderately wide (120-149 ms) QRS has not been fully evaluated. The purpose of this study was to investigate the therapeutic effect of aCRT compared with conventional biventricular CRT (BiV-CRT) regardless of QRS morphology.

METHODS

Seventeen consecutive patients with a QRS ≥120 ms, regardless of morphology, underwent CRT device implantation with an aCRT pacing algorithm. Propensity score matched analysis was performed to evaluate the impact of aCRT on the improvement in mechanical and electrical parameters after CRT device implantation using historical controls (HC) from the clinical registry of BiV-CRT (START trial).

RESULTS

Left ventricular (LV) volume significantly decreased after CRT in all patients in both the aCRT and HC groups. The difference in relative reduction of LV end-systolic volume (LVESV) was not significantly different between the 2 arms. QRS shortening after CRT was significantly greater in the aCRT group than in the BiV-CRT group, and the difference was prominent in patients with a moderately wide QRS (120-149 ms). In patients with a moderately wide QRS, the relative reduction in LVESV [39 (29-47)% vs. 2 (-6-20)%, p = 0.04] and proportion of LV volume responders (90% vs. 38%, p = 0.04) were significantly greater in the aCRT group than in the HC group. The proportion of volume responders was not significantly different in patients with a wide QRS (≥150 ms).

CONCLUSIONS

The aCRT algorithm improved electrical and mechanical parameters in patients with a moderately wide QRS, regardless of QRS morphology.

Improvement of electrical synchrony in cardiac resynchronization therapy using dynamic atrioventricular delay programming and multipoint pacing

BACKGROUND

Optimization of cardiac resynchronization therapy (CRT) is often time-consuming and therefore underused in a clinical setting. Novel device-based algorithms aiming to simplify optimization include a dynamic atrioventricular delay (AVD) algorithm (SyncAV, Abbott) and multipoint pacing (MPP, Abbott). This study examines the acute effect of SyncAV and MPP on electrical synchrony in patients with newly and chronically implanted CRT devices.

METHODS

Patients with SyncAV and MPP enabled devices were prospectively enrolled during implant or scheduled follow-up. Blinded 12-lead electrocardiographic acute measurements of QRS duration (QRSd) were performed for intrinsic QRSd (Intrinsic), bi-ventricular pacing (BiV), MPP, BiV with SyncAV at default offset 50 ms (BiVSyncAV_def ), BiV with SyncAV at patient-specific optimised offset (BiVSyncAV_opt ), MPP with SyncAV at default offset 50 ms (MPPSyncAV_def ), and MPP with SyncAV at patient-specific optimised offset (MPPSyncAV_opt ).

RESULTS

Thirty-three patients were enrolled. QRSd for Intrinsic, BiV, MPP, BiVSyncAV_def , BiVSyncAV_opt , MPPSyncAV_def , MPPSyncAV_opt were 160.4 ± 20.6 ms, 141.0 ± 20.5 ms, 130.2 ± 17.2 ms, 121.7 ± 20.9 ms, 117.0 ± 19.0 ms, 121.2 ± 17.1 ms, 108.7 ± 16.5 ms respectively. MPPSyncAV_opt led to greatest reduction of QRSd relative to Intrinsic (-31.6 ± 11.1%; p < .001), showed significantly shorter QRSd compared to all other pacing configurations (p < .001) and shortest QRSd in every patient. Shortening of QRSd was not significantly different between newly and chronically implanted devices (-51.6 ± 14.7 ms vs. -52.7 ± 21.9 ms; p = .99).

CONCLUSION

SyncAV and MPP improved acute electrical synchrony in CRT. Combining both technologies with patient-specific optimization resulted in greatest improvement, regardless of time since implantation. Whats new Novel device-based algorithms like a dynamic AVD algorithm (SyncAV, Abbott) and multipoint pacing (MPP, Abbott) aim to simplify CRT optimization. Our data show that a combination of patient tailored SyncAV optimization and MPP results in greatest improvement of electrical synchrony in CRT measured by QRS duration, regardless if programmed in newly or chronically implanted devices. This is the first study to our knowledge to examine a combination of these device-based algorithms. The results help understanding the ideal ventricular excitation in heart failure.

