History Of Atrial Tachyarrhythmias Research Articles

Validation of coala heart monitor

Abstract Background/Introduction Atrial fibrillation (AF) can be asymptomatic and it is associated with stroke and heart failure which can present as first symptoms [1,2]. There is increasing evidence of benefits of screening for AF to prevent ischemic stroke by initiating anticoagulation therapy in affected individuals [3]. There are several devices used for screening of AF [4] and one of them is Coala Heart Monitor (CHM), which is a handheld device, connected by blue-tooth to a smartphone for registration of the rhythm from the chest and the thumbs. The aim with this this study was to validate the accuracy of CHM for detecting atrial tachyarrhythmia (ATA) (AF, atrial flutter or atrial tachycardia) compared to 12-lead-ECG. Methods Eligible participants were ≥18 years of age, planned for a 12-lead-ECG, with a history of ATA. Exclusion criteria were; pacemaker or implantable cardioverter-defibrillator (ICD)-treatment, ongoing arrhythmia that was not ATA or if the patient was unwilling or unable to provide informed consent. One hundred and eleven 12-lead-ECG were collected and immediately after a 30 + 30 second thumb-and chest-registration from CHM where collected. 12-lead-ECG independently interpreted by two electrophysiologist was used as the reference standard (100% coherence). In one patient neither chest nor thumb-registration could be interpreted due to bad quality, and this was not included in the analysis. Eight thumb-registrations and three chest-registrations could not be interpreted and in these cases the other registration could be interpreted. In one case there was disagreement between interpreter one and two, and in this case a third interpreter was involved. Results Mean age was 65.2±12.1 years and 28.8% were female. Prevalence of ATA was 36.4%. The sensitivity for ATA was 100% (95% CI, 96.3% - 100%) and the specificity was 100% (95% CI, 96.3% - 100%). Conclusion CHM provides excellent sensitivity and specificity for ATA compared to 12-lead-ECG. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swedish Research Council

Incidence of left atrial appendage thrombus on pre-procedural TOE before catheter ablation of atrial tachyarrhythmias

Abstract Introduction Transoesophageal echocardiography (TOE) is routinely performed before catheter ablation of atrial tachyarrhythmias to rule out the presence of possible left atrial thrombi. However, data to support this practice are scarce. Methods We analysed consecutive pre-procedural TOE in a high-volume electrophysiology centre for the presence of left atrial thrombi and a relevant flow reduction in the left atrial appendage (LAA) defined as LAA sludge or pronounced spontaneous echo contrast. Possible predictors of reduced flow were recorded and compared in a multivariate logistic regression analysis. Results 1676 consecutive TOE were included (1122 before pulmonary vein isolation (PVI), 436 before atrial flutter ablation, 166 before other EP studies in patients with a history of atrial tachyarrhythmias). 543 patients (32%) were female, mean age was 63±12 years and BMI was 27±5 kg/m2. Nine patients (0.5%) had an LAA thrombus on pre-procedural TOE. Ninety-five further patients (5.7%) had a relevant reduction in LAA flow as characterized by LAA sludge or spontaneous echo contrast. Further patient characteristics by LAA flow state are shown in the table. While a higher CHA2DS2-VaSc-Score was associated with the presence of LAA sludge and LAA thrombus (p=0.01), no further clinical parameters such as choice of oral anticoagulation agent were independently predictive of reduced flow velocities or thrombus in a logistic regression model (see table). Importantly, LAA thrombi also occurred in patients with a CHA2DS2-VaSc-Score ≤1 (n=1) or in sinus rhythm (n=2). Of note, 6 out of 9 patients with a LAA thrombus were anticoagulated with phenprocoumon. Conclusion LAA thrombus is a rare occurrence before an elective catheter ablation. In patients with CHA2DS2-VaSc-Score ≤1 the likelihood of LAA thrombus is so low (0.2%) that it may be considered to give up routine TOE before an EP study/ablation. Funding Acknowledgement Type of funding sources: None.

