Results from a nationwide atrial fibrillation screening effort in Belgium

Introduction

Atrial Fibrillation (AF) is associated with an increased risk of stroke that can be mitigated with anticoagulation therapy. Opportunistic screening for AF for primary stroke prevention is recommended in subjects above 65. However, the paroxysmal and asymptomatic nature of AF hampers early detection with a single time point screening. Multiple time point measurements are superior to single time point measurements for the detection of AF. New technologies such as photoplethysmography (PPG) enable large scale AF screening with repetitive measurements at low-cost using only a smartphone.

Purpose

To explore an entirely online AF screening program in subjects with an elevated stroke risk.

Methods

The Belgian Heart Rhythm Association launched a digital marketing campaign, to promote AF screening during “The Belgian Week of the Heart Rhythm”. Candidates were referred to an online questionnaire to calculate their CHADS-VASC score. Subjects older than 18 with a CHADS-VASC score of 2 or more were allowed to enter the screening program. AF screening was performed with a PPG-based smartphone application. A 60-second PPG trace is captured by placing a fingertip on the smartphone's camera. The smartphone application analyses the PPG trace with an artificial intelligence software. Subjects were instructed to perform measurement twice daily and while experiencing symptoms over the course of 7 days. Measurements were classified as AF or non-AF by the algorithm and were reviewed by medical technicians.

Results

Of the 12.602 candidates who completed the questionnaire, 6.020 subjects met the inclusion criteria and were offered screening. However, only 2.111 (35%) participated in the screening program. The mean age of participants was 63±11 years, 37.3% was male, median CHADS-VASC was 2 (2–3). 257 participants (12.2%) were previously known with AF. In total 25.362 PPG recordings of 60 seconds were performed of which 258 demonstrated AF. AF was detected in 56 participants (2.7%). This was a new finding in 36 participants (1.7%) meaning that 64.3% of participants demonstrating AF were not previously known with AF. The number needed to screen was 58.6 to detect AF in a population without a history of AF and the number needed to invite was 167.2. Only 20 participants (7.8%) with a history of AF demonstrated AF during the screening program.

Conclusions

AF screening in subjects with an elevated stroke risk is feasible with an entirely online screening program without the need for medical hardware or medical personnel with an acceptable number needed to screen. However, this approach failed to target subjects in the highest age groups and since almost two thirds of the subjects interested in the screening program failed to commence screening, approaches to increase this response (specifically in high-risk groups) needs to be explored.

Funding Acknowledgement

Type of funding sources: None.

Paroxysmal atrial fibrillation with high vs. low arrhythmia burden: atrial remodelling and ablation outcome

AIMS

The relation between atrial tachyarrhythmia (ATA) burden in paroxysmal atrial fibrillation (AF), atrial remodelling, and efficacy of catheter ablation (CA) is unknown. We investigated whether high vs. low-burden paroxysmal AF patients have distinct clinical characteristics or electro-mechanical properties of the left atrium (LA) and whether burden impacts outcome of CA.

METHODS AND RESULTS

Atrial tachyarrhythmia burden, defined as the percentage of time spent in ATA, was assessed by insertable cardiac monitors in 105 patients before and after CA. Clinical characteristics and electro-mechanical properties of LA were compared between patients with high vs. low ATA burden. Catheter ablation efficacy was assessed by reduction in ATA burden and 1-year freedom from any ATA. Median ATA burden was 2.7% (highest tertile 9.3%). Clinical characteristics and electrical properties of LA (refractoriness, conduction velocity, low voltage) did not differ between high (≥9.3%) vs. low ATA burden (<9.3%) patients. High ATA burden patients had larger LA diameter (46.5 ± 6 vs. 42.5 ± 6mm, P < 0.01), volume (93.8 ± 22 vs. 80.4 ± 21mL, P = 0.01), and lower LA reservoir and contractile strain (19.7 ± 6 vs. 24.7 ± 6%, P < 0.01; 10.3 ± 3 vs. 12.8 ± 4%, P = 0.01). Catheter ablation reduced ATA burden by 100% (100-100) in both groups (P = 1.0). Freedom from ATA after CA was equally high (83% vs. 89%, P = 0.38).

