Electrogram morphology discriminators in implantable cardioverter defibrillators: A comparative evaluation.

BACKGROUND: Morphology algorithms are currently recommended as a standalone discriminator in single-chamber implantable cardioverter defibrillators (ICDs). However, these proprietary algorithms differ in both design and nominal programming. OBJECTIVE: To compare three different algorithms with nominal versus advanced programming in their ability to discriminate between ventricular (VT) and supraventricular tachycardia (SVT). METHODS: In nine European centers, VT and SVTs were collected from Abbott, Boston Scientific, and Medtronic dual- and triple-chamber ICDs via their respective remote monitoring portals. Percentage morphology matches were recorded for selected episodes which were classified as VT or SVT by means of atrioventricular comparison. The sensitivity and related specificity of each manufacturer discriminator was determined at various values of template match percentage from receiving operating characteristics (ROC) curve analysis. RESULTS: A total of 534 episodes were retained for the analysis. In ROC analyses, Abbott Far Field MD (area under the curve [AUC]: 0.91; P < .001) and Boston Scientific RhythmID (AUC: 0.95; P < .001) show higher AUC than Medtronic Wavelet (AUC: 0.81; P < .001) when tested for their ability to discriminate VT from SVT. At nominal % match threshold all devices provided high sensitivity in VT identification, (91%, 100%, and 90%, respectively, for Abbott, Boston Scientific, and Medtronic) but contrasted specificities in SVT discrimination (85%, 41%, and 62%, respectively). Abbott and Medtronic's nominal thresholds were similar to the optimal thresholds. Optimization of the % match threshold improved the Boston Scientific specificity to 79% without compromising the sensitivity. CONCLUSION: Proprietary morphology discriminators show important differences in their ability to discriminate SVT. How much this impact the overall discrimination process remains to be investigated.

Early Detection and Treatment of Atrial Arrhythmias Alleviates the Arrhythmic Burden in Paced Patients: The SETAM Study.

BACKGROUND: Remote monitoring (RM) can remotely detect atrial tachyarrhythmias (ATAs). The benefit of RM compared to conventional follow-up in the detection and management of ATA was assessed in recipients of dual-chamber pacemakers. METHODS: The multicenter randomized SETAM study enrolled 595 patients in sinus rhythm with a CHA2 DS2 -VASc score ≥2, without ATA history and untreated with antiarrhythmics and antithrombotics, randomly assigned to RM (RM-ON; n = 291) versus ambulatory follow-up (RM-OFF; n = 304) during 12.8 ± 3.3 months. ATA occurrence, burden, and management were analyzed together with adverse clinical events. RESULTS: Patients were 79 ± 8 years old, 63% men, with a CHA2 DS2 -VASc score of 3.7± 1.2. ATA were detected in 83 patients (28%) in the RM-ON versus 66 (22%) in the RM-OFF group (P = 0.06). The median time between the pacemaker implantation and the first treated ATA was 114 days [44; 241] in the RM-ON versus 224 days [67; 366] in the RM-OFF group (hazard ratio [HR] = 0.56; 95% confidence interval [CI]: 0.37-0.86; P = 0.01). Therapies for ATA were initiated in 92 patients and the time to treatment of ATA was shortened by 44% in the RM-ON group (HR = 0.565; 95% CI: 0.37-0.86; P = 0.01). Over the last 4 months of follow-up, the mean ATA burden was alleviated by 4 hours/day (18%) in the RM-ON group. The rate of adverse clinical events was similar in both groups. CONCLUSION: Remotely monitored patients were diagnosed and treated earlier for ATA, and subsequently had a lower ATA burden.

Impact of pacing site on QRS duration and its relationship to hemodynamic response in cardiac resynchronization therapy for congestive heart failure.

