Atrial Defibrillation Research Articles

P-297 Internal atrial defibrillation and early reinitiation of atrial fibrillation guiding ablation of focal atrial fibrillation

P-297 Internal atrial defibrillation and early reinitiation of atrial fibrillation guiding ablation of focal atrial fibrillation

P-284 Triazolam sedation decreases pain and anxiety with atrial defibrillation therapy

P-284 Triazolam sedation decreases pain and anxiety with atrial defibrillation therapy

P-297 Internal atrial defibrillation and early reinitiation of atrial fibrillation guiding ablation of focal atrial fibrillation

P-297 Internal atrial defibrillation and early reinitiation of atrial fibrillation guiding ablation of focal atrial fibrillation

Circadian variation of arrhythmia onset patterns in patients with persistent atrial fibrillation

Background The circadian onset patterns and cycle lengths of atrial tachyarrhythmias (AT) were determined in a group of patients with persistent atrial fibrillation. Methods Fifteen patients, mean age 63 ± 14 years and 80% male, were implanted with the Jewel AF atrial defibrillator (Medtronic, Minneapolis, Minn) for persistent atrial fibrillation only. Onset times of AT and median onset atrial cycle lengths were determined from device memory. Results Over a follow-up period of 23.3 ± 7 months, 227 episodes of persistent AT were treated by patient-activated atrial defibrillation. The peak onset of persistent AT was nocturnal, with 74% of episodes initiating between 8 pm and 8 am. Eighty-seven percent of the patients experienced an additional 403 paroxysmal AT episodes. These episodes showed a “double-peaked” pattern with the least number of episodes occurring between midnight and 8 am. The mean onset atrial cycle length of persistent AT was significantly shorter than the paroxysmal AT episodes (200 ± 37 ms vs 240 ± 39 ms, P < .005). The atrial cycle lengths at arrhythmia onset of both paroxysmal and persistent AT episodes also demonstrated circadian variation. Conclusion There is a circadian distribution of onsets for persistent AT with predominance at night. Patients with persistent AF have >1 type of atrial arrhythmia with differences in the onset patterns and atrial cycle lengths, suggesting different triggers and onset mechanisms.

Implantable cardioverter-defibrillators in cardiovascular care: technologic advances and new indications.

Present generation implantable cardioverter-defibrillators (ICD) have become a proven primary therapeutic option in management of symptomatic ventricular arrhythmias and are now being increasingly used for primary prevention. The addition of biventricular pacing and atrial defibrillation to these devices has had an impact on the management of several new patient populations. The widespread application of these devices requires precise knowledge of their potential benefits and factors that could adversely affect device function. ICD therapy has improved the survival of coronary disease patients with left ventricular dysfunction by reducing sudden death rate. In congestive heart failure patients, ICD therapy and biventricular pacing improves heart failure status thus improving overall survival and quality of life. Atrial defibrillation can establish rhythm control in drug refractory atrial fibrillation usually in a "hybrid therapy" prescription. Implantable cardioverter defibrillators have proven to be invaluable in the primary and secondary prevention of sudden cardiac death. Incorporation of new technology in these devices has resulted in expanded indications that improve survival and quality of life of new patient populations.

Sleep Quality Among Patients Treated with Implantable Atrial Defibrillation Therapy:

The Medtronic ICD-AT has atrial/ventricular therapies, which can be programmed to deliver atrial defibrillation during sleep, intended to potentially decrease shock anxiety/pain and lifestyle disruption. However, these shocks may diminish sleep quality. This study examined atrial shock characteristics (i.e., mode, frequency), AF symptoms, and psychological factors as determinants of sleep quality. The 96 ICD-AT patients were mostly men (72%; M age 65 +/- 12 years) and implanted for 1.6 years (SD = 0.8 years). Patients were divided into shock groups based on the proportion of mode (> or =90%) of total atrial shocks received. Patients were grouped into either automatic-nocturnal shock group (8 P.M.-8 A.M.; n = 35) or manual-awake shock group (n = 42). Psychological measures included Pittsburgh Sleep Quality Index (PSQI), Center for Epidemiology Studies-Depression Scale, State-Trait Anxiety Inventory, and Illness Intrusiveness Rating Scale. Atrial fibrillation disease burden was assessed via atrial symptom score and atrial shock use. PSQI global scores were similar between manual (7.67 +/- 2.53) and automatic shock (8.20 +/- 2.93) groups. A multiple hierarchical regression analysis indicated that no atrial shock variables were predictive of sleep quality; yet, both AF symptom (B = 0.226, P = 0.040) and depression (B = 0.392, P = 0.034) scores predicted diminished sleep quality, accounting for 42% of the variance in global sleep quality (P < 0.001). These results suggest that atrial defibrillation therapy does not have a deleterious impact on sleep. However, the significance of AF symptoms and depression indicate that comprehensive care of both physical and psychological symptomatology may improve sleep quality in ICD-AT patients.

