Insights from a cardiac resynchronization optimization clinic as part of a heart failure disease management program. J Am Coll Cardiol. 2009;53:765-773. [PMID: 19245967 DOI: 10.1016/j.jacc.2008.11.024]

Long-term follow-up after cardiac resynchronization therapy-optimization in a real-world setting: A single-center cohort study

BACKGROUND

Suboptimal device programming is among the reasons for reduced response to cardiac resynchronization therapy (CRT). However, whether systematic optimization is beneficial remains unclear, particularly late after CRT implantation. The aim of this single-center cohort study was to assess the effect of systematic atrioventricular delay (AVD) optimization on echocardiographic and device parameters.

METHODS

Patients undergoing CRT optimization at the University Hospital Zurich between March 2011 and January 2013, for whom a follow-up was available, were included. AVD optimization was based on 12-lead electrocardiography (ECG) and echocardiographic left ventricular inflow characteristics. Parameters were assessed at the time of CRT optimization and follow-up, and were compared between patients with AVD optimization (intervention group) and those for whom no AVD optimization was deemed necessary (control group).

RESULTS

Eighty-one patients with a mean age of 64 ± 11 years were included in the analysis. In 73% of patients, AVD was deemed suboptimal and was changed accordingly. After a median follow-up time of 10.4 (IQR 6.2 to 13.2) months, the proportion of patients with sufficient biventricular pacing (> 97% pacing) was greater in the intervention group (78%) compared to controls (50%). Furthermore, AVD adaptation was associated with an improvement in interventricular mechanical delay (decrease of 6.6 ± 26.2 ms vs. increase of 4.3 ± 17.7 ms, p = 0.034) and intraventricular septal-to-lateral delay (decrease of 0.9 ± 48.1 ms vs. increase of 15.9 ± 15.7 ms, p = 0.038), as assessed by tissue Doppler imaging. Accordingly, a reduction was observed in mitral regurgitation along with a trend towards reduced left ventricular volumes.

CONCLUSIONS

In this "real-world" setting systematic AVD optimization was associated with beneficial effects regarding biventricular pacing and left ventricular remodeling. These data show that AVD optimization may be advantageous in selected CRT patients.

Echocardiographic Assessment of Right Ventriculo-arterial Coupling: Clinical Correlates and Prognostic Impact in Heart Failure Patients Undergoing Cardiac Resynchronization Therapy

BACKGROUND

Right ventriculo-arterial coupling (RV-PA) can be estimated by echocardiography using the ratio between tricuspid annular plane systolic excursion (TAPSE) and pulmonary artery systolic pressure (PASP) and it has prognostic value in the general heart failure (HF) population. We aimed to study the clinical correlates and prognostic value of RV-PA in HF patients undergoing cardiac resynchronization therapy (CRT).

METHODS

We retrospectively studied 70 HF patients undergoing CRT implantation.

RESULTS

RV-PA coupling was estimated by TAPSE/PASP ratio using baseline echocardiography. Non-response to CRT was defined as improvement of left ventricular ejection fraction < 5% in a follow-up echo 6-12 months after CRT. Those with lower TAPSE/PASP ratios (worse RV-PA coupling) had higher NT-proBNP concentrations and increased E/e' ratio. TAPSE/PASP ratio and PASP, but not TAPSE, predicted nonresponse to CRT with TAPSE/PASP ratio showing the best discriminative ability with a sensitivity of 76% and specificity of 71%. Among these parameters, PASP independently predicted all-cause mortality.

CONCLUSIONS

RV-PA coupling estimated by TAPSE/PASP ratio was associated with established prognostic markers in HF. It numerically outperformed PASP and TAPSE in predicting the response to CRT. Our data suggest that this simple and widely available echocardiographic parameter conveys significant pathophysiological and prognostic meaning in HF patients undergoing CRT.

Computational models in cardiology

The treatment of individual patients in cardiology practice increasingly relies on advanced imaging, genetic screening and devices. As the amount of imaging and other diagnostic data increases, paralleled by the greater capacity to personalize treatment, the difficulty of using the full array of measurements of a patient to determine an optimal treatment seems also to be paradoxically increasing. Computational models are progressively addressing this issue by providing a common framework for integrating multiple data sets from individual patients. These models, which are based on physiology and physics rather than on population statistics, enable computational simulations to reveal diagnostic information that would have otherwise remained concealed and to predict treatment outcomes for individual patients. The inherent need for patient-specific models in cardiology is clear and is driving the rapid development of tools and techniques for creating personalized methods to guide pharmaceutical therapy, deployment of devices and surgical interventions.

Efficacy of a Device-Based Continuous Optimization Algorithm for Patients With Cardiac Resynchronization Therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) is less effective in patients with mildly wide QRS or non-left bundle branch block (non-LBBB). A new algorithm of every minute's optimization (adaptive CRT: aCRT algorithm) is effective in patients with CRT devices. This study investigated the clinical effect of the aCRT algorithm, especially in mildly wide QRS (120≤QRS<150 ms) or non-LBBB patients receiving CRT.Methods and Results:This study included 104 CRT patients (48 patients using the aCRT algorithm [adaptive group] and 56 patients not using the aCRT algorithm [non-adaptive group]). The primary endpoint was a composite clinical outcome of cardiac death and/or heart failure (HF) hospitalization. During a median follow-up of 700 days (interquartile range 362-1,173 days), aCRT reduced the risk of the clinical outcome, even in patients with mildly wide QRS or non-LBBB (log-rank P=0.0030 and P=0.0077, respectively) by Kaplan-Meier analysis. Use of the aCRT algorithm was an independent predictor of clinical outcomes in the multivariate analysis (hazard ratio (HR) 0.28, 95% confidence interval (CI): 0.096-0.78, P=0.015), the same as in patients with mildly wide QRS (HR 0.12, 95% CI: 0.006-0.69, P=0.015).

