Artificial intelligence for detection of ventricular oversensing: Machine learning approaches for noise detection within nonsustained ventricular tachycardia episodes remotely transmitted by pacemakers and implantable cardioverter-defibrillators.

BACKGROUND: Pacemakers (PMs) and implantable cardioverter-defibrillators (ICDs) increasingly automatically record and remotely transmit nonsustained ventricular tachycardia (NSVT) episodes, which may reveal ventricular oversensing. OBJECTIVES: We aimed to develop and validate a machine learning algorithm that accurately classifies NSVT episodes transmitted by PMs and ICDs in order to lighten health care workload burden and improve patient safety. METHODS: PMs or ICDs (Boston Scientific, St Paul, MN) from 4 French hospitals with ≥1 transmitted NSVT episode were split into 3 subgroups: training set, validation set, and test set. Each NSVT episode was labeled as either physiological or nonphysiological. Four machine learning algorithms-2DTF-CNN, 2D-DenseNet, 2DTF-VGG, and 1D-AgResNet-were developed using training and validation data sets. Accuracies of the classifiers were compared with an analysis of the remote monitoring team of the Bordeaux University Hospital using F2 scores (favoring sensitivity over predictive positive value) using an independent test set. RESULTS: A total of 807 devices transmitted 10,471 NSVT recordings (82% ICD; 18% PM), of which 87 devices (10.8%) transmitted 544 NSVT recordings with nonphysiological signals. The classification by the remote monitoring team resulted in an F2 score of 0.932 (sensitivity 95%; specificity 99%) The 4 machine learning algorithms showed high and comparable F2 scores (2DTF-CNN: 0.914; 2D-DenseNet: 0.906; 2DTF-VGG: 0.863; 1D-AgResNet: 0.791), and only 1D-AgResNet had significantly different labeling from that of the remote monitoring team. CONCLUSION: Machine learning algorithms were accurate in detecting nonphysiological signals within electrograms transmitted by PMs and ICDs. An artificial intelligence approach may render remote monitoring less resourceful and improve patient safety.

Outcome of patients with early repolarization pattern and syncope.

BACKGROUND: Syncope in patients with an early repolarization (ER) pattern presents a challenge for clinicians as it has been identified as an indicator of a higher risk of life-threatening ventricular arrhythmias (VAs). OBJECTIVES: This study aimed to analyze the outcome of patients with an ER pattern and syncope and to evaluate the factors predictive of VAs. METHODS: Over a period of 5 years, we enrolled 143 patients with an ER pattern and syncope in a multicenter prospective registry. RESULTS: After the initial examinations, 97 patients (67.8%) were implanted with a device allowing electrocardiogram monitoring, including 84 (58.7%) with an implantable loop recorder. During a mean follow-up period of 68 ± 34 months, we documented 16 arrhythmias presumably responsible for syncope (5 VAs, 10 bradycardias, and 1 supraventricular tachycardia). Additionally, recurrent syncope not associated with electrocardiogram documentation occurred in 16 patients (11.2%). The cause of syncope was identified in 23 of 97 patients with a monitoring device (23.8%). The 5-year incidence of VAs and arrhythmic events presumably responsible for syncope was 4.9% and 11.0%, respectively. Patients who developed VAs showed no prodromes or specific triggers at the time of syncope. Neither the presence of a family history of sudden cardiac death nor the previously reported high-risk electrocardiographic parameters differed between patients with and without VAs. CONCLUSION: VAs occurred in 4.9% of patients with an ER pattern and syncope. Device implantation based on detailed history taking seems to be a reasonable strategy. Previously reported high-risk electrocardiographic patterns did not identify patients with VAs.

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.

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.

Accuracy and clinical outcomes of CT image integration with Carto-Sound compared to electro-anatomical mapping for atrial fibrillation ablation: a randomized controlled study.

