Recurring patterns of atrial fibrillation in surface ECG predict restoration of sinus rhythm by catheter ablation

Background Non-invasive tools to help identify patients likely to benefit from catheter ablation (CA) of atrial fibrillation (AF) would facilitate personalised treatment planning. Aim To investigate atrial waveform organisation through recurrence plot indices (RPI) and their ability to predict CA outcome. Methods One minute 12-lead ECG was recorded before CA from 62 patients with AF (32 paroxysmal AF; 45 men; age 57±10 years). Organisation of atrial waveforms from i) TQ intervals in V1 and ii) QRST suppressed continuous AF waveforms (CAFW), were quantified using RPI: percentage recurrence (PR), percentage determinism (PD), entropy of recurrence (ER). Ability to predict acute (terminating vs. non-terminating AF), 3-month and 6-month postoperative outcome (AF vs. AF free) were assessed. Results RPI either by TQ or CAFW analysis did not change significantly with acute outcome. Patients arrhythmia-free at 6-month follow-up had higher organisation in TQ intervals by PD (

Arrhythmias After Tetralogy of Fallot Repair

Tetralogy of Fallot is the most common cyanotic congenital heart disease, with a good outcome after total surgical correction. In spite of a low perioperative mortality and a good quality of life, late sudden death remains a significant clinical problem, mainly related to episodes of sustained ventricular tachycardia and ventricular fibrillation. Fibro-fatty substitution around infundibular resection, intraventricular septal scar, and patchy myocardial fibrosis, may provide anatomical substrates of abnormal depolarization and repolarization causing reentrant ventricular arrhythmias. Several non-invasive indices based on classical examination such as ECG, signal-averaging ECG, and echocardiography have been proposed to identify patients at high risk of sudden death, with hopeful results. In the last years other more sophisticated invasive and non-invasive tools, such as heart rate variability, electroanatomic mapping and cardiac magnetic resonance added a relevant contribution to risk stratification. Even if each method per se is affected by some limitations, a comprehensive multifactorial clinical and investigative examination can provide an accurate risk evaluation for every patien

Predviđanje postoperacijske fibrilacije atrija korištenjem SVM klasifikatora.

In patients undergoing Coronary Artery Bypass G rafting (CABG) surgery postoperative atrial fibrillation (AF) occurs with prevalence of up to 40%. The highest incidence is between the second and third day after the operation. Following cardiac surgery AF causes various complications, hemodynamic instability, and can cause heart attack, cerebral and other thromboemolisms. AF increases morbidity, duration and expense of medical treatment. This study aims to identify patients at high risk of postoperative AF. An early prediction of AF would provide a timely prophylactic treatment and would reduce incidence of arrhythmia. Patients at low risk of postoperative AF could be excluded from the side effects of anti-arrhythmic drugs. The investigation included 50 patients in whom lead II electrocardiograms were continuously recorded for 48 hours following CABG. Univariate statistical analysis was used in the search of signal features that might predict AF. The most promising identified features were: P wave duration, RR interval duration and PQ segment level. On the basis of these a nonlinear multivariate prediction model was made deploying a Support Vector Machine (SVM) classifier. The prediction accuracy was found uprising over the time. At 48 hours following CABG; the measured best average sensitivity was 95 . 9% and specificity 93. 4% . The positive and negative predictive accuracy were 88. 9% and 98. 8% , respectively and the overall accuracy was 94. 6% . In regard to the prediction accuracy, the risk assessment and prediction of postoperative A F are optimal to be done in the period between 24 and 48 hours following CABG.Postoperacijska fibrilacija atrija (AF) pojavljuje se u oko 40% pacijenata podvrgnutih operaciji aortokoronarnog premoštenja (CABG), s najvećom učestalosti pojavljivanja oko trećeg dana nakon operacije. Postoperacijska AF može stvoriti brojne komplikacije poput hemodinamske nestabilnosti, srčanog udara, cerebralnih i drugih tromboembolija; povećava morbiditet, trajanje i troškove liječenja. S tudija ima za cilj rano otkrivanje pacijenta sa visokim rizikom razvoja postoperacijske AF, što bi osiguralo pravovremenu profilaktičku terapiju i smanjilo učestalost aritmije, dok bi pacijenti sa niskim rizikom razvoja postoperacijske AF bili pošteđeni nuspojava antiaritmičkih lijekova. Podatkovni skup uključuje 50 pacijenata, snimanih II standardnim odvodom elektrokardiografa, kontinuirano u razdoblju od 48 sati nakon operacije. Univarijatna statistička analiza korištena je za određivanje parametara signala koji bi mogli predvidjeti AF, te su kao najznačajniji određeni: trajanje P vala, trajanje RR intervala i razina PQ spojnice; na temelju kojih je izveden nelinearni multivarijatni predikcijski model zasnovan na SVM klasifikatoru. Ukupna predikcijska točnost modela povećava se s vremenom. U 48 . satu nakon operacije najbolje prosječne značajke iznosile su: osjetljivost 95 , 9%, specifičnost 93, 4% , pozitivna prediktivnost 88, 9% , negativna prediktivnost 98 , 8% te ukupna točnost 94, 6% . Prema rezultatima predikcijske točnosti, procjenu rizika i predikciju postoperacijske AF optimalno bilo bi načiniti u periodu između 24-tog i 48-og sata nakon operacije ugradnje aortokoronarnih premosnica

