Biomarkers in Atrial Fibrillation: Pathogenesis and Clinical Implications

Biomarkers derived from the key components of the pathophysiology of atrial fibrillation (AF) and its complications have the potential to play an important role in earlier characterization of AF phenotype and in risk prediction of adverse clinical events, which may translate into improved management strategies. C-reactive protein, natriuretic peptides, cardiac troponins, growth differentiation factor-15, and fibroblast growth factor-23 have been shown to be the most promising biomarkers in AF. Some biomarkers have already been included in clinical risk scores to predict postoperative AF, thromboembolism, major bleeding, and death. Considerably more work is needed to bring these novel biomarkers into routine clinical management of patients with AF.

Ventricular arrhythmia burden during the coronavirus disease 2019 (COVID-19) pandemic

AIMS

Our objective was to determine the ventricular arrhythmia burden in implantable cardioverter-defibrillator (ICD) patients during COVID-19.

METHODS AND RESULTS

In this multicentre, observational, cohort study over a 100-day period during the COVID-19 pandemic in the USA, we assessed ventricular arrhythmias in ICD patients from 20 centres in 13 states, via remote monitoring. Comparison was via a 100-day control period (late 2019) and seasonal control period (early 2019). The primary outcome was the impact of COVID-19 on ventricular arrhythmia burden. The secondary outcome was correlation with COVID-19 incidence. During the COVID-19 period, 5963 ICD patients underwent remote monitoring, with 16 942 episodes of treated ventricular arrhythmias (2.8 events per 100 patient-days). Ventricular arrhythmia burden progressively declined during COVID-19 (P < 0.001). The proportion of patients with ventricular arrhythmias amongst the high COVID-19 incidence states was significantly reduced compared with those in low incidence states [odds ratio 0.61, 95% confidence interval (CI) 0.54-0.69, P < 0.001]. Comparing patients remotely monitored during both COVID-19 and control periods (n = 2458), significantly fewer ventricular arrhythmias occurred during COVID-19 [incident rate ratio (IRR) 0.68, 95% CI 0.58-0.79, P < 0.001]. This difference persisted when comparing the 1719 patients monitored during both the COVID-19 and seasonal control periods (IRR 0.69, 95% CI 0.56-0.85, P < 0.001).

CONCLUSIONS

During COVID-19, there was a 32% reduction in ventricular arrhythmias needing device therapies, coinciding with measures of social isolation. There was a 39% reduction in the proportion of patients with ventricular arrhythmias in states with higher COVID-19 incidence. These findings highlight the potential role of real-life stressors in ventricular arrhythmia burden in individuals with ICDs.

TRIAL REGISTRATION

Australian New Zealand Clinical Trial Registry; URL: https://www.anzctr.org.au/; Unique Identifier: ACTRN12620000641998.

Associations of anemia with stroke, bleeding, and mortality in atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Anemia frequently coexists with atrial fibrillation (AF) and has been variably associated with worse outcomes. We performed a systematic review and meta-analysis to comprehensively assess the effect of anemia on mortality, stroke/systemic thromboembolism, and bleeding events in patients with AF.

METHODS

MEDLINE and Embase were searched from inception until May 2020. Studies examining associations of anemia with the above outcomes in AF patients were included, and maximally adjusted hazard ratios (HRs) meta-analysed. PROSPERO registration number CRD42020171113.

RESULTS

Twenty-eight studies involving 365 484 patients (41% female, mean age 74.7 years) were included. The average study follow-up ranged from 0.2 to 4.0 years, and the prevalence of anemia was 16%. Anemia was associated with a 78% increase in all-cause mortality (HR, 1.78; 95% confidence interval [CI], 1.44-2.20), 60% increase in cardiovascular mortality (HR, 1.60; 95% CI, 1.17-2.19), 134% increase in noncardiovascular mortality (HR, 2.34; 95% CI, 1.58-3.47) 15% increase in stroke/systemic thromboembolism (HR, 1.15; 95% CI, 1.01-1.31), 78% increase in major bleeding (HR, 1.78; 95% CI, 1.54-2.05), and 77% increase in gastrointestinal bleeding (HR, 1.77; 95% CI, 1.23-2.55). Sensitivity analyses including studies that reported odds ratios did not result in any material change.