BACKGROUND: Carto-Sound integrates 2D intra-cardiac ultrasound imaging into a 3D environment to allow left atrial mapping from the right atrium without fluoroscopic assistance. We conducted an open randomized controlled study to compare procedural, clinical and accuracy parameters between CT integrated Carto-Sound and electro-anatomic mapping (EAM) for AF ablation. METHODS: Sixty index AF ablation patients were randomized equally to either the Carto-Sound or EAM mapping/navigation for their procedure performed at a single institution. Procedure and X-ray times, X-ray dose, navigational accuracy and clinical success were assessed. The study was powered to the primary outcome of fluoroscopy time. RESULTS: Total procedure (232 ± 60 vs 223 ± 48 min; p = 0.51), ablation (p = 0.84) and mapping times (p = 0.11) were similar in each group. In contrast, Carto-Sound reduced total X-ray time (65 ± 18 vs 51 ± 12 min; p = 0.001), via a reduction in both mapping (p<0.001) and remaining procedure X-ray time (p = 0.03). Left atrial access time (p = 0.03) was also reduced using Ultra-sound assisted 3D mapping compared to the EAM group. Carto-Sound maps demonstrated equivalent mean navigational accuracy (p>0.17) compared to EAM. Ultra-sound assisted 3D mapping did not improve single procedure drug free clinical success (EAM: 13/30 [43%] vs Carto-Sound: 15/30 [50%]) at a mean of 13 ± 5 months (p = 0.79). CONCLUSIONS: In the context of long left atrial procedures with high radiation doses, reduced X-ray and left atrial access times using CT integrated Carto-Sound mapping/navigation may have implications for patients and laboratory staff, albeit at an extra financial cost and the requirement of an additional access site for a right sided catheter. TRIAL REGISTRATION NUMBER: ACTRN12612000089831.

Flecainide therapy reduces exercise-induced ventricular arrhythmias in patients with catecholaminergic polymorphic ventricular tachycardia.

OBJECTIVES: This study evaluated the efficacy and safety of flecainide in addition to conventional drug therapy in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT). BACKGROUND: CPVT is an inherited arrhythmia syndrome caused by gene mutations that destabilize cardiac ryanodine receptor Ca(2+) release channels. Sudden cardiac death is incompletely prevented by conventional drug therapy with ß-blockers with or without Ca(2+) channel blockers. The antiarrhythmic agent flecainide directly targets the molecular defect in CPVT by inhibiting premature Ca(2+) release and triggered beats in vitro. METHODS: We collected data from every consecutive genotype-positive CPVT patient started on flecainide at 8 international centers before December 2009. The primary outcome measure was the reduction of ventricular arrhythmias during exercise testing. RESULTS: Thirty-three patients received flecainide because of exercise-induced ventricular arrhythmias despite conventional (for different reasons, not always optimal) therapy (median age 25 years; range 7 to 68 years; 73% female). Exercise tests comparing flecainide in addition to conventional therapy with conventional therapy alone were available for 29 patients. Twenty-two patients (76%) had either partial (n = 8) or complete (n = 14) suppression of exercise-induced ventricular arrhythmias with flecainide (p < 0.001). No patient experienced worsening of exercise-induced ventricular arrhythmias. The median daily flecainide dose in responders was 150 mg (range 100 to 300 mg). During a median follow-up of 20 months (range 12 to 40 months), 1 patient experienced implantable cardioverter-defibrillator shocks for polymorphic ventricular arrhythmias, which were associated with a low serum flecainide level. In 1 patient, flecainide successfully suppressed exercise-induced ventricular arrhythmias for 29 years. CONCLUSIONS: Flecainide reduced exercise-induced ventricular arrhythmias in patients with CPVT not controlled by conventional drug therapy.

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.

Outcomes of long-standing persistent atrial fibrillation ablation: a systematic review.

BACKGROUND: Ablation of long-standing persistent atrial fibrillation (AF) is highly variable, with differing techniques and outcomes. OBJECTIVE: The purpose of this study was to undertake a systematic review of the literature with regard to the impact of ablation technique on the outcomes of long-standing persistent AF ablation. METHODS: A systematic search of the contemporary English scientific literature (from January 1, 1990 to June 1, 2009) in the PubMed database identified 32 studies on persistent/long-standing persistent or long-standing persistent AF ablation (including four randomized controlled trials). Data on single-procedure, drug-free success, multiple procedure success, and pharmaceutically assisted success at longest follow-up were collated. RESULTS: Four studies performed pulmonary vein isolation alone (21%-22% success). Four studies performed pulmonary vein antrum ablation with isolation (PVAI; n = 2; 38%-40% success) or without confirmed isolation (PVA; n = 2; 37%-56% success). Ten studies performed linear ablation in addition to PVA (n = 5; 11%-74% success) or PVAI (n = 5; 38%-57% success). Three studies performed posterior wall box isolation (n = 3; 44%-50% success). Five studies performed complex fractionated atrial electrogram ablation (n = 5; 24%-63% success). Six studies performed complex fractionated atrial electrogram ablation as an adjunct to PVA (n = 2; 50%-51% success), PVAI (n = 3; 36%-61% success), or PVAI and linear (n = 1; 68% success) ablation. Five studies performed the stepwise ablation approach (38%-62% success). CONCLUSION: The variation in success within and between techniques suggests that the optimal ablation technique for long-standing persistent AF is unclear. Nevertheless, long-standing persistent AF can be effectively treated with a composite of extensive index catheter ablation, repeat procedures, and/or pharmaceuticals.