CORRELATION BETWEEN EPICARDIAL ADIPOSE TISSUE AND ATRIAL FIBRILLATION BURDEN IN PATIENTS UNDERGOING CORONARY ARTERY BYPASS GRAFT SURGERY

ABSTRACT Background: The epicardial adipose tissue is located between the myocardium and the visceral pericardium, lying directly above the myocardium without any fascia. Epicardial adipose tissue presents itself with histological features typical of the brown adipose tissue. It plays a cardioprotective role through thermoregulation, energy homeostasis and anti-inflammatory regulation. However, in pathological conditions, epicardial adipose tissue may have a pro-inflammatory effect. Less is known about the role played by epicardial adipose tissue in patients with a history of atrial fibrillation. Some studies suggest an association between increased epicardial adipose tissue (volume and thickness) and atrial fibrillation. Nonetheless, there is little data about histological characterisation of epicardial adipose tissue in patients with a history of atrial fibrillation. Aim of the study: To evaluate the quantitative (using echocardiography) and qualitative characteristics (intra-operatory biopsy for histological characterisation) of epicardial adipose tissue in relation to atrial fibrillation burden after coronary artery bypass graft. Patients and methods: Prospective single-centre study approved by the ethics committee of Verona and Rovigo in July 2018. Patients undergoing coronary artery bypass graft with preserved left ventricular ejection fraction were included, after giving informed consent. Patients with atrial fibrillation and immunosuppressive therapy history were excluded. All enrolled patients underwent a medical evaluation to collect clinical history, a transthoracic echocardiography to measure epicardial adipose tissue thickness and collection of a bioptic sample containing right appendage and epicardial adipose tissue during coronary artery bypass graft. After surgery post-surgical clinical course and telemetry were collected. Lastly, histological characterisation (PLIN1 and fibrosis) of the bioptic samples was performed. Results: 56 patients undergoing coronary artery bypass graft were enrolled between 10th September 2018 and 3rd September 2019 in Cardiology and Cardiac Surgery departments. The mean hospitalisation was 11,9 \ub1 6,9 days and the postsurgical hospitalisation was 7,9 \ub1 3,7 days. 44 (78,6%) patients were male and the median age was 68,45 \ub1 9,2 years. All patients were continuously monitored with telemetry from the day of cardiac surgery until discharge. No major complications occurred, only one death unrelated to the surgery. Out of the total number of patients, 22 (39%) had at least one episode of atrial fibrillation. In the population that developed atrial fibrillation there was a bigger atrial volume, a higher degree of diastolic disfunction (E/A rate), a thicker layer of epicardial adipose tissue and an older median age in comparison to the group that did not develop it. Epicardial adipose tissue measured using echocardiogram with a cut off of 4 mm was a predictor of atrial fibrillation with an OR of 1,49 [1,09-2,04], 73% of sensibility and 89% of specificity. Furthermore, from the histological analyses of biopsies, the patients with atrial fibrillation had a significantly higher percentage of fibrosis, while adipose infiltration was not significantly higher. Through univariate analysis, atrial volume (OR 1,05 CI 1,01-1,09, p 0,022), E/A rate (OR 0,04 CI 0,02-0,72 p 0,29), the percentage of fibrosis (OR 1,12 CI 1,00-1,25 p 0,045) and age (OR 1,17 CI 1,07-1,28 p 0,001) were predictors of atrial fibrillation as well as the thickness of the epicardial adipose tissue. Through multivariate analysis atrial volume (p 0,027), fibrosis (p 0,003) and age (p 0,039) were independent predictors of atrial fibrillation. Conclusion: Post cardiac surgical atrial fibrillation is frequent. Epicardial adipose tissue measured by echocardiogram, atrial volume, fibrosis and age are predictors of post cardiac surgical atrial fibrillation