INTRODUCTION: Recent studies have demonstrated that left ventricular (LV) pacing site is a critical parameter in optimizing cardiac resynchronization therapy (CRT). The present study evaluates the effect of pacing from different LV locations on QRS duration (QRSd) and their relationship to acute hemodynamic response in congestive heart failure patients. METHODS AND RESULTS: Thirty-five patients with nonischemic dilated cardiomyopathy and left bundle branch block referred for CRT device implantation were studied. Eleven predetermined LV pacing sites were systematically assessed in random order: epicardial: coronary sinus (CS); endocardial: basal and mid-cavity (septal, anterior, lateral, and inferior), apex, and the endocardial site facing the CS pacing site. For each patient QRSd and +dP/dtmax during baseline (AAI) and DDD LV pacing at 2 atrioventricular delays were compared. Response to CRT was significantly better in patients with wider baseline QRSd (≥150 milliseconds). Hemodynamic response was inversely correlated to increase of QRSd during LV pacing (short atrioventricular [AV] delay: r = 0.44, P < 0.001; long AV delay: r = 0.59, P < 0.001). Compared to baseline, LV pacing at the site of shortest QRSd significantly improved +dP/dtmax (+18 ± 25%, P < 0.001) but was not superior to other conventional strategy (lateral wall, CS pacing, and echo-guided) and was inferior to a hemodynamically guided strategy. CONCLUSIONS: In our study, we have demonstrated that changes of QRSd during LV pacing correlated with acute hemodynamic response and that LV pacing location was a primary determinant of paced QRSd. Although QRSd did not predict the maximum hemodynamic response, our results confirm the link between electrical activation and hemodynamic response of the LV during CRT.

Remote interrogation and reprogramming of cardiac implantable electronic devices using a custom multivendor solution.

BACKGROUND: Until recently, remote interrogation and reprogramming of therapeutic cardiac implantable electronic devices (CIEDs) have been virtually nonexistent owing to technical challenges and safety concerns. It could be extremely useful, in particular in case of emergencies, when patients live far from CIED professionals or during enforced physical distancing. OBJECTIVE: We investigated the feasibility and safety of a custom solution for remote interrogation and reprogramming of CIEDs from various manufacturers in various clinically relevant situations. METHODS: Our solution consists of remote controlling CIED programmers through screen capture and remote cursor control. In this multicenter feasibility study, the primary outcome was technical feasibility (% of success) and safety (absence of complication) of interrogation and reprogramming when indicated in clinically driven encounters. RESULTS: A total of 115 remote interrogations were performed in 110 patients: within the hospital (n = 73), medium range (50-100 km; n = 22), and long range (>5000 km; n = 20). Implanted devices were pacemakers (n = 85) and implantable cardioverter-defibrillators (n = 25) from Abbott (N=13), Biotronik (n = 65), and MicroPort (n = 32). Patients were located in the outpatient clinic, cardiology department, radiology department (magnetic resonance imaging), operating room (per implantation), and intensive care unit. Teleworking was performed in 39 cases. Complete CIED interrogations succeeded in all patients with reprogramming in 56 of 115 sessions (49%). No clinical or technical complications occurred. The time lag for screen interaction was below 1 second. CONCLUSION: Remote interrogation and reprogramming of CIEDs are feasible and safe across disparate clinical contexts and distances. This strategy may enhance health care access and facilitate medical training, tele-expertise, and telework worldwide.

Long-term outcomes after pocket or scar revision and reimplantation of pacemakers with preerosion.

