Influence of sex on efficacy of exercise training for patients with symptomatic atrial fibrillation: insights from the ACTIVE-AF randomized controlled trial

AIMS

Exercise training reduces recurrence of arrhythmia and symptom severity amongst patients with symptomatic, non-permanent atrial fibrillation (AF). However, there is little evidence on whether this effect is modified by patient sex. In a sub-analysis from the ACTIVE-AF (A Lifestyle-based, PhysiCal AcTIVity IntErvention for Patients With Symptomatic Atrial Fibrillation) randomized controlled trial, we compared the effects of exercise training on AF recurrence and symptom severity between men and women.

METHODS AND RESULTS

The ACTIVE-AF study randomized 120 patients (69 men, 51 women) with paroxysmal or persistent AF to receive an exercise intervention combining supervised and home-based aerobic exercise over 6 months or to continue standard medical care. Patients were followed over a 12-month period. The co-primary outcomes were recurrence of AF, off anti-arrhythmic medications and without catheter ablation, and AF symptom severity scores. By 12 months, recurrence of AF was observed in 50 (73%) men and 34 (67%) women. In an intention-to-treat analysis, there was a between-group difference in favour of the exercise group for both men [hazard ratio (HR) 0.52, 95% confidence interval (CI): 0.29-0.91, P = 0.022] and women (HR 0.47, 95% CI: 0.23-0.95, P = 0.035). At 12 months, symptom severity scores were lower in the exercise group compared with controls amongst women but not for men.

CONCLUSION

An exercise-based intervention reduced arrhythmia recurrence for both men and women with symptomatic AF. Symptom severity was reduced with exercise in women at 12 months. No difference was observed in symptom severity for men.

REGISTRATION

Australia and New Zealand Clinical Trials Registry: ACTRN12615000734561.

Identification of Subclinical Heart Failure With Preserved Ejection Fraction in Patients With Symptomatic Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) and heart failure with preserved ejection fraction (HFpEF) commonly coexist. We hypothesize that patients with symptomatic AF but without overt clinical HF commonly exhibit subclinical HFpEF according to established hemodynamic criteria.

OBJECTIVES

The authors sought to use invasive hemodynamics to investigate the prevalence and implications of subclinical HFpEF in AF ablation patients.

METHODS

Consecutive symptomatic AF ablation patients were prospectively recruited. Diagnosis of subclinical HFpEF was undertaken by invasive assessment of left atrial pressure (LAP). Participants had HFpEF if the baseline mean LAP was >15 mm Hg and early HFpEF if the mean LAP was >15 mm Hg after a 500-mL fluid challenge. LA compliance was assessed invasively by monitoring the LAP and LA diameter during direct LA infusion of 15 mL/kg normal saline. LA compliance was calculated as Δ LA diameter/ΔLAP. LA cardiomyopathy was further studied with exercise echocardiography and electrophysiology study. Functional impact was evaluated using cardiopulmonary exercise testing and the AF Symptom Severity questionnaire.

RESULTS

Of 120 participants, 57 (47.5%) had HFpEF, 31 (25.8%) had early HFpEF, and 32 (26.7%) had no HFpEF. Both HFpEF and early HFpEF were associated with lower LA compliance compared with those without HFpEF (P < 0.001). Participants with HFpEF and early HFpEF also displayed decreased LA emptying fraction (P = 0.004), decreased LA voltage (P = 0.001), decreased VO2peak (P < 0.001), and increased AF symptom burden (P = 0.002) compared with those without HFpEF.

CONCLUSIONS

Subclinical HFpEF is common in AF ablation patients and is characterized by a LA cardiomyopathy, decreased cardiopulmonary reserve and increased symptom burden. The diagnosis of HFpEF may identify patients with AF with the potential to benefit from novel HFpEF therapies. (Characterising Left Atrial Function and Compliance in Atrial Fibrillation; ACTRN12620000639921).

Associations of dietary patterns, ultra-processed food and nutrient intake with incident atrial fibrillation

OBJECTIVE

To examine the associations between specific dietary patterns and incident atrial fibrillation (AF).

METHODS

Using data from the UK Biobank, dietary intakes were calculated from 24-hour diet recall questionnaires. Indices representing adherence to dietary patterns (Mediterranean-style, Dietary Approaches to Stop Hypertension (DASH) and plant-based diets) were scored, and ultra-processed food consumption was studied as a percentage of total food mass consumed. Incident AF hospitalisations were assessed in Cox regression models.

RESULTS

A total of 121 300 individuals were included, with 4 579 incident AF cases over a median follow-up of 8.8 years. Adherence to Mediterranean-style or DASH diets was associated with a lower incidence of AF in minimally adjusted analyses (HR for highest vs lowest quintile 0.87 (95% CI 0.80-0.96) and HR 0.78 (95% CI 0.71-0.86), respectively). However, associations were no longer significant after accounting for lifestyle factors (HR 0.95 (95% CI 0.87-1.04) and 0.94 (95% CI 0.86-1.04) respectively), with adjustment for body mass index responsible for approximately three-quarters of the effect size attenuation. Plant-based diets were not associated with AF risk in any models. Greatest ultra-processed food consumption was associated with a significant increase in AF risk even in fully adjusted models (HR 1.13 (95% CI 1.02-1.24)), and a 10% increase in absolute intake of ultra-processed food was associated with a 5% increase in AF risk (HR 1.05 (95% CI 1.01-1.08)).

CONCLUSION

With the possible exception of reducing ultra-processed food consumption, these findings suggest that attention to other modifiable risk factors, particularly obesity, may be more important than specific dietary patterns for the primary prevention of AF.

Safety and performance of MR-conditional pacing systems with automated MRI mode at 1.5 and 3 Tesla

OBJECTIVES

To evaluate at 1.5 and 3 T MRI the safety and performance of trademarked ENO®, TEO®, or OTO® pacing systems with automated MRI Mode and the image quality of non-enhanced MR examinations.