Predictors of New-Onset Atrial Tachyarrhythmias After Transcatheter Atrial Septal Defect Closure in Adults

New-onset atrial tachyarrhythmia (ATA) often develops after atrial septal defect (ASD) closure. Its development raises some potential concerns such as stroke and bleeding complications caused by anticoagulant therapy and limited access to the left atrium for catheter ablation. Although it is essential to identify the risk factors of new-onset ATA, few studies have examined these factors. This study investigated unknown risk factors for the development of new-onset ATA after transcatheter ASD closure in patients without a history of ATA. A total of 238 patients without a history of ATA, aged ≥18 years and who underwent transcatheter ASD closure at the current hospital were reviewed. Patient characteristics were compared between the groups with and without new-onset ATA. The factors associated with new-onset ATA were examined using univariate and multivariable analyses. Thirteen (13) (5.5%) patients experienced ATA during follow-up (mean, 21±14 months). Compared with patients without new-onset ATA, patients with new-onset ATA were older (48±18 vs 66±11 years; p<0.001) and had high brain natriuretic peptide (BNP) levels (36±36 vs 177±306 pg/mL; p<0.001). On multivariable analysis, BNP ≥40 pg/mL before ASD closure was associated with new-onset ATA after adjusting for age (OR, 4.91; 95% CI, 1.22-19.8; p=0.025). Patients with BNP levels >40 pg/mL before transcatheter ASD closure may have a higher risk of developing new-onset ATA.

Hospitalization for HeartFailure and Subsequent Ventricular Tachyarrhythmias in Patients With LeftVentricular Dysfunction.

This study aimed to evaluate the risk of sustained life-threatening ventricular tachyarrhythmias (VTAs) after hospitalization for heart failure (HHF). HHF is common among patients with an implantable cardioverter-defibrillator (ICD). We analyzed all 5,511 ICD patients enrolled in the landmark MADIT (Multicenter Automatic Defibrillator Implantation Trial) and RAID (Ranolazine in High-Risk Patients With Implanted Cardioverter-Defibrillator) trials. Multivariate Cox regression was used to evaluate the association of in-trial HHF occurrence with the risk of subsequent VTA and the composite end point of VTA or cardiac death. Mean age was 64 ± 11 years, 23% were women, 62% were ischemic, and 40% had cardiac resynchronization therapy with defibrillators. The 3-year cumulative rate of VTA subsequent to HHF was significantly higher than the corresponding rate without HHF (44% vs. 24%, respectively; p<0.001). After multivariable adjustment, time-dependent HHF was shown to be associated with a 79% increased risk for VTA and a 2.9-fold increased risk for VTA/cardiac death (p<0.001 for both). In-trial development of atrial tachyarrhythmia (ATA) was also identified as an independent risk factor for the VTA and VTA/cardiac death end points (hazard ratio [HR]: 1.59 and 1.43, respectively; p≤ 0.001 for both) but did not affect the association of HHF with VTA. Subgroup analysis demonstrated that the association of HHF with the risk of subsequent VTA was maintained among risk subsets categorized by age, sex, history of ATA, and implantation indication, but was significantly more pronounced among patients with nonischemic versus ischemic cardiomyopathy (HR: 2.54 and 1.43, respectively; p for interaction = 0.017). HHF is a powerful risk factor for subsequent VTA in patients implanted with an ICD. These data may be used for improved risk stratification in this population.

Postoperative and short-term atrial tachyarrhythmia burdens after transcatheter vs surgical pulmonary valve replacement among congenital heart disease patients.

