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.

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.

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).

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.

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.

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.

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.

Extraction of old pacemaker or cardioverter-defibrillator leads by laser sheath versus femoral approach.

BACKGROUND: Some operators routinely extract chronically implanted transvenous leads from a femoral, whereas others prefer a superior approach. This prospective study compared the safety and effectiveness of laser sheaths versus femoral snare extractions. METHODS AND RESULTS: The single-center study comprised 101 patients referred for unequivocal indications to extract > or =1 transvenous lead(s). Patients were >4 years of age and were randomly assigned to extractions with a laser sheath (group 1: n=50) versus a snare via femoral approach (group 2: n=51). The multicenter study comprised 358 patients who underwent extraction of old transvenous leads using laser sheaths (n=218, group 3) in 3 centers and from a femoral approach (n=138, group 4) in 3 other centers. In the single-center study, the success and complications rates were similar in groups 1 and 2. No patient died of a periprocedural complication. The procedural duration (51+/-22 versus 86+/-51 minutes) and duration of total fluoroscopic exposure (7+/-7 versus 21+/-17 minutes) were significantly shorter (each P<0.01) in group I than in group 2. In the multicenter study, we observed 2 procedure-associated deaths in group 3 versus 1 in group 4. Major procedural complications were observed in 3% of patients in group 3, versus 3% in group 4 (P=NS). The rates of complete, partial, and unsuccessful extractions were similar in groups 3 and 4. CONCLUSIONS: Old transvenous leads were extracted with similar success and complication rates by the femoral and laser approaches. However, the femoral approach was associated with longer procedures and a longer duration of fluoroscopic exposure.

Identification and characterization of super-responders after cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) has been shown to induce a spectacular effect on left ventricular (LV) function in certain patients. Our aim was to analyze and characterize the super-responders (SRs) to CRT using echocardiography in 186 patients with a conventional indication according to the European Society Cardiology guidelines. The investigation took place before and 6 months after implantation. CRT-SRs were defined by an improvement of the New York Heart Association functional class and LV ejection fraction to > or = 50% in absolute values associated with a relative LV end-systolic volume reduction of > or = 15%. Of the 186 patients, 18 (9.7%) were identified as CRT-SRs and had a significantly lower prevalence of ischemic etiology (11%), lower LV dimensions, lower left atrial volume, and greater global longitudinal strain at baseline. Receiver operating characteristics curves identified global longitudinal strain as the strongest parameter for predicting CRT-SRs, with a cutoff value of -12% (area under the curve 0.87, sensitivity 71%, and specificity 85%, p <0.01). In conclusion, in the present retrospective study, only a left atrial volume <55 ml and global longitudinal strain < or = -12% were independent predictors of CRT-SRs.

[Atrial fibrillation: practical questions. Who are the best candidates for atrial fibrillation ablation?]. / Fibrillation atriale : questions pratiques. Quels sont les meilleurs candidats à l'ablation de la fibrillation atriale?

Ablation of paroxysmal AF in symptomatic patients is a clear indication after failure of anti-arrhythmic therapy (class IIa according to the recommendations). Ablation of persistent AF is feasible, as second line after failure of medical treatment, although there is no real consensus on ablative techniques : this procedure is long and complex, exposure to ionizing radiation is important. Regarding ablation of persistent AF, a careful selection of patients and multiple interventions are often necessary to increase the success rate. Standardization of the procedure and better reproducibility of results are essential to increase the indications for ablation in patients with persistent AF. Improvements are expected concerning the operative strategy, the targets of ablation and available tools.

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.

Optimizing hemodynamics in heart failure patients by systematic screening of left ventricular pacing sites: the lateral left ventricular wall and the coronary sinus are rarely the best sites.

OBJECTIVES: We sought to evaluate the impact of the left ventricular (LV) pacing site on hemodynamic response to cardiac resynchronization therapy (CRT). BACKGROUND: CRT reduces morbidity and mortality in heart failure patients. However, 20% to 40% of eligible patients may not fully benefit from CRT device implantation. We hypothesized that selecting the optimal LV pacing site could be critical in this issue. METHODS: Thirty-five patients with nonischemic dilated cardiomyopathy referred for CRT device implantation were studied. Intraventricular dyssynchrony and latest activated LV wall were defined by tissue Doppler imaging analysis before the study. Eleven predetermined LV pacing sites were systematically assessed in random order: basal and mid-cavity (septal, anterior, lateral, inferior), apex, coronary sinus (CS), and the endocardial site facing the CS pacing site. For each patient, +dP/dT(max), -dP/dT(min), pulse pressure, and end-systolic pressure during baseline (AAI) and DDD LV pacing were compared. Two atrioventricular delays were tested. RESULTS: Major interindividual and intraindividual variations of hemodynamic response depending on the LV pacing site were observed. Compared with baseline, LV DDD pacing at the best LV position significantly improved +dP/dT(max) (+31 +/- 26%, p < 0.001) and was superior to pacing the CS (+15 +/- 23%, p < 0.001), the lateral LV wall (+18 +/- 22%, p < 0.001), or the latest activated LV wall (+11 +/- 17%, p < 0.001). CONCLUSIONS: The pacing site is a primary determinant of the hemodynamic response to LV pacing in patients with nonischemic dilated cardiomyopathy. Pacing at the best LV site is associated acutely with fewer nonresponders and twice the improvement in +dP/dT(max) observed with CS pacing.

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.

Absence of additional improvement in outcome of patients receiving cardiac resynchronization therapy paced at the most delayed left ventricular region.