METHODS

A total of 267 implanted patients underwent MRI examination (brain, cardiac, shoulder, cervical spine) at 1.5 (n = 126) or 3 T (n = 141). MRI-related device complications, lead electrical performances stability at 1-month post-MRI, proper functioning of the automated MRI mode and image quality were evaluated.

RESULTS

Freedom from MRI-related complications at 1 month post-MRI was 100% in both 1.5 and 3 T arms (both p < 0.0001). The stability of pacing capture threshold was respectively at 1.5 and 3 T (atrial:: 98.9% (p = 0.001) and 100% (p < 0.0001); ventricular: both 100% (p < 0001)). The stability of sensing was respectively at 1.5 and 3 T (atrial: 100% (p = 0.0001) and 96.9% (p = 0.01); ventricular: 100% (p < 0.0001) and 99.1% (p = 0.0001)). All devices switched automatically to the programmed asynchronous mode in the MRI environment and to initially programmed mode after the MRI exam. While all MR examinations were assessed as interpretable, artifacts deteriorated a subset of examinations including mostly cardiac and shoulder ones.

CONCLUSION

This study demonstrates the safety and electrical stability of ENO®, TEO®, or OTO® pacing systems at 1 month post-MRI at 1.5 and 3 T. Even if artifacts were noticed in a subset of examinations, overall interpretability was preserved.

CLINICAL RELEVANCE STATEMENT

ENO®, TEO®, and OTO® pacing systems switch to MR-mode when detecting magnetic field and switch back on conventional mode after MRI. Their safety and electrical stability at 1 month post MRI were shown at 1.5 and 3 T. Overall interpretability was preserved.

KEY POINTS

• Patients implanted with an MRI conditional cardiac pacemaker can be safely scanned under 1.5 or 3 Tesla MRI with preserved interpretability. • Electrical parameters of the MRI conditional pacing system remain stable after a 1.5 or 3 Tesla MRI scan. • The automated MRI mode enabled the automatic switch to asynchronous mode in the MRI environment and to initial settings after the MRI scan in all patients.

Factors affecting electrogram sensing in an insertable cardiac monitor: Insights from surface electrocardiogram mapping analysis

BACKGROUND

Fidelity of electrogram sensing may reduce false alerts from an insertable cardiac monitor (ICM).

OBJECTIVE

The purpose of this study was to assess the effect of vector length, implant angle, and patient factors on electrogram sensing using surface electrocardiogram (ECG) mapping.

METHODS

Twelve separate precordial single-lead surface ECGs were acquired from 150 participants at 2 interelectrode distances (75 and 45 mm), at 3 vector angles (vertical, oblique, and horizontal), and in 2 postures (upright and supine). A subset of 50 patients also received a clinically indicated ICM implant in 1:1 ratio (Reveal LINQ [Medtronic, Minneapolis, MN]/BIOMONITOR III [Biotronik, Berlin, Germany]). All ECGs and ICM electrograms were analyzed by blinded investigators using DigitizeIt software (V2.3.3, Braunschweig, Germany). The P-wave visibility threshold was set at > 0.015 mV. Logistic regression was used to identify factors affecting P-wave amplitude.

RESULTS

A total of 1800 tracings from 150 participants (44.5% [n = 68] female; median age 59 [35-73] years) were assessed. The median P- and R-wave amplitudes were 45% and 53% larger with vector lengths of 75 and 45 mm, respectively (P < .001 for both). The oblique orientation yielded the best P- and R-wave amplitudes, while posture change did not affect P-wave amplitude. Mixed effects modeling found that visible P-waves occur more frequently with a vector length of 75 mm than with 45 mm (86% vs 75%, respectively; P < .0001). A longer vector length improved both P-wave amplitude and visibility in all body mass index categories. There was a moderate correlation of P- and R-wave amplitudes from the ICM electrograms to those from surface ECG recordings (intraclass correlation coefficient 0.74 and 0.80, respectively).

CONCLUSION

Longer vector length and oblique implant angle yielded the best electrogram sensing and are relevant considerations for ICM implantation procedures.

Poor health-related quality of life in postural orthostatic tachycardia syndrome in comparison with a sex- and age-matched normative population

PURPOSE

The effect of postural orthostatic tachycardia syndrome (POTS) on health-related quality of life (HrQoL) remains poorly studied. Here, we sought to compare the HrQoL in individuals with POTS to a normative age-/sex-matched population.

METHODS

Participants enrolled in the Australian POTS registry between 5 August 2021 and 30 June 2022 were compared with propensity-matched local normative population data from the South Australian Health Omnibus Survey. The EQ-5D-5L instrument was used to assess HrQoL across the five domains (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) with global health rating assessed with a visual analog scale (EQ-VAS). A population-based scoring algorithm was applied to the EQ-5D-5L data to calculate utility scores. Hierarchical multiple regression analyses were undertaken to explore predictors of low utility scores.

RESULTS

A total of 404 participants (n = 202 POTS; n = 202 normative population; median age 28 years, 90.6% females) were included. Compared with the normative population, the POTS cohort demonstrated significantly higher burden of impairment across all EQ-5D-5L domains (all P < 0.001), lower median EQ-VAS (p < 0.001), and lower utility scores (p < .001). The lower EQ-VAS and utility scores in the POTS cohort were universal in all age groups. Severity of orthostatic intolerance symptoms, female sex, fatigue scores, and comorbid diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome were independent predictors of reduced HrQoL in POTS. The disutility in those with POTS was lower than many chronic health conditions.

CONCLUSIONS

This is the first study to demonstrate significant impairment across all subdomains of EQ-5D-5L HrQoL in the POTS cohort as compared with a normative population.

