Longer Left Ventricular Electric Delay Reduces Mitral Regurgitation After Cardiac Resynchronization Therapy: Mechanistic Insights From the SMART-AV Study (SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy)

Effect of adaptive cardiac resynchronization therapy in heart failure patients with pacemaker dependency

BACKGROUND

An adaptive cardiac resynchronization therapy (aCRT) algorithm allows continuous adjustments of pacing timings of atrioventricular delays by periodic automatic evaluation of electrical conduction. This applies to patients with an atrioventricular block and is effective in cardiac resynchronization therapy (CRT) devices; however, whether this algorithm benefits patients with pacemaker dependency is uncertain.

METHODS

This study examined the clinical impact of an aCRT algorithm in patients diagnosed with heart failure with reduced ejection fraction and pacemaker dependency. A total of 359 patients underwent CRT between January 2016 and December 2022. Patients undergoing pacemaker-dependent CRT with the aCRT algorithm function were selected. Sixty-four patients with pacemaker dependency (31 with aCRT algorithm and 33 without) were included. Pacemaker dependency was defined as the absence of spontaneous ventricular activity during the sensing test at VVI 30 bpm or prolonged atrioventricular delay (> 300 ms). The primary endpoint was the composite clinical outcome of all-cause death or hospitalization for heart failure.

RESULTS

No significant differences were observed in baseline characteristics between groups. During a median follow-up of 1,067 days (interquartile range 553-1,776 days), aCRT reduced the risk of composite clinical outcomes in patients with pacemaker dependency (log-rank P = 0.028). In addition, using the aCRT algorithm was an independent predictor of the composite clinical outcomes in the multivariate analysis (hazard ratio 0.34, 95% confidence interval: 0.12-0.94, P = 0.038).

CONCLUSION

The aCRT algorithm significantly reduced the risk of adverse clinical outcomes in patients with pacemaker dependency. This algorithm may be an important tool for managing such patients.

Left ventricular electrical delay predicts volumetric response to leadless cardiac resynchronization therapy

BACKGROUND

Leadless left ventricular (LV) endocardial pacing is an emerging cardiac resynchronization therapy (CRT) technology. Predictors of response to leadless CRT are poorly understood. Implanting the LV endocardial pacing electrode in sites with increased electrical latency (Q-LV) may improve response rates.

OBJECTIVE

The purpose of this study was to examine the association between Q-LV and echocardiographic remodeling response to leadless CRT delivered with the WiSE-CRT system.

METHODS

A post hoc analysis (n = 122) of the SOLVE-CRT trial examined the relationship between LV pacing site Q-LV with rate of left ventricular end-systolic volume (LVESV) reduction >15% at 6 months. Multivariable regression analysis, adjusting for age, sex, previous CRT nonresponse, cardiomyopathy etiology, QRS morphology, and QRS duration was performed, followed by receiver operating characteristic analysis and analysis of variance by Q-LV quartile. A subgroup analysis of the ischemic cardiomyopathy cohort was undertaken.

RESULTS

Complete Q-LV data were available for 122 of 153 patients (80%) in the active arms SOLVE-CRT. Overall, the 6-month LVESV response rate was 46%. Logistic regression identified Q-LV as an independent response predictor with borderline significance (adjusted odds ratio 1.015; P = .05). Analysis by Q-LV quartile demonstrated a significant improvement in response rate in quartile 4 (longest Q-LV 64%) compared to quartile 1 (shortest Q-LV 28%) (P <.01). This association was primarily driven by strong Q-LV-response correlation in patients with ischemic cardiomyopathy, demonstrated by subgroup logistic regression (adjusted odds ratio 1.034; P = .004).

CONCLUSION

Increased Q-LV was associated with improved reverse remodeling following leadless CRT. Targeting LV endocardial sites of high Q-LV may deliver additional benefit compared to empirical LV electrode implantation.

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

BACKGROUND

This study compared the stability of the Medtronic Attain Stability Quad (ASQ), a novel quadripolar active fixation left ventricular (LV) lead with a side helix, to that of conventional quadripolar leads with passive fixation (non-ASQ) and evaluated their LV lead performance.

