Abstract
Atrial fibrillation (AF) is a supraventricular arrhythmia characterized by irregular atrial stimulation resulting in ineffective atrial contraction. The surface ECG exhibits completely irregular RR intervals while there are no distinct P waves. Electrical activity can be seen on the electrocardiogram (ECG) as thin, in the form of fine irregular fluctuations of the baseline, with varying morphology (f). In order to be diagnosed, an AF episode should be lasted at least 30 seconds or longer, according to the European Cardiology Society (ESC) 2016 guidelines for AF management.According to the current ESC guidelines for the management of AF, AF is presented in various patterns forms and is classified as follows: first diagnosed AF, paroxysmal AF, persistent AF, long-lasting persistent AF, and permanent AF.The clinical manifestation of arrhythmia for patients varies from patient to patient, and may include: fatigue, dizziness, palpitations, chest pain, angina, dyspnoea, syncope, and heart fa ...
Atrial fibrillation (AF) is a supraventricular arrhythmia characterized by irregular atrial stimulation resulting in ineffective atrial contraction. The surface ECG exhibits completely irregular RR intervals while there are no distinct P waves. Electrical activity can be seen on the electrocardiogram (ECG) as thin, in the form of fine irregular fluctuations of the baseline, with varying morphology (f). In order to be diagnosed, an AF episode should be lasted at least 30 seconds or longer, according to the European Cardiology Society (ESC) 2016 guidelines for AF management.According to the current ESC guidelines for the management of AF, AF is presented in various patterns forms and is classified as follows: first diagnosed AF, paroxysmal AF, persistent AF, long-lasting persistent AF, and permanent AF.The clinical manifestation of arrhythmia for patients varies from patient to patient, and may include: fatigue, dizziness, palpitations, chest pain, angina, dyspnoea, syncope, and heart failure. Many patients, however, remain asymptomatic.The natural history of AF after the first symptomatic episode is not fully known, as most data are derived from long-term follow-up on the basis of symptomatic episodes of the arrhythmia. The actual incidence of AF remains unclear given the sporadic occurrence of the disease episodes and the fact that many of them are asymptomatic. Characteristically, at least one-third of patients do not report symptoms or impair of their quality of life. In these cases the diagnosis is accidental or due to the complications of the disease, such as thromboembolic events.Patients with AF may be symptomatic or asymptomatic ("silent" AF). In addition, many patients may experience both symptomatic and asymptomatic episodes. Arrhythmia is usually diagnosed in patients in the course of a symptomatic AF episode or at random in an opportunistic screening for AF of a patient in cases of asymptomatic arrhythmia. "Silent" AF is common, while asymptomatic AF episodes are at least as dangerous as the symptomatic, with the patient experiencing a similar thromboembolic risk.Currently available devices for AF detection such as Holter monitoring and external electrocardiographic recorders are of limited value, given that their efficacy depends on the appearance of the arrhythmic episode during the specific period of time selected for monitoring. Furthermore external electrocardiographic recorders albeit showing an increased diagnostic yield, have low acceptance by patients. On the other hand, monitoring devices activated by the patients have limited value given that the majority of episodes of AF are silent and the symptoms that patients attribute to the arrhythmia are in fact unrelated to it. There is significant evidence that prolonged ECG monitoring enhances the detection of undiagnosed AF, e.g. follow-up for 72 hours after a stroke or even longer. In addition, in stroke patients, additional long-term non-invasive ECG monitoring or placement of an implantable loop recorder (ILR) should be evaluated by the physician in accordance with latest ESC guidelines for the detection of asymptomatic AF (IIa, B).Recently, small sized devices placed through a small incision with local anesthesia, the implantable loop recorders (ILR) are capable of long-term monitoring and detection of AF episodes. These devices have a high sensitivity (96.1-100%) and a good specificity (67-85.4%) in the detection of AF episodes. These devices incorporate sophisticated algorithms that recognize AF based on the degree of scattering of the R-R intervals during a timeframe of 2 minutes. ILR continuously monitor patient’s subcutaneous ECG (for up to 3 years) with almost 50 minutes of ECG storage and therefore can provide continuous long-term rhythm monitoring. AIMThe aim of the present study is to evaluate comprehensively, the impact of the ILRs in reducing morbidity and mortality and the natural course of the arrhythmia, among patients presenting with their first symptomatic episode. Furthermore, we aim to identify predictors of AF recurrence as well as factors related to the occurrence of symptomatic AF episodes.The present study will ensure optimal long-term rhythm monitoring of patients presenting with a first documented AF episode with the use of an ILR specifically designed for AF detection. The study findings expected to elucidate the