Prognostic predictors and echocardiographic time course after device replacement in patients treated chronically with cardiac resynchronization therapy devices

The prognostic predictors of death or heart failure hospitalization and the echocardiographic response after initial cardiac resynchronization therapy (CRT) device replacement (CRT-r) remain unclear. We evaluated the predictors and the echocardiographic time course in patients after CRT-r. Consecutive 60 patients underwent CRT-r because of battery depletion. Patients were divided into two groups depending on the chronic echocardiographic response to CRT (left ventricular end-systolic volume [LVESV] reduction of ≥ 15%) at the time of CRT-r: CRT responders (group A; 35 patients) and CRT nonresponders (group B; 25 patients). The primary endpoint was a composite of death from any cause or heart failure hospitalization. Changes in LVESV and left ventricular ejection fraction (LVEF) after CRT-r were also analyzed. During the mean follow-up of 46 ± 33 months after CRT-r, the primary endpoint occurred more frequently in group B (group A versus group B; 8/35 [23%] patients versus 19/25 [76%] patients, p < 0.001). No significant changes in LVESV and LVEF were observed at the mean of 46 ± 29 months after CRT-r in both groups. A multivariate analysis identified echocardiographic nonresponse to CRT, chronic kidney disease, atrial fibrillation, and New York Heart Association functional class III or IV at the time of CRT-r as independent predictors of the primary endpoint in all patients. Residual echocardiographic nonresponse, comorbidities, and heart failure symptoms at the time of CRT-r predict the subsequent very long-term prognosis after CRT-r. No further echocardiographic response to CRT was found after CRT-r.

Adaptive Cardiac Resynchronization Therapy Effect on Electrical Dyssynchrony (aCRT-ELSYNC): A randomized controlled trial

BACKGROUND

Adaptive cardiac resynchronization therapy (aCRT) is known to have clinical benefits over conventional CRT, but the mechanisms are unclear.

OBJECTIVE

Compare effects of aCRT and conventional CRT on electrical dyssynchrony.

METHODS

A prospective, double-blind, 1:1 parallel-group assignment randomized controlled trial in patients receiving CRT for routine clinical indications. Participants underwent cardiac computed tomography and 128-electrode body surface mapping. The primary outcome was change in electrical dyssynchrony measured on the epicardial surface using noninvasive electrocardiographic imaging before and 6 months post-CRT. Ventricular electrical uncoupling (VEU) was calculated as the difference between the mean left ventricular (LV) and right ventricular (RV) activation times. An electrical dyssynchrony index (EDI) was computed as the standard deviation of local epicardial activation times.

RESULTS

We randomized 27 participants (aged 64 ± 12 years; 34% female; 53% ischemic cardiomyopathy; LV ejection fraction 28% ± 8%; QRS duration 155 ± 21 ms; typical left bundle branch block [LBBB] in 13%) to conventional CRT (n = 15) vs aCRT (n = 12). In atypical LBBB (n = 11; 41%) with S waves in V5-V6, conduction block occurred in the anterior RV, as opposed to the interventricular groove in strict LBBB. As compared to baseline, VEU reduced post-CRT in the aCRT (median reduction 18.9 [interquartile range 4.3-29.2 ms; P = .034]), but not in the conventional CRT (21.4 [-30.0 to 49.9 ms; P = .525]) group. There were no differences in the degree of change in VEU and EDI indices between treatment groups.

CONCLUSION

The effect of aCRT and conventional CRT on electrical dyssynchrony is largely similar, but only aCRT harmoniously reduced interventricular dyssynchrony by reducing RV uncoupling.

Contemporary ICD Use in Patients with Heart Failure

Despite constant breakthroughs in heart failure (HF) therapy, the population of HF patients resume to grow and is linked to increased mortality and morbidity. Ventricular arrhythmias (VA) are one of the leading causes of mortality in HF subjects. Implantable cardioverter-defibrillators (ICDs) are currently the gold standard in treatment, preventing arrhythmic sudden cardiac death (SCD) episodes. However, the death rates related to HF remain elevated, as not all HF subjects benefit equally. Cardiac resynchronization therapy (CRT) has emerged as a novel approach for HF patients. These devices have been thoroughly investigated in major randomized controlled studies but continue to be underutilized in various countries. This review discusses the use of ICD in HF populations on top of treatments.

Advances in cardiac resynchronization and implantable cardioverter/defibrillator therapy: Medtronic Cobalt and Crome

Cardiovascular implantable electronic devices have revolutionized the management of heart failure with reduced ejection fraction. New device generations tend to be launched every few years, with incremental improvements in performance and safety and with an expectation that these will improve patient management and outcomes while remaining cost-effective. As a result, today's cardiac resynchronization therapy (CRT) and implantable cardioverter defibrillator devices are quite different from the pioneering but often bulky devices of the late 20th century. This review discusses new and improved features developed to target specific needs in managing heart failure patients, some of which are especially pertinent to the current worldwide healthcare situation, with focus on the latest generation of CRTs with defibrillator (CRT-Ds) and implantable cardioverter defibrillators from Medtronic.