CONCLUSION

Anemia is a frequently observed comorbidity in patients with AF, and is associated with an increased risk of all-cause, cardiovascular and noncardiovascular mortality, stroke/systemic thromboembolism, and major and gastrointestinal bleeding. Future studies are required to explore the causes of anemia in AF, and whether investigation and treatment may be clinically beneficial in affected individuals.

Atrial Fibrillation and Heart Failure: Epidemiology, Pathophysiology, Prognosis, and Management

Atrial fibrillation (AF) and heart failure (HF) have similar risk factors, frequently coexist, and potentiate each other in a vicious cycle. Evidence suggests the presence of AF in both HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF) increases the risk of all-cause mortality and stroke, particularly when AF is incident. Catheter ablation may be an effective strategy in controlling symptoms and improving quality of life in AF-HFrEF. Strong data guiding management of AF-HFpEF are lacking largely due to its challenging diagnosis. Improving outcomes associated with these coexistent conditions requires further careful investigation.

Trends in the use, complications, and costs of permanent pacemakers in Australia: A nationwide study from 2008 to 2017

OBJECTIVE

To characterize contemporary pacemaker procedure trends.

METHODS

Nationwide analysis of pacemaker procedures and costs between 2008 and 2017 in Australia. The main outcome measures were total, age- and gender-specific implant, replacement, and complication rates, and costs.

RESULTS

Pacemaker implants increased from 12,153 to 17,862. Implantation rates rose from 55.3 to 72.6 per 100,000, a 2.8% annual increase (incidence rate ratio [IRR] 1.028; 95% CI, 1.02-1.04; p < .001). Pacemaker implants in the 80+ age group were 17.37-times higher than the < 50 group (95% CI 16.24-18.59; p < .001), and in males were 1.48-times higher than in females (95% CI 1.42-1.55; p < .001). However, there were similar increases according to age (p = .10) and gender (p = .68) over the study period. Left ventricular lead rates were stable (IRR 0.995; 95% CI 0.98-1.01; p = .53). Generator replacements decreased from 20.5 to 18.3 per 100,000 (IRR 0.975; 95% CI 0.97-0.98; p < .001). Although procedures for generator-related complications were stable (IRR 0.995; 95% CI 0.98-1.01; p = .54), those for lead-related complications decreased (IRR 0.985; 95% CI 0.98-0.99; p < .001). Rates for all pacemaker procedures were consistently greater in males (p < .001). Although annual costs of all pacemaker procedures increased from $178 million to $329 million, inflation-adjusted costs were more stable, rising from $294 million to $329 million.

CONCLUSIONS

Increasing demand for pacemaker implants is driven by the ageing population and rising rates across all ages, while replacement and complication procedure rates appeared more stable. Males have consistently greater pacemaker procedure rates than females. Our findings have significant clinical and public health implications for healthcare resource planning.

Factors Contributing to Exercise Intolerance in Patients With Atrial Fibrillation

BACKGROUND

Reduced exercise capacity and exercise intolerance are commonly reported by individuals with atrial fibrillation (AF). Our objectives were to evaluate the contributing factors to reduced exercise capacity and describe the association between subjective measures of exercise intolerance versus objective measures of exercise capacity.

METHODS

Two hundred and three (203) patients with non-permanent AF and preserved ejection fraction undergoing cardiopulmonary exercise testing (CPET) were recruited. Clinical characteristics, AF-symptom evaluation, and transthoracic echocardiography measures were collected. Peak oxygen consumption (VO_2peak) was calculated during CPET as an objective measure of exercise capacity. We assessed the impact of 16 pre-defined clinical features, comorbidities and cardiac functional parameters on VO_2peak.