METHODS AND RESULTS

In all, 183 consecutive patients (69 ASQ, 114 non-ASQ) who underwent cardiac resynchronization therapy (CRT) between January 2018 and June 2021 were enrolled. Complications, including elevated pacing capture threshold (PCT) levels, phrenic nerve stimulation (PNS), and LV lead dislodgement, were analyzed during the postimplantation period until the first outpatient visit after discharge. The frequency of LV lead-related complications was significantly lower in the ASQ than non-ASQ group (14% vs. 30%, respectively; P=0.019). Specifically, LV lead dislodgement occurred only in the non-ASQ group, and elevated PCT levels were significantly lower in the ASQ group (7% vs. 23%; P=0.007). Kaplan-Meier analysis confirmed a significantly lower incidence of LV lead-related complications in the ASQ group (log-rank P=0.005). Cox multivariable regression analysis showed a significant reduction in lead-related complications associated with ASQ (hazard ratio 0.44; 95% confidence interval 0.23-0.83; P=0.011).

CONCLUSIONS

The ASQ group exhibited fewer LV lead-related complications requiring reintervention and setting changes than the non-ASQ group. Thus, the ASQ may be a favorable choice for CRT device implantation.

Evolution and prognosis of tricuspid and mitral regurgitation following cardiac implantable electronic devices: a systematic review and meta-analysis

AIMS

Significant changes in tricuspid regurgitation (TR) and mitral regurgitation (MR) post-cardiac implantable electronic devices (CIEDs) are increasingly recognized. However, uncertainty remains as to whether the risk of CIED-associated TR and MR differs with right ventricular pacing (RVP) via CIED with trans-tricuspid RV leads, compared with cardiac resynchronization therapy (CRT), conduction system pacing (CSP), and leadless pacing (LP). The study aims to synthesize extant data on risk and prognosis of significant post-CIED TR and MR across pacing strategies.

METHODS AND RESULTS

We searched PubMed, EMBASE, and Cochrane Library databases published until 31 October 2023. Significant post-CIED TR and MR were defined as ≥ moderate. Fifty-seven TR studies (n = 13 723 patients) and 90 MR studies (n = 14 387 patients) were included. For all CIED, the risk of post-CIED TR increased [pooled odds ratio (OR) = 2.46 and 95% CI = 1.88-3.22], while the risk of post-CIED MR reduced (OR = 0.74, 95% CI = 0.58-0.94) after 12 and 6 months of median follow-up, respectively. Right ventricular pacing via CIED with trans-tricuspid RV leads was associated with increased risk of post-CIED TR (OR = 4.54, 95% CI = 3.14-6.57) and post-CIED MR (OR = 2.24, 95% CI = 1.18-4.26). Binarily, CSP did not alter TR risk (OR = 0.37, 95% CI = 0.13-1.02), but significantly reduced MR (OR = 0.15, 95% CI = 0.03-0.62). Cardiac resynchronization therapy did not significantly change TR risk (OR = 1.09, 95% CI = 0.55-2.17), but significantly reduced MR with prevalence pre-CRT of 43%, decreasing post-CRT to 22% (OR = 0.49, 95% CI = 0.40-0.61). There was no significant association of LP with post-CIED TR (OR = 1.15, 95% CI = 0.83-1.59) or MR (OR = 1.31, 95% CI = 0.72-2.39). Cardiac implantable electronic device-associated TR was independently predictive of all-cause mortality [pooled hazard ratio (HR) = 1.64, 95% CI = 1.40-1.90] after median of 53 months. Mitral regurgitation persisting post-CRT independently predicted all-cause mortality (HR = 2.00, 95% CI = 1.57-2.55) after 38 months.

CONCLUSION

Our findings suggest that, when possible, adoption of pacing strategies that avoid isolated trans-tricuspid RV leads may be beneficial in preventing incident or deteriorating atrioventricular valvular regurgitation and might reduce mortality.