Economic implications of adding a novel algorithm to optimize cardiac resynchronization therapy: rationale and design of economic analysis for the AdaptResponse trial

AIMS

Although cardiac resynchronization therapy (CRT) has proven beneficial in several randomized trials, a subset of patients have limited clinical improvement. The AdaptivCRT algorithm provides automated selection between synchronized left ventricular or biventricular pacing with optimization of atrioventricular delays. The rationale and design of the economic analysis of the AdaptResponse clinical trial are described.

RATIONALE

The costs associated with HF hospitalization are substantial and are compounded by a high rate of readmission. HF hospitalization payments range from $1,001 for Greece to $12,235 for US private insurance. When examining the breakdown of HF-related costs, it is clear that approximately 55% of the hospitalization costs are directly attributable to length of stay. Notably, the mean costs of a CRT patient in need of a HF-related hospitalization are currently estimated to be an average of $10,679.

METHODS

The economic analysis of the AdaptResponse trial has two main objectives. The hospital provider objective seeks to test the hypothesis that AdaptivCRT reduces the incidence of all-cause re-admissions after a heart failure admission within 30 days of the index event. A negative binomial regression model will be used to estimate and compare the number of readmissions after an index HF hospitalization. The payer economic objective will assess cost-effectiveness of CRT devices with the AdaptivCRT algorithm relative to traditional CRT programming. This analysis will be conducted from a U.S. payer perspective. A decision analytic model comprised of a 6-month decision tree and a Markov model for long term extrapolation will be used to evaluate lifetime costs and benefits.

CONCLUSION

AdaptivCRT may offer improvements over traditional device programming in patient outcomes. How the data from AdaptResponse will be used to demonstrate if these clinical benefits translate into substantial economic gains is herein described.

Differences in clinical characteristics and reported quality of life of men and women undergoing cardiac resynchronization therapy

AIMS

Response to cardiac resynchronization therapy (CRT) is known to be associated with a number of clinical characteristics, including QRS duration and morphology, gender, height, and the aetiology of heart failure (HF). We assessed the relation of gender and baseline characteristics with QRS duration and Kansas City Cardiomyopathy Questionnaire.

METHODS AND RESULTS

AdaptResponse is a global randomized trial. The trial enrolled CRT-indicated patients with New York Heart Association classes II-IV HF, left bundle branch block (QRS ≥ 140 ms in men, ≥130 ms in women), and baseline PR interval ≤200 ms. In total, 3620 patients were randomized, including 1569 women (43.3%) approaching the actual proportion of women in the HF population. Women were older and more often New York Heart Association class III or IV than men (55.6% vs. 48.7%), had less frequent ischaemic cardiomyopathy (21.2% vs. 39.5%), and had a 5.1 ms shorter QRS duration than men. Women were more often depressed (18.5% vs. 9.7%), had a significantly lower Kansas City Cardiomyopathy Questionnaire score, and had differences in medication prescriptions.

CONCLUSIONS

AdaptResponse is the largest randomized CRT trial and enrolled more women than any other landmark CRT trial. Women differed from men with regard to baseline characteristics and quality of life. Whether these differences translate into clinical outcome differences will be examined further in the AdaptResponse trial.

Electrical wavefront fusion in heart failure patients with left bundle branch block and cardiac resynchronization therapy: Implications for optimization

BACKGROUND

Novel metrics of electrical dyssynchrony based on multi-electrode mapping and ECG-based markers of fusion are better predictors of cardiac resynchronization therapy (CRT) response than QRS duration.

OBJECTIVE

To describe a new methodology for measuring electrical synchrony based on wavefront fusion and electrocardiographic cancellation in patients with CRT and its potential for CRT optimization.

METHODS

Patients with left bundle branch block (LBBB) type conduction and CRT (n = 84) were studied at multiple device settings using an ECG belt (53 anterior and posterior electrodes). The area between combinations of anterior and posterior curves (AUC) was calculated and cardiac resynchronization index (CRI) defined as percent change in AUC compared to LBBB.