We examined the atrial tachyarrhythmia (AT) burden among patients with congenital heart disease (CHD) following transcatheter (TC-) or surgical (S-) pulmonary valve replacement (PVR). This was a retrospective observational study of patients who underwent PVR from 2010 to 2016 at UCLA Medical Center. Patients of all ages who had prior surgical repair for CHD were included. Patients with a history of congenitally corrected transposition of the great arteries, underwent a hybrid PVR procedure, or had permanent atrial fibrillation (AF) without a concomitant ablation were excluded. The primary outcome was a time-to-event analysis of sustained AT. Sustained ATs were defined as focal AT, intra-atrial reentrant tachycardia/atrial flutter, or AF lasting at least 30seconds or terminating with cardioversion or antitachycardia pacing. Two hundred ninety-seven patients (TC-PVR, n=168 and S-PVR, n=129) were included. During a median follow-up of 1.2years, nine events occurred in TC-PVR group (5%) vs 23 events in S-PVR group (18%). In the propensity adjusted models, the following factors were associated with significant risk of AT after PVR: history of AT, age at valve implantation, severe right atrial enlargement, and S-PVR. In the secondary analysis, TC-PVR was associated with lower adjusted risk of AT events in the postoperative epoch (first 30days), adjusted IRR 0.31 (0.14-0.97), P=.03, but similar risk in the short-term epoch, adjusted IRR 0.64 (0.14-2.94), P=.57. There was an increased risk of AT in the first 30days following S-PVR compared to TC-PVR. Additional factors associated with risk of AT events after PVR were a history of AT, age at valve implantation, and severe right atrial enlargement.

Reduction in Inappropriate ICD Therapy in MADIT-RIT Patients Without History of Atrial Tachyarrhythmia.

There are limited data whether history of atrial tachyarrhythmia (AT) modifies the risk of inappropriate ICD therapy, or the efficacy of novel ICD programming to reduce inappropriate ICD therapy events. In MADIT-RIT, we investigated the effects of novel ICD programming with high-rate cut-off VT zone ≥ 200 bpm (arm B), or 60-second delayed therapy in the VT zone 170-199 bpm (arm C), compared to conventional programming VT zone>170 bpm (arm A) on first inappropriate ICD therapy in those with or those without AT prior to enrollment. In patients with prior AT (n = 203, 14%) there was a higher risk of inappropriate ICD therapy (HR = 2.10, 95% CI: 1.38-3.20, P < 0.001), and inappropriate ICD shock (HR = 2.56, 95% CI: 1.38-4.74, P = 0.003) compared to those with no prior AT. The effects of innovative programming to reduce inappropriate ICD therapy with either high-rate cut-off or delayed VT therapy were similar in patients with prior AT (arm B vs. A HR = 0.11, P < 0.001, arm C vs. A HR = 0.17, P < 0.001), and also in patients without prior AT before enrollment (arm B vs. A HR = 0.15, P < 0.001, arm C vs. A HR = 0.24, P < 0.001, interaction P-values >0.10 for all). Novel ICD programming with a high-rate cut-off or delayed therapy is equally beneficial to reduce inappropriate ICD therapy in patients with or without prior AT, despite the lower risk of inappropriate ICD therapy in patients without prior AT.

Contemporary predictors of death and sustained ventricular tachycardia in patients with repaired tetralogy of Fallot enrolled in the INDICATOR cohort

ObjectivePatients with repaired tetralogy of Fallot (TOF) experience increased rates of mortality and morbidity in adulthood. This study was designed to identify risk factors for death and ventricular tachycardia (VT)...

Frequency of Atrial Tachyarrhythmias in Patients Treated by Cardiac Resynchronization (from the Prospective, Multicenter Mona Lisa Study)

