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Background: Heart rate score (HRSc), the percentage of atrial depolarizations in the largest paced and sensed 10-beats/min histogram bin recorded in cardiac devices, is associated with several adverse outcomes, but it remains uncertain whether HRSc independently predicts atrial high-rate episodes (AHREs) in patients with sinus node dysfunction (SND) undergoing pacemaker (PM) implantation., Objective: This study aimed to determine whether initial HRSc after PM implantation predicts new-onset AHREs in patients with SND., Methods: Patients had Boston Scientific PMs implanted for SND from 2012 to 2021 at Cleveland Clinic, University of Occupational and Environmental Health, Japan, Kyushu Rosai Hospital, and JCHO Kyushu Hospital. Patients were excluded if they had atrial fibrillation before PM implantation or AHREs within 3 months after implantation. Subsequent AHREs after implantation were evaluated and correlated with HRSc., Results: During 48.9 (interquartile range, 25.7-50.4) months, 130 consecutive PM patients (76 ± 10 years; 40% male) had a median initial HRSc of 74% (57%-86%). AHREs defined by >1%, >6 h/d burden, and atrial tachycardia response events >24 hours developed in 27 of 130 (21%), 15 of 130 (12%), and 9 of 130 (7%), respectively. For each definition, patients with HRSc ≥80% had higher occurrence of AHREs than those with HRSc <80% (both P = .008, log-rank test). After adjustment for age, race, comorbidities, left ventricular ejection fraction, left atrial diameter, and cumulative percentage of right atrial and right ventricular pacing, initial HRSc ≥80% (hazard ratio, 3.33; 95% CI, 1.35-8.18; P = .009) and male sex (hazard ratio, 2.59; 95% CI, 1.06-6.33; P = .04) independently predicted AHREs., Conclusion: HRSc ≥80% is associated with new-onset, device-determined AHREs for patients undergoing PM implantation for SND. HRSc may have prognostic and therapeutic implications., Competing Interests: Disclosures H.A.: research grant: Boston Scientific, Medtronic, Abbott. A.D.S.: consultant: VivaQuant, CardioSignal. G.Y.H.L.: consultant and speaker: BMS/Pfizer, Boehringer Ingelheim, Daiichi-Sankyo, Anthos. N.V.: research/consultant: Abbott, Biotronik, Boston Scientific, EP solutions, Implicity, Impulse Dynamics, Medtronic, Pacemate. B.L.W.: consultant and speaker: Boston Scientific, Medtronic, Abbott, Biotronik., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: No real-world large database associates lower rate limit (LRL) programming and survival of subjects with cardiac resynchronization therapy-defibrillators (CRT-Ds)., Objective: The purpose of this study was to test the hypothesis that lower LRL programming is independently associated with survival, and that LRL and heart rate score (HrSc) are associated., Methods: All dual-chamber CRT-D devices in the Remote Patient Monitoring (RPM) ALTITUDE database (2006-2011) were queried. Baseline HrSc was defined as the percentage of all atrial sensed and paced beats in the tallest 10-beat histogram bin postimplant. LRL was assessed during repeated RPM uploads. Using a Cox model multivariable analysis, relationships between LRL, survival, HrSc, and other variables were evaluated. Survival was determined by query of death indices., Results: Data analyzed included 61,881 subjects (mean follow-up 2.9 years). LRL ranged from 40 to 85 bpm. Baseline lower LRL was associated with younger age, less atrial fibrillation, female sex, and lower HrSc (P <.001 for all covariates). Lower LRL was associated with improved survival, with LRL 40 associated with the largest survival benefit. This was significant for all 3 HrSc subgroups (P <.001). An interaction between HrSc and LRL was observed, with the largest survival difference between HrSc groups observed at LRL-40 (P <.001)., Conclusion: LRL programming and HrSc were associated, and lower values of both were associated with improved survival in a large database of CRT-D subjects. Relationships between survival, LRL programming, and HrSc merit further study., (Copyright © 2021. Published by Elsevier Inc.)