RESULTS

In 14 patients with complete heart block or atrial fibrillation, CRI at optimal ventriculo-ventricular delay (VVD) (40 ± 19 ms) was significantly higher than with simultaneous biventricular pacing (BiVp) (90 ± 8.6% vs. 54.2 ± 24.2%, p < 0.001). In all 70 patients paced LV-only, LV-paced wavefront was ahead of native wavefront at short atrio-ventricular delay (AVD) and CRI increased with increase in AVD, peaked, and then decreased. Optimal CRI during LV-only pacing was significantly better than optimal CRI with simultaneous BiVp (89.6 ± 8% vs. 64.4 ± 22%, p < 0.001), and occurred at AVD 68 ± 22 ms less than the atrial-RV sensed interval. With sequential BiVp, best CRI was 83.9 ± 13% (with LV preactivation of 40 ± 20 ms). Best CRI at any setting was markedly better than CRI at standard setting (91.6 ± 7.7% vs. 52.7 ± 23.3, p < 0.001).

CONCLUSION

We describe a novel non-invasive investigational tool that quantifies wavefront fusion and electrical dyssynchrony, and may allow for individualized CRT optimization.

Optimization of Chronic Cardiac Resynchronization Therapy Using Fusion Pacing Algorithm Improves Echocardiographic Response

Background

Whether reprogramming of cardiac resynchronization therapy (CRT) to increase electrical synchrony translates into echocardiographic improvement remains unclear. SyncAV is an algorithm that allows fusion of intrinsic conduction with biventricular pacing. We aimed to assess whether reprogramming chronically implanted CRT devices with SyncAV is associated with improved echocardiographic parameters.

Methods

Patients at a quaternary center with previously implanted CRT devices with a programmable SyncAV algorithm underwent routine electrocardiography-based SyncAV optimization during regular device clinic visits. This analysis included only patients who could be programmed to the SyncAV algorithm (i.e., in sinus rhythm with intrinsic atrioventricular conduction). Echocardiography was performed before and 6 months after CRT optimization.

Results

Of 64 consecutive, potentially eligible patients who underwent assessment, 34 who were able to undergo SyncAV programming were included. Their mean age was 74 ± 9 years, 41% were female, and 59% had ischemic cardiomyopathy. The mean time from CRT implant to SyncAV optimization was 17.8 ± 8.5 months. At 6-month follow-up, SyncAV optimization was associated with a significant increase in left ventricular ejection fraction (LVEF) (mean LVEF 36.5% ± 13.3% vs 30.9% ± 13.3%; P < 0.001) and a reduction in left ventricular end-systolic volume (LVESV) (mean LVESV 110.5 ± 57.5 mL vs 89.6 ± 52.4 mL; P < 0.001) compared with baseline existing CRT programming.

Conclusion

CRT reprogramming to maximize biventricular fusion pacing significantly increased LVEF and reduced LVESV in patients with chronic CRT devices. Further studies are needed to assess if a continuous fusion pacing algorithm improves long-term clinical outcomes and to identify which patients are most likely to derive benefit.

Non-invasively quantified changes in left ventricular activation predict outcomes in patients undergoing cardiac resynchronization therapy

BACKGROUND

Changes in left ventricular (LV) activation after cardiac resynchronization therapy (CRT) influence survival but are difficult to quantify noninvasively.

METHODS AND RESULTS

We studied 527 CRT patients to assess whether noninvasive quantification of changes in LV activation, defined by change (Δ) in QRS area (QRSA), can predict outcomes after CRT. The study outcome was time until LV assist device(LVAD), cardiac transplant, or death. The three-dimensional QRSA was measured from clinical 12 lead ECGs which were transformed into vectorcardiograms using the Kors method. QRSA was calculated as (QRSx²  + QRSy²  + QRSz² )^1/2 ; ΔQRSA was calculated as post-QRSA minus pre-QRSA, where a negative value represents a reduction in LV activation delay. Kaplan-Meier plots and multivariable Cox proportional hazards models were used to relate ΔQRSA area with outcomes after stratifying the population into quartiles of ΔQRSA. The median baseline QRSA of 93.6 µVs decreased to 59.7 µVs after CRT. Progressive reductions in QRSA with CRT were associated with a lower rate of LVAD, transplant, or death across patient quartiles (P < .001). In Cox regression analyses, ΔQRSA was associated with outcomes independent of QRS morphology and other clinical variables (Q1[greatest decrease] vs Q4[smallest change=reference], HR 0.45, CI, 0.30-0.70, P < .001). There was no interaction between ΔQRSA and QRS morphology.

CONCLUSIONS

CRT induced ΔQRSA was associated with clinically meaningful changes in event-free survival. ΔQRSA may be a novel target to guide lead implantation and device optimization.