RESULTS

Across this cohort (Age 66±11 years, 40.4% female and 32% in AF), the mean VO_2peak was 20.3±6.3 mL/kg/min. 24.9% of patients had a VO_2peak considered low (<16 mL/kg/min). In multivariable analysis, echocardiography-derived estimates of elevated left ventricular (LV) filling pressure (E/E') and reduced chronotropic index were significantly associated with lower VO_2peak. The presence of AF at the time of testing was not significantly associated with VO_2peak but was associated with elevated minute ventilation to carbon dioxide production indicating impaired ventilatory efficiency. There was a poor association between VO_2peak and subjectively reported exercise intolerance and exertional dyspnoea.

CONCLUSION

Reduced exercise capacity in AF patients is associated with elevated LV filling pressure and reduced chronotropic response rather than rhythm status. Subjectively reported exercise intolerance is not a sensitive assessment of reduced exercise capacity. These findings have important implications for understanding reduced exercise capacity amongst AF patients and the approach to management in this cohort. (ACTRN12619001343190).

Cerebral Blood Flow and Cognitive Performance in Postural Tachycardia Syndrome: Insights from Sustained Cognitive Stress Test

Background

The physiology underlying "brain fog" in the absence of orthostatic stress in postural tachycardia syndrome (POTS) remains poorly understood.

Methods and Results

We evaluated cognitive and hemodynamic responses (cardiovascular and cerebral: heart rate, blood pressure, end‐tidal carbon dioxide, and cerebral blood flow velocity (CBFv) in the middle cerebral artery at baseline, after initial cognitive testing, and after (30‐minutes duration) prolonged cognitive stress test (PCST) whilst seated; as well as after 5‐minute standing in consecutively enrolled participants with POTS (n=22) and healthy controls (n=18). Symptom severity was quantified with orthostatic hypotensive questionnaire at baseline and end of study. Subjects in POTS and control groups were frequency age‐ and sex‐matched (29±11 versus 28±13 years; 86 versus 72% women, respectively; both P≥0.4). The CBFv decreased in both groups (condition, P=0.04) following PCST, but a greater reduction in CBFv was observed in the POTS versus control group (−7.8% versus −1.8%; interaction, P=0.038). Notably, the reduced CBFv following PCST in the POTS group was similar to that seen during orthostatic stress (60.0±14.9 versus 60.4±14.8 cm/s). Further, PCST resulted in greater slowing in psychomotor speed (6.1% versus 1.4%, interaction, P=0.027) and a greater increase in symptom scores at study completion (interaction, P<0.001) in the patients with POTS, including increased difficulty with concentration. All other physiologic responses (blood pressure and end‐tidal carbon dioxide) did not differ between groups after PCST (all P>0.05).

Conclusions

Reduced CBFv and cognitive dysfunction were evident in patients with POTS following prolonged cognitive stress even in the absence of orthostatic stress.

Remote Monitoring Alert Burden: An Analysis of Transmission in >26,000 Patients

OBJECTIVES

This study sought to determine the remote monitoring (RM) alert burden in a multicenter cohort of patients with a cardiac implantable electronic device (CIED).

BACKGROUND

RM of CIEDs allows timely recognition of patient and device events requiring intervention. Most RM involves burdensome manual workflow occurring exclusively on weekdays during office hours. Automated software may reduce such a burden, streamlining real-time alert responses.

METHODS

We retrospectively analyzed 26,713 consecutive patients with a CIED undergoing managed RM utilizing PaceMate software between November 2018 and November 2019. Alerts were analyzed according to type, acuity (red indicates urgent, and yellow indicates nonurgent) and CIED category.

RESULTS

In total, 12,473 (46.7%) patients had a permanent pacemaker (PPM), 9,208 (34.5%) had an implantable cardioverter-defibrillator (ICD), and 5,032 (18.8%) had an implantable loop recorder (ILR). Overall, 82,797 of the 205,804 RM transmissions were alerts, with the remainder being scheduled transmissions. A total of 14,638 (54.8%) patients transmitted at least 1 alert. Permanent pacemakers were responsible for 25,700 (31.0%) alerts, ICDs for 15,643 (18.9%) alerts, and ILRs for 41,454 (50.1%) alerts, with 3,935 (4.8%) red alerts and 78,862 (95.2%) yellow alerts. ICDs transmitted 2,073 (52.7%) red alerts; 5,024 (32.1%) ICD alerts were for ventricular tachyarrhythmias and antitachycardia pacing/shock delivery.