Background: Heart rate score (HRSc) ≥70%, a novel parameter, predicts risk of mortality in patients with implantable cardioverter-defibrillators and identifies patients who have survival benefit with DDDR vs DDD pacing., Objective: The purpose of this study was to determine if DDDR pacing lowers HRSc, and a blended sensor with minute ventilation (MV) and accelerometer (XL) improves HRSc more than accelerometer (XL) alone in patients requiring pacemakers (PMs)., Methods: HRSc, the percentage of all beats in the tallest 10-beat/min device histogram bin, was calculated. Data from the Limiting Chronotropic Incompetence for Pacemaker Recipients Study, a prospective randomized trial of PM patients, comparing XL to blended-sensor (XL + MV) rate-responsive pacing, were analyzed retrospectively for HRSc changes from baseline. The relationship of patient activity (sensor-detected from device memory) to HRSc was examined., Results: Of the 501 randomized patients, 215 (43%) patients had HRSc ≥70% during DDD pacing at baseline. In these patients, HRSc decreased after DDDR programming by 14.2%, while it increased by 0.4% in those with baseline HRSc <70% (n = 286) (HRSc ≥70% vs HRSc <70%; P < .01). No differences were detected between the 2 randomized sensor-based groups at baseline. Blended-sensor (MV + XL) programming reduced HRSc more than the XL sensor alone (MV + XL: 18% vs XL: 10%; P < .001). No correlation was observed between patient activity and HRSc (correlation = -0.14; P = .07)., Conclusion: HRSc improved (reduced) with rate-response (DDDR) programming in PM patients with high HRSc during DDD pacing. Blended sensors (MV + XL) improved HRSc more than XL alone. HRSc does not correlate with patient activity levels, suggesting that other patient factors determine this parameter. This programming approach needs to be investigated prospectively in a PM outcomes trial., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Routine atrioventricular optimization (AVO) has not been shown to improve outcomes with cardiac resynchronization therapy (CRT). However, more recently subgroup analyses of multicenter CRT trials have identified electrocardiographic or lead positions associated with benefit from AVO. Therefore, the purpose of this analysis was to evaluate whether interventricular electrical delay modifies the impact of AVO on reverse remodeling with CRT., Methods: This substudy of the SMART-AV trial (SMARTDELAY Determined AV Optimization) included 275 subjects who were randomized to either an electrogram-based AVO (SmartDelay) or nominal atrioventricular delay (120 ms). Interventricular delay was defined as the time between the peaks of the right ventricular (RV) and left ventricular (LV) electrograms (RV-LV duration). CRT response was defined prospectively as a >15% reduction in LV end-systolic volume from implant to 6 months., Results: The cohort was 68% men, with a mean age of 65±11 years and LV ejection fraction of 28±8%. Longer RV-LV durations were significantly associated with CRT response ( P<0.01) for the entire cohort. Moreover, the benefit of AVO increased as RV-LV duration prolonged. At the longest quartile, there was a 4.26× greater odds of a remodeling response compared with nominal atrioventricular delays ( P=0.010)., Conclusions: Baseline interventricular delay predicted CRT response. At long RV-LV durations, AVO can increase the likelihood of reverse remodeling with CRT. AVO and LV lead location optimized to maximize interventricular delay may work synergistically to increase CRT response., Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT00874445.

