Rationale and design of the PACE HFpEF trial: Physiologic accelerated pacing as a holistic treatment of heart failure with preserved ejection fraction.

Background: In heart failure with preserved ejection fraction (HFpEF), it has been assumed that pharmacologic heart rate suppression should provide clinical benefits through an increase in diastolic filling time. Contrary to this assumption, heart rate lowering in patients with preserved left ventricular ejection fraction and hypertension or coronary artery disease results in adverse outcomes and suggests that the opposite may be beneficial. Namely, shortening the diastolic filling time with a higher heart rate might normalize the elevated filling pressures that are the sine qua non of HFpEF. Initial clinical studies that assessed the effects of accelerated heart rates in pacemaker patients with preclinical and overt HFpEF provide support for this latter hypothesis, having shown improvements in quality of life, natriuretic peptide and activity levels, and atrial fibrillation burden. Objective: The study sought to determine the effects of continued resting heart rate elevation with and without superimposed nocturnal pacing in HFpEF patients without standard pacing indication. Methods: The physiologic accelerated pacing as treatment for heart failure with preserved ejection fraction (PACE HFpEF) trial is an investigator-initiated, prospective, patient-blinded multiple crossover pilot study that assesses the impact of accelerated pacing on quality of life, physical activity, N-terminal pro-B-type natriuretic peptide, and echocardiographic measures of cardiac structure and function. Results: Twenty patients were enrolled and underwent dual-chamber pacemaker implantation under U.S. Food and Drug Administration investigational device exemption with both atrial and ventricular physiologic lead placement targeting the Bachmann bundle and the His bundle. Conclusion: This manuscript describes the rationale and design of the PACE HFpEF trial, which tests the safety and feasibility of continuous accelerated physiological pacing as a treatment strategy in HFpEF.

Effect of paced heart rate on quality of life and natriuretic peptides for stage B or C heart failure with preserved ejection fraction: A secondary analysis of the myPACE trial.

AIM: Emerging evidence suggests a beneficial effect of higher heart rates in some patients with heart failure with preserved ejection fraction (HFpEF). This study aimed to evaluate the impact of higher backup pacing rates in HFpEF patients with preexisting pacemaker systems that limit pacemaker-mediated dyssynchrony across left ventricular (LV) volumes and LV ejection fraction (LVEF). METHODS AND RESULTS: This is a post-hoc analysis of the myPACE clinical trial that evaluated the effects of personalized accelerated pacing setting (myPACE) versus standard of care on changes in Minnesota Living with Heart Failure Questionnaire (MLHFQ) score, N-terminal pro-brain natriuretic peptide (NT-proBNP), pacemaker-detected activity levels, and atrial fibrillation (AF) burden in patients with HFpEF with preexisting pacemakers. Between-treatment comparisons were performed using linear regression models adjusting for the baseline value of the exposure (ANCOVA design). This study included 93 patients with pre-trial transthoracic echocardiograms available (usual care n = 49; myPACE n = 44). NT-proBNP levels and MLHFQ scores improved in a higher magnitude in the myPACE group at lower indexed LV end-diastolic volumes (iLVEDV) (NT-proBNP-iLVEDV interaction p = 0.006; MLHFQ-iLVEDV interaction p = 0.068). In addition, personalized accelerated pacing led to improved changes in activity levels and NT-proBNP, especially at higher LVEF (activity levels-LVEF interaction p = 0.009; NT-proBNP-LVEF interaction p = 0.058). No evidence of heterogeneity was found across LV volumes or LVEF for pacemaker-detected AF burden. CONCLUSIONS: In the post-hoc analysis of the myPACE trial, we observed that the benefits of a personalized accelerated backup pacing on MLHFQ score, NT-proBNP, and pacemaker-detected activity levels appear to be more pronounced in patients with smaller iLVEDV and higher LVEF.

Effects of Continuous Accelerated Pacing on Cardiac Structure and Function in Patients With Heart Failure With Preserved Ejection Fraction: Insights From the myPACE Randomized Clinical Trial.