CONCLUSION

Paroxysmal AF patients with high ATA burden have altered LA mechanical properties, reflected by larger size and impaired function. Despite mechanical remodelling of the atria, they are excellent responders to CA. Most likely the lack of fibrosis and/or advanced electrical remodelling explain why pulmonary veins remain the dominant trigger for AF in this patient cohort.

Relationship between mortality after ICD implantation and center volume in Belgium

Introduction

In Belgium ICD implantation is restricted to 23 centers. A previous analysis of our group based on aggregated results per center showed that 3y mortality varied significantly between centers ranging from 7.5 to 23.4%. Multivariate analysis demonstrated that volume, infection rate and a higher proportion of implantations in primary prevention were predictors of 3y-mortality. These findings needed to be confirmed on a patient level since they could be caused by inter-patient rather than inter-hospital differences.

Methods

The QERMID-ICD database is a retrospective database of all patients implanted with an ICD in Belgium managed by the governmental health care institution (RIZIV/INAMI). Participation is mandatory for reimbursement. We analyzed data of 9896 new implantations performed between 2010 and 2016. Following patient characteristics were available: demographics (gender, NYHA class, primary vs secondary prevention, underlying heart disease, type of device, QRS duration, age and ejection fraction (EF)), comorbidities (atrial fibrillation, diabetes, COPD, neurological disease, oncological disease and renal failure), volume of center (low &lt; median of 65 primo-implantations/year vs high &gt;65 implantations/year) and the average income of the arrondissement in which the patient lived (low income &lt; p25, median p25-p75, high &gt; p75). The primary endpoint was 3y-mortality. Chi-squared test and Mann-Whitney U test with correction for multiple testing were used and multivariate logistic regression was performed to determine the corrected odds ratio for 3-year mortality. Finally, Kaplan-Meier survival analysis was performed.

Results

Low volume centers treated different patients than high volume centers. They implant more primary prevention (66.5 vs. 61.6%), more often patients with ischemic cardiomyopathy (49.8 vs 47.9%), less often arrhythmogenic heart disease (13.2 vs 16.6%) and patients with more co-morbidities and from communities with lower average income. High volume centers used more cardiac resynchronization therapy (26.8 vs 22.5%) despite no difference in QRS width. 1 and 3-y mortality were significantly higher in the low volume centers, respectively 5.6 vs. 4.4% and 16 vs. 11.1%. This was also confirmed in Kaplan Meier survival analysis. In multivariate logistic regression underlying heart disease, income, age, EF, NYHA class, CRT, indication and most comorbidities were significantly associated with mortality, but center volume remained an independent risk factor for 3-y mortality (OR = 0.749 (0.702–0.937), p&lt;0.001).

Conclusion

Patients treated in low and high-volume centers in Belgium are different. However, there remained an association between volume and mortality of centers when controlling for these differences. Further research to elucidate if this association is due to statistical limitations of our analysis, referral bias or differences in quality of care is necessary.

Funding Acknowledgement

Type of funding source: None

P576The first handheld device for autonomic self-detection of symptomatic acute coronary artery occlusion: feasibility, performance and implications for time-efficient self-triage of outpatients with CAD

Background

Time delay between onset of symptoms and seeking medical attention is a major determinant of mortality and morbidity in patients with acute coronary artery occlusion (ACAO). Response time might be reduced by reliable self-detection of ACAO. Currently no self-applicable device can accurately detect ACAO. We have recently shown that an automatic algorithm based upon a three lead system (RELF method) accurately detects ACAO.

Purpose

In this multicenter observational study we tested the operational feasibility, sensitivity and specificity of our RELF method, built into a mobile handheld device, for detection of ACAO.

Methods

Patients with planned elective percutaneous coronary intervention (PCI), who were able to use a smartphone, were asked to perform random ambulatory self-recordings for at least one week. A similar self-recording was made before angioplasty and at 60 s of balloon occlusion.