BACKGROUND: The choice of the optimal left ventricular (LV) pacing site remains an issue in patients requiring cardiac resynchronization therapy (CRT). AIM: This prospective study compared the outcome of patients paced at the most delayed LV region with that of patients paced at any other LV site. METHODS: Forty-four patients with severe heart failure underwent three-dimensional (3D) echocardiography before implantation and 3 days after implantation of a CRT device, to determine the most delayed LV region during spontaneous rhythm and during right ventricular pacing. The patients were divided subsequently into four groups: group 1 (n=19), LV lead placed at the most delayed echocardiographic site in spontaneous rhythm; group 2 (n=25), LV lead placed at any other site; group 3 (n=21), LV lead placed at the most delayed echocardiographic site during right ventricular pacing; group 4 (n=23), LV lead placed at any other site. RESULTS: No significant differences were observed between the four groups before implantation. After 6 months of CRT, no significant differences were observed between groups 1 and 2 or between groups 3 and 4 in terms of change in New York Heart Association functional class, Minnesota living with heart failure questionnaire, 6-minute walk test, peak exercise oxygen consumption, 3D ventricular dyssynchrony and 3D LV ejection fraction. CONCLUSION: Implantation of the LV lead in the most delayed region of the left ventricle determined by 3D echocardiography did not result in additional improvement in symptoms or LV function.

Additional value of three-dimensional echocardiography in patients with cardiac resynchronization therapy.

BACKGROUND: There is no gold standard technique for quantification of ventricular dyssynchrony. AIM: To investigate whether additional real-time three-dimensional morphologic assessment of ventricular dyssynchrony affects response after biventricular pacing. METHODS: Forty-one patients with severe heart failure were implanted with a biventricular pacing device and underwent two-dimensional (time dispersion of 12 left ventricular electromechanical delays) and three-dimensional echocardiographic assessment of ventricular dyssynchrony (dispersion of time to minimum regional volume for 16 left ventricular segments), before implantation, 2 days postimplantation with optimization of the pacing interventricular delay and 6 months postimplantation. RESULTS: Individual optimization of sequential biventricular pacing based on three-dimensional ventricular dyssynchrony provided more improvement (p<0.05) in left ventricular ejection fraction and cardiac output than simultaneous biventricular pacing. During the different configurations of sequential biventricular pacing, the changes in three-dimensional ventricular dyssynchrony were highly correlated with those of cardiac output (r=-0.67, p<0.001) and ejection fraction (r=-0.68, p<0.001). The correlations between two-dimensional ventricular dyssynchrony and cardiac output or ejection fraction were significant but less (r=-0.60, p<0.01 and r=-0.56, p<0.05, respectively). After 6 months, 76% of patients were considered responders (10% decrease in end-systolic volume). Before implantation, we observed a significant difference between responders and non-responders in terms of three-dimensional (p<0.05) - but not two-dimensional - ventricular dyssynchrony. CONCLUSION: This prospective study demonstrated the additional value of three-dimensional assessment of ventricular dyssynchrony in predicting response after biventricular pacing and optimizing the pacing configuration.

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.

Echocardiographic study of the optimal atrioventricular delay at rest and during exercise in recipients of cardiac resynchronization therapy systems.

BACKGROUND: It is unclear whether, in recipients of cardiac resynchronization therapy (CRT) systems, the optimal AV delay should be the same, shorter, or longer during exercise than at rest. OBJECTIVE: This study sought to examine the effects of atrioventricular (AV) delay optimization at rest and during exercise in 50 recipients of CRT systems. METHODS: We measured left ventricular (LV) outflow tract velocity time integral (OT-VTI) and LV filling time (FT) echocardiographically, at rest and during exercise to 60% of the maximal predicted heart rate, with the sensed AV delay set at 40, 70, 100, 120, 150, and 200 ms. The measurements made at rest versus those made during exercise, and among the several programmed AV delays, were compared. RESULTS: The optimal AV delay based on LVOT-VTI was shorter during exercise than at rest in 37%, unchanged in 37%, and longer in 26% of patients. The optimal AV delay based on LVFT was shorter during exercise than at rest in 27%, unchanged in 23%, and longer in 50% of patients. Optimization of the AV delay during exercise increased LVFT and LVOT-VTI significantly (P < .05) compared with (1) any other arbitrarily chosen AV delay, (2) the optimal AV delay at rest, (3) an AV delay systematically shortened from rest to exercise. CONCLUSION: Optimization of the AV delay had a positive effect on echocardiographic indices of LV function. The systematic shortening of the AV delay during exercise is not recommended because, in a high proportion of patients, the optimal AV delay was longer during exercise than at rest.

Clinical value of fibrillatory wave amplitude on surface ECG in patients with persistent atrial fibrillation.

PURPOSE: We postulated that amplitude of fibrillatory (F)-wave in patients with persistent AF would correlate with clinical characteristics and outcome in patients undergoing catheter ablation for AF. METHOD: Maximal and mean amplitude of F-waves were measured in V1 and lead II in 90 patients prior to ablation for persistent AF. F-wave amplitudes were correlated to clinical, echocardiographic variables, and outcome. RESULTS: F-wave > or = 0.1 mV in lead II and V1 was correlated with younger age and shorter AF history, and in lead II only was correlated with a smaller left atrium. Higher F-wave amplitude at baseline predicted AF termination during ablation. Maximal amplitude of > or = 0.07 mV predicted AF termination by ablation with 82%/79% sensitivity and 68%/73% specificity in V1/lead II respectively. An association between F-wave amplitude and AF recurrence was observed. Forty-three percent of patients with mean f wave amplitude <0.05 in lead V1 had AF recurrence compared to 12% of those with F-wave > or = 0.05 (p = 0.004). CONCLUSION: Longer AF duration, older age and larger LA size are associated with fine AF amplitude. High F-wave amplitude predicts procedural termination of arrhyhmia in patients with persistent AF and freedom from AF upon follow-up.

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.