TRIAL REGISTRATION

ACTRN12621001034820.

High incidence of autonomic dysfunction and postural orthostatic tachycardia syndrome in patients with long-COVID: Implications for management and healthcare planning

BACKGROUND

Autonomic dysfunction including postural orthostatic tachycardia syndrome (POTS) has been reported in individuals with post-acute sequelae of Covid-19 (PASC). However, the degree of dysautonomia in PASC has not been compared to those with POTS and healthy controls.

METHODS

All participants were prospectively enrolled between 5^th August 2021 and 31^st October 2022. Autonomic testing included beat-to-beat hemodynamic monitoring to assess respiratory sinus arrhythmia, Valsalva ratio and orthostatic changes during a 10-minute active standing test as well as Sudomotor assessment. The Composite Autonomic Symptom Score (COMPASS-31) was used to assess symptoms and the Euroquol 5-Dimension survey (EQ-5D-5L) was used to assess health-related quality of life (HrQoL) measures.

RESULTS

A total of 99 participants (n=33 PASC, n=33 POTS and n=33 healthy controls; median age 32 [18], 85.9% females) were included. Compared to healthy controls, the PASC and POTS cohorts demonstrated significantly reduced respiratory sinus arrhythmia (p<0.001), greater heart rate increase during 10-minute active standing test (p<0.001), greater burden of autonomic dysfunction evidenced by higher COMPASS-31 scores across all subdomains (all p<0.001) and poor HrQoL across all EQ-5D-5L domains (all p<0.001), lower median EQ-VAS (p<0.001) and lower utility scores (p<0.001). The majority (79%) of those with PASC met the internationally established criteria for POTS.

CONCLUSION

The prevalence of autonomic symptomology or POTS was high in those with PASC, leading to poor HrQoL and high health disutility. Autonomic testing should be routinely undertaken in those with PASC to aid diagnosis and direct appropriate management to improve health outcomes.

TRIAL REGISTRATION

ANZCTR 12621000476831.

The Burden of Cardiac Implantable Electronic Device Checks in the Peri-MRI Setting: The CHECK-MRI Study

BACKGROUND

Most modern cardiac implantable electronic device (CIED) systems are now compatible with magnetic resonance imaging (MRI) scans. The requirement for both pre- and post-MRI CIED checks imposes significant workload to the cardiac electrophysiology service. Here, we sought to determine the burden of CIED checks associated with MRI scans.

METHODS

We identified all CIED checks performed peri-MRI scans at our institution over a 3-year period between 1 July 2017 to 30 June 2020, comprising three separate financial years (FY). Device check reports, MRI scan reports and clinical summaries were collated. The workload burden was determined by assessing the occasions and duration of service. Analysis was performed to determine cost burden/projections for this service and identify factors contributing to the workload.

RESULTS

A total of 739 CIED checks were performed in the peri-MRI scan setting (370 pre- and 369 post-MRI scan), including 5% (n=39) that were performed outside of routine hours (weekday <8 am or >5 pm, and weekends). MRIs were performed for 295 patients (75±13 years old, 64% male) with a CIED (88% permanent pacemaker, and 12% high voltage device), including 49 who had more than one MRI scan. The proportion of total MRI scans for patients with a CIED in-situ increased each FY (from 0.5% of all MRIs in FY1, to 0.9% in FY2, to 1.0% in FY3). The weekly workload increased (R²=0.2, p<0.001), but with week-to-week variability due to ad hoc scheduling (209 days with only one MRI vs 78 days with ≥2 MRIs for CIED patients). The projected annual cost of this service will increase to AUD$161,695 in 10 years for an estimated annual 546 MRI scans for CIED patients.

CONCLUSIONS

There is an increasing workload burden and expense associated with CIED checks in the peri-MRI setting. Appropriate budgeting, staff allocation and standardisation of automated CIED pre-programming features among manufacturers are urgently needed.

Diagnostic yield of an insertable cardiac monitor in a large patient population

Background

Insertable cardiac monitors (ICMs) are increasingly used for cardiac rhythm diagnosis with expanding indications. Little has been reported about their use and efficacy.

Objective

The study sought to evaluate the clinical utility of a novel ICM (Biotronik BIOMONITOR III) including the time to diagnosis in unselected patients with different ICM indications.

Methods

Patients from 2 prospective clinical studies were included to determine the diagnostic yield of the ICM. The primary endpoint was time to clinical diagnosis per implant indication or to the first change in atrial fibrillation (AF) therapy.

Results

A total of 632 patients were included with a mean follow-up of 233 ± 168 days. Of 384 patients with (pre)syncope, 34.2% had a diagnosis at 1 year. The most frequent therapy was permanent pacemaker implantation. Of 133 patients with cryptogenic stroke, 16.6% had an AF diagnosis at 1 year, resulting in oral anticoagulation. Of 49 patients with an indication for AF monitoring, 41.0% had a relevant change in AF therapy based on ICM data at 1 year. Of 66 patients with other indications, 35.4% received a rhythm diagnosis at 1 year. Moreover, 6.5% of the cohort had additional diagnoses: 26 of 384 patients with syncope, 8 of 133 patients with cryptogenic stroke, and 7 of 49 patients with AF monitoring.

Conclusion

In a large unselected patient population with heterogeneous ICM indications, the primary endpoint of rhythm diagnosis was achieved in ∼1 in 4, and additional clinically relevant findings was achieved in 6.5% of patients at short-term follow-up.

Trends in myocardial infarction and coronary revascularisation procedures in Australia, 1993-2017

OBJECTIVE

Prior data have shown rising acute myocardial infarction (MI) trends in Australia; whether these increases have continued in recent years is not known. This study thus sought to characterise contemporary nationwide trends in MI hospitalisations and coronary procedures in Australia and their associated economic burden.

