Atrial Fibrillation and Chronic Kidney Disease: Aetiology and Management.

Chronic kidney disease (CKD) and atrial fibrillation (AF) are associated with significant cardiovascular morbidity and mortality. Recent studies have highlighted an increased prevalence and incidence of AF in patients with CKD. This article aims to provide a comprehensive review of current management strategies and considerations of treating atrial fibrillation with concomitant CKD. Potential electrophysiological mechanisms between AF and CKD are explored. Current evidence and literature focusing on pharmacological rate and rhythm control along with procedural intervention is reviewed and presented. The management of AF and CKD together is complex, but particularly pertinent when considering the close cyclical relationship in the progression of both diseases.

Application of two novel electrical restitution-based ECG markers of ventricular arrhythmia to patients with nonischemic cardiomyopathy.

INTRODUCTION: Sudden cardiac death (SCD) risk assessment is limited, particularly in patients with nonischemic cardiomyopathies. This is the first application, in patients with cardiomyopathies, of two novel risk markers, regional restitution instability index (R2I2) and peak electrocardiogram restitution slope (PERS), which have been shown to be predictive of ventricular arrhythmias (VA) or death in ischemic heart disease patients. METHODS: Blinded retrospective study of 50 patients: 33 dilated cardiomyopathy and 17 other; undergoing electrophysiological study (EPS) for SCD risk stratification, and 29 controls with structurally normal hearts undergoing EPS. R2I2 was calculated from an EPS using electrocardiogram surrogates for action potential duration and diastolic interval. Cut-offs for high and low R2I2/PERS were predefined. RESULTS: R2I2 was significantly higher in study than control patients (0.99 ± 0.05 vs. 0.63 ± 0.04, p < .001). PERS showed a trend to higher values in the study group (1.18[0.63] vs. 1.09[0.54], p = .07). During median follow up of 5.6 years [interquartile range 1.9 years], nine study patients reached the endpoint of VA/death. Patients who experienced VA/death showed trends to higher mean R2I2 (1.14 ± 0.07 vs.0.95 ± 0.05, p = .12) and PERS (1.46[0.49] vs. 1.13[0.62], p = .22). A Cox proportional hazards model using grouped markers: R2I2 < 1.03 + PERS < 1.21/either R2I2 ≥ 1.03 or PERS ≥ 1.21/R2I2 ≥ 1.03 + PERS ≥ 1.21; significantly predicted VA/death (p = .02) with a hazard ratio per positive component of 3.2 (95% confidence interval 1.2-8.8). CONCLUSION: R2I2≥ 1.03 + PERS ≥ 1.21 may predict VA/death in patients with cardiomyopathies. R2I2 ≥ 1.03 + PERS ≥ 1.21 have the potential to play an important role in SCD risk stratification in cardiomyopathies but their validity should be confirmed in a larger study.

Palpitation referrals from primary care to a secondary care cardiology outpatient clinic: assessing adherence to guidelines.

BACKGROUND AND AIMS: Palpitations are a common presentation in primary care. Guidelines have been developed to identify patients with palpitations who require further assessment by a cardiologist in secondary care. However, patients that do not meet guideline thresholds for referrals are still referred to secondary care services. This audit evaluated the adherence to referral guidelines at our trust and assessed the characteristics of patients who were referred appropriately versus those referred without meeting guideline referral thresholds (inappropriate referral). RESULTS: Palpitation referrals to a single cardiology outpatient clinic were assessed (n = 66). Half the patients referred for palpitations were referred inappropriately (n = 34, 51.5%). Patients referred inappropriately were more likely to have a benign diagnosis after assessment (91.2%). These patients also had significantly fewer investigations [mean difference of 1.1 (confidence interval: 0.6-1.6)]. Specialist investigations, such as cardiac event recorders (P < 0.05) and cardiac magnetic resonance imaging (P < 0.05) were less likely to be used in inappropriately referred patients. CONCLUSIONS: The results from this audit provide early evidence that there are a significant number of patients who are being referred that could be managed in primary care. Further studies are needed to confirm our findings in larger cohorts and to establish the underlying reasons for inappropriate referrals.

Consideration for primary prevention implantable cardioverter defibrillators differ between specialities.