BACKGROUND: Heart failure with preserved ejection fraction ≥50% is prevalent with few evidence-based therapies. In a trial of patients with heart failure with preserved ejection fraction with specialized pacemakers, treatment with accelerated personalized pacing averaging 75 bpm (myPACE) markedly improved quality of life, NT-proBNP (N-terminal pro-brain natriuretic peptide), physical activity, and atrial fibrillation burden compared with the standard lower rate setting of 60 bpm (usual care). METHODS AND RESULTS: In this exploratory study, provider-initiated echocardiographic studies obtained before and after the trial were assessed for changes in left ventricular (LV) structure and function among participants who continued their pacing assignment. The analytic approach aimed to detect differences in standard and advanced echocardiographic parameters within and between study arms. Of the 100 participants, 16 myPACE and 20 usual care arm had a qualifying set of echocardiograms performed a mean (SD) 3 (2.0) years apart. Despite similar baseline echocardiogram measures, sustained exposure to moderately accelerated pacing resulted in reduced septal wall thickness (in cm: myPACE 1.1 [0.2] versus usual care 1.2 [0.2], P=0.008) and lower LV mass to systolic volume ratio (in g/mL: myPACE 4.8 [1.9] versus usual care 6.8 [3.1], P=0.038) accompanied by a minor reduction in LV ejection fraction (in %: myPACE 55 [5] versus usual care 60 [5], P=0.015). These changes were paralleled by improvements in heart failure-related quality of life (myPACE Minnesota Living with Heart Failure Questionnaire improved by 16.1 [13.9] points, whereas usual care worsened by 6.9 [11.6] points, P<0.001). Markers of diastolic function and LV performance were not affected. CONCLUSIONS: Exposure to continuous accelerated pacing in heart failure with preserved ejection fraction is associated with a reduced LV wall thickness and a small amount of LV dilation with small reduction in ejection fraction.

Personalized accelerated physiologic pacing.

Heart failure with preserved ejection fraction (HFpEF) is increasingly prevalent with a high socioeconomic burden. Pharmacological heart rate lowering was recommended to improve ventricular filling in HFpEF. This article discusses the misperceptions that have resulted in an overprescription of beta-blockers, which in all likelihood have untoward effects on patients with HFpEF, even if they have atrial fibrillation or coronary artery disease as a comorbidity. Directly contradicting the lower heart rate paradigm, faster heart rates provide haemodynamic and structural benefits, amongst which lower cardiac filling pressures and improved ventricular capacitance may be most important. Safe delivery of this therapeutic approach is feasible with atrial and ventricular conduction system pacing that aims to emulate or enhance cardiac excitation to maximize the haemodynamic benefits of accelerated pacing. This conceptual framework was first tested in the myPACE randomized controlled trial of patients with pre-existing pacemakers and preclinical or overt HFpEF. This article provides the background and path towards this treatment approach.

Beta-Blocker Use and Heart Failure Outcomes in Mildly Reduced and Preserved Ejection Fraction.

BACKGROUND: Although studies consistently show that beta-blockers reduce morbidity and mortality in patients with reduced ejection fraction (EF), data are inconsistent in patients with heart failure with mildly reduced ejection fraction (HFmrEF) and suggest potential negative effects in heart failure with preserved ejection fraction (HFpEF). OBJECTIVES: The purpose of this study was to examine the association of beta-blockers with heart failure (HF) hospitalization and death in patients with HF and EF ≥40% METHODS: Beta-blocker use was assessed at first encounter in outpatients ≥65 years of age with HFmrEF and HFpEF in the U.S. PINNACLE Registry (2013-2017). The associations of beta-blockers with HF hospitalization, death, and the composite of HF hospitalization/death were assessed using propensity-score adjusted multivariable Cox regression models, including interactions of EF × beta-blocker use. RESULTS: Among 435,897 patients with HF and EF ≥40% (HFmrEF, n = 75,674; HFpEF = 360,223), 289,377 (66.4%) were using a beta-blocker at first encounter; more commonly in patients with HFmrEF vs HFpEF (77.7% vs 64.0%; P < 0.001). There were significant interactions between EF × beta-blocker use for HF hospitalization, death, and composite of HF hospitalization/death (P < 0.001 for all), with higher risk with beta-blocker use as EF increased. Beta-blockers were associated with decreased risk of HF hospitalization and death in patients with HFmrEF but a lack of survival benefit and a higher risk of HF hospitalization in patients with HFpEF, particularly when EF was >60%. CONCLUSIONS: In a large, real-world, propensity score-adjusted cohort of older outpatients with HF and EF ≥40%, beta-blocker use was associated with a higher risk of HF hospitalization as EF increased, with potential benefit in patients with HFmrEF and potential risk in patients with higher EF (particularly >60%). Further studies are needed to understand the appropriateness of beta-blocker use in patients with HFpEF in the absence of compelling indications.