METHODS

The primary outcome measure was the incidence and time trends of total MI, ST-elevation myocardial infarction (STEMI) and non-ST-elevation myocardial infarction (NSTEMI) hospitalisations from 1993 to 2017. The incidence and time trends of coronary procedures were additionally collected, alongside MI hospitalisation costs.

RESULTS

Adjusted for population changes, annual MI incidence increased from 216.2 cases per 100 000 to a peak of 270.4 in 2007 with subsequent decline to 218.7 in 2017. Similarly, NSTEMI incidence increased from 68.0 cases per 100 000 in 1993 to a peak of 192.6 in 2007 with subsequent decline to 162.6 in 2017. STEMI incidence decreased from 148.3 cases per 100 000 in 1993 to 56.2 in 2017. Across the study period, there were annual increases in MI hospitalisations of 0.7% and NSTEMI hospitalisations of 5.6%, and an annual decrease in STEMI hospitalisations of 4.8%. Angiography and percutaneous coronary intervention increased by 3.4% and 3.3% annually, respectively, while coronary artery bypass graft surgery declined by 2.2% annually. MI hospitalisation costs increased by 100% over the study period, despite a decreased average length of stay by 45%.

CONCLUSIONS

The rising incidence of MI hospitalisations appear to have stabilised in Australia. Despite this, associated healthcare expenditure remains significant, suggesting a need for continual implementation of public health policies and preventative strategies.

Insertable cardiac monitor with a long sensing vector: Impact of obesity on sensing quality and safety

Background

Fat layers in obese patients can impair R-wave detection and diagnostic performance of a subcutaneous insertable cardiac monitor (ICM). We compared safety and ICM sensing quality between obese patients [body mass index (BMI) ≥ 30 kg/m²] and normal-weight controls (BMI <30 kg/m²) in terms of R-wave amplitude and time in noise mode (noise burden) detected by a long-sensing-vector ICM.

Materials and methods

Patients from two multicentre, non-randomized clinical registries are included in the present analysis on January 31, 2022 (data freeze), if the follow-up period was at least 90 days after ICM insertion, including daily remote monitoring. The R-wave amplitudes and daily noise burden averaged intraindividually for days 61-90 and days 1-90, respectively, were compared between obese patients (n = 104) and unmatched (n = 268) and a nearest-neighbour propensity score (PS) matched (n = 69) normal-weight controls.

Results

The average R-wave amplitude was significantly lower in obese (median 0.46 mV) than in normal-weight unmatched (0.70 mV, P < 0.0001) or PS-matched (0.60 mV, P = 0.003) patients. The median noise burden was 1.0% in obese patients, which was not significantly higher than in unmatched (0.7%; P = 0.056) or PS-matched (0.8%; P = 0.133) controls. The rate of adverse device effects during the first 90 days did not differ significantly between groups.

Conclusion

Although increased BMI was associated with reduced signal amplitude, also in obese patients the median R-wave amplitude was >0.3 mV, a value which is generally accepted as the minimum level for adequate R-wave detection. The noise burden and adverse event rates did not differ significantly between obese and normal-weight patients.Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04075084 and NCT04198220.

An Exercise and Physical Activity Program in Patients With Atrial Fibrillation: The ACTIVE-AF Randomized Controlled Trial

BACKGROUND

There are limited data on the effect of exercise interventions on atrial fibrillation (AF) recurrence and symptoms.

OBJECTIVES

The aim of this study was to determine the efficacy of an exercise and physical activity intervention on AF burden and symptoms among patients with symptomatic AF.

METHODS

This prospective, randomized controlled trial included 120 patients with paroxysmal or persistent, symptomatic AF, randomized 1:1 to receive an exercise intervention, combining home and supervised aerobic exercise over 6 months, or to receive usual care. The coprimary outcomes were: 1) AF recurrence, off antiarrhythmic medications and without catheter ablation; and 2) symptom severity assessed by using a validated questionnaire.

RESULTS

By 12 months, freedom from AF was achieved in 24 (40%) of 60 patients in the exercise group and 12 (20%) of 60 patients in the control group (HR: 0.50: 95% CI: 0.33 to 0.78). At 6 months, AF symptom severity was lower in the exercise group compared with the control group (mean difference -2.3; 95% CI: -4.3 to -0.2; P = 0.033). This difference persisted at 12 months (-2.3; 95% CI: -4.5 to -0.1; P = 0.041). Total symptom burden was lower at 6 months in the exercise group but not at 12 months. Peak oxygen consumption was increased in the exercise group at both 6 and 12 months. There were no between-group differences in cardiac structure or function, body mass index, or blood pressure.

CONCLUSIONS

Participation in an exercise-based intervention over 6 months reduced arrhythmia recurrence and improved symptom severity among patients with AF. (A Lifestyle-based, PhysiCal AcTIVity IntErvention for Patients With Symptomatic Atrial Fibrillation [the ACTIVE-AF Study]; ACTRN12615000734561).

Cardiorespiratory fitness, obesity and left atrial function in patients with atrial fibrillation

Background

Low cardiorespiratory fitness (CRF) and obesity are related to the development and maintenance of atrial fibrillation (AF). The aim of this study was to determine the association between CRF, obesity and left atrial (LA) mechanical parameters in patients with AF.

Methods

A cohort of 154 consecutive paroxysmal and persistent AF patients (Age: 62 ± 10, 26% female) referred for exercise stress testing and transthoracic echocardiography were included. We included patients in sinus rhythm with preserved left ventricular ejection fraction who were able to complete a maximal exercise test. Left atrial strain in the reservoir (LASr), booster (LASb) and conduit (LASc) phases were assessed using dedicated software. LA stiffness, emptying fraction (LAEF) and LA to LV ratio were calculated using previously described formulas.