Results

The operational feasibility of ambulatory self-recordings in enrolled patients with CAD was 59/64 (92.1%, 95% CI: 83.0–96.6). Of all self-recordings 91.1% (n=4567) were automatically classified as successful within one minute. The mean false positive rate during daily life conditions was 4.19% (95% CI: 3.29–5.10). Amongst 65 balloon occlusions, 63 index-tests at 60 s of occlusion were available. The sensitivity for the target conditions “ACAO”, “ACAO with ECG changes” and “ACAO with ECG changes and ST segment elevation myocardial infarction (STEMI) criteria” was respectively 55/63 (0.87; 95% CI: 0.77–0.93), 54/57 (0.95; 95% CI: 0.86–0.98) and 35/35 (1.00). The figure depicts all (n=3936) ST difference vector (STDVn) measurements obtained during ambulatory postural changes, exercise and coronary artery occlusion with and without ECG changes and/or STEMI criteria. Receiver Operator Curve (ROC) for ACAO at different cut-off values of the magnitude of STDVn was 0.973 (95% CI: 0.956–0.990).

Boxplots of all STDVn test recordings

Conclusions

Self-recording with our RELF device is feasible for the majority of patients with CAD. The sensitivity and specificity for automatic detection of the earliest phase of acute coronary artery occlusion support the concept of our RELF device for patient empowerment to reduce delay and increase survival without overloading emergency services. This is the first clinical study that confirms the proof-of-concept of self-detection of acute coronary artery occlusion in outpatients with CAD.

Acknowledgement/Funding

Ghent University, Industrial Research Fund (IOF reference: F2015/IOF-advanced/084).

[Practical considerations for the treatment of acute rhythm disturbances. Report of Belgium Interdisciplinary Working Group on Acute Cardiology]

Acute arrhythmia is a condition covering a wide variety of rhythm disturbances. The aim of the article is to give practical recommendations for the approach and the treatment of the patient presenting with an acute arrhythmia. We discuss bradycardia and tachycardia. Tachycardias are divided into the small QRS complex tachycardias and the wide QRS complex tachycardias. Another important distinction with immediate therapeutic consequences is that between the hemodynamic stable and unstable patient. Flowcharts with diagnostic means and therapeutic schemes are added and a table with practical considerations for electrical cardioversion.

[Recommendations for management of acute chest pain. Report of the Belgium Interdisciplinary Working Group on Acute Cardiology]

The Belgium Interdisciplinary Working group on Acute Cardiology, including cardiologists, intensivists and urgentists was formed to provide consensus regarding the management of acute chest pain in the prehospital and the early hospital phase. General recommendations and critical pathways are proposed to improve the treatment of the patients with acute coronary syndromes.

[Recommendations for the management of acute chest pain. Report of the Belgian Interdisciplinary Group on Acute Cardiology]

The Belgium Interdisciplinary Working Group on Acute Cardiology (BIWAC), including cardiologists, intensivists and urgentists was formed to give consensus regarding the management of acute chest pain in the prehospital and the early hospital phases. General recommendations and critical pathways are proposed to improve the treatment of the patients with acute coronary syndromes.

Conversion of atrial fibrillation to sinus rhythm and rate control by digoxin in comparison to placebo

AIMS

A randomized, double-blind study with a high dose of digoxin administered intravenously for conversion of atrial fibrillation (not due to haemodynamic alternations) to sinus rhythm, and for rate control in converters and non-converters was set up. Outcome measures were conversion within 12 h; time to conversion; early rate control; and stable slowing within 12 h.

METHODS

We studied 40 patients with recent onset (< 1 week) atrial fibrillation; controls received saline intravenously, the other patients digoxin 1.25 mg.

RESULTS

One patient converted before digoxin administration. Conversion occurred in 9/19 patients on digoxin and in 8/20 on placebo (ns). The mean time to conversion tended to be shorter only for digoxin. Two late conversions on placebo were observed within 24 h. Heart rate during atrial fibrillation decreased after 30 min for converters and non-converters (P < 0.05). For all patients on digoxin, heart rate after 30 min was lower compared to baseline (P < 0.002) and to placebo (P < 0.02). Persistent, stable slowing occurred only in 3/10 non-converters on digoxin (P < 0.05), and two patients developed bradyarrhythmias. QTc was shortened immediately after conversion in all patients. Converters had baseline characteristics similar to those of non-converters.