CONCLUSIONS

The new aCRT algorithm was useful and significantly reduced the risk of the clinical outcome, even in patients with mildly wide QRS.

Patient-tailored SyncAV algorithm: A novel strategy to improve synchrony and acute hemodynamic response in heart failure patients treated by cardiac resynchronization therapy

INTRODUCTION

Several automatic algorithms have developed to optimize the timing cycle setting in cardiac resynchronization therapy (CRT). The present study aims to investigate whether the novel device-based SyncAV algorithm could elicit better synchrony and acute hemodynamic response.

METHODS AND RESULTS

Thirty five patients undergoing CRT implantation were prospectively studied. The device was programmed to three biventricular (BiV) pacing modes sequentially after the procedure: QuickOpt algorithm (mode I), SyncAV algorithm with default 50 ms offset (mode II), and SyncAV algorithm with optimized offset minimizing QRS duration (QRSd) (mode III). After each setting, electrocardiographic and echocardiographic data were collected. As a result, QRSd was reduced from 172.8 ± 17.9 ms during intrinsic conduction to 153.1 ± 15.9 ms in mode I, further narrowed to 140.5 ± 16.7 ms in mode II, and reached shortest (134.8 ± 16.1 ms) in mode III (P < .01 for all). Besides, significantly shorter QT intervals were observed in mode I (453.2 ± 45.5 ms), mode II (443.9 ± 34.2 ms) and mode III (444.1 ± 28.7 ms), compared with native condition (472.5 ± 51.2 ms) (P < .01). All three BiV modes exhibited comparable T_p T_e interval and T_p T_e /QT ratio (P > .05). Mode I presented significantly higher aortic velocity time integral than intrinsic conduction (21.0 ± 6.4 cm vs 18.4 ± 5.5 cm; P < .01), which was even higher in mode II (22.0 ± 6.5 cm) and mode III (23.7 ± 6.5 cm). All three BiV modes significantly reduced standard deviation of time to peak contraction of 12-LV segments (Ts-SD) (Mode I: 55.2 ± 16.5 ms, Mode II: 50.2 ± 14.7 ms, Mode III: 45.4 ± 14.4 ms) compared with intrinsic conduction (66.3 ± 18.4 ms) (P < .01), with Mode III demonstrating the smallest (P < .01).

CONCLUSION

SyncAV CRT ameliorated electrical and mechanical synchrony as well as acute hemodynamic response beyond conventional QuickOpt optimization. An additional individualized adjustment to the SyncAV offset added to its advantage.

Coronary venoplasty during cardiac resynchronization therapy device implantations: Acute results and clinical outcomes

BACKGROUND

Optimal left ventricular (LV) lead placement improves response to cardiac resynchronization therapy (CRT) but can be hindered by unfavorable venous anatomy. Interventional procedures in the coronary veins have been described with promising short-term outcomes.

OBJECTIVE

The purpose of this study was to establish the safety and efficacy of percutaneous coronary venoplasty (PCV) during CRT implantation and assess medium-term lead performances and clinical outcomes against matched controls not requiring PCV.

METHODS

Each consecutive PCV case was matched according to age, gender, and bundle branch morphology to 2 controls from a large prospective registry of CRT recipients. Demographics, procedural success, lead performance, and response to CRT were tracked using a comprehensive electronic medical records system.

RESULTS

Of 422 consecutive CRT recipients treated between 2012 to 2018, 29 patients (6.9%; mean age 65.7 ± 10.7 years; 7 female; 17 ischemic cardiomyopathy; 22 left bundle branch block) required PCV, which was successful in 21 cases (72%). Target veins measuring 1.1 ± 0.6 mm were dilated by noncompliant balloons with mean diameter 2.8 ± 0.5 mm. No complications occurred. Fluoroscopic and procedural durations were longer in the PCV group (P <.01) Over mean follow-up of 33.0 ± 25.0 months, no differences in lead performance, CRT response, or 2-year survival were observed compared to the control group.

CONCLUSION

PCV during CRT device implant is typically successful, safe and associated with long-term clinical outcomes comparable to patients who did not need PCV. This is an important technique to optimize LV lead placement and maximize CRT response.