Results

CRF was positively associated with LAEF (β = 1.3, 95% CI 0.1–2.3, p = 0.02), reservoir (β = 1.5, 95% CI 0.9–2.1, p < 0.001), booster (β = 0.8, 95% CI 0.4–1.2, p < 0.001) and conduit strain (β = 0.7, 95% CI 0.3–1.1, p = 0.001). We observed an inverse association between CRF and both LA stiffness index (β = −0.02, 95% CI (−0.03)–(−0.01), p < 0.001) and LA to LV ratio (β = −0.03, 95% CI (−0.04)–(−0.01), p < 0.001). Obese patients had significantly higher indexed LA volumes compared to overweight and normal BMI patients. The association between obesity and measures of LA function and stiffness did not reach statistical significance.

Conclusion

Among AF patients, higher CRF was independently associated with greater LA function and compliance. Obesity was associated with higher LA volumes yet preserved mechanical function.

Anemia and iron deficiency in patients with atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac tachyarrhythmia and has a rising global prevalence. Given the increasing burden of AF-related symptoms and complications, new approaches to management are required. Anemia and iron deficiency are common conditions in patients with AF. Furthermore, emerging evidence suggests that the presence of anemia may be associated with worse outcome in these patients. The role of anemia and iron deficiency has been extensively explored in other cardiovascular states, such as heart failure and ischemic heart disease. In particular, the role of iron repletion amongst patients with heart failure is now an established treatment modality. However, despite the strong bidirectional inter-relationship between AF and heart failure, the implications of anemia and iron-deficiency in AF have been scarcely studied. This area is of mechanistic and clinical relevance given the potential that treatment of these conditions may improve symptoms and prognosis in the increasing number of individuals with AF. In this review, we summarise the current published literature on anemia and iron deficiency in patients with AF. We discuss AF complications such as stroke, bleeding, and heart failure, in addition to AF-related symptoms such as exercise intolerance, and the potential impact of anemia and iron deficiency on these. Finally, we summarize current research gaps on anemia, iron deficiency, and AF, and underscore potential research directions.

PULSED-FIELD ABLATION: COMPUTATIONAL MODELLING OF ELECTRIC FIELDS FOR LESION DEPTH ANALYSIS

Background

Pulsed-field ablation (PFA) is an emerging and promising nonthermal technology for cardiac ablation. The effective applied voltage to achieve adequate irreversible myocardial injury is not well studied. The pulsed-field strength remains independent of tissue contact; therefore, PFA is assumed to be an ablation technology, not mandating the need for tissue contact.

Objective

Determine the effect of applied voltage and distance to surface on depth of myocardial injury using PFA.

Methods

A computational model was developed and validated based on extracted data from in vivo studies to examine the effect of different applied voltages and the impact of distance between the catheter and endocardial surface on the depth of irreversible myocardial injury using PFA.

Results

The depth of lesions created by PFA are dose-dependent, and there is a direct correlation between applied PFA voltages and depth of irreversible myocardial injury. The minimum applied voltage of PFA required to create a lesion deeper than 1 mm is 300 volts. The catheter-tissue contact plays a pivotal role in determining lesion depth. With optimal catheter contact in the absence of trabeculation, the minimal applied energy required to achieve a 3-mm-deep lesion is 700 volts. A minor increase in the catheter-tissue distance of 1–2 mm doubles the minimum required applied voltage, increasing it to 1500 volts.

Conclusion

PFA is an important new technology that is proposed to be more efficacious and safer than currently used thermal ablation. Here we demonstrate the impact of dose dependence and the need for maintaining tissue contact during ablation.

Endomysial fibrosis, rather than overall connective tissue content, is the main determinant of conduction disturbances in human atrial fibrillation

Aims

Although in persistent atrial fibrillation (AF) a complex AF substrate characterized by a high incidence of conduction block has been reported, relatively little is known about AF complexity in paroxysmal AF (pAF). Also, the relative contribution of various aspects of structural alterations to conduction disturbances is not clear. In particular, the contribution of endomysial fibrosis to conduction disturbances during progression of AF has not been studied yet.

Methods and results

During cardiac surgery, epicardial high-density mapping was performed in patients with acutely induced (aAF, n = 11), pAF (n = 12), and longstanding persistent AF (persAF, n = 9) on the right atrial (RA) wall, the posterior left atrial wall (pLA) and the LA appendage (LAA). In RA appendages, overall and endomysial (myocyte-to-myocyte distances) fibrosis and connexin 43 (Cx43) distribution were quantified. Unipolar AF electrogram analysis showed a more complex pattern with a larger number of narrower waves, more breakthroughs and a higher fractionation index (FI) in persAF compared with aAF and pAF, with no differences between aAF and pAF. The FI was consistently higher at the pLA compared with the RA. Structurally, Cx43 lateralization increased with AF progression (aAF = 7.5 ± 8.9%, pAF = 24.7 ± 11.1%, persAF = 35.1 ± 11.4%, P < 0.001). Endomysial but not overall fibrosis correlated with AF complexity (r = 0.57, P = 0.001; r = 0.23, P = 0.20; respectively).

Conclusions

Atrial fibrillation complexity is highly variable in patients with pAF, but not significantly higher than in patients with acutely induced AF, while in patients with persistent AF complexity is higher. Among the structural alterations studied, endomysial fibrosis, but not overall fibrosis, is the strongest determinant of AF complexity.

Alcohol intake and bradyarrhythmia risk: a cohort study of 407 948 individuals

AIMS 

There is a paucity of epidemiological evidence on alcohol and the risk of bradyarrhythmias. We thus characterized associations of total and beverage-specific alcohol consumption with incident bradyarrhythmias using data from the UK Biobank.