CONCLUSIONS

In an RM cohort of 26,713 patients with CIEDs, 54.8% of patients transmitted at least 1 alert during a 12-month period, totaling over 82,000 alerts. ILRs were overrepresented, and ICDs were underrepresented, in these alerts. The enormity of the number of transmissions and the growing ILR alert burden highlight the need for new management pathways for RM.

Predictors of Anticoagulation Use in Indigenous and Non-Indigenous Australians With Atrial Fibrillation

OBJECTIVE

Prior studies have demonstrated that anticoagulation underutilisation for atrial fibrillation (AF) and elevated stroke risk is common. However, there is little data on factors associated with appropriate anticoagulation, particularly in Indigenous Australians who face a disproportionate burden of AF and stroke. We thus sought to determine factors associated with anticoagulation use in Australians with AF.

DESIGN

Administrative, clinical, prescriptive and laboratory data were linked and aggregated over a 12-year period.

SETTING

Single tertiary teaching hospital.

PARTICIPANTS

19,305 (98%) and 308 (2%) consecutive non-Indigenous and Indigenous Australians with AF identified from administrative databases.

MAIN OUTCOME MEASURES

Associations of anticoagulation use according to ethnicity.

RESULTS

Significant independent predictors of anticoagulation use included hypertension (odds ratio [OR] 1.25, 95% confidence interval [CI] 1.17-1.34; p<0.001), diabetes (OR 1.14, 95% CI 1.05-1.24; p=0.002), heart failure (OR 1.54 95% CI 1.43-1.66; p<0.001) and prior stroke or transient ischaemic attack (OR 2.07, 95% CI 1.84-2.33; p<0.001). In contrast, increasing age (OR 0.99, 95% CI 0.98-0.99; p<0.001), female gender (OR 0.88, 95% CI 0.82-0.93; p<0.001), and vascular disease (OR 0.72, 95% CI 0.64-0.80; p<0.001) were significant predictors of no anticoagulation. Hypertension was associated with less anticoagulation use in Indigenous compared to non-Indigenous Australians (p=0.02).

CONCLUSIONS

Anticoagulation for AF was suboptimal in both Indigenous and non-Indigenous Australians. Older age, female gender, and comorbid vascular disease were found to be negatively associated with anticoagulation. Importantly, hypertension may also be under-recognised as a stroke risk factor in Indigenous Australians. Future efforts to encourage anticoagulation use in accordance with guideline recommendations is likely to reduce the burden of AF-related stroke in both Indigenous and non-Indigenous populations.

The "Road" to Atrial Fibrillation: The Role of the Cardiac Autonomic Nervous System

At the population level, there is a parallel escalation in the healthcare burden of both, atrial fibrillation (AF) as well its risk factors. Compounding this relationship, AF is associated with escalating burden at an individual level, due its self-perpetuating and progressive nature. The mechanisms by which these risk factors interact to produce atrial remodelling and subsequent AF are unclear. This intersection is critical to the development of strategies to combat this disease at both the individual and population-level. It is well known that AF can manifest from disturbances in autonomic activity. At the population level, there is growing data to suggest a role of the autonomic nervous system in the future incidence of AF. Here, we provide an overview of the association of cardiac autonomic dysfunction with the incidence of AF, review the role of the autonomic nervous system (ANS) as an intermediary between risk factors and the development of AF and finally, we discuss the bidirectional relationship between AF and cardiac autonomic nervous system dysfunction; to determine whether this is implicated in the progression of AF.

False remote monitoring alerts from explanted cardiac implantable electronic device: How is this possible?