Clinical aspects of device-detected arrhythmias

INTRODUCTION Cardiac implantable electronic devices (CIEDs) enable continuous monitoring of the heart rhythm. CIEDs constitute a unique opportunity for detecting arrhythmias, as the duration of cardiac monitoring is of the utmost importance for the detection rate. The CIED population consists mostly of patients from older age categories where risk factors for atrial fibrillation (AF) are common. A dual-chamber device can detect and store episodes with a high atrial rate, i.e. atrial high-rate episodes (AHREs). AHREs confirmed to be AF, atrial flutter or focal atrial tachycardia are termed subclinical AF. Both terms refer to patients with no symptoms attributed to AF, with no previous diagnosis of clinical AF. These episodes of device-detected AF are associated with increased risk of ischaemic stroke, although the risk seems to be lower than in patients with documented clinical AF, and the benefit of oral anticoagulation (OAC) treatment in this population has not been established. Patients presenting with syncope represent a diagnostic challenge. Initial evaluation can provide the underlying mechanism in up to half of the patients. However, the mechanism remains unexplained in many patients, and long-term electrocardiogram (ECG) monitoring with an implantable loop recorder (ILR) enables ECG recording at the time of syncope recurrence, which can reveal the underlying mechanism. The aim of this thesis is to highlight different aspects of arrhythmias diagnosed with CIEDs, both from a diagnostic and a therapeutic point of view. More specifically, it aims to describe the incidence of subclinical AF/AHREs in a pacemaker population, along with its OAC treatment, and the incidence of ischaemic stroke and vascular dementia. In addition, it will explore the role of the baseline 12-lead ECG in predicting the syncope mechanism during ILR monitoring, and whether age and gender impact the evaluation before the implantation and subsequent diagnostic yield of the ILR. Finally, the thesis will test the hypothesis that patients with incident AF during inpatient care after coronary artery bypass graft (CABG) surgery often experience a relapse of AF within a year, with little chance of detection. METHODS AND RESULTS In study I, consecutive patients were enrolled who had been implanted with a dual-chamber device for the indication of sinus node disease or atrioventricular block/ bundle branch block between 2010 and 2014 in Halland County in Sweden. The incidence of subclinical AF/AHREs, ischaemic stroke, or vascular dementia, and the initiation of and/or any change of OAC treatment were recorded during follow-up. At inclusion, 271 patients had clinical/known AF, of which 80% (216/271) were on OAC treatment. Four hundred eleven patients had no history of AF, and of these 30% (125/411) were diagnosed with subclinical AF/AHREs during a mean follow-up of 38 months. 62% of these were prescribed OAC treatment. Patients with congestive heart failure (p= .03) and age >75 years (p= .0002) were more often diagnosed with subclinical AF/AHREs. The annual stroke incidence was 2.1% in patients with clinical/known AF, 1.9% in patients with subclinical AF/AHREs, and 1.4% in patients with no AF. Corresponding values for a diagnosis of vascular dementia was 11.2%, 5.6% (p= .09), and 6.2% (p= .048). The study population in studies II and III consisted of consecutive patients with unexplained syncope in Halland County in Sweden, who had been selected to be implanted with an ILR after an initial non-diagnostic evaluation between 2007 and 2016. In study II, baseline 12- lead ECG was compared with clinically adjudicated cause of syncope. In study III the role of age and gender in the evaluation before implantation, and in the diagnostic yield of the ILR, was reported. There is a notable difference between the two terms ILR-guided diagnosis (study II) and ECG-based diagnosis (study III). ILR-guided diagnosis refers to all patients where the ILR has informed the clinical diagnosis, i.e. where captured ECG recordings both during syncope recurrence or other times have enabled a clinical diagnosis to be made, while ECG-based diagnosis only includes patients with syncope recurrence. In total, 300 (147 women) patients were included. The mean age was 66±16 years. In study II, 49% (146/300) received an