His-Optimized Cardiac Resynchronization Therapy to Maximize Electrical Resynchronization: A Feasibility Study

Background Cardiac resynchronization therapy (CRT) is an established therapy for patients with cardiomyopathy, left bundle branch block, and heart failure. His bundle pacing (HBP) may also improve clinical outcomes by narrowing QRS duration. The QRS narrowing by HBP may not always be optimal. The aim of the study was to determine if CRT could be optimized by sequential HBP followed by left ventricular (LV) pacing (His-Optimized CRT [HOT-CRT]) to maximize electrical resynchronization. Methods We attempted permanent HBP in 27 patients (left bundle branch block 17, intraventricular conduction defect 5, and right ventricular pacing 5) referred for CRT in addition to LV lead. HBP was followed by LV pacing at a delay equal to His-ventricular interval. QRS duration at baseline, during HBP, biventricular pacing, and HOT-CRT was measured. Echocardiographic parameters and New York Heart Association functional class were assessed at baseline and during follow-up. Results HOT-CRT was successful in 25 of 27 patients (age 72±15 years, men 23, ischemic 21). QRS duration at baseline was 183±27 ms and significantly narrowed to 162±17 ms with biventricular pacing ( P=0.003), to 151±24 ms during HBP ( P<0.0001), and further to 120±16 ms during HOT-CRT ( P<0.0001). During a mean follow-up of 14±10 months, LV ejection fraction improved from 24±7% to 38±10% ( P<0.0001), and New York Heart Association functional class changed from 3.3 to 2.04. Twenty-one of 25 patients (84%) were clinical responders while 23 of 25 (92%) showed echocardiographic response. Conclusions In this feasibility cohort, HOT-CRT resulted in improved electrical resynchronization. HOT-CRT may improve clinical and echocardiographic outcomes in advanced heart failure patients requiring CRT.

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

BACKGROUND

Optimal timing of the atrioventricular delay in cardiac resynchronization therapy (CRT) can improve synchrony in patients suffering from heart failure. The purpose of this study was to evaluate the impact of SyncAV™ on electrical synchrony as measured by vectorcardiography (VCG) derived QRS metrics during bi-ventricular (BiV) pacing.

METHODS

Patients implanted with a cardiac resynchronization therapy (CRT) device and quadripolar left ventricular (LV) lead underwent 12‑lead ECG recordings. VCG metrics, including QRS duration (QRSd) and area, were derived from the ECG by a blinded observer during: intrinsic conduction, BiV with nominal atrioventricular delays (BiV Nominal), and BiV with SyncAV programmed to the optimal offset achieving maximal synchronization (BiV + SyncAV Opt).

RESULTS

One hundred patients (71% male, 40% ischemic, 65% LBBB, 32 ± 9% ejection fraction) completed VCG assessment. QRSd during intrinsic conduction (166 ± 25 ms) was narrowed successively by BiV Nominal (137 ± 23 ms, p < .05 vs. intrinsic) and BiV + SyncAV Opt (122 ± 22 ms, p < .05 vs. BiV Nominal). Likewise, 3D QRS area during intrinsic conduction (90 ± 42 mV ∗ ms) was reduced by BiV Nominal (65 ± 39 mV ∗ ms, p < .05 vs. intrinsic) and further by BiV + SyncAV Opt (53 ± 30 mV ∗ ms, p = .06 vs. BiV Nominal).

CONCLUSION

With VCG-based, patient-specific optimization of the programmable offset, SyncAV reduced electrical dyssynchrony beyond conventional CRT.

Rationale and design of the IRON-CRT trial: effect of intravenous ferric carboxymaltose on reverse remodelling following cardiac resynchronization therapy

AIMS

Iron deficiency is common in heart failure with reduced ejection fraction (HFrEF). In patients with cardiac resynchronization therapy (CRT), it is associated with a diminished reverse remodelling response and poor functional improvement. The latter is partially related to a loss in contractile force at higher heart rates (negative force-frequency relationship).

METHODS AND RESULTS

The effect of intravenous ferric carboxymaltose on reverse remodelling following cardiac resynchronization therapy (IRON-CRT) trial is a multicentre, prospective, randomized, double-blind controlled trial in HFrEF patients who experienced incomplete reverse remodelling (defined as a left ventricular ejection fraction below <45%) at least 6 months after CRT. Additionally, patients need to have iron deficiency defined as a ferritin below 100 μg/L irrespective of transferrin saturation or a ferritin between 100 and 300 μg/L with a transferrin saturation <20%. Patients will be randomized to either intravenous ferric carboxymaltose (dose based according to Summary of Product Characteristics) or intravenous placebo. The primary objective is to evaluate the effect of ferric carboxymaltose on metrics of cardiac reverse remodelling and contractility, measured by the primary endpoint, change in left ventricular ejection fraction assessed by three-dimensional (3D) echo from baseline to 3 month follow-up and the secondary endpoints change in left ventricular end-systolic and end-diastolic volume. The secondary objective is to determine if ferric carboxymaltose is capable of improving cardiac contractility in vivo, by assessing the force-frequency relationship through incremental biventricular pacing. A total of 100 patients will be randomized in a 1:1 fashion.

CONCLUSIONS

The IRON-CRT trial will determine the effect of ferric carboxymaltose on cardiac reverse remodelling and rate-dependent cardiac contractility in HFrEF patients.

Novel Device-Based Algorithm Provides Optimal Hemodynamics During Exercise in Patients With Cardiac Resynchronization Therapy

BACKGROUND

An adaptive cardiac resynchronization therapy (aCRT) algorithm has been described for synchronized left ventricular (LV) pacing and continuous optimization of cardiac resynchronization therapy (CRT). However, there are few algorithmic data on the effect of changes during exercise.Methods and Results:We enrolled 27 patients with availability of the aCRT algorithm. Eligible patients were manually programmed to optimal atrioventricular (AV) and interventricular (VV) delays by using echocardiograms at rest or during 2 stages of supine bicycle exercise. We compared the maximum cardiac output between manual echo-optimization and aCRT-on during each phase. After initiating exercise, the optimal AV delay progressively shortened (P<0.05) with incremental exercise levels. The manual-optimized settings and aCRT resulted in similar cardiac performance, as demonstrated by a high concordance correlation coefficient between the LV outflow tract velocity time integral (LVOT-VTI) during each exercise stage (Ex.1: r=0.94 P<0.0008, Ex.2: r=0.88 P<0.001, respectively). Synchronized LV-only pacing in patients with normal AV conduction could provide a higher LVOT-VTI as compared with manual-optimized conventional biventricular pacing at peak exercise (P<0.05).