Lower heart rates and beta-blockers are associated with new-onset atrial fibrillation.

Background: Lower heart rates (HRs) prolong diastole, which increases filling pressures and wall stress. As a result, lower HRs may be associated with higher brain natriuretic peptide (BNP) levels and incident atrial fibrillation (AF). Beta-blockers may increase the risk for AF due to suppression of resting HRs. Objective: Examine the relationships of HR, BNP, beta-blockers and new-onset AF in the REVEAL-AF and SPRINT cohort of subjects at risk for developing AF. Methods: In REVEAL-AF, 383 subjects without a history of AF and a mean CHA2DS2VASC score of 4.4 ± 1.3 received an insertable cardiac monitor and were followed up to 30 months. In SPRINT, 7595 patients without prior history of AF and a mean CHA2DS2VASC score of 2.3 ± 1.2 were followed up to 60 months. Results: The median daytime HR in the REVEAL-AF cohort was 75bpm [IQR 68-83]. Subjects with below-median HRs had 2.4-fold higher BNP levels compared to subjects with above-median HRs (median BNP [IQR]: 62 pg/dl [37-112] vs. 26 pg/dl [13-53], p < 0.001). HRs <75bpm were associated with a higher incidence of AF: 37% vs. 27%, p < 0.05. This was validated in the SPRINT cohort after adjusting for AF risk factors. Both a HR < 75bpm and beta-blocker use were associated with a higher rate of AF: 1.9 vs 0.7% (p < 0.001) and 2.5% vs. 0.6% (p < 0.001), respectively. The hazard ratio for patients on beta-blockers to develop AF was 3.72 [CI 2.32, 5.96], p < 0.001. Conclusions: Lower HRs are associated with higher BNP levels and incident AF, mimicking the hemodynamic effects of diastolic dysfunction. Suppression of resting HR by beta-blockers could explain their association with incident AF.

Effect of Personalized Accelerated Pacing on Quality of Life, Physical Activity, and Atrial Fibrillation in Patients With Preclinical and Overt Heart Failure With Preserved Ejection Fraction: The myPACE Randomized Clinical Trial.

Importance: Patients with heart failure with preserved ejection fraction (HFpEF) with a pacemaker may benefit from a higher, more physiologic backup heart rate than the nominal 60 beats per minute (bpm) setting. Objective: To assess the effects of a moderately accelerated personalized backup heart rate compared with 60 bpm (usual care) in patients with preexisting pacemaker systems that limit pacemaker-mediated dyssynchrony. Design, Setting, and Participants: This blinded randomized clinical trial enrolled patients with stage B and C HFpEF from the University of Vermont Medical Center pacemaker clinic between June 2019 and November 2020. Analysis was modified intention to treat. Interventions: Participants were randomly assigned to personalized accelerated pacing or usual care and were followed up for 1 year. The personalized accelerated pacing heart rate was calculated using a resting heart rate algorithm based on height and modified by ejection fraction. Main Outcomes and Measures: The primary outcome was the serial change in Minnesota Living with Heart Failure Questionnaire (MLHFQ) score. Secondary end points were changes in N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, pacemaker-detected physical activity, atrial fibrillation from baseline, and adverse clinical events. Results: Overall, 107 participants were randomly assigned to the personalized accelerated pacing (n = 50) or usual care (n = 57) groups. The median (IQR) age was 75 (69-81) years, and 48 (48%) were female. Over 1-year follow-up, the median (IQR) pacemaker-detected heart rate was 75 (75-80) bpm in the personalized accelerated pacing arm and 65 (63-68) bpm in usual care. MLHFQ scores improved in the personalized accelerated pacing group (median [IQR] baseline MLHFQ score, 26 [8-45]; at 1 month, 15 [2-25]; at 1 year, 9 [4-21]; P < .001) and worsened with usual care (median [IQR] baseline MLHFQ score, 19 [6-42]; at 1 month, 23 [5-39]; at 1 year, 27 [7-52]; P = .03). In addition, personalized accelerated pacing led to improved changes in NT-proBNP levels (mean [SD] decrease of 109 [498] pg/dL vs increase of 128 [537] pg/dL with usual care; P = .02), activity levels (mean [SD], +47 [67] minutes per day vs -22 [35] minutes per day with usual care; P < .001), and device-detected atrial fibrillation (27% relative risk reduction compared with usual care; P = .04) over 1-year of follow-up. Adverse clinical events occurred in 4 patients in the personalized accelerated pacing group and 11 patients in usual care. Conclusions and Relevance: In this study, among patients with HFpEF and pacemakers, treatment with a moderately accelerated, personalized pacing rate was safe and improved quality of life, NT-proBNP levels, physical activity, and atrial fibrillation compared with the usual 60 bpm setting. Trial Registration: ClinicalTrials.gov Identifier: NCT04721314.