A 72-year-old woman with a dual-chamber implantable cardioverter-defibrillator (Biotronik Lumax 540 DR-T) at elective replacement indicator presented for generator replacement. A new MicroPort generator (Platinium DR) was attached to her existing leads. Eight days later, multiple red alert messages were received on the Biotronik remote monitoring system from the explanted generator. Investigations revealed alert transmission via a CardioMessenger Smart mobile device registered to another patient that came into proximity of the explanted generator. The Biotronik remote monitoring system is unique in that red alerts could be sent through any CardioMessenger Smart device regardless of whether they were paired.

Late-onset thyrotoxicosis after the cessation of amiodarone

Introduction

Amiodarone is a highly effective antiarrhythmic-drug with well recognized toxic side-effects. The effects of the drug late in patients with atrial fibrillation (AF) is not well described.

Methods and results

We present a single centre prospectively collected series of patients with thyrotoxicosis occurring late after the cessation of amiodarone. Between 2006 and 2018, 8 patients were identified with amiodarone induced thyrotoxicosis (AIT). Amiodarone was prescribed for AF in 7 patients and ventricular tachycardia in 1 patient. Mean duration of therapy was 329 [42–1092] days, mean dose of 200 ± 103.5 mg/day. Amiodarone use was short term (<140 days) in 4 of the 8 cases, with one treated for 42 days. Patients presented with symptoms including weight loss, tremors, palpitations, AF, sweats all indicative of AIT at a median of 347 [60–967] days post cessation. Thyroid function testing confirmed suppressed thyroid stimulating hormone and elevated T levels in all patients. Nuclear thyroid imaging in all cases demonstrated low uptake of iodine indicative of Type II AIT. All patients recovered following pharmaceutical treatment with Carbimazole and Prednisolone.

Conclusions

We describe a series of patients with late thyrotoxicosis after exposure to amiodarone. Our findings highlight the need for a high-index of clinical suspicion for AIT regardless of treatment duration or time after cessation of amiodarone.

70Autonomic dysfunction in atrial fibrillation (AF) patients: absent vasomotor reflex to decreased cardiac venous return during af in comparison to sinus rhythm; implications for earlier rhythm control

Funding Acknowledgements

Dr Malik is supported by an Australian Postgraduate Award Scholarship from the University of Adelaide.

OnBehalf

Centre for Heart Rhythm Disorders, University of Adelaide & Royal Adelaide Hospital

Background

A bi-directional relationship exists between AF and the autonomic nervous system (ANS). Patients with AF studied in sinus rhythm (SR) have impaired vasomotor responses to decreased cardiac volume. Whether autonomic dysfunction worsens during AF itself, is unknown. 

Purpose

We examined haemodynamic responses to lower body negative pressure (LBNP) in patients with persistent AF compared to AF studied in SR. LBNP decreases cardiac volume, deactivates atrial stretch receptors and induces a reflex to maintain blood pressure by increasing systemic vascular resistance (SVR). 

Methods

21 consecutive patients with paroxysmal or persistent AF were studied; during AF (n = 8) or SR (n = 13). Anti-arrhythmic and anti-hypertensives were withheld for 5 half-lives. Patients underwent LBNP using a custom-made chamber sealing both lower limbs. Negative pressure at sham (-0 mmHg), low (-20 mmHg) and high level (-40 mmHg) was applied for 5 minutes each. Finger photo plethysmography was used for beat-beat-blood pressure. Computation of SVR during AF is not feasible with this method. Therefore, the right forearm was used to perform venous occlusion plethysmography (VOP); non-invasive, well validated with LBNP and impervious to AF: to estimate forearm blood flow (FBF) and SVR (inversely proportional). 

Results

Baseline characteristics and responses to LBNP are presented in Table 1. MAP was maintained, and HR rose slightly, in the SR group. MAP and HR decreased in the AF group. VOP demonstrates a reduction in FBF in the SR group (vasoconstriction); whereas the vasomotor response to LBNP was absent during AF. Figure 1 (Panels A-C). 