INTRODUCTION: Cardiac pacemakers with preerosion are often reimplanted. Preerosion may be caused by an evolving local infectious process affecting the entire pacing system or by mechanical migration of the device causing ischemic necrosis of the skin tissues. We examined the long-term outcome of 33 patients who underwent pocket or scar revision and submuscular reimplantation of cardiac pacemakers in our institution. METHODS: Before undergoing pocket or scar revision and reimplantation, all patients (1) had negative serial blood cultures, (2) had no vegetation on transesophageal echocardiography, (3) had a normal blood C-reactive protein concentrations, (4) were afebrile, (5) had no cutaneous breakthrough, and (6) presented with preerosion of the pulse generator or granulomatous-like scar abnormality. RESULTS: THE mean follow-up was 37 ± 12 months. Among 16 patients presenting with preerosion associated with signs of local cutaneous inflammation, 62.5% developed an infection of the pacing system requiring later explantation. Of eight patients presenting initially with migration of the pulse generator and mechanical protrusion, none required subsequent explantation of the system. Among nine patients presenting initially with granulomatous-like scar abnormalities, 55.6% underwent explantation of the pacing system during follow-up for management of documented local infection. CONCLUSIONS: The reimplantation of pulse generators with preerosion in the presence of local inflammatory manifestations or granulomatous-like changes of the scar is complicated by documented cardiac pacemaker infection in >50% of cases. In these patients, the explantation of the pacing system is recommended before the development of prognostically much more serious spread of infection to the leads and cardiac tissues.

Safety of deferring the reimplantation of pacing systems after their removal for infectious complications in selected patients: a 1-year follow-up study.

INTRODUCTION: Recent expert consensus guidelines mention that one of the principles for infected device replacement following removal is to "reevaluate carefully if there is a continued need for a new cardiac device replacement." This is a Class I recommendation, which nevertheless suffers from a very low level of evidence (level of evidence C), since no study has revisited the systematic practice of reimplanting the same device based on a meticulous clinical reassessment. In the present paper, we examined the safety of withholding the implantation of pacing systems in selected patients. METHODS AND RESULTS: Between January 2005 and December 2007, 188 consecutive patients underwent extractions of infected pacing systems at 2 medical centers. "Low-risk" patients were identified by (1) a spontaneous heart rate >45 bpm, (2) no symptomatic asystole during monitoring, (3) QRS duration <120 ms when history of AV block was noted, (4) no high-degree AV block during continuous monitoring. They remained device-free, unless an adverse clinical event occurred mandating the reimplantation. The primary study endpoint was rate of sudden death and syncope after a 12-month follow-up. Among the 74 (39.4%) "low-risk" patients, a single patient suffered a bradycardia-related syncopal event corresponding to a 1.3% (95% CI, 0.0-3.9) rate of primary endpoint. Pacing systems were also reimplanted in 24 patients (32.4%) for syncope (n = 1), nonsevere bradycardia-reated symptoms (n = 17), cardiac resynchronization (n = 2), and for reassurance in 4 asymptomatic patients. CONCLUSION: After removal of infected pacing systems, these preliminary data demonstrated that a strategy of nonsystematic device reimplantation associated with close surveillance was safe in "low-risk" patients, allowing the administration of antimicrobials in a device-free state.

Reliability and reproducibility of QRS duration in the selection of candidates for cardiac resynchronization therapy.

BACKGROUND: A QRS >120 ms remains the recommended criterion for the selection of cardiac resynchronization therapy (CRT) candidates. However, the reproducibility of this measurement has not been studied thoroughly. METHODS: QRS duration was measured by 3 experienced cardiologists and by automatic measurement on 228 electrocardiograms (ECGs) randomly collected from 188 subjects, including neonates, healthy adults, patients with complete and incomplete bundle branch block, and CRT candidates. All ECGs were recorded at a 25 mm/s sweep speed. Forty recordings were duplicated and 50 ECGs were recorded at both 25 and 50 mm/s. RESULTS: Significant interobserver differences (P < 0.001) were found between each combination of paired observers, with an up to 50-ms absolute variability between cardiologists and low concordance with computerized measurements. Intraobserver absolute variability was also significant (P < 0.01) for the 3 observers. These significant differences persisted (P < 0.01) when focusing our interest on the ECGs in the 100-140 ms range (defined as at least one out of the 4 measures in this range). Considering the 120 ms limit, 22 (27.5%) ECGs were differently classified by at least one of the cardiologists. We observed similar interobserver differences between each combination of paired observers with a 50 mm/s sweep speed. CONCLUSION: Manual QRS duration measurements were associated with significant inter- and intraobserver variability and low concordance with computerized measurements. The measurement of QRS is, therefore, operator-dependent and a reevaluation of the measurement methods may be essential to develop clinical and investigative standards.