Location, Location, Location: A Pilot Study to Compare Electrical with Echocardiographic-Guided Targeting of Left Ventricular Lead Placement in Cardiac Resynchronisation Therapy

Introduction: Cardiac resynchronisation therapy is ineffective in 30-40% of patients with heart failure with reduced ejection fraction. Targeting non-scarred myocardium by selecting the site of latest mechanical activation using echocardiography has been suggested to improve outcomes but at the cost of increased resource utilisation. The interval between the beginning of the QRS complex and the local LV lead electrogram (QLV) might represent an alternative electrical marker. Aims: To determine whether the site of latest myocardial electrical and mechanical activation are concordant. Methods: This was a single-centre, prospective pilot study, enrolling patients between March 2019 and June 2021. Patients underwent speckle-tracking echocardiography (STE) prior to CRT implantation. Intra-procedural QLV measurement and R-wave amplitude were performed in a blinded fashion at all accessible coronary sinus branches. Pearson's correlation coefficient and Cohen's Kappa coefficient were utilised for the comparison of electrical and echocardiographic parameters. Results: A total of 20 subjects had complete data sets. In 15, there was a concordance at the optimal site between the electrically targeted region and the mechanically targeted region; in four, the regions were adjacent (within one segment). There was discordance (≥2 segments away) in only one case between the two methods of targeting. There was a statistically significant increase in procedure time and fluoroscopy duration using the intraprocedural QLV strategy. There was no statistical correlation between the quantitative electrical and echocardiographic data. Conclusions: A QLV-guided approach to targeting LV lead placement appears to be a potential alternative to the established echocardiographic-guided technique. However, it is associated with prolonged fluoroscopy and overall procedure time.

Perspectives on Secondary Mitral Regurgitation in Heart Failure

PURPOSE OF THE REVIEW

This review focuses on broader perspectives of mitral regurgitation (MR) in patients with heart failure.

RECENT FINDINGS

The ratio of regurgitant volume to end-diastolic volume appears to help identify patients who may benefit from valve interventions. Secondary MR is not only attributed to geometric changes of the LV but also related to the structural changes in the mitral valve that include fibrosis of the mitral leaflets and changes in the extracellular matrix. The transition from mild to severe secondary MR can occur at different rates, from a slow LV remodeling process to a more abrupt process precipitated by an inciting event such as atrial fibrillation. Septal flash and apical rocking, two new visual markers of LV mechanical dyssynchrony, appear to be predictive of MR reduction following cardiac resynchronization therapy. Optimal guideline-directed medical therapy has been shown to decrease the severity of secondary MR effectively. A theoretical framework to characterize secondary MR as it relates to the onset of MR is proposed. Type A: Early onset of MR contemporaneous with myocardial injury. The maladaptive LV remodeling occurs in parallel with MR. Type B: LV remodeling proceeds without significant MR until the LV is moderately dilated, which coincides with or without inciting factors such as atrial fibrillation. Type C: LV remodeling proceeds after myocardial injury without significant MR until the LV is severely dilated. MR is a late manifestation of LV remodeling.

Outcomes following transcatheter repair in patients with functional mitral regurgitation not receiving guideline directed medical therapy in Israel

BACKGROUND

Transcatheter edge to edge repair (TEER) improves prognosis in patients with functional mitral regurgitation (FMR) receiving guideline directed medical therapy (GDMT). Many patients with FMR do not receive GDMT and the utility of TEER in this population remains unclear.

METHODS

We retrospectively studied patients undergoing TEER. Clinical, echocardiographic and procedural variables were recorded. GDMT was defined as use of RAAS inhibitors and MRAs unless GFR was under 30 as well as beta blockers. The primary endpoint of the study was one year mortality.

RESULTS

168 patients (mean age 71.3 ± 9.3; 66% males) with FMR who underwent TEER were included of whom 116 (69%) received GDMT at the time of TEER and 52 (31%) did not. There were no significant demographic or clinical differences between the groups. There were no significant differences in procedural success and complications between groups. One year mortality was identical in the two groups (15% vs. 15%; RR 1.06, CI 0.43-2.63, P = 0.90).

CONCLUSIONS

Our findings suggest that procedural success and one year mortality following TEER was not significantly different in HFREF patients with FMR with or without GDMT. Larger, prospective studies are necessary to define the benefit of TEER in this population.