Conclusion

The presence of AF is associated with autonomic dysfunction from impaired cardiac volume regulation. This novel finding may contribute to the known risk of falls and syncope due to AF. Further studies are needed to evaluate whether abnormal cardiac reflexes are involved in atrial remodelling and AF progression.

Table 1 Baseline Characteristics During AF During SR P Value Age 65 ± 5 59 ± 3 0.4 AAD & Anti-HTN medications withheld (%) 75 85 0.6 Resting mean arterial pressure (MAP) 109 ± 9 93 ± 6 0.1 Resting heart rate (HR) 94 ± 6 60 ± 4 0.0001* Haemodynamic response to LBNP % Δ MAP due to LBNP -9 ± 5 +0.5 ± 3 0.2 % Δ HR due to LBNP -6 ± 3 +5 ± 3 0.03* % Δ FBF due to LBNP +75 ± 59 -27 ± 8 0.02* AAD Anti-arrhthmic. HTN: Hypertension. Mean +/- SEM.

Abstract Figure. Vasomotor response to LBNP: in AF vs SR

Pharmacological inhibition of sodium-proton-exchanger subtype 3-mediated sodium absorption in the gut reduces atrial fibrillation susceptibility in obese spontaneously hypertensive rats

Background

Increased sodium uptake has been shown to contribute to hypertension and cardiac end-organ damage. The sodium-proton-exchanger subtype 3 (NHE3) is an important mediator of intestinal sodium absorption. Whether a reduction in intestinal sodium absorption can prevent the development of an atrial arrhythmogenic substrate in hypertension is unknown.

Methods

Eight-week-old obese spontaneously hypertensive rats (SHR-ob) were treated for six weeks with the gut-specific NHE3-inhibitor SAR (1-(β-D-glucopyranosyl)-3-{3-[(4S)-6,8-dichloro-2-methyl-1,2,3,4-tetrahydroiso-chinolin-4-yl]phenyl}urea, 1 mg/kg/d in chow, SHR-ob SAR, n = 7) and compared to aged-matched placebo-treated SHR-ob (SHR-ob PLAC, n = 8). Cardiac magnetic resonance imaging was performed at the end of the treatment period to assess atrial emptying function. Afterwards, local conduction disturbances and inducible atrial fibrillation (AF) duration were determined and histological analysis to quantify atrial fibrosis amount were performed.

Results

Inhibition of intestinal NHE3 by SAR increased fecal sodium excretion, resulted in marked changes in feces electrolyte concentrations and water content, reduced blood pressure and preserved atrial emptying function (active total percent emptying: SHR-ob SAR: 0.47 ± 0.05% vs. SHR-ob PLAC: 0.38 ± 0.007, p < 0.0001). Atrial fibrosis content was lower (21.4 ± 2.5% vs. 36.7 ± 1.2%, p < 0.0001) and areas of slow conduction were smaller (2.5 ± 0.09% vs. 5.3 ± 0.2%, p < 0.0001) in SHR-ob SAR compared to SHR-ob PLAC. Left atrial burst stimulation resulted in shorter inducible AF-durations in SHR-ob SAR compared to SHR-ob PLAC.

Conclusions

Reduction of intestinal sodium absorption and subsequent changes in feces milieu by pharmacological NHE3 inhibition in the gut preserved atrial emptying function and reduced AF susceptibility. Whether pharmacological NHE3 inhibition in the gut prevents AF in humans warrants further study.

Miniaturized implantable cardiac monitor with a long sensing vector (BIOMONITOR III): Insertion procedure assessment, sensing performance, and home monitoring transmission success

BACKGROUND

Implantable Cardiac Monitors (ICMs) are used for long-term monitoring of arrhythmias. BIOMONITOR III is a novel ICM with a miniaturized profile, long sensing vector due to a flexible antenna, simplified implantation with a dedicated insertion tool for pocket formation and ICM placement in a single step, and daily automatic Home Monitoring (HM) function.