PURPOSE: Implantable cardioverter defibrillator (ICD) implantation rates remain variable despite established guideline recommendations. This study aims to assess whether being managed by a cardiologist has an impact on whether patients are considered for an ICD for primary prevention of sudden cardiac death. DESIGN/METHODS: Single-centre, retrospective, observational study of patients identified to have severe left ventricular systolic dysfunction (LVSD) on echocardiography (n = 129) between 1 and 30 June 2016 with cross-sectional assessment at 1 year. An assessment of ICD consideration at 1 year following the echocardiogram was documented, in addition to the specialty of the managing physician (group 1-electrophysiologist/heart failure specialist; group 2-all other cardiologists; group 3-non-cardiologist). RESULTS: 129/1173 (11%) transthoracic echocardiographies (s) were identified to have severe LVSD. 52 (40%), 37 (29%) and 40 (31%) were managed by group 1, group 2 and group 3, respectively. Mean age was 74.7 (±12.6) years with a predominance of male gender (70.5%). An ICD was not considered in 47.3%. Those managed by a cardiologist were more likely to be considered for an ICD than a non-cardiologist (63.9% vs 30.0%; OR 4.0, 95% CI 1.8 to 8.8, p = 0.001) with a greater survival at 1 year (89.9% vs 52.5%, OR 8.1 95% CI 3.2 to 20.4, p < 0.001). Group 1 were more likely to consider ICD than group 2 cardiologists (75.0% vs 45.9%; OR 3.5; 95% CI 1.4 to 8.7, p = 0.005). CONCLUSION: There is significant variation between cardiologists and non-cardiologists, as well as within different cardiology subspecialists, when considering the option of ICD therapy for primary prevention.

Body surface mapping of P-waves in sinus rhythm to predict recurrence following cardioversion for atrial fibrillation.

Background: Direct current cardioversion (DCCV) is used as elective and emergency rhythm control for atrial fibrillation (AF). We aimed to explore the role of P-wave parameters measured during sinus rhythm using body surface mapping (BSM) in predicting successful DCCV for persistent atrial fibrillation (persAF) at 12 months. Methods: This case-control study included 56 males >18 years old who underwent DCCV for persAF. P-wave parameter collection after DCCV for AF was done using 128 unipolar leads. A band-pass filter of 1-50 Hz was utilised. Corrected P-wave duration (PWDc), P-wave amplitude, and P-wave dispersion were measured to predict 12-month outcomes and time of recurrence. Results: The mean age was 64 ± 4 years, and 23 patients (44%) were on amiodarone. The 12-month success rate was 44% (n = 23), while the rest reverted to AF after 2.6 ± 0.4 months. The parameters were comparable between successful and failed DCCV in the entire cohort and patients not on amiodarone. In patients on amiodarone, patients with failed arms had higher PWDc than those with successful arms (188 vs. 150 ms, P = 0.04). Receiver operator characteristic curve analysis for PWDc in the amiodarone cohort showed an area under the curve (AUC) of 0.75 and P = 0.049. A recurrence cut-off >161 ms had a sensitivity of 69% and a specificity of 100%, with a hazard ratio of 10.7, P = 0.004. The parameters were not predictive of the time of recurrence. Conclusion: In patients on amiodarone, increased PWDc measured using BSM was associated with higher AF recurrence at 12 months following DCCV for persAF.

The Feasibility, Safety and Outcome of Very High-Power Short Duration Radiofrequency Ablation in Pulmonary Vein Isolation: A Real-World Observation Study.

Background: Pulmonary vein isolation (PVI) ablation is the established gold standard therapy for patients with symptomatic drug refractory atrial fibrillation (AF). Advancements in radiofrequency (RF) ablation, have led to the development of the novel contact force-sensing temperature-controlled very high-power short-duration (vHPSD) RF ablation. This setting delivers 90 W for up to 4 seconds with a constant irrigation flow rate of 8 mL/min. The aim of this study was to compare procedural outcomes and safety with conventional radiofrequency ablation. Methods: An observational study was conducted with patients who underwent first time PVI ablation between August 2020 and January 2022. The cohort was divided into: (1) vHPSD ablation; (2) High-power short duration (HPSD) ablation; (3) THERMOCOOL SMARTTOUCH™ SF (STSF). The vHPSD ablation group was prospectively recruited while the HPSD and STSF group were retrospectively collected. Primary outcomes were procedural success, PVI duration, ablation duration and incidence of perioperative adverse events. Secondary outcomes were intraprocedural morphine and midazolam requirement. Results: A total of 175 patients were included in the study with 100, 30 and 45 patients in the vHPSD, HPSD and STSF group, respectively. PVI was successfully attained in all vHPSD patients. vHPSD demonstrated significantly reduced time required for PVI and total energy application in comparison to the HPSD and STSF groups (67.7 ± 29.7 vs. 92.9 ± 25.7 vs. 93.6 ± 29.1 min, p < 0.0001; 9.87 ± 4.16 vs. 33.9 ± 7.49 vs. 36.0 ± 10.5 min, p < 0.0001, respectively). Intravenous morphine and midazolam requirement was lower in the vHPSD group compared to the HPSD and STSF groups (10.2 ± 3.43 vs. 16.1 ± 4.58 vs. 15.3 ± 3.94 mg, p < 0.0001; 4.04 ± 3.24 vs. 8.63 ± 5.22 vs. 8.58 ± 4.72 mg, p < 0.0001). One cardiac tamponade was observed in both the vHPSD and HPSD groups while the STSF group exhibited an embolic stoke and two pericardial effusions that did not require drainage. Conclusions: In this study, vHPSD demonstrated a comparable safety profile to the other treatment arms. Procedural duration and energy application time was substantially reduced along with sedation requirement notwithstanding the limitations of observational study design, these preliminary findings are promising with respect to periprocedural outcomes and safety of vHPSD however longitudinal outcomes will be essential to assessing the overall efficacy of this novel technology.