The continuous measurement of sustained atrial tachyarrhythmia (AT) is now possible with some permanently implanted devices. Data on this subject remain controversial. The aim of this study was to evaluate the incidence of sustained AT in patients treated with cardiac resynchronization therapy using pacemakers without backup defibrillators (CRT-P), within the first year after implantation, using strict definition criteria for sustained AT and a systematic review of all high-quality electrographically recorded episodes. The Mona Lisa study was a prospective, multicenter, cohort study carried out from February 2004 to February 2006, with a 12-month follow-up period. Sustained AT was defined as an episode lasting > or =5 minutes; episodes were confirmed by a systematic review of electrograms in the whole study population. Of the 198 patients who underwent CRT-P device implantation and were enrolled in the study, 173 were in stable sinus rhythm at baseline and were included in the analysis (mean age 70 +/- 9 years, 66% men, 91% in New York Heart Association class III, mean QRS duration 164 +/- 26 ms, mean left ventricular ejection fraction 25 +/- 7%). During a mean follow-up period of 9.9 +/- 3.6 months, 34 patients experienced > or =1 episode of sustained AT, for an incidence rate of 27.5% (95% confidence interval 18.2 to 36.7). Only a history of AT was independently associated with the occurrence of sustained AT within the 12 months after CRT-P device implantation (hazard ratio 2.3, 95% confidence interval 1.2 to 4.4, p = 0.02). In conclusion, this first prospective electrogram-based evaluation of AT incidence demonstrated that 27% of patients developed > or =1 episode of sustained AT lasting > or =5 minutes in the 12 months after CRT-P device implantation.

The MINERVA study design and rationale: A controlled randomized trial to assess the clinical benefit of minimizing ventricular pacing in pacemaker patients with atrial tachyarrhythmias

Dual-chamber (DDD) pacing has generally been regarded as "physiologic pacing" and therefore expected to be superior to ventricular pacing. Major randomized trials have so far failed to demonstrate significant reductions in the incidences of mortality, stroke, and heart failure. It has been shown that unnecessary ventricular pacing in patients with sinus node dysfunction or only intermittent atrioventricular block is associated with ventricular desynchronization and increased risk of atrial tachyarrhythmias (ATA). The MINimizE Right Ventricular pacing to prevent Atrial fibrillation and heart failure (MINERVA) study is a prospective, multi-center, randomized, international, single-blind, controlled trial designed to determine whether physiologic pacing through the managed ventricular pacing (MVP) algorithm combined with preventive atrial pacing (PAP) and atrial antitachycardia pacing (ATP) is superior to standard DDD pacing in terms of 2-year reduction in death, permanent ATA, and cardiovascular hospitalizations. Patients with standard class I or II indications for permanent DDD pacing and history of ATA will receive a Medtronic EnRhythm implantable pacemaker (Medtronic, Minneapolis, MN). After a 1-month run-in period, patients will be randomized in a 1:1:1 manner to the DDD (control group, all OFF), the DDDRP (MVP + PAP + ATP ON), and the MVP group (only MVP ON). Up to 1,300 patients will be included in approximately 70 centers in Europe, the Middle East, and Asia. The MINERVA study will make an important contribution to the management of patients with paroxysmal ATA and accepted indications for dual-chamber pacemaker implantation by determining whether physiologic pacing combined with PAP and ATP is superior to standard DDD pacing in terms of reduction of mortality, incidence of permanent ATA, and cardiovascular hospitalizations.

Predictors of Atrial Arrhythmias After Device Closure of Secundum Type Atrial Septal Defects in Adults

Atrial tachyarrhythmias (ATs) contribute substantially to morbidity in adult patients with secundum atrial septal defects (ASDs). The purpose of this study was to prospectively determine the incidence of AT in adults with an ASD and identify predictors of AT occurrence after closure. This was a prospective study of 200 adult patients undergoing closure of a secundum ASD. Arrhythmic events were defined as sustained or symptomatic AT requiring treatment. Twenty percent of patients (mean age 50 +/- 17 years; 26% men) referred for ASD closure had a history of AT. Early follow-up was available for 90% of patients, and the prevalence of AT was 17%. Of 171 patients with late follow-up (mean 1.9 +/- 0.9 years), data were available for 90%. AT was detected in 16% of these patients. Closure resulted in alleviation of symptoms (p <0.001), but symptoms alone did not identify patients at risk of recurrent AT. After closure of the ASD, the likelihood of remaining arrhythmia free was highest in patients without a history of AT (p = 0.001) and those <40 years at closure (p = 0.04). In conclusion, transcatheter ASD closure in patients without a history of arrhythmias and those <40 years of age conferred the highest likelihood of a patient remaining arrhythmia free in follow-up. An arrhythmia-specific treatment strategy should be considered for patients with documented established AT before ASD closure, in addition to shunt relief.