Facilitating electrical cardioversion of persistant atrial fibrillation by antiarrhythmic drugs: update on clinical trial results.

Results from clinical trials suggest that antiarrhythmic drugs (AD) can facilitate electrical cardioversion (EC) for persistent atrial fibrillation (AF) (duration >48 hours, no spontaneous termination) by suppression of immediate reinitiation of AF following the procedure. Class IC agents may increase the atrial defibrillation threshold (DFT) by significantly reducing the availability of Na+-channel for depolarization. In contrast, class III agents may decrease the atrial DFT by markedly prolonging atrial refractoriness. Among all AD, ibutilide and amoidarone have been shown to be most effective in enhancing the acute outcome of EC. In patients who are over 65 years of age at high risks of stroke (e.g., atherosclerotic cardiovascular disease, diabetes, hypertension, previous thromboembolism, etc.), the rhythm control strategy offers no survival advantage over the rate control strategy and frequently subjects patients to serious adverse effects of AD therapy. It can not be overemphasized that adequate anticoagulation (INR 2.0-3.0) with warfarin is needed regardless of whichever strategy is chosen unless there are contraindications. On the other hand, in patients who are under 65 years of age without structural heart disease or other risk factors of stroke, rhythm control can be the treatment of choice. Specifically, if a patient has failed EC alone or if the patient has characteristics (e.g., duration of AF >6 months, left atrium >50 mm, etc.) that EC could fail, AD may be given before the procedure to facilitate EC. In the subgroup of patients who are symptomatic with hypertrophic cardiomyopathy and severe diastolic dysfunction requiring maintenance of sinus rhythm to have sufficient ventricular function for optimization of cardiac output, an aggressive approach for rhythm control with amiodarone along with adequate anticoagulation with warfarin should be encouraged.

Patient experiences with atrial fibrillation and treatment with implantable atrial defibrillation therapy

Background Patient perspectives about their illness experiences, symptoms, and treatment are essential aspects of quality of life and provide direction for patient and provider decision making regarding innovative therapies such as implantable devices for arrhythmia. Purpose The purpose of this qualitative study was to describe: 1) the experience of patients living with symptomatic, drug-refractory atrial fibrillation (AF) and 2) patient experiences and acceptance of treatment with the implantable cardioverter defibrillator (ICD) with atrial therapies (ICD-AT) including ventricular and atrial defibrillation therapy. Participants Subjects were 3 women and 8 men, 35 to 80 years of age, who received the Medtronic Jewel AF 7250 ICD-AT as therapy for recurrent, drug-refractory AF, had a history of AF for 3 to 20 years and had experienced multiple treatment modalities including frequent external cardioversion in an effort to control their AF. Methods A semi-structured interview addressed experiences of symptoms and prior treatment for AF and experiences, concerns, and perceived benefits of the ICD-AT. Interviews were recorded and transcribed verbatim. Narratives were coded and categorized using Atlas Ti® software. Qualitative interpretive analysis methods were used to identify key themes. Results Before ICD-AT, patient themes focused on AF that was: 1) misdiagnosed, minimized, and poorly treated; 2) distressful because of frequent and intense AF symptoms (fatigue, dizziness, shortness of breath, and anxiety) before ICD-AT; 3) limiting of activities of daily living; 4) associated with distress from enduring previous treatment; and 5) associated with the continuous pursuit of successful treatment and maintenance of normalcy. Decision making regarding ICD-AT therapy included weighing symptom or treatment distress versus anticipated risks or benefits, hope for better outcomes, and lack of options. After ICD-AT, themes included positive perceptions of the device because of AF symptom relief, ability to resume normalcy, and medication tolerance; incorporation of shock experiences into life routines; and patient suggestions regarding preparation and social support. Implications Symptoms of AF have a major negative impact on overall quality of life. Treatment with the ICD-AT confers a sense of security and reduced symptom distress. Greater provider attention to patient preparation and facilitating social support are important for future ICD-AT patient care.

Is There a Role for Repeated Cardioversion in Patients with Recurrent Atrial Fibrillation?