METHODS

In 47 patients undergoing BIOMONITOR III insertion for any ICM indication, 16 investigators at 10 Australian sites assessed handling characteristics of the insertion tool, R-wave amplitudes, noise burden, P-wave visibility, and HM transmission success. Patients were followed for 1 month.

RESULTS

All 47 attempted insertions were successful. Median time from skin incision to removal of the insertion tool after ICM insertion was 39 s (IQR 19-65) and to wound closure and cleaning was 4.7 min (IQR 3.5-7.8). All aspects of the insertion tool were rated as "good" or "excellent" in ≥97.9% and "fair" in ≤2.1% of patients, except for "force needed for tunnelling" (91.5% good/excellent, 8.5% fair). Based on HM data, R-waves in the first month were stable at 0.70 ± 0.37 mV. Median noise burden (disabling automatic rhythm evaluation) was 0.19% (IQR 0.00-0.93), equivalent to 2.7 min (IQR 0.0-13.4) per day. In HM-transmitted ECG strips with regular sinus rhythm, P-waves were visible in 89 ± 24% of heart cycles. Patient-individual automatic Home Monitoring transmission success was 98.0% ± 5.5%.

CONCLUSIONS

The novel ICM performed well in all aspects studied, including fast insertion, reliable R-wave sensing, good P-wave visibility, and highly successful HM transmissions.

Polypharmacy and health outcomes in atrial fibrillation: a systematic review and meta-analysis

Objective

To undertake a systematic review and meta-analysis examining the impact of polypharmacy on health outcomes in atrial fibrillation (AF).

Data sources

PubMed and Embase databases were searched from inception until 31 July 2019. Studies including post hoc analyses of prospective randomised controlled trials or observational design that examined the impact of polypharmacy on clinically significant outcomes in AF including mortality, hospitalisations, stroke, bleeding, falls and quality of life were eligible for inclusion.

Results

A total of six studies were identified from the systematic review, with three studies reporting on common outcomes and used for a meta-analysis. The total study population from the three studies was 33 602 and 37.2% were female. Moderate and severe polypharmacy, defined as 5–9 medicines and >9 medicines, was observed in 42.7% and 20.7% of patients respectively, and was associated with a significant increase in all-cause mortality (Hazard ratio [HR] 1.36, 95% CI 1.20 to 1.54, p<0.001; HR 1.84, 95% CI 1.40 to 2.41, p<0.001, respectively), major bleeding (HR 1.32, 95% CI 1.14 to 1.52, p<0.001; HR 1.68, 95% CI 1.35 to 2.09, p<0.001, respectively) and clinically relevant non-major bleeding (HR 1.12, 95% CI 1.03 to 1.22, p<0.01; HR 1.48, 95% CI 1.33 to 1.64, p<0.01, respectively). There was no statistically significant association between polypharmacy and stroke or systemic embolism or intracranial bleeding. Among other examined outcomes, polypharmacy was associated with cardiovascular death, hospitalisation, reduced quality of life and poorer physical function.

Conclusions

Polypharmacy is highly prevalent in the AF population and is associated with numerous adverse outcomes.

PROSPERO registration number

CRD42018105298.

Atrial Fibrillation Is Associated With Syncope and Falls in Older Adults: A Systematic Review and Meta-analysis

OBJECTIVE

To examine the potential association of atrial fibrillation (AF) to syncope and falls, we undertook a systematic review and meta-analysis given the increasing prevalence of AF in older adults as well as emerging data that it is a risk factor for dementia.

PATIENTS AND METHODS

CENTRAL, PubMed, and EMBASE databases were searched from inception to January 31, 2019, to retrieve relevant studies. Search terms consisted of MeSH, tree headings, and keywords relating patients with "AF," "falls," "syncope," and "postural hypotension." When possible; results were pooled using a random-effects model.