Echocardiography- versus intracardiac electrocardiogram-based optimization of cardiac resynchronization therapy: A systematic review

OBJECTIVE

This systematic review aimed to evaluate the performance of echocardiography-based programming in comparison with the intracardiac electrocardiogram (IEGM)-based method for the optimization of cardiac resynchronization therapy (CRT).

METHODS

A literature review was conducted using digital databases to systematically identify the studies reporting CRT optimization through echocardiography compared with IEGM. Detailed patient-level study characteristics including the type of study, sample size, therapy, the New York Heart Classification (NYHA) status, lead placement, and other parameters were abstracted. Finally, postprogramming outcomes were extracted for each article.

RESULTS

In a total of 11 studies, 919 patients were recruited for the final analysis. Overall, 692 (75.29%) were males. The mean duration of the QRS complex in our study population ranged from 145.2 ± 21.8 ms to 183 ± 19.9 ms. There was an equal improvement in the NYHA class between the two methods while the left ventricular ejection fraction (LVEF) demonstrated an improvement by IEGM. Many studies supported IEGM to increase the 6-minute walk test and left ventricular outflow tract velocity time interval (LVOT VTI) when compared to echocardiography. The mean time for echocardiography-based optimization was 60.15 min while that of IEGM-based optimization was 6.65 min.

CONCLUSION

IEGM is an alternative method for CRT optimization in improving the NYHA class, LVEF, and LVOT VTI, and is less time-consuming when compared to the echocardiography-based methods.

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

BACKGROUND

Pacing at sites of longest interventricular delay has been associated with greater reverse remodeling in cardiac resynchronization therapy (CRT). However, the effects of pacing at such sites on clinical outcomes is less well studied.

OBJECTIVE

The purpose of this study was to assess the association between interventricular delay and clinical outcomes in CRT patients implanted with quadripolar left ventricular (LV) leads.

METHODS

RALLY-X4 was a registry study of the Acuity X4 quadripolar LV leads. Interventricular delay was measured during unpaced basal rhythm from the right ventricular (RV) lead to the LV lead electrode (E1 to E4) chosen for CRT pacing. Patients were stratified by median RV-LV delay (80 ms) into short and long delay groups; they also were analyzed by multivariable modeling. The primary composite outcome measure was all-cause mortality and heart failure hospitalization (HFH) at 18 months.

RESULTS

A total of 581 patients had complete RV-LV delay data. Mean LV ejection fraction was 27%, and 73% had typical left bundle branch block. Predictors of long RV-LV delay included female sex, left bundle branch block, and QRS duration >150 ms. Survival free of the primary outcome at 18-month follow-up was 87% in the long activation delay group compared with 77% in the short delay group (P = .0042). Multivariate analysis showed that RV-LV delay was an independent predictor of survival free of HFH (P = .028).

CONCLUSION

Among CRT patients with quadripolar LV pacing leads, longer baseline interventricular activation delay was significantly associated with the composite endpoint of all-cause mortality and HFH.

Impact of S-Wave Amplitude in Right Precordial Leads on Improvement in Mitral Regurgitation following Cardiac Resynchronization Therapy

Background: The therapeutic strategy for mitral regurgitation (MR) in patients with advanced heart failure and wide QRS complex who are indicated for both intervention to MR and cardiac resynchronization therapy (CRT), remains unclear. Objective: We aimed to determine electrocardiogram parameters that associate with MR reduction following CRT implantation. Methods: Among the patients with advanced heart failure and functional MR who intended to receive CRT implantation, baseline QRS morphology, electrical axis, PR interval, QRS duration, and averaged S-wave in right precordial leads (V1 to V3) in surface electrocardiogram were measured. The impact of these parameters on MR reduction following CRT implantation, which was defined as a reduction in MR ≥1 grade six months later, was investigated. Results: In 35 patients (median 71 years old, 18 men), 17 (49%) achieved an MR reduction following CRT implantation. Among baseline characteristics, only the higher S-wave amplitude in right precordial leads was an independent predictor of MR reduction (odds ratio 14.00, 95% confidence interval 1.65–119.00, p = 0.016) with a cutoff of 1.3 mV calculated through the area under the curve. The cutoff significantly stratified the cumulative incidences of heart failure re-admission and percutaneous mitral valve repair following CRT implantation (p = 0.032 and p = 0.011, respectively). Conclusions: In patients with advanced heart failure and functional MR, the baseline higher amplitude of S-wave in the right precordial leads might be a good indicator of MR improvement following CRT.