Clinical impact of Bachmann's bundle pacing defined by electrocardiographic criteria on atrial arrhythmia outcomes.

AIMS: Evaluate whether Bachmann's bundle pacing (BBp) defined by electrocardiographic (ECG) criteria is associated with less atrial fibrillation/tachycardia (AF/AT) compared with anatomically defined right atrial septal pacing (RASp) and right atrial appendage pacing (RAAp). METHODS AND RESULTS: This is a retrospective study comparing BBp with non-specific RASp and RAAp on new incidence, burden, and recurrence of AF/AT. We included patients who underwent atrial lead placement between 2006 and 2019 and received > 20% atrial pacing. BBp was defined by paced P-wave morphology and fluoroscopic lead position. Compared with RASp (n = 107) and RAAp (n = 108), AF/AT burden was lower in the BBp (n = 134) group by repeated measures ANOVA (P < 0.001). Over 2-year follow-up, AF/AT burden increased in the RASp (P < 0.01) and RAAp (P < 0.01) groups but did not significantly change in the BBp group (P = 0.91). Atrial arrhythmia burden was lower in the BBp group than the RASp and RAAp groups at 12-15, 18-21, and 24-27 months (P < 0.05) after pacemaker placement. Risk of AF/AT recurrence was lower in BBp than RASp (HR 0.43; P < 0.01) and RAAp patients (HR 0.29, P < 0.01). Risk of de novo AF/AT was also lower in BBp than in RASp (OR 0.12; P < 0.01) and RAAp patients (OR 0.20, P < 0.01). CONCLUSION: Bachmann's bundle pacing defined using P-wave criteria was associated with decreased atrial arrhythmia burden, recurrence, and de novo incidence compared with right atrial septal pacing and right atrial appendage pacing.

Personalized pacing for diastolic dysfunction and heart failure with preserved ejection fraction: Design and rationale for the myPACE randomized controlled trial.

BACKGROUND: Patients with pacemakers and heart failure with preserved ejection fraction (HFpEF) or isolated diastolic dysfunction (DD) may benefit from a higher backup heart rate (HR) setting compared with the standard setting of 60 bpm. OBJECTIVE: The purpose of this study was to assess the effects of a personalized backup HR setting (myPACE group) compared with 60 bpm (control group). METHODS: In this prospective, blinded, randomized controlled study, pacemaker patients with DD or HFpEF and atrial pacing with intrinsic ventricular conduction or conduction system or biventricular pacing are randomized to the myPACE group or control group for 1 year. The primary outcome is the change in Minnesota Living with Heart Failure Questionnaire (MLHFQ) scores. Secondary endpoints include changes in N-terminal pro-brain natriuretic peptide levels, physical and emotional MLHFQ subscores, and pacemaker-detected atrial arrhythmia burden, patient activity levels, and thoracic impedance; hospitalization for heart failure, atrial fibrillation, cerebrovascular accident, or myocardial infarction; and loop diuretic or antiarrhythmic medication initiation or up-titration. A sample size of 118 subjects is expected to allow detection of a 5-point change in MLHFQ score in an intention-to-treat analysis and allow initial assessment of clinical outcomes and subgroup analyses. RESULTS: Enrollment began in July 2019. As of November 2020, 107 subjects have been enrolled. It is projected that the 1-year follow-up will be completed by December 2021. CONCLUSION: Atrial pacing with intrinsic ventricular conduction or advanced ventricular pacing at a higher, personalized backup HR may be a therapeutic target for patients with isolated DD or HFpEF. The myPACE trial is designed to test this hypothesis.