natural course of AF after the first documented episode and to clarify the following clinically relevant issues:•Impact of ILR-XT on the composite end point of morbidity and mortality.So far therapeutic strategy after the first AF episode is to some extend arbitrary. Antiarrhythmic and antithrombotic drugs are recommended based on the symptomatic AF episodes or episodes that by chance are recorded during ambulatory monitoring. This strategy however does not seem optimal. For example a high percentage of patients after their first AF episode do not suffer any other episode in the future. In these patients antithrombotic therapy which is associated with an unfavorable side-effect profile may not be necessary. •Recognition of time distribution, duration and true AF recurrence rate.Data retrieval will verify the true AF recurrence rate including both symptomatic and asymptomatic episodes, the 24-hour distribution and duration of every recurrent episode as well as the total AF burden. The documentation of the duration and pattern of AF recurrences is of clinical relevance in order to define the need for ‘early’ initiation of anticoagulation treatment among patients presenting with a first AF episode. •Estimation of the percentage of asymptomatic episodes. Our study findings will allow the calculation of the number and total burden of asymptomatic AF episodes. Furthermore, we aim to identify characteristics associated with the occurrence of symptoms during arrhythmia recurrence (e.g. average ventricular rate and RR variability during AF recurrence, age) and the impact of co-administered rate reducing agents (beta-blockers, calcium channel blockers, digitalis) on the relative percentage of asymptomatic episodes. •Identification of factors which are prognostic of AF recurrence.The documentation of prognostic factors may identify a certain subgroup of patients that are at higher risk for AF recurrence after a first documented episode. Documentation of similar factors (e.g. cardiovascular risk factors, diabetes, obesity, sleep-apnoea, vascular disease, coronary artery disease, structural heart disease, renal dysfunction as well as fibrogenic or inflammatory factors) could formulate a certain profile of patients with a need for more aggressive ECG screening and potentially a lower threshold for initiation of antithrombotic therapy upon first AF documentation. •Prospective evaluation of AF progression.Prospective long-term rhythm monitoring of our patient cohort will provide information regarding AF progression, increments in duration of subsequent AF recurrences, time frame for progression from paroxysmal to persistent AF. Furthermore, we could identify factors associated with accelerated or delayed AF progression.•Efficacy of various therapeutic approaches aiming to restore and maintain sinus rhythm.•Relation of AF duration and pattern of AF recurrence with patient prognosis and occurrence of AF-related complications. METHODSThirty (30) consecutive patients older than 18 years (mean age 66.9 ± 10 years; 14 men) who had had a first ECG documented episode of paroxysmal AF were included. After sinus rhythm restoration, an ILR (Reveal XT 9529; Medtronic, Minneapolis, Minnesota, USA) was inserted subcutaneously under local anesthesia. Patients’ medical history was recorded, and a physical examination, a 12-lead standard ECG recording, and an echocardiographic study were performed at the time of enrollment. The patients underwent a stress ECG with the Bruce treadmill protocol and/or nuclear single photon emission computed tomography (SPECT) stress testing using thallium nuclear agents, in order to determine the possibility of coronary artery disease (CAD). If there was strong evidence of CAD a coronary angiogram was performed. Stroke risk was assessed by the CHA2DS2-VASc score. The EHRA score was used for the classification of the AF-related symptoms. Follow-up visits were scheduled to be performed after one month, three months, and every three months thereafter for a period of three years.All patients gave written informed consent, the study was organized according to ethical considerations, as described in the Declaration of Helsinki for human medical studies, and the protocol was approved by the institutional medical ethics committee. Types of AF were defined according to the 2016 ESC guidelines.Exclusion criteria included: •patients with permanent AF•patients with an episode of AF attributed to reversible or transient causes such as acute myo- or peri-carditis, acute coronary syndromes, acute pulmonary embolism, metabolic disorders (hyperthyroidism, pheochromocytoma), drug abuse (e.g cocaine) and caffeine and alcohol intake (holiday heart syndrome).