Predictors of persistence of functional mitral regurgitation after cardiac resynchronization therapy: Review of literature

Functional mitral regurgitation is a common finding among heart failure patients with ischemic and non-ischemic dilated cardiomyopathies. The presence of moderate or severe mitral regurgitation is associated with higher morbidity and mortality. Heart failure patients meeting electrocardiogram and left ventricle function criteria are good candidates for cardiac resynchronization therapy, which may reduce the degree of functional mitral regurgitation in the short and long term, specifically targeting myocardial dyssynchrony and inducing left ventricle reverse remodeling. In this article, we analyze data from the literature about predictors of mitral regurgitation improvement after cardiac resynchronization therapy implantation.

AV timing in pacemaker patients with first-degree AV block: which is preferable, intrinsic AV conduction or pacing?

Some patients with pacemakers present with first-degree atrioventricular (AV) block. To avoid right ventricular (RV) pacing, preserving intrinsic AV conduction as much as possible is recommended. However, there is no clear cutoff AV interval to determine whether intrinsic AV conduction should be preserved or RV pacing should be delivered. This study aimed to compare a pacing mode-preserving, intrinsic AV conduction with the DDD mode delivering RV pacing in terms of echocardiographic parameters in patients with first-degree AV block and to investigate whether RV pacing induces heart failure (HF). Stroke volume (SV) was measured to determine the optimal AV delay with the intrinsic AV conduction rhythm and the DDD pacing delivering RV pacing. Echocardiographic evaluation was performed for 6-month follow-up period. Seventeen patients were studied. At baseline, mean intrinsic PQ interval was 250 ± 40 ms. SV was greater with RV pacing with optimal AV delay of 160 ms than with intrinsic AV conduction rhythm in all patients. Therefore, pacemakers were set to the DDD to deliver RV pacing. During follow-up, seven patients developed HF. Mean baseline E/E′ ratio in patients who developed HF (HF group) during RV pacing was higher than in patients without HF (non = HF group; 17.9 ± 8 versus 11.5 ± 2, P = 0.018) Even within HF group patients without a high baseline E/E′ ratio, it increased with RV pacing (22.2 ± 6 versus 11.6 ± 2; P < 0.001). In patients with pacemaker and first-degree AV block, RV pacing with the optimal AV delay of 160 ms increased SV. However, the risk of HF may be increased with RV pacing if the E/Eʹ ratio is > 15 during intrinsic AV conduction or RV pacing. RV pacing should be avoided in patients with high E/Eʹ ratio under intrinsic AV conduction or RV pacing.

Impact of physiological pacing on functional mitral regurgitation in systolic dysfunction: Initial echocardiographic remodeling findings after His bundle pacing

BACKGROUND

Although His bundle pacing (HBP) has been shown to improve left ventricular ejection fraction (LVEF), its impact on mitral regurgitation (MR) remains uncertain.

OBJECTIVES

The aim of this study was to evaluate change in functional MR after HBP in patients with left ventricular (LV) systolic dysfunction.

METHODS

Paired echocardiograms were retrospectively assessed in patients with reduced LVEF (<50%) undergoing HBP for pacing or resynchronization. The primary outcomes assessed were change in MR, LVEF, LV volumes, and valve geometry pre- and post-HBP. MR reduction was characterized as a decline in ≥1 MR grade post-HBP in patients with ≥grade 3 MR at baseline.

RESULTS

Thirty patients were analyzed: age 68 ± 15 years, 73% male, LVEF 32% ± 10%, 38% coronary artery disease, 33% history of atrial fibrillation. Baseline QRS was 162 ± 31 ms: 33% left bundle branch block, 37% right bundle branch block, 17% paced, and 13% narrow QRS. Significant reductions in LV end-systolic volume (122 mL [73-152 mL] to 89 mL [71-122 mL], P = .006) and increase in LV ejection fraction (31% [25%-37%] to 39% [30%-49%], P < .001) were observed after HBP. Ten patients had grade 3 or 4 MR at baseline, with reduction in MR observed in 7. In patients with at least grade 3 MR at baseline, reduction in LV volumes, improved mitral valve geometry, and greater LV contractility were associated with MR reduction. Greater reduction in paced QRS width was present in MR responders compared to non-MR responders (-40% vs -25%, P = .04).