Comparison of left ventricular and biventricular pacing: Rationale and clinical implications

Cardiac resynchronization therapy constitutes a cornerstone in advanced heart failure treatment, when there is evidence of dyssynchrony, especially by electrocardiography. However, it is plagued both by persistently high (~30%) rates of nonresponse and by deterioration of right ventricular function, owing to iatrogenic dyssynchrony in the context of persistent apical pacing to ensure delivery of biventricular pacing. Left ventricular pacing has long been considered an alternative to standard biventricular pacing and can be achieved as easily as inserting a single pacing electrode in the coronary sinus. Although monoventricular left ventricular pacing has been proven to yield comparable results with the standard biventricular modality, it is the advent of preferential left ventricular pacing, combining both the powerful resynchronization potential of multipolar coronary sinus and right-sided electrodes acting in concert and the ability to preserve intrinsic, physiological right ventricular activation. In this review, we aim to present the underlying principles and modes for delivering left ventricular pacing, as well as to highlight advantages of preferential over monoventricular configuration. Finally, current clinical evidence, following implementation of automated algorithms, regarding performance of left ventricular as compared with biventricular pacing will be discussed. It is expected that the field of preferential left ventricular pacing will grow significantly over the following years, and its combination with other advanced pacing modalities may promote clinical status and prognosis of patients with advanced dyssynchronous heart failure.

Devices in Heart Failure Patients-Who Benefits From ICD and CRT?

Despite advances in heart failure treatment, this condition remains a relevant medical issue and is associated with a high morbidity and mortality. The cause of death in patients suffering from heart failure is not only a result of hemodynamic failure, but can also be due to ventricular arrhythmias. Implantable cardioverter defibrillators (ICDs) are these days the only tool to significantly reduce arrhythmic sudden death; but not all patients benefit to the same extend. In addition, cardiac resynchronization therapy (CRT) is another tool which is used in patients suffering from heart fialure. Even though both devices have been investigated in large randomized trials, both ICD and CRT remain underutilized in many countries. This brief review focuses on various aspects in this regard including a short overview on upcoming device novelties in the near future.

Efficacy of Cardiac Resynchronization Therapy Using Automated Dynamic Optimization and Left Ventricular-only Pacing

BACKGROUND

Although device-based optimization has been developed to overcome the limitations of conventional optimization methods in cardiac resynchronization therapy (CRT), few real-world data supports the results of clinical trials that showed the efficacy of automatic optimization algorithms. We investigated whether CRT using the adaptive CRT algorithm is comparable to non-adaptive biventricular (BiV) pacing optimized with electrocardiogram or echocardiography-based methods.

METHODS

Consecutive 155 CRT patients were categorized into 3 groups according to the optimization methods: non-adaptive BiV (n = 129), adaptive BiV (n = 11), and adaptive left ventricular (LV) pacing (n = 15) groups. Additionally, a subgroup of patients (n = 59) with normal PR interval and left bundle branch block (LBBB) was selected from the non-adaptive BiV group. The primary outcomes included cardiac death, heart transplantation, LV assist device implantation, and heart failure admission. Secondary outcomes were electromechanical reverse remodeling and responder rates at 6 months after CRT.

RESULTS

During a median 27.5-month follow-up, there was no significant difference in primary outcomes among the 3 groups. However, there was a trend toward better outcomes in the adaptive LV group compared to the other groups. In a more rigorous comparisons among the patients with normal PR interval and LBBB, similar patterns were still observed.

CONCLUSION

In our first Asian-Pacific real-world data, automated dynamic CRT optimization showed comparable efficacy to conventional methods regarding clinical outcomes and electromechanical remodeling.

Optimizing Cardiac Resynchronization Therapy Devices in Follow-up to Improve Response Rates and Outcomes

Although cardiac resynchronization therapy (CRT) will improve symptoms and survival in selected heart failure patients, there still remains a high percentage of CRT recipients who do not obtain benefit from the therapy. During CRT follow-up, an effort should be made to identify and to treat reversible causes of nonresponse to CRT. This effort includes optimization of medical therapy, checking for appropriate and effective biventricular pacing, and treatment of arrhythmias and other reversible causes of CRT malfunction.