Relationship between left ventricular stimulation characteristics at implantation and echocardiographic response after 6 months of cardiac resynchronization therapy.

AIMS: Although the electrical stimulation of an ischaemic tissue adversely affects the left ventricular (LV) systolic function, the optimal stimulation site in patients with non-ischaemic cardiomyopathy has not been systematically studied. We hypothesized that the local stimulation characteristics at the time of device implantation predict the response to cardiac resynchronization therapy (CRT). METHODS AND RESULTS: We measured the impedance, sensing, and capture threshold of a bipolar LV lead in 138 patients with non-ischaemic cardiomyopathy undergoing first implantation of CRT device for drug refractory heart failure. All patients underwent echocardiography at baseline and at 6 months post-implantation. An absence of favourable response to CRT was defined as <15% decrease in echocardiographic LV end-systolic volume (LVESV) at 6 months. Echocardiographic response to CRT was observed in 70% of patients. The LV lead measurements predicted neither the optimal stimulation site nor the response to CRT. Left ventricular capture threshold (1.50 ± 1.1 vs. 1.32 ± 0.8 V) and impedance (725 ± 287 vs. 720 ± 261 Ω) were similar between the responders and the non-responders. Independent of baseline LV ejection fraction or ESV, the LV R-wave amplitude at implantation was significantly higher (P = 0.0038) in responders (12.7 ± 5.2 mV) than in non-responders (9.7 ± 6.3 mV), with an area under the receiver operating characteristic curve of 0.7. CONCLUSION: Response to CRT, as determined by decrease in LVESV at 6 months, was associated with significantly higher LV R-wave amplitude at the time of device implantation.

Validation of an echocardiographic multiparametric strategy to increase responders patients after cardiac resynchronization: a multicentre study.

AIMS: We sought to develop and validate a multiparametric algorithm by applying previously validated criteria to predict cardiac resynchronization therapy (CRT) response in a multicentre study. Thirty per cent of patients treated by CRT fail to respond to the treatment. Although dyssynchrony by echocardiography has been used to improve the selection of patients, the complexity of myocardial contraction has generated a moderate improvement using any of several individual parameters. METHODS AND RESULTS: Two hundred end-stage heart failure patients [NYHA 3-4 and left ventricular ejection fraction (LVEF)<35%] with QRS>120 ms were included. Echocardiography analysis focused on the following parameters: atrioventricular dyssynchrony, interventricular dyssynchrony, and intraventricular dyssynchrony that integrated radial (PSAX M-mode) and longitudinal [tissue Doppler imaging (TDI)] evaluations for spatial (wall to wall) and temporal (wall end-systole to mitral valve opening) dyssynchrony diagnosis. Following CRT implantation, patients were monitored for 6 months with functional and echo evaluations defining responders by a 15% reduction in end-systolic volume. Mean QRS duration and LVEF were 152 +/- 17 ms and 25 +/- 8%. There was a CRT response in 57% of patients, independent of QRS width. Mean prevalence of positive criteria was 34 +/- 8%. Feasibility and variability averages were 81 +/- 20% and 9 +/- 4%. In a single parametric approach, ranges of sensitivities and specificities were 18-65% and 45-84% with a mean of 41% and 66%. A multiparametric approach by focusing on criteria combination decreased the mean rate of false-positive results to 14 +/- 12%, 5 +/- 4%, 2 +/- 2%, and 1 +/- 2% from one to four parameters, respectively. More than three parameters were associated with a specificity above 90% and a positive predictive value above 65%. Reproducibility of this global strategy was 91%. CONCLUSION: A multiparametric echocardiographic strategy based on the association of conventional criteria is a better indicator of CRT response than the existing single parametric approaches.