CONCLUSIONS

In this initial detailed echocardiographic analysis in patients with LV systolic dysfunction, HBP reduced functional MR through favorable ventricular remodeling.

Comparative efficacy of image-guided techniques in cardiac resynchronization therapy: a meta-analysis

Background

Several studies have illustrated the use of echocardiography, magnetic resonance imaging, and nuclear imaging to optimize left ventricular (LV) lead placement to enhance the response of cardiac resynchronization therapy (CRT) in heart failure patients. We aimed to conduct a meta-analysis to determine the incremental efficacy of image-guided CRT over standard CRT.

Methods

We searched PubMed, Cochrane library, and EMBASE to identify relevant studies. The outcome measures of cardiac function and clinical outcomes were CRT response, concordance of the LV lead to the latest sites of contraction (concordance of LV), heart failure (HF) hospitalization, mortality rates, changes of left ventricular ejection fraction (LVEF), and left ventricular end-systolic volume (LVESV).

Results

The study population comprised 1075 patients from eight studies. 544 patients underwent image-guided CRT implantation and 531 underwent routine implantation without imaging guidance. The image-guided group had a significantly higher CRT response and more on-target LV lead placement than the control group (RR, 1.33 [95% CI, 1.21 to 1.47]; p < 0.01 and RR, 1.39 [95% CI, 1.01 to 1.92]; p < 0.05, respectively). The reduction of LVESV in the image-guided group was significantly greater than that in the control group (weighted mean difference, − 12.46 [95% CI, − 18.89 to − 6.03]; p < 0.01). The improvement in LVEF was significantly higher in the image-guided group (weighted mean difference, 3.25 [95% CI, 1.80 to 4.70]; p < 0.01). Pooled data demonstrated no significant difference in HF hospitalization and mortality rates between two groups (RR, 0.89 [95% CI, 0.16 to 5.08]; p = 0.90, RR, 0.69 [95% CI, 0.37 to 1.29]; p = 0.24, respectively).

Conclusions

This meta-analysis indicates that image-guided CRT is correlated with improved CRT volumetric response and cardiac function in heart failure patients but not with lower hospitalization or mortality rate.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02061-y.

Bridging the gap between heart failure and the device clinic

INTRODUCTION

While cardiac resynchronization therapy (CRT) is a mainstay in the management of selected patients with chronic systolic dysfunction, many patients are noted to experience less than expected or no benefit at all from the therapy. Multidisciplinary care has been shown to provide benefit in follow up for patients receiving CRT devices. Areas covered: This review will focus on the apparent reasons behind less than optimal outcomes following CRT as well as multidisciplinary approaches to treating patients with CRT devices. The literature review focused mainly on the data behind multidisciplinary care of CRT patients. Expert commentary: A multidisciplinary approach incorporating input from various cardiology backgrounds is an important strategy in ensuring optimal outcomes in patients receiving CRT devices. Breaking down the 'silo' effect amongst cardiac subspecialties is vital in achieving high level multidisciplinary care.

A Review of Image-guided Approaches for Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) is a standard treatment for patients with heart failure; however, the low response rate significantly reduces its cost-effectiveness. A favourable CRT response primarily depends on whether implanters can identify the optimal left ventricular (LV) lead position and accurately place the lead at the recommended site. Myocardial imaging techniques, including echocardiography, cardiac magnetic resonance imaging and nuclear imaging, have been used to assess LV myocardial viability and mechanical dyssynchrony, and deduce the optimal LV lead position. The optimal position, presented as a segment of the myocardial wall, is then overlaid with images of the coronary veins from fluoroscopy to aid navigation of the LV lead to the target venous site. Once validated by large clinical trials, these image-guided techniques for CRT lead placement may have an impact on current clinical practice.