Rationale and design of the AdaptResponse trial: a prospective randomized study of cardiac resynchronization therapy with preferential adaptive left ventricular-only pacing

The AdaptResponse trial is designed to test the hypothesis that preferential adaptive left ventricular‐only pacing with the AdaptivCRT^® algorithm reduces the incidence of the combined endpoint of all‐cause mortality and intervention for heart failure (HF) decompensation, compared with conventional cardiac resynchronization therapy (CRT), among patients with a CRT indication, left bundle branch block (LBBB) and normal atrioventricular (AV) conduction. The AdaptResponse study is a prospective, randomized, controlled, single‐blinded, multicentre, clinical trial (ClinicalTrials.gov Identifier: NCT02205359), conducted at up to 200 centres worldwide. Following enrolment and baseline assessment, eligible subjects will be implanted with a CRT system containing the AdaptivCRT algorithm, and randomized in a 1:1 fashion to either a treatment (‘AdaptivCRT’) or control (‘Conventional CRT’) group. The study is designed to observe a primary endpoint in 1100 patients (‘event‐driven’) and approximately 3000 patients will be randomized. The primary endpoint is the composite of all‐cause mortality and intervention for HF decompensation; secondary endpoints include all‐cause mortality, intervention for HF decompensation, clinical composite score (CCS) at 6 months, atrial fibrillation, quality of life measured by the Kansas City Cardiomyopathy Questionnaire (KCCQ), health outcome measured by the EQ‐5D instrument, all‐cause readmission after a HF admission, and cost‐effectiveness. The AdaptResponse clinical trial is powered to assess clinical endpoints and is expected to provide definitive evidence on the incremental utility of AdaptivCRT‐enhanced CRT systems.

Influence of automatic frequent pace-timing adjustments on effective left ventricular pacing during cardiac resynchronization therapy

Aims

Cardiac resynchronization therapy (CRT) requires effective left ventricular (LV) pacing (i.e. sufficient energy and appropriate timing to capture). The AdaptivCRT™ (aCRT) algorithm serves to maintain ventricular fusion during LV or biventricular pacing. This function was tested by comparing the morphological consistency of ventricular depolarizations and percentage effective LV pacing in CRT patients randomized to aCRT vs. echo-optimization.

Methods and results

Continuous recordings (≥20 h) of unipolar LV electrograms from aCRT (n = 38) and echo-optimized patients (n = 22) were analysed. Morphological consistency was determined by the correlation coefficient between each beat and a template beat. Effective LV pacing of paced beats was assessed by algorithmic analysis of negative initial EGM deflection in each evoked response. The %CRT pacing delivered, %effective LV pacing (i.e. % of paced beats with effective LV pacing), and overall %effective CRT (i.e. product of %CRT pacing and %effective LV pacing) were compared between aCRT and echo-optimized patients. Demographics were similar between groups. The mean correlation coefficient between individual beats and template was greater for aCRT (0.96 ± 0.03 vs. 0.91 ± 0.13, P = 0.07). Although %CRT pacing was similar for aCRT and echo-optimized (median 97.4 vs. 98.6%, P = 0.14), %effective LV pacing was larger for aCRT [99.6%, (99.1%, 99.9%) vs. 94.3%, (24.3%, 99.8%), P=0.03]. For aCRT vs. echo-optimized groups, the proportions of patients with ≥90% effective LV pacing was 92 vs. 55% (P = 0.002), and with ≥90% effective CRT was 79 vs. 45%, respectively (P = 0.018).

Conclusion

AdaptivCRT™ significantly increased effective LV pacing over echo-optimized CRT.

The Role of Echocardiography in the Optimization of Cardiac Resynchronization Therapy: Current Evidence and Future Perspectives

Background:

Cardiac resynchronization therapy (CRT) has become a mainstay in the management of heart failure. Up to one-third of patients who received resynchronization devices do not experience the full benefits of CRT. The clinical factors influencing the likelihood to respond to the therapy are wide QRS complex, left bundle branch block, female gender, non-ischaemic cardiomyopathy (highest responders), male gender, ischaemic cardiomyopathy (moderate responders) and narrow QRS complex, non-left bundle branch block (lowest, non-responders).

Objective:

This review provides a conceptual description of the role of echocardiography in the optimization of CRT.

Method:

A literature survey was performed using PubMed database search to gather information regarding CRT and echocardiography.

Results:

A total of 70 studies met selection criteria for inclusion in the review. Echocardiography helps in the initial selection of the patients with dyssynchrony, which will benefit the most from optimal biventricular pacing and provides a guide to left ventricular (LV) lead placement during implantation. Different echocardiographic parameters have shown promise and can offer the possibility of patient selection, response prediction, lead placement optimization strategies and optimization of device configurations.