METHODS AND RESULTS 

Alcohol consumption reported at baseline was calculated as UK standard drinks (8 g alcohol)/week. Bradyarrhythmia events were defined as sinus node dysfunction (SND), high-level atrioventricular block (AVB), and permanent pacemaker implantations. Outcomes were assessed through hospitalization and death records, and dose-response associations were characterized using Cox regression models with correction for regression dilution bias. We studied 407 948 middle-aged individuals (52.4% female). Over a median follow-up time of 11.5 years, a total of 8 344 incident bradyarrhythmia events occurred. Increasing total alcohol consumption was not associated with an increased risk of bradyarrhythmias. Beer and cider intake were associated with increased bradyarrhythmia risk up to 12 drinks/week; however, no significant associations were observed with red wine, white wine, or spirit intake. When bradyarrhythmia outcomes were analysed separately, a negative curvilinear was observed for total alcohol consumption and risk of SND, but no clear association with AVB was observed.

CONCLUSION 

In this predominantly White British cohort, increasing total alcohol consumption was not associated with an increased risk of bradyarrhythmias. Associations appeared to vary according to the type of alcoholic beverage and between different types of bradyarrhythmias. Further epidemiological and experimental studies are required to clarify these findings.

Autonomic Afferent Dysregulation in Atrial Fibrillation

OBJECTIVES

This study sought to evaluate the role of cardiac afferent reflexes in atrial fibrillation (AF).

BACKGROUND

Efferent autonomic tone is not associated with atrial remodeling and AF persistence. However, the role of cardiac afferents is unknown.

METHODS

Individuals with nonpermanent AF (n = 48) were prospectively studied (23 in the in-AF group and 25 in sinus rhythm [SR]) with 12 matched control subjects. We performed: 1) low-level lower body negative pressure (LBNP), which decreases cardiac volume, offloading predominantly cardiac afferent (volume-sensitive) low-pressure baroreceptors; 2) Valsalva reflex (predominantly arterial high-pressure baroreceptors); and 3) isometric handgrip reflex (both baroreceptors). We measured beat-to-beat mean arterial pressure (MAP) and heart rate (HR). LBNP elicits reflex vasoconstriction, estimated using venous occlusion plethysmography-derived forearm blood flow (∝1/vascular resistance), maintaining MAP. To assess reversibility, we repeated LBNP (same day) after 1-hour low-level tragus stimulation (in n = 5 in the in-AF group and n = 10 in the in-SR group) and >6 weeks post-cardioversion (n = 7).

RESULTS

The 3 groups were well matched for age (59 ± 12 years, 83% male), body mass index, and risk factors (P = NS). The in-AF group had higher left atrial volume (P < 0.001) and resting HR (P = 0.01) but similar MAP (P = 0.7). The normal LBNP vasoconstriction (-49 ± 5%) maintaining MAP (control subjects) was attenuated in the in-SR group (-12 ± 9%; P = 0.005) and dysfunctional in the in-AF group (+11 ± 6%; P < 0.001), in which MAP decreased and HR was unchanged. Valsalva was normal throughout. Handgrip MAP response was lowest in the in-AF group (P = 0.01). Interestingly, low-level tragus stimulation and cardioversion improved LBNP vasoconstriction (-48 ± 15%; P = 0.04; and -32 ± 9%; P = 0.02, respectively).

CONCLUSIONS

Cardiac afferent (volume-sensitive) reflexes are abnormal in AF patients during SR and dysfunctional during AF. This could contribute to AF progression, thus explaining "AF begets AF." (Characterisation of Autonomic function in Atrial Fibrillation [AF-AF Study]; ACTRN12619000186156).

Computerized tomography image correlation of His bundle/deep septal pacing location and outcomes: an analysis from the Canberra HIs bundle/deep septal Pacing Study (CHIPS)

Background

Localisation of the conduction system under fluoroscopy is not easy and the ideal location of the pacing leads in physiological pacing is still being debated.

Objective

The primary aim was to assess the lead locations using cardiac CT scan. Secondary aims were clinical outcomes including success and safety of the procedure and lead performance.

Methods

Of the 100 consecutive patients who received physiological pacing, 34 patients underwent follow-up cardiac CT scan. The four different types of pacing were identified as His bundle (HBP), para-Hisian, left bundle branch (LBBP), and deep septal pacing.

Results

Most patients had successful HBP via the right atrium (RA) (87.5%) as compared to the right ventricle (RV) (12.5%). Lower thresholds were observed when leads were placed within 2 mm of the junction of the membranous and muscular ventricular septum. Unlike HBP, LBBP was possible at a wide region of the septum and selective capture of individual fascicles was feasible. LBBP showed deeper penetration of leads into the septum, as compared to deep septal pacing (70% vs. 45%). Approximately, 80% of patients did not have an intra-ventricular portion of the membranous septum.

Conclusions

The anterior part of the atrio-ventricular (AV) septum at the junction between the membranous and muscular septum via RA appeared to be the best target to successfully pace His bundle. LBBP was possible at a wide region of the septum and selective capture of individual fascicle was feasible. Adequate depth of penetration of lead was very important to capture the left bundle.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10840-022-01133-z.

Predictive role of atrial fibrillation in cognitive decline: a systematic review and meta-analysis of 2.8 million individuals

Aims

To systematic review and meta-analyse the association and mechanistic links between atrial fibrillation (AF) and cognitive impairment.