Background: Pacing at sites with late electrical activation or greater interventricular delay is associated with improvement in measures of cardiac resynchronization therapy (CRT) response, primarily reverse remodeling. However, little is known about whether such lead positions improve heart failure (HF) clinical outcomes., Objective: The purpose of this study was to assess the association between interventricular electrical delay and HF clinical outcomes., Methods: The Pacing Evaluation-Atrial SUpport Study was a multicenter randomized trial of patients undergoing CRT-defibrillator implantation. Interventricular delay was measured as the unpaced right ventricle-left ventricle (RV-LV) interval in sinus rhythm. The HF clinical composite score was the primary end point. In addition, the time to first HF hospitalization or death was measured and events were adjudicated by a blinded core laboratory. The cohort was divided at the median RV-LV interval into short (<67 ms) and long (≥67 ms) subgroups. In addition, receiver operating characteristic curves were constructed to identify the optimal cutoff of the RV-LV interval and spline analysis was performed to assess RV-LV interval as a continuous variable., Results: A total of 1342 patients were included in this study. The clinical composite score at 1 year differed between groups, with more patients improving and fewer patients worsening in the long RV-LV group (P = .014). The time to first HF hospitalization or mortality also differed with a lower risk of an event in the long RV-LV group (hazard ratio 0.62; P = .002). Multivariate analysis showed that RV-LV time (hazard ratio 0.71; P = .038) and sex were independent predictors of this outcome., Conclusion: Baseline interventricular delay is a strong independent predictor of clinical response to CRT., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Rate-responsive pacing (DDDR) versus nonrate-responsive pacing (DDD) has shown no survival benefit for patients undergoing cardiac resynchronization therapy defibrillator (CRT-D) implants. The heart rate score (HRSc), an indicator of heart rate variation, may predict survival. We hypothesized that high-risk HRSc CRT-D patients will have improved survival with DDDR versus DDD alone., Methods and Results: All CRT-D patients in LATITUDE remote monitoring (2006-2011), programmed DDD, had HRSc calculated at first data upload after implant (median 1.4 months). Patients subsequently reprogrammed to DDDR 7.6 median months later were compared with a propensity-matched DDD group and followed for 21.4 median months by remote monitoring. Data were adjusted for age, sex, lower rate limit, percent atrial pacing, percent biventricular pacing, and implant year. The social security death index was used to identify deaths. Remote monitoring provided programming and histogram data. DDDR programming in CRT-D patients was associated with improved survival (adjusted hazard ratio =0.77; P<0.001). However, only those with baseline HRSc ≥70% (2308/6164) had improved HRSc with DDDR (from 88±9% to 78±15%; P<0.001) and improved survival (hazard ratio =0.74; P<0.001). Patients with a high baseline HRSc and significant improvement over time were more likely to survive (hazard ratio =0.63; P=0.006). For patients with HRSc <70%, DDDR reprogramming increased the HRSc from 46±11% to 50±15% (P<0.001); survival did not change. The HRSc did not change with DDD pacing over time., Conclusions: In CRT-D patients with HRSc ≥70%, DDDR reprogramming improved the HRSc and was associated with survival. Patients with lower HRSc had no change in survival with DDDR programming., (© 2016 American Heart Association, Inc.)

Introduction: Cardiac resynchronization therapy (CRT) improves hemodynamic function, as well as reduces hospitalizations and mortality among patients with systolic dysfunction, QRS prolongation, and heart failure. The magnitude of the hemodynamic response is associated with improved outcomes, so optimization of this parameter is a goal of therapy. The purpose of this study was to evaluate the effect of left ventricular (LV) electrical delay, as assessed by the QLV interval, on the acute hemodynamic response to CRT., Methods and Results: This study included 31 patients undergoing biventricular ICD placement. At implant, invasive LV dP/dt was measured by a micromanometer catheter during biventricular (BV) or LV only pacing. Both atrial sensing (AS) and atrial pacing (AP) modes were evaluated at 5 different AV delays, tested in randomized order. The QLV interval was measured at the LV pacing site. Compared with intrinsic rhythm, CRT increased LV dP/dtmax by 9.5 ± 8.8% with BV pacing and 10.0 ± 9.2% with LV pacing (P = 0.38) during AS. With AP, CRT increased LV dP/dtmax by 16.0 ± 10.8% and 15.3 ± 11.1%, respectively (P = 0.47). QLV was strongly correlated with the hemodynamic response in all pacing configurations. Multivariate analysis showed that with BV pacing QLV was an independent predictor of the hemodynamic response with a 1.7% increase in %LV dP/dt for every 10 milliseconds prolongation of QLV., Conclusions: LV electrical delay is a strong predictor of the acute hemodynamic response to CRT. This relationship is independent of pacing mode., (© 2014 Wiley Periodicals, Inc.)