Beta-Blocker Use in Hypertension and Heart Failure (A Secondary Analysis of the Systolic Blood Pressure Intervention Trial).

Given the concern that beta-blocker use may be associated with an increased risk for heart failure (HF) in populations with normal left ventricular systolic function, we evaluated the association between beta-blocker use and incident HF events, as well as loop diuretic initiation in the Systolic Blood Pressure Intervention Trial (SPRINT). SPRINT demonstrated that a blood pressure target of <120 mm Hg reduced cardiovascular outcomes compared with <140 mm Hg in adults with at least one cardiovascular risk factor and without HF. The lower rate of the composite primary outcome in the 120 mm Hg group was primarily driven by a reduction in HF events. Subjects on a beta blocker for the entire trial duration were compared with subjects who never received a beta blocker after 1:1 propensity score matching. A competing risk survival analysis by beta-blocker status was performed to estimate the effect of the drug on incident HF and was then repeated for a secondary end point of cardiovascular disease death. Among the 3,284 propensity score-matched subjects, beta-blocker exposure was associated with an increased HF risk (hazard ratio 5.86; 95% confidence interval 2.73 to 13.04; p <0.001). A sensitivity analysis of propensity score-matched cohorts with a history of coronary artery disease or atrial fibrillation revealed the same association (hazard ratio 3.49; 95% confidence interval 1.15 to 10.06; p = 0.028). In conclusion, beta-blocker exposure in this secondary analysis was associated with increased incident HF in subjects with hypertension without HF at baseline.

Platelet reactivity in response to aspirin and ticagrelor in African-Americans and European-Americans.

Platelet gene polymorphisms are associated with variable on-treatment platelet reactivity and vary by race. Whether differences in platelet reactivity and aspirin or ticagrelor exist between African-American and European-Americans remains poorly understood. Biological samples from three prior prospective antiplatelet challenge studies at the Duke Clinical Research Unit were used to compare platelet reactivity between African-American and European-American subjects. Platelet reactivity at baseline, on-aspirin, on-ticagrelor, and the treatment effect of aspirin or ticagrelor were compared between groups using an adjusted mixed effects model. Compared with European-Americans (n = 282; 50% female; mean ± standard deviation age, 50 ± 16), African-Americans (n = 209; 67% female; age 48 ± 12) had lower baseline platelet reactivity with platelet function analyzer-100 (PFA-100) (p < 0.01) and with light transmission aggregometry (LTA) in response to arachidonic acid (AA), adenosine diphosphate (ADP), and epinephrine agonists (p < 0.05). African-Americans had lower platelet reactivity on aspirin in response to ADP, epinephrine, and collagen (p < 0.05) and on ticagrelor in response to AA, ADP, and collagen (p < 0.05). The treatment effect of aspirin was greater in European-Americans with an AA agonist (p = 0.002). Between-race differences with in vitro aspirin mirrored those seen in vivo. The treatment effect of ticagrelor was greater in European-Americans in response to ADP (p < 0.05) but with collagen, the treatment effect was greater for African-Americans (p < 0.05). Platelet reactivity was overall lower in African-Americans off-treatment, on aspirin, and on ticagrelor. European-Americans experienced greater platelet suppression on aspirin and on ticagrelor. The aspirin response difference in vivo and in vitro suggests a mechanism intrinsic to the platelet. Whether the absolute level of platelet reactivity or the degree of platelet suppression after treatment is more important for clinical outcomes is uncertain.

Influence of Sex on Platelet Reactivity in Response to Aspirin.