Methods and results

PubMed, EMBASE, and Cochrane Library were searched up to 27 March 2021 and yielded 4534 citations. After exclusions, 61 were analysed; 15 and 6 studies reported on the association of AF and cognitive impairment in the general population and post-stroke cohorts, respectively. Thirty-six studies reported on the neuro-pathological changes in patients with AF; of those, 13 reported on silent cerebral infarction (SCI) and 11 reported on cerebral microbleeds (CMB). Atrial fibrillation was associated with 39% increased risk of cognitive impairment in the general population [n = 15: 2 822 974 patients; hazard ratio = 1.39; 95% confidence interval (CI) 1.25–1.53, I² = 90.3%; follow-up 3.8–25 years]. In the post-stroke cohort, AF was associated with a 2.70-fold increased risk of cognitive impairment [adjusted odds ratio (OR) 2.70; 95% CI 1.66–3.74, I² = 0.0%; follow-up 0.25–3.78 years]. Atrial fibrillation was associated with cerebral small vessel disease, such as white matter hyperintensities and CMB (n = 8: 3698 patients; OR = 1.38; 95% CI 1.11–1.73, I² = 0.0%), SCI (n = 13: 6188 patients; OR = 2.11; 95% CI 1.58–2.64, I² = 0%), and decreased cerebral perfusion and cerebral volume even in the absence of clinical stroke.

Conclusion

Atrial fibrillation is associated with increased risk of cognitive impairment. The association with cerebral small vessel disease and cerebral atrophy secondary to cardioembolism and cerebral hypoperfusion may suggest a plausible link in the absence of clinical stroke. PROSPERO CRD42018109185.

Atrial fibrillation incidence, prevalence, predictors, and adverse outcomes in acute coronary syndromes: A pooled analysis of data from 8 million patients

OBJECTIVE

To summarize data on the prevalence/incidence, risk factors and prognosis of atrial fibrillation (AF) in patients with acute coronary syndromes (ACS).

METHODS

MEDLINE, Embase, and Web of Science were searched to identify all published studies providing relevant data through August 23, 2020. Random-effects meta-analysis method was used to pool estimates.

RESULTS

We included 109 studies reporting data from a pooled population of 8 239 364 patients. The prevalence rates were 5.8% for pre-existing AF, 7.3% for newly diagnosed AF, and 11.3% for prevalent (total) AF, in patients with ACS. Predictors of newly diagnosed AF included age (per year increase) (adjusted odds ratio [aOR]: 1.05), C-reactive protein (aOR: 1.49), left atrial (LA) diameter (aOR: 1.08), LA dilatation (aOR: 2.32), left ventricular ejection fraction <40% (aOR: 1.82), hypertension (aOR: 1.87), and Killip ˃ 1 (aOR: 1.85), p < .01 in all analyzes. Newly diagnosed AF was associated with an increased risk of acute heart failure (adjusted hazard ratio [aHR]: 3.20), acute kidney injury (aHR: 3.09), re-infarction (aHR: 1.96), stroke (aHR: 2.15), major bleeding (aHR: 2.93), and mortality (aHR: 1.80) in the short term; and with an increased risk of heart failure (aHR: 2.21), stroke (aHR: 1.75), mortality (aHR: 1.67), CV mortality (aHR: 2.09), sudden cardiac death (aHR: 1.53), and a composite of major adverse cardiovascular events (aHR: 1.54) in the long term (beyond 1 month), p < .05 in all analyzes.

CONCLUSION

One in nine patients with ACS has AF, with a high proportion of newly diagnosed AF. AF, in particular newly diagnosed AF, is associated with poor short-term and long-term outcomes in patients with ACS.

Heart failure with preserved ejection fraction: An alternative paradigm to explain the clinical implications of atrial fibrillation

Atrial fibrillation (AF) is associated with exercise intolerance, stroke, and all-cause mortality. However, whether this can be solely attributable to the arrhythmia itself or alternative mechanisms remains controversial. Heart failure with preserved ejection (HFpEF) commonly coexists with AF and may contribute to the poor outcomes associated with AF. Indeed, several invasive hemodynamic studies have confirmed that patients with AF are at increased risk of underlying HFpEF and that the presence of HFpEF may have important prognostic implications in these patients.

Mechanistically, AF and HFpEF are closely linked. Both conditions are driven by the presence of common cardiovascular risk factors and are associated with left atrial (LA) myopathy, characterized by mechanical and electrical dysfunction. Progressive worsening of this left atrial (LA) myopathy is associated with both increased AF burden and worsening HFpEF. In addition, there is growing evidence to suggest that worsening LA myopathy is associated with poorer outcomes in both conditions and that reversal of the LA myopathy could improve outcomes. In this review article, we will present the epidemiologic and mechanistic evidence underlying the common coexistence of AF and HFpEF, discuss the importance of a progressive LA myopathy in the pathogenesis of both conditions, and review the evidence from important invasive hemodynamic studies. Finally, we will review the prognostic implications of HFpEF in patients with AF and discuss the relative merits of AF burden reduction vs HFpEF reduction in improving outcomes of patients with AF and HFpEF.

Cardiac Implantable Electronic Devices: Reoperations and the Competing Risk of Death

BACKGROUND

The use of cardiac implantable electronic devices (CIED), which includes pacemakers, implantable cardioverter-defibrillators (ICD), cardiac resynchronisation therapy pacemakers (CRT-P) and cardiac resynchronisation therapy defibrillators (CRT-D) has increased over the past 20 years, but there is a lack of real world evidence on the longevity of these devices in the older population which is essential to inform health care delivery and support clinical decisions.

METHODS AND RESULTS

We conducted a retrospective cohort study using data from the Australian Government Department of Veterans' Affairs database. The cohort consisted of people who had a CIED procedure between 2005 and 2015. The cumulative risk of generator replacement/reoperations was estimated accounting for the competing risk of death. A total of 16,662 patients were included. In pacemaker recipients with an average age of 85 years, the 5-year risk of reoperation ranged from 2.8% in single chamber, 3.6% in dual chamber to 7.6% in CRT-P recipients, while the 5-year risk of dying with the index pacemaker in situ was 63% in single chamber, 46% in dual chamber and 56% in CRT-P recipients. In defibrillator recipients with an average age of 80 years, the 5-year risk of reoperation ranged from 11% in single chamber, 13% in dual chamber to 24% in CRT-D recipients, while the 5-year risk of dying with the index defibrillator in situ was 46% in single chamber, 40% in dual chamber and 41% in CRT-D recipients.