Catheter ablation of atrial tachycardia following atrial fibrillation ablation.

Atrial tachycardias represent the second front of atrial fibrillation (AF) ablation. They are frequently encountered during the index ablation for patients with persistent AF and are common following ablation of persistent AF, occurring in half of all patients who have had AF successfully terminated. An atrial tachycardia is rightly seen as a failure of AF ablation, as these tachycardias are poorly tolerated by patients. This article describes a simple, practical approach to diagnosis and ablation of these atrial tachycardias.

Remote implantable cardioverter defibrillator monitoring in a Brugada syndrome population.

AIMS: The diagnosis of Brugada syndrome (BS) is typically made in a young and otherwise healthy population. In patients with a high risk of sudden cardiac death (SCD), the only currently recommended therapy is an implantable cardioverter defibrillator (ICD), but these are not without complications. We investigated whether remote ICD monitoring could simplify follow-up and detect potential complications in these patients. METHODS AND RESULTS: Thirty-five consecutive patients (26 males, 44 +/- 11 years) implanted with an ICD for BS with a remote monitoring ['Home Monitoring' (HM), Biotronik, Germany] system were prospectively enrolled in this study. They were matched for age, sex, and follow-up duration with 35 BS patients implanted with an ICD without this capability. During a mean follow-up of 33 +/- 17 months, the number of cardiology consultations was significantly lower in the HM group (3 +/- 2 vs. 7 +/- 3; P < 0.001). Inappropriate shock(s) [IS(s)] occurred in three patients (8.5%) in the HM group vs. six (17%) in the control group (P = NS). Ten patients in the HM group had a median of four alerts ('ventricular tachycardia/ventricular fibrillation detection' in all patients, 'shock' in three, 'ineffective shock' in two patients with shock on noise, 'extreme ventricular pacing impedance' in one patient due to lead failure, and 'deactivated therapy' in two patients with lead failure before replacement). In 5 of these 10 patients, prompt reprogramming of the ICD may have prevented IS(s). CONCLUSION: Remote ICD monitoring in patients with BS decreases outpatient consultations and may help prevent ISs.

Electrocardiogram-based algorithm to predict the left ventricular lead position in recipients of cardiac resynchronization systems.

INTRODUCTION: Biventricular pacing is associated with various electrocardiographic patterns depending on the position of the left ventricular (LV) lead. We aimed to develop an electrocardiogram-based algorithm to predict the position of the LV lead. METHODS: The algorithm was developed in 100 consecutive recipients of cardiac resynchronization therapy (CRT) systems. QRS axis, morphology, and polarity were analyzed with a view to define the specific electrocardiographic characteristics associated with the various LV lead positions. The algorithm was prospectively validated in 50 consecutive CRT device recipients. RESULTS: The first analysis of the algorithm was the QRS morphology in V(1). A positive R wave in V(1) suggested LV lateral or posterior wall stimulation. A QS pattern was specific of anterior LV leads. In the presence of an R wave in V(1), V(6) was analyzed to distinguish between an inferior and anterior LV lead. Inferior leads were never associated with a positive V(6). To differentiate between lateral and posterior positions, we analyzed the pattern in V(2). Lateral leads were associated with an R morphology in V(1) and a negative V(2). Posterior leads were associated with an R morphology in V(1) and V(2). The algorithm allowed a reliable distinction between an inferior or anterior and a lateral or posterior lead position in 90% of patients. Inferior, anterior, lateral, and posterior positions were reliably distinguished in 80% of patients. CONCLUSION: This algorithm predicted the position of the LV lead with a high sensitivity and predictive value.

Left atrial linear lesions are required for successful treatment of persistent atrial fibrillation.