CONCLUSIONS

Intravenous digoxin offers no substantial advantages over placebo in recent onset atrial fibrillation with respect to conversion, and provides weak rate control.

Optimal defibrillation strategy and follow-up of out-of-hospital cardiac arrest. The Belgian CPCR Study Group

In the current climate of rising healthcare cost, resuscitation efforts performed outside the hospital are critically evaluated because of their limited success rate in some settings. As part of a quality assurance program between the 1st January 1991 and 31st December 1993, six centres of the Belgian CPCR study group prospectively registered cardiac arrest (CA) patients and their treatment according to the Ustein Style recommendations. In the group (n = 511) of patients initially found in ventricular fibrillation (VF) a significantly better survival rate was observed for those patients who received a 1st defibrillatory shock by the 1st tier (n = 142 (27.8%)) as compared to those defibrillated after arrival of the 2nd tier (n = 369 (72.2%)). Median time to delivery of the first shock was significantly shorter (5 min) in the 1st tier group. In a second part of the study we describe long-term management of the 28 surviving VF patients, treated by the single EMS system of Brugge between 1st January 1991 and 30th April 1995: only 6 patients eventually received an implantable cardioverter defibrillator (ICD), whereas coronary revascularization was performed in 9 patients, and 3 patients were discharged on amiodarone only. Satisfactory long-term survival after out-of-hospital VF can be achieved by an early shock followed by advanced life support and appropriate definitive treatment.

Plasma lipoprotein(a) values and severity of coronary artery disease in a large population of patients undergoing coronary angiography

To determine possible associations between lipoprotein(a) [Lp(a)] and the severity of coronary artery lesions, we measured lipid, apolipoprotein, and Lp(a) in a large population of Belgian patients (n = 1054) undergoing coronary angiography. In both women and men, univariate analysis demonstrated significant differences in the Lp(a) concentrations according to the severity of the coronary stenosis. However, after adjustment for possible confounding factors, many of these differences were attenuated, indicating that other variables that differentiate patients from control subjects also influence Lp(a) distribution. Differences in lipid, apolipoprotein, and Lp(a) concentrations between male and female patients are discussed.

Plasma Lipoprotein(a) Values and Severity of Coronary Artery Disease in a Large Population of Patients Undergoing Coronary Angiography

To determine possible associations between lipoprotein(a) [Lp(a)] and the severity of coronary artery lesions, we measured lipid, apolipoprotein, and Lp(a) in a large population of Belgian patients (n = 1054) undergoing coronary angiography. In both women and men, univariate analysis demonstrated significant differences in the Lp(a) concentrations according to the severity of the coronary stenosis. However, after adjustment for possible confounding factors, many of these differences were attenuated, indicating that other variables that differentiate patients from control subjects also influence Lp(a) distribution. Differences in lipid, apolipoprotein, and Lp(a) concentrations between male and female patients are discussed.

Functional and phenotypic differences between CD4+ and CD4- T cell receptor-gamma delta clones from peripheral blood