The Influence of Symptoms and Device Detected Atrial Tachyarrhythmias on Medical Management: Insights from A‐HIRATE

The influence of symptoms and device-detected atrial tachyarrhythmias (AT) on the management of AT in a pacemaker population has not been well described. We report the influence of symptoms and device detected AT on pharmacological disease management. Group 1 (n = 331) included patients without and Group 2 (n = 96) included patients with prior history of AT with an approved pacemaker indication. Dual chamber pacemakers, (kappa 700 or kappa 900, Medtronic, Minneapolis, MN, USA) were implanted. The impact of symptoms, AT burden, a history of AT, and time since implant on changes in the use of anticoagulation, beta-blockers, and antiarrhythmic drugs was analyzed. A total of 232 patients experienced at least one atrial high rate episode (AHRE). AT burden was higher in Group 2. Symptoms were reported by 154 patients in Group 1 and 47 patients in Group 2. Among patients experiencing AHRE, symptoms were reported in 17 patients in Group 1 (5.3%) and 22 patients in Group 2 (24.7%). Changes in antiarrhythmic drugs and anticoagulation were influenced by history of AT and AT burden, while changes in the use of beta-blockers were influenced by symptoms. The probability of a pharmacologic therapy change decreased with time since implant for all agents except coumadin. Pharmacologic AT therapy is differentially influenced by patient-reported symptoms of AT compared to device-detected asymptomatic AT. Anticoagulation and antiarrhythmic therapies are influenced by device detection of asymptomatic AT, whereas initiation of beta-blockers is more strongly influenced by symptoms.

Incidence of Atrial Tachyarrhythmias in Pacemaker Patients: Results from the Balanced Evaluation of Atrial Tachyarrhythmias in Stimulated Patients (BEATS) Study

The prospective Balanced Evaluation of Atrial Tachyarrhythmias in Stimulated patients (BEATS) study compared atrial tachyarrhythmia (AT) detection by means of serial ECG recordings versus device detection. The annual incidence of AT in patients with dual-chamber pacemakers may be significantly underestimated based on ECG and Holter recordings. A DDD(R) device capable of AT-triggered dual-channel electrogram (EGM) storage was implanted in 254 patients (70 +/- 11 years, 159 men) with a class I pacing indication. Patients were seen at 6, 26, and 52 weeks after pacemaker implantation. At all visits, symptoms were checked, surface ECGs were recorded including a 24-hour Holter recording at 6 weeks, and the pacemakers were interrogated. Primary study endpoint was AT documentation by surface ECG/Holter versus stored EGMs. Secondary endpoints consisted of the association between patients' symptoms and AT documentation, and of the AT incidence depending on pacing indication and a history of AT. ATs were documented by ECG/Holter recordings in 37 patients (15%) and by stored EGMs in 137 patients (54%) (P < 0.0001). Symptoms were absent in 108 of 137 patients (79%) with device-documented AT but present in 70 of 117 patients (60%) without AT documentation. AT documentation was more frequent in patients with a history of AT but not in patients with sinus node compared to AV node disease. ATs occur in pacemaker patients significantly more frequently than estimated by ECG/Holter recordings. Only the analysis of device-stored EGMs allows reliable assessment of the AT burden.

P2-34: Analysis of a new AT/AF detection algorithm in patients with atrial arrhythmias: Experience from the AWARE trial

Previously, Auto Mode Switch (AMS) algorithms have been used extensively to assess the frequency and pattern of atrial tachyarrhythmia (AT) or atrial fibrillation (AF) in dual-chamber pacemakers (PMs). Although these algorithms provide effective therapy in stabilizing ventricular rates during atrial arrhythmia (AA), AMS has limited diagnostic capabilities. St. Jude Medical (SJM) has introduced a new AT/AF detection algorithm in the ADx family of PMs, which is designed detect the presence of AT/AF episodes, as well as provide clinicians with enhanced long-term patient diagnostics. The AWARE trial evaluated the incidence of AT/AF and inappropriate detection of AT/AF events in patients with a history of AT or AF by analyzing AT/AF triggered electrograms (EGMs).