AIMS: This study evaluates the clinical outcome and incidence of left atrial (LA) macro re-entrant atrial tachycardia (AT) in patients in whom persistent atrial fibrillation (AF) terminated during catheter ablation without the need of roof and mitral lines. METHODS AND RESULTS: Persistent AF was terminated by ablation in 154 of 180 consecutive patients. AF history was 60 months including 11 months of continuous AF. Patients were divided into two groups: those who had not required both LA linear lesions to terminate AF (group A, 85 patients), and those who had (group B, 69 patients). There was no difference in clinical and echocardiographic characteristics between both groups except for a shorter duration of continuous AF in group A (9 vs.12 months, respectively) (P = 0.03). After 28 months of follow-up, the incidence of LA macro re-entrant AT necessitating linear ablation was higher in group A (76%) compared with group B (33%) (P = 0.002). When complete linear block could not be achieved during the index procedure, the incidence of subsequent roof (P = 0.008) or mitral isthmus (P = 0.010) dependent macro re-entrant AT was higher. CONCLUSION: Although persistent AF can be terminated by catheter ablation without linear lesions, the majority will require linear lesions for macro re-entrant AT.

Early recurrences after atrial fibrillation ablation: prognostic value and effect of early reablation.

INTRODUCTION: Early arrhythmia recurrences are common within the first month after atrial fibrillation (AF) ablation. The long-term consequences of these early recurrences (ER) are controversial. We investigated whether ER were predictive of late recurrences and the impact of early reablation on clinical outcome. METHODS: Three hundred two consecutive patients with paroxysmal or persistent AF were studied. Arrhythmia recurrence was defined as documented episode of AF or atrial tachycardia. Of 151 patients with ER, a subset of 61 patients had reablation within the first month following the index ablation (early reablation). In the remaining 90 patients, a repeat procedure was only performed for later arrhythmia recurrences occurring beyond 1 month. Patients were followed with clinical interview and ambulatory 24 hours monitoring. RESULTS: Patients with and without early reablation had similar baseline characteristics including echocardiographic parameters and type of AF. During a mean follow-up of 11 +/- 11 months, 82 patients (91%) without early reablation experienced late clinical recurrences. In contrast, patients with early reablation had lower rate of clinical recurrences (51% vs 91%, P < 0.0001) and fewer additional procedures (36% vs 91%, P < 0.0001). However, the total number of procedures over the entire follow-up was greater in those patients with early reablation (2.5 +/- 0.7 vs 2.2 +/- 0.6, P = 0.02). CONCLUSION: An overwhelming majority of patients with recurrences within the first month after ablation have late recurrences. An early reablation reduces the incidence of further recurrences. However, the overall number of procedures is higher in the medium-term follow-up. The optimal timing for the second procedure remains to be defined.

Impact of a patent foramen ovale on paroxysmal atrial fibrillation ablation.

INTRODUCTION: A patent foramen ovale (PFO) is located at the anterior and superior part of the anatomical interatrial septum, the area that is targeted during transseptal puncture. This study sought to investigate the impact of accessing the left atrium via a PFO on paroxysmal AF ablation. METHODS: From March 2004, 203 patients (55 +/- 11 years) underwent catheter ablation for paroxysmal AF (80 +/- 71 months), with the endpoint being electrical isolation of all pulmonary veins (PV) and AF noninducibility. The presence of a PFO was determined by both transesophageal echocardiography and catheter probing. Procedural difficulty was evaluated by radiofrequency (RF), procedural, and fluoroscopic durations. Clinical follow-up was also investigated. RESULTS: A PFO was detected in 27 patients (13%) by transesophageal echocardiography and in 22 additional patients (total 49 patients, 24%), by catheter probing (P < 0.001). A PFO was associated with longer total RF applications (57 +/- 19 vs 51 +/- 18 min, P = 0.04) and RF applications to isolate the PVs (42 +/- 16 vs 35 +/- 12 min, P = 0.001). Procedural and fluoroscopic times were unaffected. Seventy-three patients (36%) required a second procedure; there was no difference in the number of PV reconnections (1.3 vs 1.8 veins, P = NS). After a mean follow-up of 19 +/- 9 months, 194/203 patients (96%) were free of AF, with no difference in patients in whom a PFO had been used. CONCLUSION: Although isolation of PVs is longer, overall procedural duration and success is not affected when using a PFO compared with a transseptal puncture. The presence of a PFO is underestimated by transesophageal echocardiography with brachial injection when compared with catheter probing.