ILR-guided diagnosis. Bifascicular block was the second most common pathological baseline 12-lead ECG finding (n=33). It was most common in patients ≥60 years of age (31/33), and more common in patients who received an ILR-guided diagnosis (bifascicular block: 25/33, 76%; normal baseline 12-lead ECG: 90/205, 44%, p< .001). Among patients with bifascicular block, 96% (24/25) were clinically adjudicated to have an arrhythmia-caused syncope, and of these, 23 had ECG recordings of a bradyarrhythmia. Bifascicular block was a strong predictor of a clinically adjudicated arrhythmia-caused syncope, with an adjusted odds ratio of 5.5 (95%CI (confidence interval) 2.3-13.2), p< .001, and a positive predictive value of 73%. In the total population, bifascicular block predicted a clinically adjudicated arrhythmia-caused syncope due to bradyarrhythmia, with an adjusted odds ratio of 11.4 (95%CI 5.0-26.2), p< .001. In study III, women experienced syncope recurrence and received an ECG-based diagnosis more often than men (women: 56/147, 38%; men: 33/153, 22%; p= .001), mainly because of a higher incidence of non-arrhythmic syncope recurrence, i.e. syncope with a normal ECG recording (women: 27/147, 18%; men: 15/153, 10%; p= .045). Patients ≥60 years of age had the lowest rate of pre-implant tests (<40 years: 6.5±1.2; 40-59 years: 5.75±1.0; and ≥60 years: 5.1±1.9; p= .002) but the highest rate of arrhythmic syncope (<40 years: 3/11, 27%; 41-59 years: 7/18, 39%; and ≥60 years: 37/60, 62%; p= .045). Fifty patients with no recurrent syncope had ECG findings potentially indicative of recurrent syncope. Study IV was a sub-study of the prospective AFAF study (Atrial Fibrillation AFter CABG and percutaneous coronary intervention). In short, the AFAF study investigates the incidence of AF after percutaneous coronary intervention or CABG surgery by non-invasive handheld ECG recordings. It is investigated three times daily during the first postoperative month, and thereafter for two weeks at three, 12 and 24 months in addition to routine care. This sub-study added continuous ECG monitoring with an ILR. The primary endpoint was the proportion of patients with incident or recurrent AF during the 12-month monitoring period. The secondary endpoints were the proportion of patients who developed persistent AF and calculated AF burden. In total, 27/40 (68%) patients were diagnosed with incident AF, 21 in hospital and six later. Eighteen of these 27 (67%) also experienced AF recurrence, and three patients progressed into persistent AF. The incidence of AF episodes was highest during the first 30 postoperative days, as 17/40 patients had episodes of AF after discharge within this period. The rate of incident and recurrent AF after the first 30 days was low: three patients had incident AF and 10 patients recurrent AF. The CHA2DS2-VASc (Congestive heart failure, Hypertension, Age >75 years (2 points), Diabetes, Stroke (2 points), Vascular disease, Age 65-74 and Sex (female)) score was higher in patients with AF than in patients who remained in sinus rhythm: median 4 (IQR (interquartile range) 1) and median 3 (IQR 2) respectively, p= .006. In patients with paroxysmal AF, the AF burden was low: 0.1% (IQR 0.28). Handheld ECG identified fewer patients with AF after discharge than the ILR (handheld ECG: 9/20, 45%; ILR: 20/20, 100%; p= .001). CONCLUSIONS CIEDs are a valuable asset in arrhythmia diagnostics, and can inform clinical decisions. Subclinical AF/AHREs were common, and were associated with older age and congestive heart failure. The stroke incidence was low, but clinical/known AF was associated with an increased risk of vascular dementia. In syncope patients bifascicular block at baseline 12-lead ECG predicted a clinically adjudicated arrhythmia-caused syncope, commonly due to intermittent complete heart block. Women experienced syncope recurrence more often than men, especially for non-arrhythmic reasons. The highest rate of arrhythmic syncope and the lowest rate of pre-implant tests were found in patients ≥60 years of age. In patients treated with CABG surgery, the recurrence rate of AF was high in patients with incident AF during hospitalisation, especially during the first postoperative month. After the first month, the rate of incident and recurrent AF was low. The ILR was more effective in detecting patients with AF than handheld ECG