CONCLUSIONS

The aCRT algorithm was physiologically sound during exercise by patients.

Cardiac resynchronization therapy-heart failure (CRT-HF) clinic: A novel model of care

Background

Post-implant care of patients with heart failure (HF) undergoing cardiac resynchronization therapy (CRT) is not addressed in current HF or CRT guidelines and is often fragmented with poor communication between specialties. We sought to develop a new model of post-CRT care which could be implemented in busy clinical settings.

Methods and results

We designed a novel, multidisciplinary approach to standardizing post CRT care. All patients receiving a CRT device at the Cleveland Clinic between March 2017 and August 2018 were invited to be seen in the clinic 6 months post implant. A one-time collaborative visit encompassing cardiac imaging, heart failure, and electrophysiology care was performed. We recorded the operational feasibility of the clinic in terms of patient throughput as well as patient characteristics, interventions, and new diagnoses made. Between September 2017 and February 2019, 150 patients were seen in the clinic. Of these, 125 patients had their index CRT implanted for standard indications and were included in the current analysis. Approximately 45 minutes were dedicated for each patient visit. Interventions in care were made in 95% of patients, with CRT non-responders offered a higher number of interventions as compared to responders (median 3 versus 2 interventions). Types of interventions were device-related (26% of population), medication-related (74%), and referral for alternate medical services (80%).

Conclusions

Multidisciplinary post-implant care of patients with HF receiving CRT devices, regardless of CRT response status, is feasible and results in frequent medical interventions.

Device therapy in heart failure with reduced ejection fraction-cardiac resynchronization therapy and more

In patients with heart failure with reduced ejection fraction (HFrEF), optimal medical treatment includes beta-blockers, ACE inhibitors/angiotensinreceptor-neprilysin inhibitors (ARNI), mineralocorticoid receptor antagonists, and ivabradine when indicated. In device therapy of HFrEF, implantable cardioverter-defibrillators and cardiac resynchronization therapy (CRT) have been established for many years. CRT is the therapy of choice (class I indication) in symptomatic patients with HFrEF and a broad QRS complex with a left bundle branch block (LBBB) morphology. However, the vast majority of heart failure patients show a narrow QRS complex or a non-LBBB morphology. These patients are not candidates for CRT and alternative electrical therapies such as baroreflex activation therapy (BAT) and cardiac contractility modulation (CCM) may be considered. BAT modulates vegetative dysregulation in heart failure. CCM improves contractility, functional capacity, and symptoms. Although a broad data set is available for BAT and CCM, mortality data are still lacking for both methods. This article provides an overview of the device-based therapeutic options for patients with HFrEF.

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.

Cost-Effectiveness Analysis of Quadripolar Versus Bipolar Left Ventricular Leads for Cardiac Resynchronization Defibrillator Therapy in a Large, Multicenter UK Registry

OBJECTIVES

The objective of this study was to evaluate the cost-effectiveness of quadripolar versus bipolar cardiac resynchronization defibrillator therapy systems.

BACKGROUND

Quadripolar left ventricular (LV) leads for cardiac resynchronization therapy reduce phrenic nerve stimulation (PNS) and are associated with reduced mortality compared with bipolar leads.

METHODS

A total of 606 patients received implants at 3 UK centers (319 Q, 287 B), between 2009 and 2014; mean follow-up was 879 days. Rehospitalization episodes were costed at National Health Service national tariff rates, and EQ-5D utility values were applied to heart failure admissions, acute coronary syndrome events, and mortality data, which were used to estimate quality-adjusted life-year differences over 5 years.

RESULTS

Groups were matched with regard to age and sex. Patients with quadripolar implants had a lower rate of hospitalization than those with bipolar implants (42.6% vs. 55.4%; p = 0.002). This was primarily driven by fewer hospital readmissions for heart failure (51 [16%] vs. 75 [26.1%], respectively, for quadripolar vs. bipolar implants; p = 0.003) and generator replacements (9 [2.8%] vs. 19 [6.6%], respectively; p = 0.03). Hospitalization for suspected acute coronary syndrome, arrhythmia, device explantation, and lead revisions were similar. This lower health-care utilization cost translated into a cumulative 5-year cost saving for patients with quadripolar systems where the acquisition cost was <£932 (US $1,398) compared with bipolar systems. Probabilistic sensitivity analysis results mirrored the deterministic calculations. For the average additional price of £1,200 (US $1,800) over a bipolar system, the incremental cost-effective ratio was £3,692 per quality-adjusted life-year gained (US $5,538), far below the usual willingness-to-pay threshold of £20,000 (US $30,000).

CONCLUSIONS

In a UK health-care 5-year time horizon, the additional purchase price of quadripolar cardiac resynchronization defibrillator therapy systems is largely offset by lower subsequent event costs up to 5 years after implantation, which makes this technology highly cost-effective compared with bipolar systems.