Digitally enabled acute care for atrial fibrillation: conception, feasibility and early outcomes of an AF virtual ward.

BACKGROUND: Atrial fibrillation (AF) represents a growing healthcare challenge, mainly driven by acute hospitalisations. Virtual wards could be the way forward to manage acute AF patients through remote monitoring, especially with the rise in global access to digital telecommunication and the growing acceptance of telemedicine post-COVID-19. METHODS: An AF virtual ward was implemented as a proof-of-concept care model. Patients presenting acutely with AF or atrial flutter and rapid ventricular response to the hospital were onboarded to the virtual ward and managed at home through remote ECG-monitoring and 'virtual' ward rounds, after being given access to a single-lead ECG device, a blood pressure monitor and pulse oximeter with instructions to record daily ECGs, blood pressure, oxygen saturations and to complete an online AF symptom questionnaire. Data were uploaded to a digital platform for daily review by the clinical team. Primary outcomes included admission avoidance, readmission avoidance and patient satisfaction. Safety outcomes included unplanned discharge from the virtual ward, cardiovascular mortality and all-cause mortality. RESULTS: There were 50 admissions to the virtual ward between January and August 2022. Twenty-four of them avoided initial hospital admission as patients were directly enrolled to the virtual ward from outpatient settings. A further 25 readmissions were appropriately prevented during virtual surveillance. Patient satisfaction questionnaires yielded 100% positive responses among participants. There were three unplanned discharges from the virtual ward requiring hospitalisation. Mean heart rate on admission to the virtual ward and discharge was 122±26 and 82±27 bpm respectively. A rhythm control strategy was pursued in 82% (n=41) and 20% (n=10) required 3 or more remote pharmacological interventions. CONCLUSION: This is a first real-world experience of an AF virtual ward that heralds a potential means for reducing AF hospitalisations and the associated financial burden, without compromising on patients' care or safety.

Non-invasive markers for sudden cardiac death risk stratification in dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a common yet challenging cardiac disease. Great strides have been made in improving DCM prognosis due to heart failure but sudden cardiac death (SCD) due to ventricular arrhythmias remains significant and challenging to predict. High-risk patients can be effectively managed with implantable cardioverter defibrillators (ICDs) but because identification of what is high risk is very limited, many patients unnecessarily experience the morbidity associated with an ICD implant and many others are not identified and have preventable mortality. Current guidelines recommend use of left ventricular ejection fraction and New York Heart Association class as the main markers of risk stratification to identify patients who would be at higher risk of SCD. However, when analysing the data from the trials that these recommendations are based on, the number of patients in whom an ICD delivers appropriate therapy is modest. In order to improve the effectiveness of therapy with an ICD, the patients who are most likely to benefit need to be identified. This review article presents the evidence behind current guideline-directed SCD risk markers and then explores new potential imaging, electrophysiological and genetic risk markers for SCD in DCM.

The Influence of Environmental Air Pollution on Ventricular Arrhythmias: A Scoping Review.

INTRODUCTION: Exposure to air pollution is a recognised risk factor for cardiovascular disease and has been associated with supraventricular arrhythmias. The effect of air pollution on ventricular arrhythmias is less clear. This scoping review assessed the effects of particulate and gaseous air pollutants on the incidence of ventricular arrhythmias. METHODS: MEDLINE and EMBASE databases were searched for studies assessing the effects of air pollutants on ventricular tachycardia and ventricular fibrillation. These pollutants were particulate matter (PM) 2.5, PM10, Nitrogen Dioxide (NO2), Carbon Monoxide (CO), Sulphur Dioxide (SO2), and Ozone (O3). RESULTS: This review identified 27 studies: nine in individuals with implantable cardioverter defibrillators, five in those with ischaemic heart disease, and 13 in the general population. Those with ischaemic heart disease appear to have the strongest association with ventricular arrhythmias in both gaseous and particulate pollution, with all three studies assessing the effects of PM2.5 demonstrating some association with ventricular arrythmia. Results in the general and ICD population were less consistent. CONCLUSION: Individuals with ischaemic heart disease may be at an increased risk of ventricular arrhythmias following exposure to air pollution.