Recent clinical and experimental studies have demonstrated that atrial fibrillation (AF) alters the electrical and mechanical remodeling of the atrium which subsequently promote the maintenance and recurrence of AF. If atrial remodeling can be prevented with prompt and repeated cardioversion, the likelihood of AF recurrence may be reduced. Recent clinical studies have demonstrated that the strategies of transesophageal echocardiography facilitated early cardioversion and early repeated cardioversion may be clinically valuable in some patients who have persistent AF and recurrence of arrhythmia after the initial cardioversion. Furthermore, the use an implantable atrial defibrillator (IAD) for early repeated device-based cardioversion to maintain sinus rhythm appears to be safe and clinically feasible. Early cardioversion by IAD reduces AF burden, reverses atrial remodeling and prevents subsequent AF recurrence in selected patients without structural heart disease implanted with this device, indicating possible "sinus rhythm begets sinus rhythm". Despite this encouraging initial observation, further long-term clinical studies in a larger patient population are needed to confirm this finding. Furthermore, whether the use of IAD in the fully automatic mode to provide immediate termination of AF episodes could intensify the potential beneficial effect and the clinical efficacy of this approach in patients with structural heart disease remains to be evaluated.

ATRIAL FIBRILLATION STORMS

SUMMARYEvolving pacemaker and device technology now allows the onset pattern of arrhythmias to be identified. It is recognised that some cardiac arrhythmias have a circadian pattern of onset and that ventricular arrhythmias can occur in clusters of electrical storms. The long‐term follow‐up of patients with an atrial defibrillator suggests that in some patients persistent atrial fibrillation recurrences are not random, but can occur in clusters of ‘atrial fibrillation storms’. A case report is used to demonstrate this newly recognised phenomenon.

Dose-response relationship for successful internal atrial defibrillation.

The dose-response relationship for successful defibrillation has been determined in man for the ventricle but not for the atrium. The purpose of this study was to determine the dose-response relationship for internal atrial defibrillation in humans. Seventy-seven consecutive patients underwent internal atrial defibrillation for acute (n = 14) or chronic AF (n = 63). Shocks were delivered in 40-V increments between electrodes positioned in the coronary sinus and the right atrium until successful conversion or a maximum of 400 V was reached. The shock strength versus success of shock data were subjected to a Kaplan-Meier survival analysis combined with a nonparametric probability analysis to arrive at the dose-response relationship. Using this relationship, comparisons were made between acute and chronic AF and clinical relevant conversion percentages (20, 50, 80 and 95%) were estimated and were compared with the conventional mean threshold. There were significant dose-response relationships in both patients groups (P < 0.05). The Kaplan-Meier analysis comparing patients with chronic and acute AF showed significant differences in their dose-response relationships (P < 0.001). The estimated shock intensity for 95% conversion in patients with acute and chronic AF was 279 V (2.9 J) and 433 V (6.6 J), respectively (P < 0.001). The conventional mean defibrillation threshold in patients with acute (192 +/- 15 V. 1.4 +/- 0.2 J) and chronic AF (343 +/- 8 V, 4.4 +/- 0.2 J) predicted the 60% and 45% chance of successful conversion, respectively. In conclusion, this study demonstrates that single shock conversion data can be used to determine a dose-response relationship, which can be used to estimate the shock intensity required for specific successful atrial defibrillation efficacy and to compare different clinical factors that affect defibrillation efficacy.

1236: Patient experiences with Atrial Fibrillation and Treatment with the Implantable Atrial Defibrillator (IAVD)

1236: Patient experiences with Atrial Fibrillation and Treatment with the Implantable Atrial Defibrillator (IAVD)

P1534 Evaluation of myocardial damage, neurohormonal activation, inflammation and ventricular dysfunction prior to, and following internal atrial defibrillation

P1534 Evaluation of myocardial damage, neurohormonal activation, inflammation and ventricular dysfunction prior to, and following internal atrial defibrillation

P382 Comparison of the atrial defibrillation threshold in patients with and without coronary sinus lead

P382 Comparison of the atrial defibrillation threshold in patients with and without coronary sinus lead