Imaging in catheter ablation for atrial fibrillation: enhancing the clinician's view.

Catheter ablation is an effective treatment for symptomatic atrial fibrillation. A thorough understanding of the left atrium anatomy and its adjacent structures is critical for the success of the procedure and for avoiding complications. Pre-procedural imaging aims at determining left atrial size, anatomy, and function and is also used to rule out an atrial thrombus. During the procedure, while fluoroscopy remains the gold standard imaging modality for guiding transseptal catheterization and catheter ablation, numerous other imaging modalities have been developed to improve 3D navigation and ablation. Finally, post-operative imaging intends to monitor heart function and to search for potential complications like pulmonary vein stenosis or the rare but dramatic atrio-oesophageal fistula. This review discusses the relative merits of all imaging modalities available in the context of catheter ablation of atrial fibrillation.

Cardiac Rhythm Disturbances in Hemodialysis Patients: Early Detection Using an Implantable Loop Recorder and Correlation With Biological and Dialysis Parameters.

OBJECTIVES: The aim of this study was to identify using implantable loop recorder (ILR) monitoring the mechanisms leading to sudden death (SD) in patients undergoing hemodialysis (HD). BACKGROUND: SD accounts for 11% to 25% of death in HD patients. METHODS: Continuous rhythm monitoring was performed using the remote monitoring capability of the ILR device in patients undergoing HD at 8 centers. Clinical, biological, and technical HD parameters were recorded and analyzed. RESULTS: Seventy-one patients (mean age 65 ± 9 years, 73% men) were included. Left ventricular ejection fraction was <50% in 16%. Twelve patients (17%) had histories of atrial fibrillation or flutter at inclusion. During a mean follow-up period of 21.3 ± 6.9 months, 16 patients died (14% patient-years), 7 (44%) of cardiovascular causes. Four SDs occurred, with progressive bradycardia followed by asystole. The incidence of patients presenting with significant conduction disorder and with ventricular arrhythmia was 14% and 9% patient-years, respectively. In multivariate survival frailty analyses, a higher risk for conduction disorder was associated with plasma potassium >5.0 mmol/l, bicarbonate <22 mmol/l, hemoglobin >11.5 g/dl, pre-HD systolic blood pressure >140 mm Hg, the longer interdialytic period, history of coronary artery disease, previous other arrhythmias, and diabetes mellitus. A higher risk for ventricular arrhythmia was associated with potassium <4.0 mmol/l, no antiarrhythmic drugs, and previous other arrhythmias. With ILR monitoring, de novo atrial fibrillation or flutter was diagnosed in 14 patients (20%). CONCLUSIONS: ILR may be considered in HD patients prone to significant conduction disorders, ventricular arrhythmia, or atrial fibrillation or flutter to allow early identification and initiation of adequate treatment. Therapeutic strategies reducing serum potassium variability could decrease the rate of SD in these patients. (Implantable Loop Recorder in Hemodialysis Patients [RYTHMODIAL]; NCT01252823).

Prospective randomized comparison of 8-mm gold-tip, externally irrigated-tip and 8-mm platinum-iridium tip catheters for cavotricuspid isthmus ablation.