2D/3D Echocardiographic features of patients with reverse remodeling after cardiac resynchronization therapy

PURPOSE

To describe clinical and echocardiographic characteristics associated with reverse left ventricular (LV) remodeling after 6 months of cardiac resynchronization therapy (CRT) in patients with nonischemic dilated cardiomyopathy.

METHODS

Twenty-four consecutive patients underwent 2D and 3D echocardiography before and after 6 months of CRT implant. Several echocardiographic parameters including global longitudinal strain (GLS) and 3D mechanical dyssynchrony (MD) index were calculated. CRT response was defined as a decrease in LV end-systolic volume (LVESV) of at least 10% at follow-up. Patients were divided in two groups according to CRT response.

RESULTS

Cardiac resynchronization therapy responder (CRTR+) rate was 50%. Nonresponder (CRTR-) patients showed a less significant improvement in NYHA class at follow-up. At baseline, CRTR- presented with higher LV end-diastolic volume (LVEDV) (P = 0.031), LVESV (P = 0.024), lower left ventricular ejection fraction (LVEF) (P = 0.002) and less negative GLS (P = 0.03), and with higher diastolic dysfunction, more impaired right ventricle (RV), and higher pulmonary artery systolic pressure (PASP) (P = 0.002). No significant differences in echocardiographic parameters of MD were found. Univariate determinants of CRTR+ were LVEF (OR = 1.59, CI 95% = 1.13-2.22, P = 0.007) and TAPSE (OR 1.21, CI 95% = 1.024-1.429, P = 0.025). A ROC curve analysis showed a cutoff value of LVEF of 22.15% significantly related to CRTR+ (SE 80%, SP 50%).

CONCLUSIONS

Our findings suggest that end-stage HF patients, presenting before CRT with LVEF <22.15%, may not benefit from the procedure after 6 months. Mechanical dyssyncronicity did not provide additional information to improve candidate selection.

A Post hoc analysis on rhythm and high intensity interval training in cardiac resynchronization therapy

Objectives. Evaluate the effects of a 6-month High Intensity Interval Training (HIIT) program on (1) functional capacity and health-related quality of life, (2) multiple blood biomarkers, (3) echocardiographic parameters, and (4) exercise performance, in patients in cardiac resynchronization therapy (CRT) stratified by the presence of atrial fibrillation (AF), targeting the following questions: (1) Does CRT provide similar benefits in patients in AF and sinus rhythm (SR)?; and (2) Does HIIT provides similar benefits in patients in AF and SR? Design. Estimates were available at baseline and 6 months after CRT implantation in 37 patients with heart failure. Patients were randomized after CRT to a 24-week HIIT group or to a usual care group (CON). In this sub-analysis, HIIT (AF = 7; SR = 11) and CON (AF = 9; SR = 10) were stratified by the presence of AF. Results. Patients in AF benefitted to a lesser degree from CRT in functional status than patients in SR (23.8-46.0%). However, HIIT induced superior improvements in patients in AF compared to CON (23.9-61.0%). Decreases in TNF-α (8.5-42.9%), BNP (15.3-34.6%) and left ventricular mass (9.6-26.2%) were only observed in patients in SR, whereas increases in peak oxygen uptake were only observed in patients in AF (19.5-23.2%). HIIT improved exercise capacity (8.8-59.4%) in patients in SR. Conclusions. Patients in AF or SR undergoing CRT demonstrated distinct benefits from device implantation and from HIIT as an adjunctive therapeutic strategy. This suggests that both mainstay and adjunctive therapeutics may need to be managed differently in patients in AF and SR.

Heart failure hospitalization reduction and cost savings achieved by improved delivery of effective biventricular pacing: economic implications of the OLE study under the US setting

Background: The hOLter for Efficacy analysis (OLE) study demonstrated that current device pacing diagnostics overestimate the amount of cardiac resynchronization therapy (CRT) pacing that effectively stimulates the cardiac tissue. Sub-optimal pacing increases mortality, hospitalizations, and associated health-care costs. We sought to estimate the expected number of hospital admissions due to heart failure (HF) and its respective financial impact in patients with maximized effective pacing versus conventional pacing.

Methods: A Markov model was developed to project HF hospitalizations and quantify the costs that could be avoided if pacing was maximally effective. OLE data were used to inform the prevalence of ineffective pacing among CRT patients and and average loss of pacing by causes. Adaptive CRT trial data quantified the reduction in underlying hospitalization risk by increasing effective pacing delivered. Survival was informed by a meta-analysis of 5 randomized clinical trials. Costs were analyzed from a US payer perspective.

Results: Projected average hospitalizations totaled 4.58 over a lifetime horizon for CRT patients with conventional pacing. Maximizing effective pacing delivery was projected to avoid 1.83 HF admissions/patient over the lifetime. This equates to a savings of 40% (US$22,802) compared with conventional pacing from the Medicare perspective. In a sensitivity analysis, CRT with effective pacing was projected to provide cost savings in all scenarios.

Conclusions: Maximized effective pacing leads to a lower number of HF hospitalizations, thus allowing significant cost offsets in the US setting.