Conclusion:

LV ejection fraction along with specific electrocardiographic criteria remains the cornerstone of CRT patient selection. Echocardiography is a non-invasive, cost-effective, highly reproducible method with certain limitations and accuracy that is affected by measurement errors. Echocardiography can assist with the identification of the appropriate electromechanical substrate of CRT response and LV lead placement. The targeted approach can improve the haemodynamic response, as also the patient-specific parameters estimation.

Left univentricular pacing for cardiac resynchronization therapy

This review describes the rationale and published evidence for left univentricular pacing for cardiac resynchronization therapy, gives an overview of the existing optimization algorithms featuring this mode, and discusses future perspectives.

Device pacing diagnostics overestimate effective cardiac resynchronization therapy pacing results of the hOLter for Efficacy analysis of CRT (OLÉ CRT) study

BACKGROUND

A high percentage of biventricular (BiV) or left ventricular (LV) pacing in cardiac resynchronization therapy (CRT) devices has been associated with superior clinical outcomes. However, the percent ventricular (%V) pacing reported by CRT devices simply indicates the number of paces the device has delivered and not the proportion of pacing that has captured the LV effectively.

OBJECTIVE

The purpose of this study was to determine whether a beat-by-beat evaluation of effective pacing would provide a more accurate evaluation of CRT delivery.

METHODS

An automatic electrogram (EGM)-based algorithm that classifies each LV pace as effective or ineffective based on detection of QS/QS-r morphology on the unipolar LV EGM during pacing was developed and validated. LV EGMs that were recorded by 24-hour Holter from 57 CRT patients were postprocessed. The percent effective CRT (%e-CRT) pacing was calculated by dividing the time spent in e-CRT pacing by the total time of the recording.

RESULTS

In this CRT cohort, the average %V pacing (94.8% ± 8%) significantly overestimated the %e-CRT pacing (87.5% ± 23%; P <.001). A significant minority of subjects (18%) had a discrepancy of at least 3 percentage points between %V pacing and %e-CRT pacing (mean 39% ± 41%).

CONCLUSION

Current device pacing diagnostics overestimate the amount of CRT pacing actually delivered. The new algorithm quantifies ineffective CRT pacing, which enables clinicians to identify patients with this issue and to address the reasons behind suboptimal CRT delivery.

Cardiac Resynchronization Therapy and Implantable Cardioverter Defibrillator Therapy in Advanced Heart Failure

Patients with advanced heart failure are at high risk for progression of their disease and sudden cardiac death. The role of device therapy in this patient population continues to evolve and is directed toward improving cardiac pump function and/or reducing sudden arrhythmic death.

Cardiac resynchronization therapy pacemaker: critical appraisal of the adaptive CRT-P device

Cardiac resynchronization therapy (CRT) is an effective and well-established therapy for patients suffering with heart failure, left ventricular (LV) systolic dysfunction (ejection fraction ≤35%), and electrical dyssynchrony, demonstrated by a surface QRS duration of ≥120 ms. Patients undergoing treatment with CRT have shown significant improvement in functional class, quality of life, LV ejection fraction, exercise capacity, hemodynamics, and reverse remodeling of LV, and ultimately, morbidity and mortality. However, 30%–40% of patients who receive a CRT device may not show improvement, and they are termed as non responders. The nonresponders have a poor prognosis; several methods have been developed to try to enhance response to CRT. Echocardiography-guided optimization of CRT has not resulted in significant clinical benefit, since it is done at rest with the patient in supine position. An ideal optimization strategy would provide continuous monitoring and adjustment of device pacing to provide maximal cardiac resynchronization, under a multitude of physiologic states. Intrinsic activation of the right ventricle (RV) with paced activation of the RV, even in the setting of biventricular (BiV) pacing, may result in an adverse effect on cardiac performance. With this physiology, the use of LV-only pacing may be preferred and may enhance CRT. Adaptive CRT is a novel device-based algorithm that was designed to achieve patient-specific adjustment in CRT so as to provide appropriate BiV pacing or LV-only pacing. This article will review the goals of CRT optimization, and implementation and outcomes associated with adaptive CRT.

The clinical benefit of cardiac resynchronization therapy optimization using a device-based hemodynamic sensor in a patient with dilated cardiomyopathy: a case report

Introduction

Results on the evolution of the clinical status of patients undergoing cardiac resynchronization therapy with a defibrillator after automatic optimization of their cardiac resynchronization therapy are scarce. We observed a rapid and important change in the clinical status of our non-responding patient following activation of a sensor capable of weekly atrioventricular and interventricular delays' optimization.