RESULTS

A total of 10 studies were included, with 7 studies (36,444 patients; mean ± SD age, 72±10 years) reporting an association between AF and falls and 3 studies (6769 patients; mean ± SD age, 65±3 years) reporting an association between AF and syncope. Pooled analyses demonstrate that AF is independently associated with falls (odds ratio, 1.19; 95% CI, 1.07-1.33; P=.001) and syncope (odds ratio, 1.88; 95% CI, 1.20-2.94; P=.006). There was overall moderate bias and low-moderate heterogeneity (I²=37%; P=.11) for falls and moderate bias with low statistical heterogeneity (I²=0%; P=.44) for syncope. Persistent AF, but not paroxysmal AF, was associated with orthostatic intolerance in 1 study (4408 patients; mean ± SD age, 66±6 years).

CONCLUSION

AF is independently associated with syncope and falls in older adults. Further studies are needed to delineate mechanistic links and to guide management to improve outcomes in these patients.

TRIAL REGISTRATION

PROSPERO: trial identifier: CRD4201810721.

New Findings in Atrial Fibrillation Mechanisms

This review focusses on novel findings in atrial fibrillation mechanisms derived from mapping studies. Recent panoramic mapping techniques have identified 2 arrhythmic mechanisms of interest, namely, rotational (rotors) and ectopic focal activations as drivers of atrial fibrillation. Epicardial adipose tissue and fatty infiltration into the myocardium have been described as novel substrates for atrial fibrillation. There is increasing appreciation that the thin atrial walls harbor a complex 3-dimensional electrostructural substrate to contribute to atrial fibrillation sustenance. Further research is warranted to advance the field toward more targeted therapy.

Brain fog in postural tachycardia syndrome: An objective cerebral blood flow and neurocognitive analysis

Background

It remains unclear whether brain fog is related to impaired cerebral blood flow (CBF) in postural tachycardia syndrome (POTS) patients.

Methods

We assessed CBF in the posterior cerebral artery (PCA) using transcranial Doppler with visual stimuli in 11 POTS and 8 healthy subjects in the seated position, followed by neurocognitive testing.

Results

CBF parameters were similar between the two groups. POTS patients demonstrated significantly longer latency in delayed match to sample response time and greater errors in attention switching task.

Conclusions

Impaired short-term memory and alertness may underlie the symptom of brain fog in POTS patients, despite normal CBF.

Magnetic resonance imaging in non-conditional pacemakers and implantable cardioverter-defibrillators: a systematic review and meta-analysis

Aims

There is growing evidence that magnetic resonance imaging (MRI) scanning in patients with non-conditional cardiac implantable electronic devices (CIEDs) can be performed safely. Here, we aim to assess the safety of MRI in patients with non-conditional CIEDs.

Methods and results

English scientific literature was searched using PubMed/Embase/CINAHL with keywords of ‘magnetic resonance imaging’, ‘pacemaker’, ‘implantable defibrillator’, and ‘cardiac resynchronization therapy’. Studies assessing outcomes of adverse events or significant changes in CIED parameters after MRI scanning in patients with non-conditional CIEDs were included. References were excluded if the MRI conditionality of the CIEDs was undisclosed; number of patients enrolled was &lt;10; or studies were case reports/series. 35 cohort studies with a total of 5625 patients and 7196 MRI scans (0.5–3 T) in non-conditional CIEDs were included. The overall incidence of lead failure, electrical reset, arrhythmia, inappropriate pacing and symptoms related to pocket heating, or torque ranged between 0% and 1.43%. Increase in pacing lead threshold &gt;0.5 V and impedance &gt;50Ω was seen in 1.1% [95% confidence interval (CI) 0.7–1.8%] and 4.8% (95% CI 3.3–6.4%) respectively. The incidence of reduction in P- and R-wave sensing by &gt;50% was 1.5% (95% CI 0.6–2.9%) and 0.4% (95% CI 0.06–1.1%), respectively. Battery voltage reduction of &gt;0.04 V was reported in 2.2% (95% CI 0.2–6.1%).

Conclusion

This meta-analysis affirms the safety of MR imaging in non-conditional CIEDs with no death or implantable cardioverter-defibrillator shocks and extremely low incidence of lead or device-related complications.