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

The Atrial Fibrillation and Heart Failure with Preserved Ejection Fraction "Twindemic" - Shared Root Causes and Treatment Targets

Heart failure with preserved ejection fraction (HFpEF) and atrial fibrillation (AF) are comorbid conditions that are increasingly prevalent and have a high socioeconomic burden. This article discusses their shared pathophysiology, focusing on the triad of hypertension, obesity, and aging. We highlight the misperception that pharmacologic heart rate lowering is beneficial, which has resulted in an overprescription of beta-blockers in HFpEF and AF. In contrast, heart rate modulation through accelerated pacing provides hemodynamic and structural advantages, which have yielded significant improvements in quality of life, physical activity, and AF burden in the myPACE trial of patients with preclinical or overt HFpEF.

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.

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.

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.

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.

Conduction system pacing: promoting the physiology to prevent heart failure

Cardiac conduction system pacing provides physiological ventricular activation by directly stimulating the conduction system. This review describes the two types of conduction system pacing: His bundle pacing (HBP) and left bundle area pacing (LBAP). The most significant advantage of HB pacing is that it can provide a regular, narrow QRS; however, the disadvantages are challenging implantation and a high risk of re-intervention due to lead dislodgement and the development of high pacing threshold. LBAP provides optimum physiological activation of the left ventricle by engaging the left bundle/fascicular fibers. LBAP is more physiological than traditional RV apical pacing and could be an attractive alternative to conventional cardiac resynchronization therapy (CRT). The advantages of LBAP are a relatively more straightforward implantation technique than HBP, better lead stability and pacing thresholds. HBP and LBAP are more physiological than right ventricular pacing and may be used instead of conventional pacemakers. Both HBP and LBBP are being investigated as alternatives to conventional CRT.

Are arrhythmias the drivers of sudden cardiac death in heart failure with preserved ejection fraction? A review

In patients with heart failure with preserved ejection fraction (HFpEF), sudden cardiac death (SCD) accounts for approximately 25-30% of all-cause mortality and 40% of cardiovascular mortality in properly adjudicated large clinical trials. The mechanism of SCD in HFpEF remains unknown but thought to be driven by arrhythmic events. Apart from atrial fibrillation, which is prevalent in approximately 45% of HFpEF patients, the true burden of other cardiac arrhythmias in HFpEF remains undetermined. The incidence and risk of clinically significant advanced cardiac conduction disease with bradyarrhythmias and ventricular arrhythmias remain less known. Recommendations have been made for long-term cardiac rhythm monitoring to determine the incidence of arrhythmias and clarify mechanisms and mode of death in HFpEF patients. In animal studies, spontaneous ventricular arrhythmias and SCD are significantly elevated in HFpEF animals compared with controls without heart failure. In humans, these studies are scant, with a few published small-size studies suggesting an increased incidence of ventricular arrhythmias in HFpEF. Higher rates of clinically significant conduction disease and cardiac pacing are seen in HFpEF compared with the general population. Excepting atrial fibrillation, the predictive effect of other arrhythmias on heart failure hospitalization, all-cause mortality, and precisely SCD remains unknown. Given the high occurrence of SCD in the HFpEF population, it could potentially become a target for therapeutic interventions if driven by arrhythmias. Studies to address these knowledge gaps are urgently warranted. In this review, we have summarized data on arrhythmias and SCD in HFpEF while highlighting avenues for future research in this area.