Case presentation

A 78-year-old Caucasian man presented with dilated cardiomyopathy, left bundle branch block, a left ventricular ejection fraction of 35 %, New York Heart Association class III/IV heart failure, and paroxysmal atrial fibrillation. Our patient was implanted with a cardiac resynchronization device with a defibrillator and the SonRtip atrial lead. Right ventricular and left ventricular leads were also implanted. Because of the recurrence of atrial fibrillation, the automatic optimization was set off at discharge. Consequently, the device did not optimize atrioventricular and interventricular delays (programming at discharge: 125 ms for the atrioventricular delay and 0 ms for the interventriculardelay). Our patient was treated with an anti-arrhythmic drug. Five months after implantation, his clinical status remained impaired (left ventricular ejection fraction = 30 %). The SonR signal amplitude had also decreased from 0.52 g to 0.29 g. Nevertheless, because our patient was no longer presenting with atrial fibrillation, the anti-arrhythmic treatment was stopped and the SonR optimization system was activated. After 2 months of automatic cardiac resynchronization therapy with defibrillator optimization, our patient’s clinical status had significantly improved (left ventricular ejection fraction = 60 %, New York Heart Association class II) and the SonR signal amplitude had doubled shortly after the first weekly automatic optimization.

Conclusion

In this non-responding patient, device-based automatic cardiac resynchronization therapy optimization was shown to significantly improve his clinical status.

Pacing site in pacemaker dependency: is right ventricular septal lead position the answer?

The right ventricular apex has been the traditional site for lead placement in patients with atrioventricular block. Pacing at the right ventricular apex may have long-term deleterious effects on left ventricular (LV) function, promoting heart failure and increasing mortality. Pacing at the right ventricular septum has been proposed to minimize deterioration in LV function. Although experimental data suggest that septal pacing protects LV function, clinical studies have provided conflicting results. A recent large study in patients with heart block did not show a protective effect with septal pacing. Other pacing approaches are becoming increasingly relevant; however, prediction of what method should be employed in which patient is not currently possible. Other factors such as baseline LV function and associated co-morbidities impact LV function, irrespective of pacing site. Continued monitoring of cardiac function post-implant is therefore critical to ongoing care. An algorithm for managing patients with atrioventricular block is proposed.

ECG Patterns In Cardiac Resynchronization Therapy

Cardiac resynchronization therapy is an established treatment modality in heart failure. Though non-response is a serious issue. To address this issue, a good understanding of the electrical activation during underlying intrinsic ventricular activation, biventricular as well as right- and left ventricular pacing is needed. By interpreting the 12-lead electrocardiogram, possible reasons for suboptimal treatment can be identified and addressed. This article reviews the literature on QRS morphology in cardiac resynchronization therapy and its role in optimization of therapy.

Clinical Relevance Of Systematic CRT Device Optimization

Cardiac Resynchronization Therapy (CRT) is known as a highly effective therapy in advanced heart failure patients with cardiac dyssynchrony. However, still one third of patients do not respond (or sub-optimally respond) to CRT. Among the many contributors for the high rate of non-responders, the lack of procedures dedicated to CRT device settings optimization (parameters to regulate AV synchrony and VV synchrony) is known as one of the most frequent. The most recent HF/CRT Guidelines do not recommend to carry-out optimization procedures in every CRT patient; they simply state those procedures "could be useful in selected patients", even though their role in improving response has not been proven. Echocardiography techniques still remain the gold-standard reference method to the purpose of CRT settings optimization. However, due to its severe limitations in the routine of CRT patients management (time and resource consuming, scarce reproducibility, inter and intra-operator dependency), echocardiography optimization is widely under-utilized in the real-world of CRT follow-up visits. As a consequence, device-based techniques have been developed to by-pass the need for repeated echo examinations to optimize CRT settings. In this report the available device-based optimization techniques onboard on CRT devices are shortly reviewed, with a specific focus on clinical outcomes observed in trials comparing these methods vs. clinical practice or echo-guided optimization methods. Particular emphasis is dedicated to hemodynamic methods and automaticity of optimization algorithms (making real the concept of "ambulatory CRT optimization"). In fact a hemodynamic-based approach combined with a concept of frequent re-optimization has been associated - although retrospectively - with a better clinical outcome on the long-term follow-up of CRT patients. Large randomized trials are ongoing to prospectively clarify the impact of automatic optimization procedures.