The circadian variation of atrial defibrillation thresholds

Background: A circadian variation exists for ventricular defibrillation thresholds (DFTs) with a morning peak and a corresponding decrease in therapy success rates from implantable cardioverter defibrillators. Such a variation in atrial DFTs may have implications for the timing of internal cardioversion of atrial arrhythmias. The aim of this study was therefore to determine the circadian variation of atrial DFTs in patents with recurrent atrial fibrillation (AF). Methods and results: Data were collected as part of the worldwide Jewel AF-only study. Patients had recurrent persistent AF and no history of ventricular arrhythmias. The atrial DFT was assessed at device implantation using a step-up protocol and was recorded for 100 patients (age 63.0 ± 11.7, 74% male, ejection fraction 49.6 ± 17.8%, left atrial diameter 46 ± 9 mm). The mean atrial DFT was 6.3 ± 4.3 J. For the most commonly tested lead configuration (right atrium to coronary sinus in 56 patients), the atrial DFT for patients implanted in the morning (3.3 ± 1.5 J) was significantly lower than for both the DFT measured in the afternoon (5.8 ± 3.4 J, p < 0.01) and the DFT measured in the evening (7.4 ± 5.9 J, p < 0.01). Conclusion: There may be a significant variation in measured atrial DFT for the right atrium to coronary sinus configuration, with a nadir in the morning. This is the converse to measurements of ventricular DFTs suggesting different regulatory electrophysiological mechanisms. Further investigation of this possible variation is warranted.

Echocardiographic changes and predictors of arrhythmia recurrence after long-term use of the atrial defibrillator

Background: The patient-activated atrial defibrillator allows patients to cardiovert themselves from atrial fibrillation soon after the onset of symptoms. The long-term effects of early cardioversion from persistent atrial fibrillation on left ventricular performance and left atrial size are unknown. Methods: Eighteen patients, mean age 63.4, 83% male, had the Jewel ® AF atrial defibrillator implanted for persistent atrial fibrillation only. Transthoracic echocardiography was performed 3-monthly following implant. Parasternal long axis measurements were taken using conventional M-mode techniques. Results: Over follow-up of 28.0±9 months, 377 episodes of persistent atrial fibrillation were terminated by patient-activated cardioversion (median 15 per patient). Echocardiographic measurements at implant were; left atrium 44±6 mm, left ventricular end-diastolic diameter 49±7 mm, left ventricular end-systolic diameter 34±7 mm, fractional shortening 33±10% and ejection fraction 65±17%. After 1 year there had been a significant decrease in mean left atrial size to 41±6 mm ( P=0.02) and an increase in mean ejection fraction to 73±8% ( P=0.04). At long-term follow-up however, all parameters reverted to pre-implant levels. Baseline echocardiographic variables did not predict which patients would demonstrate serial increases in sinus rhythm duration between shocks during long-term follow-up. Patients on antiarrhythmic drug therapy however were more likely to demonstrate ‘sinus rhythm begetting sinus rhythm’. Conclusions: Use of the atrial defibrillator for spontaneous persistent atrial fibrillation is associated with a medium-term (1 year) reduction in left atrial size and an increase in ejection fraction. These changes were not maintained in the long-term. Synergistic therapy with antiarrhythmic drugs may prolong periods of sinus rhythm between arrhythmia recurrences.

Effect of Atrial Fibrillation Duration on Probability of Immediate Recurrence after Transthoracic Cardioversion

An immediate recurrence of atrial fibrillation (IRAF) appears to be more common after early restoration of sinus rhythm with an implantable atrial defibrillator than after elective transthoracic cardioversion, which suggests that the probability of IRAF may be related to the duration of AF. Transthoracic cardioversion was performed 85 +/- 187 days (range 7 minutes to 8 years) after the onset of atrial fibrillation in 315 patients (mean age 61 +/- 13 years). IRAF was defined as a recurrence of AF within 60 seconds after restoration of sinus rhythm. IRAF occurred in 56% of patients when cardioversion was performed within 1 hour of the onset of AF compared with 12% of patients when cardioversion was performed after 24 hours of AF (P < 0.001). The duration of AF was the only independent predictor of IRAF among the clinical variables of age, gender, structural heart disease, antiarrhythmic drug therapy, and cardioversion energy (P < 0.01). IRAF is more likely to occur when the duration of AF is <1 hour than when the duration is >24 hours. This observation has clinical implications for the most appropriate timing of cardioversion, particularly in patients who receive device therapy for AF.