Automatic Extraction of Recurrent Patterns of High Dominant Frequency Mapping During Human Persistent Atrial Fibrillation.

Purpose: Identifying targets for catheter ablation remains challenging in persistent atrial fibrillation (persAF). The dominant frequency (DF) of atrial electrograms during atrial fibrillation (AF) is believed to primarily reflect local activation. Highest DF (HDF) might be responsible for the initiation and perpetuation of persAF. However, the spatiotemporal behavior of DF remains not fully understood. Some DFs during persAF were shown to lack spatiotemporal stability, while others exhibit recurrent behavior. We sought to develop a tool to automatically detect recurrent DF patterns in persAF patients. Methods: Non-contact mapping of the left atrium (LA) was performed in 10 patients undergoing persAF HDF ablation. 2,048 virtual electrograms (vEGMs, EnSite Array, Abbott Laboratories, USA) were collected for up to 5 min before and after ablation. Frequency spectrum was estimated using fast Fourier transform and DF was identified as the peak between 4 and 10 Hz and organization index (OI) was calculated. The HDF maps were identified per 4-s window and an automated pattern recognition algorithm was used to find recurring HDF spatial patterns. Dominant patterns (DPs) were defined as the HDF pattern with the highest recurrence. Results: DPs were found in all patients. Patients in atrial flutter after ablation had a single DP over the recorded time period. The time interval (median [IQR]) of DP recurrence for the patients in AF after ablation (7 patients) decreased from 21.1 s [11.8 49.7 s] to 15.7 s [6.5 18.2 s]. The DF inside the DPs presented lower temporal standard deviation (0.18 ± 0.06 Hz vs. 0.29 ± 0.12 Hz, p < 0.05) and higher OI (0.35 ± 0.03 vs. 0.31 ± 0.04, p < 0.05). The atrial regions with the highest proportion of HDF region were the septum and the left upper pulmonary vein. Conclusion: Multiple recurrent spatiotemporal HDF patterns exist during persAF. The proposed method can identify and quantify the spatiotemporal repetition of the HDFs, where the high recurrences of DP may suggest a more organized rhythm. DPs presented a more consistent DF and higher organization compared with non-DPs, suggesting that DF with higher OI might be more likely to recur. Recurring patterns offer a more comprehensive dynamic insight of persAF behavior, and ablation targeting such regions may be beneficial.

Disparity in implantable cardioverter defibrillator therapy among minority South Asians in the United Kingdom.

OBJECTIVE: There are large geographical differences in implantable cardioverter defibrillator (ICD) implantation rates for reasons not completely understood. In an increasingly multiethnic population, we sought out to investigate whether ethnicity influenced ICD implantation rates. METHODS: This was a retrospective, cohort study of new ICD implantation or upgrade to ICD from January 2006 to February 2019 in recipients of Caucasian or South Asian ethnicity at a single tertiary centre in the UK. Data were obtained from a routinely collected local registry. Crude rates of ICD implantation were calculated for the population of Leicestershire county and were age-standardised to the UK population using the UK National Census of 2011. RESULTS: The Leicestershire population was 980 328 at the time of the Census, of which 761 403 (77.7%) were Caucasian and 155 500 (15.9%) were South Asian. Overall, 2650 ICD implantations were performed in Caucasian (91.9%) and South Asian (8.1%) patients. South Asians were less likely than Caucasians to receive an ICD (risk ratio (RR) 0.43, 95% CI 0.37 to 0.49, p<0.001) even when standardised for age (RR 0.75, 95% CI 0.74 to 0.75, p<0.001). This remained the case for primary prevention indication (age-standardised RR 0.91, 95% CI 0.90 to 0.91, p<0.001), while differences in secondary prevention ICD implants were even greater (age-standardised RR 0.49, 95% CI 0.48 to 0.50, p<0.001). CONCLUSION: Despite a universal and free healthcare system, ICD implantation rates were significantly lower in the South Asian than the Caucasian population residing in the UK. Whether this is due to cultural acceptance or an unbalanced consideration is unclear.