Recurrence of Atrial Tachyarrhythmias in Implantable Cardioverter‐Defibrillator Recipients

Because the natural history of atrial tachyarrhythmia (AT) is not known in patients with implantable cardioverter-defibrillators (ICDs) but without device-based atrial therapies, we aimed to describe the characteristics and recurrence of AT in such patients. In this multicenter trial, 269 patients with standard indications for ICD placement and 2 episodes of AT in the preceding year received a dual-chamber ICD capable of logging AT. Patients were randomly assigned to 3-month periods of atrial therapies "on" or "off." This analysis considered only the 118 patients with atrial therapies programmed off at ICD placement. Fifty-eight patients (49%) had at least 1 AT episode longer than 1 minute, and 21 (18%) had at least 1 prolonged episode (>24 hours). The median episode frequency for each patient (episodes per month) was 1.8 episodes longer than 1 minute, 0.8 longer than 1 hour, and 0 longer than 24 hours. The median AT burden was 12.2 hours per month. Patients with standard ICD indications and history of AT have infrequent episodes, frequent short episodes, or prolonged episodes of AT-atrial fibrillation. However, the clinical characteristics examined did not distinguish among the groups. Improved diagnostic tools may help identify patients at risk for development of AT, thereby allowing specific therapies to be targeted to each group of patients.

Implantable Dual-Chamber Defibrillator for the Selective Treatment of Spontaneous Atrial and Ventricular Arrhythmias: Arrhythmia Incidence and Device Performance

Atrial tachyarrhythmias are a common co-morbidity in patients with an ICD indication. Recently introduced ICD's are equipped to independently detect and treat atrial and ventricular tachyarrhythmias. The purpose of this prospective study was to evaluate the incidence and termination of spontaneous atrial and ventricular tachyarrythmias in patients with a history of atrial tachyarrhythmias. Ninety patients, 70% male with an ICD indication and history of atrial tachyarrhythmia (LVEF 45 +/- 6%, [AT/AF indication 55 +/- 10, AT/VT 45 +/- 16], 46% CAD) were enrolled and 89 were implanted with a VENTAK PRIZM AVT (Guidant). Spontaneous atrial and ventricular tachyarrhythmias were printed and evaluated during an average follow-up period of 272 +/- 72 days utilizing the stored intracardial electrogram function of the device. Nineteen patients (21%) presented had only atrial tachyarrhythmias, 32 patients (36%) had both atrial and ventricular tachyarrhythmias and 18 patients (20%) had only ventricular tachyarrhythmias. Patients with only atrial tachyarrhythmias had a total of 3274 atrial episodes; 2002 terminated spontaneously, 1264 were treated with ATP and 8 with shock therapy. ATP was successful in 735 (58%) of 1264 episodes. Patients with both atrial and ventricular tachyarrhythmias had 7277 documented atrial tachyarrhythmias, 5231 terminated spontaneously, 1153 of 2009 were terminated by ATP (57.4%) and 37 by shock therapy (20 patient controlled). Atrial tachyarrhythmias identified as atrial flutter (AT) by the atrial rhythm classification (ARC) algorithm had a higher ATP conversion success rate than episodes identified as atrial fibrillation (AF); 66.7% for AT and 26.4% for AF. Patients with only ventricular tachyarrhythmias had 690 documented episodes, 401 terminated spontaneously, 248 (85.8%) were terminated by ATP and 41 by shock. Seventy-seven percent of patients with an ICD indication had spontaneous atrial and/or ventricular tachyharrhythmias within the first 6 months after ICD implantation. ATP therapy terminated 58% of all atrial tachyarrhytmias and 66.7% of the atrial flutters. The dual chamber ICD detected, classified and terminated all ventricular tacharrhythmias appropriately.