QUALITY OF LIFE AFTER USE OF THE PATIENT ACTIVATED ATRIAL DEFIBRILLATOR

SUMMARYThe aim of the study was to evaluate the effects of long‐term use of the patient‐activated atrial defibrillator for recurrent persistent atrial fibrillation (AF) on quality of life (QOL). Fifteen patients were implanted with the Medtronic Jewel AF 7250 device (dual chamber atrial and ventricular defibrillator) for AF only. AF recurrences were treated by out‐of‐hospital patient‐activated atrial defibrillation shocks following the self‐administration of oral sedation. QOL was assessed at pre‐implant and up to one year with SF36, symptom checklist and HADS questionnaires. A total of 238 (median 10) out‐of‐hospital patient‐activated atrial defibrillation shocks were performed. The SF36 demonstrated a trend toward improvement over the 12‐month period compared with baseline values. There was no significant change in the symptom frequency or severity scores. Pre‐implant levels of both anxiety and depression were within the predefined range of normality (6±3 and 3±2, respectively) and no significant change was seen at 6 months (5±4 and 3±3) or 12 months post implant (5±4 and 2±2, respectively). After one year of follow‐up, 13 (87%) patients said they would have the device implanted again (two were undecided). The study demonstrates that patient‐activated atrial defibrillation is a well tolerated therapeutic strategy for maintaining sinus rhythm.

The results of pacing trials for the prevention and termination of atrial tachyarrhythmias: is there any evidence of therapeutic breakthrough?

Atrial fibrillation (AF) is now recognized as the most prevalent sustained cardiac arrhythmia and it is associated with considerable mortality and morbidity. The demand for effective therapeutic strategies for AF has always been high and is anticipated to further increase. Anticoagulation and pharmacologic antiarrhythmic therapy or radiofrequency catheter ablation remain the mainstay of treatment for AF. Among the wide range of nonpharmacologic options which are presently being investigated, only ablation in or around the pulmonary veins and the surgical maze procedure have been shown to accomplish the aim of the curative treatment of the arrhythmia. Preventative atrial pacing and antitachycardia pacing may offer an attractive alternative option for the management of AF by either eliminating the triggers and/or by modifying the substrate of the arrhythmia. The results of several recent trials have shown a significant increase in the time to first AF recurrence, a decrease in atrial conduction time, and a trend towards reduction in AF burden, suggesting that atrial pacing may prevent AF due to improved synchronization of atrial depolarization. The recognition of potential triggers of AF, such as atrial premature complexes, short-long sequence, and bradycardia, has encouraged the development of novel atrial pacing algorithms designed to prevent the initiation of the arrhythmia on an individual basis. Observations of AF often starting with regular atrial activity consistent with atrial tachycardia have supported the hypothesis that early antitachycardia pacing may prevent progression to AF. The concept of "hybrid therapy" based on the combination of several different therapeutic strategies suggests that antitachycardia pacing therapy, integrated with an atrial defibrillator and preventative atrial pacing modes, may act synergistically to prevent AF. Dual chamber cardioverter-defibrillators with capacity to prevent and interrupt AF may offer more comprehensive and successful treatment for patients with advanced heart disease, frequent paroxysms of AF, and the risk of proarrhythmia.

Historical perspectives on interventional electrophysiology.

The history of interventional electrophysiology is long and fascinating. In the beginning, there is not simply the anatomy and physiology of the heart, but also analysis of the pulse, which indicates the activity of the heart. The analysis of the (peripheral) pulse as a mechanical expression of heart activity goes back several millennia. In China, in 280 B.C., Wang Chu Ho wrote ten books about the pulse. The Greeks called the pulse "sphygmos", and the sphygmology thus deals with a theory of this natural occurrence. In Roman times, Galen interpreted the various types of pulse according to the widespread presumption of the time, that each organ in every disease has its own form of pulse. The basic tool for arrhythmia diagnosis became the electrocardiography introduced by Willem Einthoven who obtained the first human electrogram 1902 in Leiden, The Netherlands. The growing clinical importance of electrical cardiac stimulation has been recognized and renewed as Zoll (1911-1999) in 1952 reported a successful resuscitation in cardiac standstill by external stimulation. Meanwhile all over the world, millions of patients with cardiac arrhythmias have been treated with pacemakers in the last 45 years. The concept of a fully automatic implantable cardioverter-defibrillator system (ICD) for recognition and treatment of ventricular tachyarrhythmias was first suggested in 1970. The first implantation of the device in a human being was performed in February 1980. Further developments concern atrial and atrioventricular defibrillators, radiofrequency ablation, laser therapy and advanced antiarrhythmic surgery, new antiarrhythmic drugs and sophisticated devices for preventive pacing. The advances in the field of diagnostic and therapeutic application of pharmacologic and electrical tools as well as alternative methods will continue as rapidly as before in order to give us further significant aid in taking care of the patient.