Non-response to Cardiac Resynchronization Therapy

PURPOSE OF REVIEW

Cardiac resynchronization therapy (CRT) is an effective treatment option for therapy-refractory mild to severe heart failure (HF) patients with reduced ejection fraction and left ventricular (LV) conduction delay. Multiple clinical trials have shown that CRT improves cardiac function and overall quality of life, as well as reduces HF hospitalizations, health care costs, and mortality.

RECENT FINDINGS

Despite its effectiveness, the "non-response" rate to CRT is around 30%, remaining a major challenge that faces electrophysiologists and researchers. It has been recently suggested that the etiology of CRT non-response is multifactorial, and it requires a multifaceted approach to address it. In this focused review, we will summarize the definitions of CRT non-response, identify key factors for CRT non-response, and offer a simplified framework to address CRT non-response with the main goal of improving CRT outcomes.

Comparison of three-dimensional echocardiography and speckle tracking echocardiography in quantification and mapping of intraventricular mechanical dyssynchrony

Objectives

The aim of the study is to compare two advanced methods of evaluation of left ventricular mechanical dyssynchrony (LVMD), the speckle tracking echocardiography (STE) and the three-dimensional echocardiography (3DE).

Methods

One hundred thirty-six subjects, with or without LV dysfunction and with or without bundle branch block (BBB), were included in this study, designed to investigate agreement between magnitude and spatial pattern of LVMD as assessed by 3DE and STE. The frequency and severity of LVMD and localization of most asynchronous segments were compared.

Results

Both 3DE and STE revealed progressive rise in frequency and magnitude of LVMD with increasing disease severity. Dyssynchrony was dependent on left ventricle ejection fraction rather than the QRS duration. The frequency and magnitude of dyssynchrony were maximum in patients having LV dysfunction with left BBB. Compared with STE, 3DE diagnosed LVMD more frequently in patients having LV dysfunction with narrow QRS (17.6% vs 60.3%, respectively; P < 0.001). When the two methods were compared for localization of most asynchronous segments, the results matched only in about 50% cases.

Conclusions

Both 3DE and STE provided consistent results with progressive rise in magnitude of LVMD, correlating with disease severity. 3DE diagnosed more patients as having LVMD in those having LV dysfunction with narrow QRS. The most delayed segment assessed by two methods matched only in about half the cases. Correlation with clinical CRT responsiveness is needed to conclude which method is more accurate in dyssynchrony mapping for targeted lead placement.

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.

Understanding non-response to cardiac resynchronisation therapy: common problems and potential solutions

Heart failure is a complex clinical syndrome associated with a significant morbidity and mortality burden. Reductions in left ventricular (LV) function trigger adaptive mechanisms, leading to structural changes within the LV and the potential development of dyssynchronous ventricular activation. This is the substrate targeted during cardiac resynchronisation therapy (CRT); however, around 30-50% of patients do not experience benefit from this treatment. Non-response occurs as a result of pre-implant, peri-implant and post implant factors but the technical constraints of traditional, transvenous epicardial CRT mean they can be challenging to overcome. In an effort to improve response, novel alternative methods of CRT delivery have been developed and of these endocardial pacing, where the LV is stimulated from inside the LV cavity, appears the most promising.

Increasing Role of Remote Monitoring of Cardiac Resynchronization Therapy Devices in Improving Outcomes

Remote monitoring has become an essential component of the care of patients with a cardiac implantable electronic device, including those undergoing cardiac resynchronization therapy-defibrillator implantations. It allows for earlier detection of battery- and lead-related issue, atrial and ventricular arrhythmias, and may facilitate early identification of patients at risk for developing an exacerbation of heart failure. The data for the clinical utility of remote monitoring have been mixed. Additional studies are ongoing to determine how best to detect heart failure in these patients and how best to manage these patients based on the information.

Electrically guided versus imaging-guided implant of the left ventricular lead in cardiac resynchronization therapy: a study protocol for a double-blinded randomized controlled clinical trial (ElectroCRT)

BACKGROUND

Cardiac resynchronization therapy (CRT) is an established treatment in patients with heart failure and prolonged QRS duration where a biventricular pacemaker is implanted to achieve faster activation and more synchronous contraction of the left ventricle (LV). Despite the convincing effect of CRT, 30-40% of patients do not respond. Among the most important correctable causes of non-response to CRT is non-optimal LV lead position.

METHODS

We will enroll 122 patients in this patient-blinded and assessor-blinded, randomized, clinical trial aiming to investigate if implanting the LV lead guided by electrical mapping towards the latest LV activation as compared with imaging-guided implantation, causes an excess increase in left ventricular (LV) ejection fraction (LVEF). The patients are randomly assigned to either the intervention group: preceded by cardiac computed tomography of the cardiac venous anatomy, the LV lead is placed according to the latest LV activation in the coronary sinus (CS) branches identified by systematic electrical mapping of the CS at implantation and post-implant optimization of the interventricular pacing delay; or patients are assigned to the control group: placement of the LV lead guided by cardiac imaging. The LV lead is targeted towards the latest mechanical LV activation as identified by echocardiography and outside myocardial scar as identified by myocardial perfusion (MP) imaging. The primary endpoint is change in LVEF at 6-month follow up (6MFU) as compared with baseline measured by two-dimensional echocardiography. Secondary endpoints include relative percentage reduction in LV end-systolic volume, all-cause mortality, hospitalization for heart failure, and a clinical combined endpoint of response to CRT at 6MFU defined as the patient being alive, not hospitalized for heart failure, and experiencing improvement in NYHA functional class or/and > 10% increase in 6-minute walk test.