Contributions of permanent cardiac pacing in the treatment of atrial fibrillation.

Newer indications for permanent cardiac stimulation include the prevention of paroxysmal atrial fibrillation (AF) and cardiac resynchronisation in patients suffering from advanced heart failure. Direct comparisons between VVI and DDD or AAI pacing showed an advantage conferred by physiological pacing on the risk of developing AF during long-term follow-up in patients with sinus node dysfunction, AV block, or both. Furthermore, in patients with conventional pacing indications and paroxysmal atrial tachyarrhythmias, a high percentage of atrial pacing was associated with a lighter AF burden. This article reviews several important issues involved in the optimisation of cardiac pacing with a view to prevent paroxysmal AF by new, dedicated pacing algorithms. The AF Suppression trade mark algorithm significantly reduced the rates of symptomatic paroxysmal AF. This algorithm, which confers its benefit by maintaining the atrial pacing rate slightly above the spontaneous sinus rate, should be activated in patients with a history of atrial tachyarrhythmia. Implanting the lead in the low atrial septum seems to reduce further the frequency of tachyarrhythmic events. Future indications for this mode of pacing may be extended to patients at high risk of new-onset or recurrent AF, such as candidates for cardiac resynchronisation therapy or implantable cardioverter/defibrillator recipients.

Diagnostic information in implantable devices that pertain to endpoints in atrial fibrillation studies

Implantable devices can store significant information about physiologic parameters relating to rhythm and rate control. The primary objective of our analysis was to evaluate the relationship between changes in these parameters and changes in clinical outcomes in patients with atrial tachyarrhythmias (AT). Because the present guidelines do not provide quantitative definition of rhythm and rate control, we used the percent of time in AT and frequency of such episodes as measures of rhythm control. Rate control was measured as the percent of time spent at a ventricular rate >120 beats/min, as well as the median ventricular rate during AT. Analysis was conducted in 643 patients with a history of AT and bradycardia receiving pacemakers to evaluate whether changes in these parameters were correlated with changes in cardiac hospitalization rates and SF-36 and symptom checklist scores. All patients were followed at 1, 4, and 7 months postimplant, during which rhythm and rate control data were collected. Positive correlation was observed between changes in cardiac hospitalization rate and changes in AT burden, as well as frequency of AT (P = 0.01, r = 0.08 for each). Changes in SF-36 or symptom checklist scores did not correlate with changes in rhythm and rate control measures. This patient cohort had relatively asymptomatic atrial fibrillation (symptom checklist frequency and severity scores of 14.3 ± 9.5 and 11.5 ± 7.9, respectively), and this may have contributed to the lack of correlation with SF-36 and symptom scores. Data stored in implantable devices offer a unique opportunity to monitor parameters of rhythm as well as rate control in patients with AT. In patients implanted with pacemakers for management of bradyarrhythmias who have a history of AT, a significantly positive but weak correlation was observed between changes in rhythm control measures (AT burden and frequency) and changes in cardiac hospitalization rate.

Effect of preventive and automatic antitachycardia atrial pacing on frequency and duration of atrial tachyarrhythmia episodes