•pregnancy•unwillingness to give written consentAfter the implantation, all the patients were trained and were instructed to activate the device after the onset of symptoms indicative of the arrhythmia (palpitations, dizziness, fast heartbeat, syncope or presyncope). The Reveal XT detects the occurrence of AF episodes using an automatic algorithm based on the pattern of R-wave interval variability within 2-minute periods. The memory of the device can store up to 22.5 min of ECG recordings from patient-activated episodes and up to 27 min of ECG recordings from automatically detected arrhythmias. For each automatically detected AF episode the Reveal XT stores an ECG of the first 2 min of the episode, while for each patient-activated episode it stores the ECG 6.5 min before the patient’s activation and 1 min after. The device’s memory was reset after a patient’s visit. All the recorded episodes were reviewed by two physicians of our department, who had full access to the data and take responsibility for their interpretation, while the statistical analyses were carried out by our department’s statistician. RESULTS & DISCUSSIONAsymptomatic versus symptomatic episodes in patients with paroxysmal atrial fibrillation via long-term monitoring with implantable loop recorders.Background: The presentation of atrial fibrillation (AF) varies remarkably, from totally asymptomatic to symptomatic patients, while the same individual may present symptomatic and asymptomatic episodes. We aimed to identify electrocardiographic differences between symptomatic and asymptomatic episodes and to find parameters related to the appearance of symptoms.Methods: Thirty (30) consecutive patients (age 66.9 ± 10 years) with paroxysmal AF received an implantable loop recorder. Three types of episodes were defined: asymptomatic (ASx), symptomatic (Sx), and mixed asymptomatic-symptomatic (AS-Sx). The heart rate (HR) and heart rate variability (HRV) were recorded during the first 2 minutes of each ASx or Sx episode, and during the first 2 minutes of both the symptomatic and asymptomatic periods in AS-Sx.Results: Eighty-two (82) episodes from twenty-five patients were evaluated. Mean HR was 142.48±25.84 bpm for Sx and 95.71±19.29 bpm for ASx (p<0.001). Mean HRV was 92.62±42.29 ms for Sx and 150.06±49.68 ms for ASx (p<0.001). In AS-Sx, mean HR was 102.91±24.54 bpm for the asymptomatic and 141.88±23.43 bpm for the symptomatic period (p<0.001). Mean HRV was 173.55±61.30 ms for the asymptomatic and 87.33±30.65 ms for the symptomatic period (p=0.003). There were no significant correlations between patients’ characteristics and the clinical presentation of the arrhythmia.Conclusions: The ASx were characterized by a lower HR and higher HRV compared to Sx. In As-Sx, the asymptomatic period was characterized by a lower HR and higher HRV compared to the symptomatic. These findings suggest a possible contribution of variations in the autonomic nervous system (ANS) activity to the perception of the arrhythmia.In this study, we found that a high percentage of paroxysmal AF episodes were asymptomatic, and for the first time we showed that symptomatic AF episodes are characterized by a higher HR and lower HRV compared to asymptomatic AF episodes. Furthermore, in many AF episodes that started as asymptomatic and were perceived later, the symptomatic period was also characterized by a higher HR and lower HRV. These findings indicate a possible contribution of variations in ANS activity to the perception of AF, but more studies are needed to confirm this hypothesis. Recurrence rate of atrial fibrillation after the first clinical episode: A prospective evaluation using continuous cardiac rhythm monitoring.Background: Decision-making regarding a patient who has experienced a first clinical episode of atrial fibrillation (AF) is challenging, and the AF recurrences should be a significant consideration. Continuous long-term rhythm monitoring via implantable loop recorders (ILRs) has enabled us to evaluate the AF recurrence profile after the first clinical episode and to investigate clinical parameters associated with the course of the arrhythmia. Hypothesis: Continuous rhythm monitoring via ILRs in AF patients after the first clinical episode is of clinical significance and precisely evaluate the AF recurrence profile.Methods: Thirty (30) consecutive patients with paroxysmal AF received an ILR after their first symptomatic episode. We evaluated the maximum duration of episodes and the recurrence rate of the arrhythmia during a follow-up period of three years. Results: Three patients (10%) had no AF recurrence, while 4 patients (13.3%) presented only one episode. Almost half of the patients (46.7%) had a low recurrence rate (<5 episodes/year), while the majority of patients (19/30) suffered from episodes with maximum duration ≤24 h. Eleven patients (36.7%) presented either no episode or a low recurrence rate with episodes lasting ≤24 h. The use of statins was greater in patients with a low recurrence rate (p=0.025).Conclusions: A significant percentage of patients either suffer no AF recurrence after their first symptomatic episode or show a low recurrence rate. Most patients present episodes of short duration. If these findings are confirmed in larger studies, they could have clinical implications ensuring individualized management of the arrhythmia in the future.In conclusion, we observed in our study that, after their first clinical AF episode, a significant percentage of patients do not suffer any other AF episode, or have a low recurrence rate of the arrhythmia. Furthermore, most of the patients presented episodes with short duration. If these findings are confirmed in larger studies, they could have clinical implications ensuring individualized evaluation and long-term management of the arrhythmia in the future. Further large randomized studies are needed, not only to evaluate such strategies, but also to elucidate the role of ILRs in the long-term management of the arrhythmia.
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