Background There are sex differences in the efficacy and safety of aspirin for the prevention of myocardial infarction and stroke. Whether this is explained by underlying differences in platelet reactivity and aspirin response remains poorly understood. Methods and Results Healthy volunteers (n=378 208 women) and patients with coronary artery disease or coronary artery disease risk factors (n=217 112 women) took aspirin for 4 weeks. Light transmittance aggregometry using platelet-rich plasma was used to measure platelet reactivity in response to epinephrine, collagen, and ADP at baseline, 3 hours after the first aspirin dose, and after 4 weeks of daily aspirin therapy. A subset of patients underwent pharmacokinetic and pharmacodynamic assessment with levels of salicylate and cyclooxygenase-1-derived prostaglandin metabolites and light transmittance aggregometry in response to arachidonic acid and after ex vivo exposure to aspirin. At baseline, women had increased platelet aggregation in response to ADP and collagen. Innate platelet response to aspirin, assessed with ex vivo aspirin exposure of baseline platelets, did not differ by sex. Three hours after the first oral aspirin dose, platelet aggregation was inhibited in women to a greater degree in response to epinephrine and to a lesser degree with collagen. After 4 weeks of daily therapy, despite higher salicylate concentrations and greater cyclooxygenase-1 inhibition, women exhibited an attenuation of platelet inhibition in response to epinephrine and ADP. Conclusions We observed agonist-dependent sex differences in platelet responses to aspirin. Despite higher cyclooxygenase-1 inhibition, daily aspirin exposure resulted in a paradoxical attenuation of platelet inhibition in response to epinephrine and ADP over time in women but not in men.

Association of ß-Blocker Use With Heart Failure Hospitalizations and Cardiovascular Disease Mortality Among Patients With Heart Failure With a Preserved Ejection Fraction: A Secondary Analysis of the TOPCAT Trial.

Importance: ß-Blockers are prescribed to most patients with heart failure (HF) with a preserved ejection fraction (HFpEF), but their effect on HFpEF remains unclear. Objective: To determine the association of ß-blocker use with HF hospitalizations and cardiovascular disease (CVD) mortality, overall and in strata of patients with an ejection fraction (EF) of 50% or greater or less than 50%. Design, Setting, and Participants: For 1761 participants from North and South America enrolled in the multicenter, double-blinded Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist randomized clinical trial of spironolactone for patients with HFpEF between August 10, 2006, and January 31, 2012, the association of baseline ß-blocker use with HF hospitalization and CVD mortality was analyzed using unadjusted and adjusted Cox proportional hazards regression models, overall and in strata of patients with an EF of 50% or greater or less than 50%. Participants had symptomatic HF with a left ventricular EF of 45% or greater, with enrollment based on either hospitalization attributed to decompensated HF in the prior year or elevated natriuretic peptide levels. Statistical analysis was performed from January 31 to May 2, 2019. Exposure: Use of ß-blockers. Main Outcomes and Measures: Incident HF hospitalization and CVD mortality. Results: Among 1761 participants included in the analysis (879 women and 882 men; mean [SD] age, 71.5 [9.6] years), 1394 (79.2%) reported ß-blocker use and 1567 (89.0%) had an EF of 50% or greater. Hospitalizations for HF occurred for 399 participants (22.7%), and CVD mortality occurred for 229 participants (13.0%). Use of ß-blockers was associated with a higher risk of HF hospitalization among patients with HFpEF with an EF of 50% or greater (hazard ratio, 1.74 [95% CI, 1.28-2.37]; P < .001) but not among patients with an EF between 45% and 49% (hazard ratio, 0.68 [95% CI, 0.28-1.63]; P = .39). There was a significant interaction between ß-blocker use and EF threshold for incident HF hospitalizations (P = .03). Use of ß-blockers was not associated with a change in CVD mortality. Conclusions and Relevance: For patients with an EF of 50% or greater, ß-blocker use was associated with an increased risk of HF hospitalizations but not CVD mortality. For patients with an EF between 45% and 49%, there was no such association.

Left Atrial Appendage Closure: A Safe and Effective Alternative to Anticoagulation?

To date, left atrial appendage closure (LAAC) devices continue to be assessed as an intuitive alternative to oral anticoagulant therapy to prevent embolic complications in patients with atrial fibrillation. Concerns remain about the up-front risks associated with device implantation as well as device efficacy in preventing embolic events as compared with anticoagulation. Currently, LAAC devices serve as a potential alternative to long-term anticoagulation with the benefit of decreased bleeding risk but with less protection against ischemic events. An individualized risk-benefit analysis with regard to stroke possibility, bleeding likelihood with long-term anticoagulation, the risks of an invasive procedure, and the risks associated with having a lifelong intracardiac device should be performed to guide careful patient selection for this operation.