Objective: To evaluate, whether frequency and duration of atrial tachyarrhythmia (AT) episodes (eps.) in patients (pts.) with a novel DDDRP pacemaker are influenced by the activation of preventive atrial pacing algorithms (alg.) and automatic atrial anti-tachycardia pacing (ATP). Methods: In 23 pts. with conventional pacing indication and documented history of AT, a novel DDDRP device (AT500, model 7253, Medtronic) was implanted. DDDR pacing (60-1201min.) and AT detection (atrial cycle length lmin and classified as atrial flutter (cycle length 220360ms, variability 1min. 0.1, #p=0.1, *p=O.09 Conclusions: Mean AT eps. frequency (per day and patient) and mean AT eps. duration decreased after activation of preventive pacing alg. and automatic atrial ATP, but not significantly. Approximately half of all AT eps. lasted >1 minute. 44% of these eps. were also classified as AFlut and thus treated by ATP delivery. INCIDENCE OF PRIOR UNKNOWN VENTRICULAR TACHYCARDIAS IN PATIENTS WITH ATRIAL TACHYARRHYTHMIAS AND BRADYINDICATED PACEMAKER C. Unterberg 1, C. Israel 2, B. Huegl 3, T. Lawo 4, J. Stevens 1, D. Vollmann 1 ~Department of Cardiology, Georg August Universi~ Goettingen, Germany, 2J.W+ Goethe University Frankfurt, Germany, Heart Center Leipzig, Germany, 4University Hospital Bochum, Germany

Reversal of atrial electrical remodeling following cardioversion of long-standing atrial fibrillation in man.

In animal studies, atrial fibrillation has been shown to shorten the atrial refractory period and impair its rate adaptation. However, little is known about the effects of chronic atrial fibrillation on atrial electrophysiology and its recovery course in humans. Nineteen patients, mean age 64 +/- 14 years, with chronic atrial fibrillation of more than six months duration were included in this study. All of them were successfully converted to sinus rhythm with an external defibrillator. Atrial effective refractory periods at right atrial appendage and distal coronary sinus were determined with five pacing cycle lengths (300, 400, 500, 600 and 700 ms) at 30 min after cardioversion and once a day for four days. The atrial conduction properties, including P wave duration of surface ECG, and right and left atrial conduction times, were also measured at the same time interval. Twenty age-matched patients without a history of atrial tachyarrhythmia were evaluated as controls. In comparison with controls, chronic atrial fibrillation significantly shortened the atrial effective refractory period, impaired its rate adaptation response, especially at distal coronary sinus, and depressed the conduction properties of atria. The atrial conduction properties did not change during the four-day follow-up period; however, the atrial effective refractory period was gradually prolonged and its rate adaptation response improved after restoration of sinus rhythm. In humans, chronic atrial fibrillation significantly shortened the atrial effective refractory period, and impaired its rate adaptation response. Restoration and maintenance of sinus rhythm could reverse these electrophysiological changes.

Physiologic cardiac pacing in patients with contemporary implantable cardioverter-defibrillators

Contemporary implantable cardioverter-defibrillators (ICD) incorporate single-chamber ventricular pacing capability. However, because poor ventricular function and/or congestive heart failure is common in the ICD population, the provision of more “physiologic” pacing modes has been receiving increased attention. To evaluate the potential impact of ICDs with physiologic pacing features, we assessed the frequency with which atrial-based pacing modes with or without rate responsiveness are currently used in ICD recipients. Further, we characterized those clinical variables at initial ICD implant that tended to be associated with subsequent need for physiologic pacing. Clinical findings were reviewed in 250 consecutive patients who received ICDs with VVI pacing capability at the University of Minnesota Cardiac Arrhythmia Center between January 1991 and February 1997. Adjunctive physiologic pacing was undertaken in 35 patients (14%): 13 before or at the same time as their ICD, and 22 within a mean of 2.5 years after initial ICD surgery. A history of atrial tachyarrhythmia before ICD implantation (p <0.0001) and treatment with antiarrhythmic drugs at the time of ICD surgery (p <0.05) were predictors of subsequent need for physiologic pacing. The type of presenting ventricular tachyarrhythmia and electrophysiologic parameters (such as the HV interval and the shortest atrial pacing cycle length associated with 1:1 anterograde atrioventricular conduction) were not associated with a subsequent decision to implant a physiologic pacing system. Thus, we conclude that despite the need to implant a second device, physiologic pacing is currently used in an important subset of ICD recipients. Further, certain clinical features at time of ICD implant appear to characterize these patients and may prove helpful in patient selection for the next generation “dual-chamber” ICD.