DISCUSSION

We assume an absolute increase in LVEF of 12% in the intervention group versus 8% in the control group. If an excess increase in LVEF can be achieved by LV lead implantation guided by electrical mapping, this study supports the conduct of larger trials investigating the impact of this strategy for LV-lead implantation on clinical outcomes in patients treated with CRT.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02346097 . Registered on 12 January 2015. Patients were enrolled between 16 February 2015 and 13 December 2017.

Cardiac resynchronization therapy: a comprehensive review

Despite improved understanding of heart failure (HF) and advances in medical treatments, its prevalence continues to rise, and the role of implantable devices continues to evolve. While cardiac resynchronization therapy (CRT) is an accepted form of treatment for many suffering from HF, there is an ever-evolving body of evidence examining novel indications, optimization of lead placement and device programming, with several competing technologies now also on the horizon. This review aims to take a clinical perspective on the major trials, current indications, controversies and emerging aspects of CRT in the treatment of HF.

Novel approach to discriminate left bundle branch block from nonspecific intraventricular conduction delay using pacing-induced functional left bundle branch block

PURPOSE

Left bundle branch block (LBBB) has a predictive value for response to cardiac resynchronization therapy as reported by Zareba et al. (Circulation 123(10):1061-1072, 2011). However, based on ECG criteria, the discrimination between complete LBBB and nonspecific intraventricular conduction delay is challenging. We tested the hypothesis that discrimination can be performed using standard electrophysiological catheters and a simple stimulation protocol.

METHODS

Fifty-nine patients were analyzed retrospectively. Patients were divided into groups of narrow QRS (n = 20), wide QRS of right bundle branch block (RBBB) morphology (n = 14), and wide QRS of LBBB morphology (n = 25). Using a diagnostic catheter placed in the coronary sinus, left ventricular activation was assessed during intrinsic conduction as well as during right ventricular (RV) stimulation.

RESULTS

In patients with narrow QRS and RBBB, the Q-LV/QRS ratio was 0.43 ± 0.013 (n = 20) and 0.41 ± 0.026 (n = 14), respectively. In patients with LBBB morphology, the Q-LV/QRS split up into a group of patients with normal (0.43 ± 0.022, n = 7) and a group with delayed left ventricular activation (0.75 ± 0.016, n = 18). By direct comparison of the Q-LV/QRS ratio during intrinsic conduction with the Q-LV/QRS ratio during RV pacing leading to a functional LBBB, a clear distinction between a group of "true LBBB" and another group of "apparent LBBB"/nonspecific intraventricular conduction delay (NICD) could be generated.

CONCLUSIONS

We present a novel and practical method that might facilitate discrimination between patients with apparent LBBB and true LBBB by comparing Q-LV/QRS ratios during intrinsic activation and during RV stimulation. Although this method can already be directly applied, validation by 3D electrical mapping and prospective correlation to cardiac resynchronization therapy (CRT) response will be required for further translation into clinical practice.

[Multipoint pacing-more CRT or a waste of battery power?]

Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in patients with broad QRS complex ≥130 ms and heart failure with reduced ejection fraction despite optimal guideline-directed medical therapy. However, approximately 30% of the patients implanted with a CRT system do not show clinical benefit. Reasons for nonresponse are complex and some aspects can be addressed during follow-up. Based on quadripolar lead technology, multipoint pacing (MPP) allows left ventricular stimulation at two different sites along the lead. In particular, in scarred and fibrotic ventricular myocardium stimulation at two different sites may overcome conduction barriers and lead to homogeneous ventricular depolarization. Especially for patients that do not respond to conventional CRT, activation of MPP may present an option to increase clinical response. On the other hand, MPP may significantly decrease battery longevity.This review offers an overview of the current knowledge and data on MPP balancing the potential clinical benefit and the possible disadvantages of this therapy.

Optimal site selection and image fusion guidance technology to facilitate cardiac resynchronization therapy

INTRODUCTION

Cardiac resynchronization therapy (CRT) has emerged as one of the few effective treatments for heart failure. However, up to 50% of patients derive no benefit. Suboptimal left ventricle (LV) lead position is a potential cause of poor outcomes while targeted lead deployment has been associated with enhanced response rates. Image-fusion guidance systems represent a novel approach to CRT delivery, allowing physicians to both accurately track and target a specific location during LV lead deployment.

AREAS COVERED

This review will provide a comprehensive evaluation of how to define the optimal pacing site. We will evaluate the evidence for delivering targeted LV stimulation at sites displaying favorable viability or advantageous mechanical or electrical properties. Finally, we will evaluate several emerging image-fusion guidance systems which aim to facilitate optimal site selection during CRT.

EXPERT COMMENTARY

Targeted LV lead deployment is associated with reductions in morbidity and mortality. Assessment of tissue characterization and electrical latency are critical and can be achieved in a number of ways. Ultimately, the constraints of coronary sinus anatomy have forced the exploration of novel means of delivering CRT including endocardial pacing which hold promise for the future of CRT delivery.