CONCLUSION

In this cohort of older patients the 5-year risk of generator reoperation was low in pacemaker recipients whereas up to one in four CRT-D recipients would have a reoperation within 5 years.

Prevalence and Assessment of Sleep-Disordered Breathing in Patients With Atrial Fibrillation: A Systematic Review and Meta-analysis

BACKGROUND

In this study, we sought to estimate the prevalence of concomitant sleep-disordered breathing (SDB) in patients with atrial fibrillation (AF) and to systematically evaluate how SDB is assessed in this population.

METHODS

We searched Medline, Embase and Cinahl databases through August 2020 for studies reporting on SDB in a minimum 100 patients with AF. For quantitative analysis, studies were required to have systematically assessed for SDB in consecutive AF patients. Pooled prevalence estimates were calculated with the use of the random effects model. Weighted mean differences and odds ratios were calculated when possible to assess the strength of association between baseline characteristics and SDB.

RESULTS

The search yielded 2758 records, of which 33 studies (n = 23,894 patients) met the inclusion criteria for qualitative synthesis and 13 studies (n = 2660 patients) met the meta-analysis criteria. The pooled SDB prevalence based on an SDB diagnosis cutoff of apnea-hypopnea index (AHI) ≥ 5/h was 78% (95% confidence interval [CI] 70%-86%; P < 0.001). For moderate-to-severe SDB (AHI ≥ 15/h), the pooled SDB prevalence was 40% (95% CI 32%-48%; P < 0.001). High degrees of heterogeneity were observed (I² = 96% and 94%, respectively; P < 0.001). Sleep testing with the use of poly(somno)graphy or oximetry was the most common assessment tool used (in 22 studies, 66%) but inconsistent diagnostic thresholds were used.

CONCLUSIONS

SDB is highly prevalent in patients with AF. Wide variation exists in the diagnostic tools and thresholds used to detect concomitant SDB in AF. Prospective systematic testing for SDB in unselected cohorts of AF patients may be required to define the true prevalence of SDB in this population.

Quality indicators for the care and outcomes of adults with atrial fibrillation

AIMS

To develop quality indicators (QIs) that may be used to evaluate the quality of care and outcomes for adults with atrial fibrillation (AF).

METHODS AND RESULTS

We followed the ESC methodology for QI development. This methodology involved (i) the identification of the domains of AF care for the diagnosis and management of AF (by a group of experts including members of the ESC Clinical Practice Guidelines Task Force for AF); (ii) the construction of candidate QIs (including a systematic review of the literature); and (iii) the selection of the final set of QIs (using a modified Delphi method). Six domains of care for the diagnosis and management of AF were identified: (i) Patient assessment (baseline and follow-up), (ii) Anticoagulation therapy, (iii) Rate control strategy, (iv) Rhythm control strategy, (v) Risk factor management, and (vi) Outcomes measures, including patient-reported outcome measures (PROMs). In total, 17 main and 17 secondary QIs, which covered all six domains of care for the diagnosis and management of AF, were selected. The outcome domain included measures on the consequences and treatment of AF, as well as PROMs.

CONCLUSION

This document defines six domains of AF care (patient assessment, anticoagulation, rate control, rhythm control, risk factor management, and outcomes), and provides 17 main and 17 secondary QIs for the diagnosis and management of AF. It is anticipated that implementation of these QIs will improve the quality of AF care.

Rationale and design of the IRON-AF study: a double-blind, randomised, placebo-controlled study to assess the effect of intravenous ferric carboxymaltose in patients with atrial fibrillation and iron deficiency

INTRODUCTION

Atrial fibrillation (AF) is associated with significantly impaired quality-of-life. Iron deficiency (ID) is prevalent in patients with AF. Correction of ID in other patient populations with intravenous iron supplementation has been shown to be a safe, convenient and effective way of improving exercise tolerance, fatigue and quality-of-life. The IRON-AF (Effect of Iron Repletion in Atrial Fibrillation) study is designed to assess the effect of iron repletion with intravenous ferric carboxymaltose in patients with AF and ID.

METHODS AND ANALYSIS

The IRON-AF study is a double-blind, randomised controlled trial that will recruit at least 84 patients with AF and ID. Patients will be randomised to receive infusions of either ferric carboxymaltose or placebo, given in repletion and then maintenance doses. The study will have follow-up visits at weeks 4, 8 and 12. The primary endpoint is change in peak oxygen uptake from baseline to week 12, as measured by cardiopulmonary exercise testing (CPET) on a cycle ergometer. Secondary endpoints include changes in quality-of-life and AF disease burden scores, blood parameters, other CPET parameters, transthoracic echocardiogram parameters, 6-minute walk test distance, 7-day Holter/Event monitor burden of AF, health resource utilisation and mortality.

ETHICS AND DISSEMINATION

The study protocol has been approved by the Central Adelaide Local Health Network Human Research Ethics Committee, Australia. The results of this study will be disseminated through publications in peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN12620000285954).

Risk factor management and atrial fibrillation

The management of atrial fibrillation (AF) is multifaceted and treatment paradigms have changed significantly in the last century. The treatment of AF requires a comprehensive approach which goes beyond the treatment of the arrhythmia alone. Risk factor management has been introduced as a crucial pillar of AF management. As a result, the landscape of care delivery is changing as well, and novel models of comprehensive care delivery for AF have been introduced. This article reviews the evidence for the role of risk factor management in AF, how this can be integrated and implemented in clinical practice by applying novel models of care delivery, and finally identifies areas for ongoing research and potential healthcare reform to comprehensively manage the burgeoning AF population.