INTRODUCTION: Radiofrequency (RF) ablation of the cavotricuspid isthmus (CTI) can be performed using different types of ablation catheter. Gold tip electrodes have the theoretical advantage of creating bigger lesions than standard platinum-iridium electrode. This prospective, randomized study compares the clinical efficacy of 8-mm gold tip catheter, externally irrigated and 8-mm platinum-iridium tip (Pt tip) catheters. METHODS AND RESULTS: Sixty consecutive patients (51 men, 60 +/- 10 years) undergoing de novo CTI ablation for documented typical atrial flutter were randomized to one of the following ablation catheters: 8-mm gold tip catheter, an externally irrigated-tip (Irr. tip) catheter, or an 8-mm Pt tip catheter. The procedural endpoint was achievement of bidirectional isthmus conduction block with < or = 20 minutes of RF energy application. The latter was achieved equally with the 3 catheters (95% for gold tip, 100% for irrigated tip, 95% for Pt tip) and the durations of RF (10 +/- 6, 10 +/- 4, 13 +/- 8 minutes), fluoroscopy (12 +/- 6, 12 +/- 7, 15 +/- 12 minutes) and the procedure (34 +/- 23, 38 +/- 24, 40 +/- 30 minutes) were similar in all groups. The maximal targeted power could not be reached in at least one location in 40% of patients with gold tip and in 35% of patients with Pt tip catheters whereas it was always achieved with an Irr. tip catheter (P = 0.003, P = 0.008). The reduction in impedance during RF delivery was greater with Irr. tip (11 +/- 7 ohms) than with gold (7 +/- 4 ohms, P = 0.02) or Pt tip (5 +/- 3 ohms, P = 0.001) catheters. CONCLUSION: This study demonstrates equivalent efficacies of gold, platinum-iridium and externally Irr. tip catheters for successful de novo ablation of the CTI.

[Arrhythmias in sleep apnea syndrome]. / Troubles du rythme cardiaque dans le syndrome d'apnée du sommeil.

Arrhythmias are more frequent in patients with sleep apnea syndrome. Bradycardias predominate. In the absence of controlled studies, it is difficult to link arrhythmias to sleep apnea syndrome or to the disease accompanying it (coronary disease, hypertension, etc.). Continuous positive airway pressure (CPAP) reduces arrhythmias significantly.

Predicting favourable outcomes in the setting of radiofrequency catheter ablation of long-standing persistent atrial fibrillation: a pilot study assessing the value of left atrial appendage peak flow velocity.

BACKGROUND: Catheter ablation is an effective and potentially curative treatment in patients with atrial fibrillation (AF). AIM: To test the hypothesis that left atrial appendage peak flow velocity (LAV) assessed by echocardiography can accurately predict successful catheter ablation as well as favourable outcome in the setting of long-standing persistent AF. METHODS: This prospective pilot study enrolled 40 patients with long-standing persistent AF (age 60 ± 11 years; persistence of AF 4.2 ± 2 years) who underwent a first catheter ablation procedure using a standardized sequential stepwise protocol. LAV was assessed before the catheter ablation procedure along with classical factors (age, sex, left atrial area, AF cycle length, AF duration and left ventricular ejection fraction), all of which were tested using logistic regression for ability to predict restoration of sinus rhythm during catheter ablation as well as absence of recurrence during a 1-year follow-up. RESULTS: Eighteen patients (45%) experienced AF termination during the procedure and 18 patients (45%) did not develop any recurrence during the first 12 months. Multivariable analysis demonstrated that high LAV (>0.3 m/s) was the only independent predictor of AF termination (odds ratio 5.91, 95% confidence interval 1.06-32.88; P=0.04) and absence of recurrence at 1 year (odds ratio 4.33, 95% confidence interval 1.05-17.81; P=0.04). CONCLUSIONS: This pilot study demonstrated the feasibility and importance of LAV measurement in the setting of long-standing persistent AF to predict successful catheter ablation and favourable mid-term outcome.