Prediction of postoperative atrial fibrillation using the electrocardiogram: A proof of concept

Hospital patients recovering from major cardiac surgery are at high risk of postoperative atrial fibrillation (POAF), an arrhythmia which can be life-threatening. With the development of a tool to predict POAF early enough, the development of the arrhythmia could be potentially prevented using prophylactic treatments, thus reducing risks and hospital costs. To date, no reliable method suitable for autonomous clinical integration has been proposed yet. This thesis presents a study on the prediction of POAF using the electrocardiogram. A novel P-wave quality assessment tool to automatically identify high-quality P-waves was designed, and its clinical utility was assessed. Prediction of paroxysmal atrial fibrillation (AF) was performed by implementing and improving a selection of previously proposed methods. This allowed to perform a systematic comparison of those methods, and to test if their combination improved prediction of AF. Finally, prediction of POAF was tested in a clinically relevant scenario. This included studying the 48 hours preceding POAF, and automatically excluding noise-corrupted P-waves using the quality assessment tool. The P-wave quality assessment tool identified high-quality P-waves with high sensitivity (0.93) and good specificity (0.84). In addition, this tool improved the ability to predict AF, since it improved the precision of P-wave measurements. The best predictors of AF and POAF were measurements of the variability in P-wave time- and morphological features. Paroxysmal AF could be predicted with high specificity (0.93) and good sensitivity (0.82) when several predictors were combined. Furthermore, POAF could be predicted 48 hours before its onset with good sensitivity (0.74) and specificity (0.70). This leaves time for prophylactic treatments to be administered and possibly prevent POAF. Despite being promising, further work is required for these techniques to be useful in the clinical setting

Circulating Levels of Ferritin, RDW, PTLs as Predictive Biomarkers of Postoperative Atrial Fibrillation Risk after Cardiac Surgery in Extracorporeal Circulation

Postoperative atrial fibrillation (POAF) is the most common arrhythmia after cardiac surgery in conventional extracorporeal circulation (CECC), with an incidence of 15-50%. The POAF pathophysiology is not known, and no blood biomarkers exist. However, an association between increased ferritin levels and increased AF risk, has been demonstrated. Based on such evidence, here, we evaluated the effectiveness of ferritin and other haematological parameters as POAF risk biomarkers in patients subjected to cardiac surgery. We enrolled 105 patients (mean age = 70.1 +/- 7.1 years; 70 men and 35 females) with diverse heart pathologies and who were subjected to cardiothoracic surgery. Their blood samples were collected and used to determine hematological parameters. Electrocardiographic and echocardiographic parameters were also evaluated. The data obtained demonstrated significantly higher levels of serum ferritin, red cell distribution width (RDW), and platelets (PLTs) in POAF patients. However, the serum ferritin resulted to be the independent factor associated with the onset POAF risk. Thus, we detected the ferritin cut-off value, which, when &gt;= 148.5 ng/mL, identifies the subjects at the highest POAF risk, and with abnormal ECG atrial parameters, such as PW indices, and altered structural heart disease variables. Serum ferritin, RDW, and PTLs represent predictive biomarkers of POAF after cardiothoracic surgery in CECC; particularly, serum ferritin combined with anormal PW indices and structural heart disease variables can represent an optimal tool for predicting not only POAF, but also the eventual stroke onset

Circulating Levels of Ferritin, RDW, PTLs as Predictive Biomarkers of Postoperative Atrial Fibrillation Risk after Cardiac Surgery in Extracorporeal Circulation

Postoperative atrial fibrillation (POAF) is the most common arrhythmia after cardiac surgery in conventional extracorporeal circulation (CECC), with an incidence of 15-50%. The POAF pathophysiology is not known, and no blood biomarkers exist. However, an association between increased ferritin levels and increased AF risk, has been demonstrated. Based on such evidence, here, we evaluated the effectiveness of ferritin and other haematological parameters as POAF risk biomarkers in patients subjected to cardiac surgery. We enrolled 105 patients (mean age = 70.1 +/- 7.1 years; 70 men and 35 females) with diverse heart pathologies and who were subjected to cardiothoracic surgery. Their blood samples were collected and used to determine hematological parameters. Electrocardiographic and echocardiographic parameters were also evaluated. The data obtained demonstrated significantly higher levels of serum ferritin, red cell distribution width (RDW), and platelets (PLTs) in POAF patients. However, the serum ferritin resulted to be the independent factor associated with the onset POAF risk. Thus, we detected the ferritin cut-off value, which, when &gt;= 148.5 ng/mL, identifies the subjects at the highest POAF risk, and with abnormal ECG atrial parameters, such as PW indices, and altered structural heart disease variables. Serum ferritin, RDW, and PTLs represent predictive biomarkers of POAF after cardiothoracic surgery in CECC; particularly, serum ferritin combined with anormal PW indices and structural heart disease variables can represent an optimal tool for predicting not only POAF, but also the eventual stroke onset