CD4+ TCR-gamma delta+ T cells comprise a very small subset of TCR-gamma delta+ T cells. CD4+ TCR gamma delta+ T cell clones were established to study the phenotypical and functional characteristics of these cells. Thirty-four CD4+ TCR-gamma delta+ T cell clones were established after sorting CD4+ T cells from a pre-expanded TCR-gamma delta+ T cell population. These clones as well as the CD4- TCR-gamma delta+ T cells from the same donor used V gamma 2 and V delta 2. In a second cloning experiment CD4+ TCR-gamma delta+ T cells were cloned directly from freshly isolated TCR-gamma delta+ T cells using a cloning device coupled to a FACS sorter. Forty-three clones were obtained, which all expressed CD4 and TCR-gamma delta. Eleven of these clones used V delta 1 and three of them coexpressed V gamma 2. The other CD4+ TCR-gamma delta+ T cell clones used both V delta 2 and V gamma 2. CD4+ TCR-gamma delta+ T cell clones expressed CD28 irrespective of the V gamma or V delta usage, and were CD11b negative. Three CD4-CD8+ TCR-gamma delta+ clones expressed CD8 alpha but not CD8 beta and were CD11b positive. CD28 expression among CD4-CD8+ and CD4-CD8- was variable but lower than on CD4+ T cell clones. CD4- TCR-gamma delta+ T cell clones using V gamma 2 and V delta 2 specifically lyse the Burkitt lymphoma cell line Daudi and secrete low levels of IFN-gamma and granulocyte-macrophage-CSF upon stimulation with Daudi. In contrast, most CD4+ T cell clones that use V gamma 2 and V delta 2 had a very low lytic activity against Daudi cells and secrete high levels of IFN-gamma and granulocyte-macrophage-CSF after stimulation with Daudi cells. The NK-sensitive cell line K562 was killed efficiently by the CD4- TCR-gamma delta+ T cell clones, but not by CD4+ TCR-gamma delta+ T cell clones, and could not induce cytokine secretion in CD4+ or CD4- T cell clones. CD4+ TCR-gamma delta+ T cell clones, but not the CD4- clones, could provide bystander cognate T cell help for production of IgG, IgM, and IgA in the presence of IL-2 and IgE in the presence of IL-4. Thus, CD4+ TCR-gamma delta+ T cells are similar to CD4+ TCR-alpha beta+ T cells in their abilities to secrete high levels of cytokines and to provide T cell help in antibody production.(ABSTRACT TRUNCATED AT 400 WORDS)

Functional and phenotypic differences between CD4+ and CD4- T cell receptor-gamma delta clones from peripheral blood

CD4+ TCR-gamma delta+ T cells comprise a very small subset of TCR-gamma delta+ T cells. CD4+ TCR gamma delta+ T cell clones were established to study the phenotypical and functional characteristics of these cells. Thirty-four CD4+ TCR-gamma delta+ T cell clones were established after sorting CD4+ T cells from a pre-expanded TCR-gamma delta+ T cell population. These clones as well as the CD4- TCR-gamma delta+ T cells from the same donor used V gamma 2 and V delta 2. In a second cloning experiment CD4+ TCR-gamma delta+ T cells were cloned directly from freshly isolated TCR-gamma delta+ T cells using a cloning device coupled to a FACS sorter. Forty-three clones were obtained, which all expressed CD4 and TCR-gamma delta. Eleven of these clones used V delta 1 and three of them coexpressed V gamma 2. The other CD4+ TCR-gamma delta+ T cell clones used both V delta 2 and V gamma 2. CD4+ TCR-gamma delta+ T cell clones expressed CD28 irrespective of the V gamma or V delta usage, and were CD11b negative. Three CD4-CD8+ TCR-gamma delta+ clones expressed CD8 alpha but not CD8 beta and were CD11b positive. CD28 expression among CD4-CD8+ and CD4-CD8- was variable but lower than on CD4+ T cell clones. CD4- TCR-gamma delta+ T cell clones using V gamma 2 and V delta 2 specifically lyse the Burkitt lymphoma cell line Daudi and secrete low levels of IFN-gamma and granulocyte-macrophage-CSF upon stimulation with Daudi. In contrast, most CD4+ T cell clones that use V gamma 2 and V delta 2 had a very low lytic activity against Daudi cells and secrete high levels of IFN-gamma and granulocyte-macrophage-CSF after stimulation with Daudi cells. The NK-sensitive cell line K562 was killed efficiently by the CD4- TCR-gamma delta+ T cell clones, but not by CD4+ TCR-gamma delta+ T cell clones, and could not induce cytokine secretion in CD4+ or CD4- T cell clones. CD4+ TCR-gamma delta+ T cell clones, but not the CD4- clones, could provide bystander cognate T cell help for production of IgG, IgM, and IgA in the presence of IL-2 and IgE in the presence of IL-4. Thus, CD4+ TCR-gamma delta+ T cells are similar to CD4+ TCR-alpha beta+ T cells in their abilities to secrete high levels of cytokines and to provide T cell help in antibody production.(ABSTRACT TRUNCATED AT 400 WORDS)

Atrial capture and dual chamber pacing

During dual chamber pacing it is sometimes impossible to assess atrial capture even on the 12-lead ECG. We developed a strategy to identify atrial capture when it is not possible to do so by ECG, and when the ECG shows no evidence of spontaneous or paced atrial activity.