His Bundle Pacing for Cardiac Resynchronization

Cardiac resynchronization therapy with left ventricular coronary sinus or epicardial pacing is an established therapy for patients with systolic heart failure and intraventricular conduction system delay, particularly left bundle branch block. Despite large-scale randomized trials demonstrating the efficacy of this therapy, clinical and echocardiographic nonresponse rates remain as high as up to 40%. His bundle pacing (HBP) has reemerged as a means to provide physiologic resynchronization in patients with bundle branch block by correcting QRS by direct capture of the His-Purkinje system. This critical appraisal reviews early clinical data, evaluates possible mechanism, and identifies areas for future investigation for HBP in resynchronization.

Patterns of physical activity and survival following cardiac resynchronization therapy implantation: the ALTITUDE activity study

Aims

Cardiac resynchronization therapy with implantable defibrillator backup (CRT-D) improves outcomes, but predictors and markers of response remain limited. Physical activity information collected by CRT devices may provide insights to CRT response and the relationship between activity changes and survival.

Methods and results

Patients entered into the LATITUDE remote monitoring system from 2008 to 2012 after receipt of a new CRT-D were eligible. Mean daily activity was calculated from LATITUDE uploads at baseline (first 3-10 days following implant) and 6 months (180-210 days). Pairwise differences for baseline-6-month activity were calculated, and survival according to quintiles of 6-month activity change was assessed. Cox regression was used to examine the adjusted association between survival and baseline-6-month activity change. A total of 26 509 patients were followed for a median of 2.3 years (mean age 70.2 ± 11.0 years, 70.7% male). Mean baseline activity was 66.2 ± 47.7 min/day, with mean paired increase at 6 months of 37.1 ± 48.2 min/day [95% CI (confidence interval), 36.5-37.6, P < 0.0001], though 15.5% of patients did not improve or worsened at 6 months. Survival at 3 years was significantly higher in the largest baseline-6-month activity change quintile vs. the lowest quintile (88.9% vs. 62.1%, log-rank P-value < 0.001). Adjusted for age and gender, higher 6-month activity change was associated with a lower risk of death (adjusted hazard ratios 0.65 per 30 min increase in activity, 95% CI, 0.63-0.67).

Conclusions

Change in physical activity between baseline and 6 months following CRT implantation is strongly associated with survival.

Contractility sensor-guided optimization of cardiac resynchronization therapy: results from the RESPOND-CRT trial

Aims

Although cardiac resynchronization therapy (CRT) is effective in patients with systolic heart failure (HF) and a wide QRS interval, a substantial proportion of patients remain non-responsive. The SonR contractility sensor embedded in the right atrial lead enables individualized automatic optimization of the atrioventricular (AV) and interventricular (VV) timings. The RESPOND-CRT study investigated the safety and efficacy of the contractility sensor system in HF patients undergoing CRT.

Methods and results

RESPOND-CRT was a prospective, randomized, double-blinded, multicentre, non-inferiority trial. Patients were randomized (2:1, respectively) to receive weekly, automatic CRT optimization with SonR vs. an Echo-guided optimization of AV and VV timings. The primary efficacy endpoint was the rate of clinical responders (patients alive, without adjudicated HF-related events, with improvement in New York Heart Association class or quality of life), at 12 months. The study randomized 998 patients. Responder rates were 75.0% in the SonR arm and 70.4% in the Echo arm (mean difference, 4.6%; 95% CI, −1.4% to 10.6%; P < 0.001 for non-inferiority margin −10.0%) (Table 2). At an overall mean follow-up of 548 ± 190 days SonR was associated with a 35% risk reduction in HF hospitalization (hazard ratio, 0.65; 95% CI, 0.46–0.92; log-rank P = 0.01).

Conclusion

Automatic AV and VV optimization using the contractility sensor was safe and as effective as Echo-guided AV and VV optimization in increasing response to CRT.

ClinicalTrials.gov number

NCT01534234

Protocol-driven remote monitoring of cardiac resynchronization therapy as part of a heart failure disease management strategy

BACKGROUND

Cardiac resynchronisation therapy (CRT) is an established treatment for heart failure (HF) with reduced ejection fraction. CRT devices are equipped with remote monitoring functions, which are pivotal in the detection of device problems, but may also facilitate disease management. The aim of this study was to provide a comprehensive overview of the clinical interventions taken based on remote monitoring.

METHODS

This is a single centre observational study of consecutive CRT patients (n = 192) participating in protocol-driven remote follow-up. Incoming technical- and disease-related alerts were analysed together with subsequently triggered interventions.

RESULTS

During 34 ± 13 months of follow-up, 1372 alert-containing notifications were received (2.53 per patient-year of follow-up), comprising 1696 unique alerts (3.12 per patient-year of follow-up). In 60%, notifications resulted in a phone contact. Technical alerts constituted 8% of incoming alerts (0.23 per patient-year of follow-up). Rhythm (1.43 per patient-year of follow-up) and bioimpedance alerts (0.98 per patient-year of follow-up) were the most frequent disease-related alerts. Notifications included a rhythm alert in 39%, which triggered referral to the emergency room (4%), outpatient cardiology clinic (36%) or general practitioner (7%), or resulted in medication changes (13%). Sole bioimpedance notifications resulted in a telephone contact in 91%, which triggered outpatient evaluation in 8% versus medication changes in 10%. Clinical outcome was excellent with 97% 1-year survival.

CONCLUSIONS

Remote CRT follow-up resulted in 0.23 technical- versus 2.64 disease-related alerts annually. Rhythm and bioimpedance notifications constituted the majority of incoming notifications which triggered an actual intervention in 22% and 15% of cases, respectively.