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.

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.

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.

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.

Management of subacute and delayed right ventricular perforation with a pacing or an implantable cardioverter-defibrillator lead.

The development of small-diameter active fixation pacing and implantable cardioverter-defibrillator leads may be associated with increased risk for delayed right ventricular perforation. The management of this unforeseen complication has been poorly described. Eleven successive patients referred for right ventricular subacute or delayed perforation (no evidence of lead perforation at the time of the procedure, perforation of the right ventricle diagnosed > or =5 days after implantation) were reviewed. The perforation was related to a pacing (n = 7) or an implantable cardioverter-defibrillator (n = 4) lead. The main symptoms were major dyspnea with pericardial effusion requiring emergency pericardial drainage (n = 3), inappropriate implantable cardioverter-defibrillator shock (n = 1), syncope (n = 2), abdominal pain (n = 1), mammary hematoma (n = 1), diaphragm stimulation (n = 1), and chest pain (n = 1). One patient was strictly asymptomatic. Signs of lead dysfunction were observed in all 11 patients. The diagnosis of lead perforation was confirmed by chest x-ray, echocardiography, or computed tomography. Surgery was directly performed in 1 patient with suspicion of digestive perforation. In the remaining 10 patients, the leads were removed by simple traction under fluoroscopic guidance in the operating room, with surgical backup support. The need for close monitoring was highlighted by the occurrence in 1 patient of tamponade requiring percutaneous pericardiocentesis and urgent surgical revision. The postoperative course of these patients was unremarkable. In conclusion, subacute ventricular perforation is a rare but potentially life threatening complication of lead implantation. In most patients, the leads can safely be removed under fluoroscopic guidance, with surgical backup support and close monitoring.

Predictors of a positive response to biventricular pacing in patients with severe heart failure and ventricular conduction delay.

BACKGROUND: Cardiac resynchronization therapy (CRT) is recommended in patients with ejection fraction <35%, QRS width> 120 ms, and New York Heart Association (NYHA) functional class III or IV despite optimal medical therapy. We aimed to define demographic, clinical, and electrocardiographic predictors of positive clinical response to CRT. METHODS AND RESULTS: Hundred consecutive patients fulfilling the recommended criteria were implanted with a CRT device. Demographic, clinical, two-dimensional echocardiographic and electrographic parameters were measured at baseline and after 6 months of simultaneous biventricular pacing. A positive response to CRT included an improvement of at least one NYHA functional class associated with an absence of hospitalization for worsening heart failure. At the end of follow-up, 12 patients were dead and 71% of the patients were classified as responders. After 6 months of CRT, the ejection fraction was significantly higher (P = 0.035) in responders versus nonresponders. Multivariate analysis identified three independent predictors of positive response to CRT: an idiopathic origin of the cardiomyopathy (P = 0.043), a wider QRS before implantation (P = 0.017), and a narrowing of the QRS after implantation (P = 0.037). CONCLUSION: An idiopathic origin of the cardiomyopathy, a wider QRS before implantation, and a narrowing of the QRS width after implantation were identified as independent predictors of clinical positive response to CRT.

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.

Impact of catheter ablation of the coronary sinus on paroxysmal or persistent atrial fibrillation.

OBJECTIVES: This study evaluated the impact of catheter ablation of the coronary sinus (CS) region during paroxysmal and persistent atrial fibrillation (AF). BACKGROUND: The CS musculature and connections have been implicated in the genesis of atrial arrhythmias. METHODS: Forty-five patients undergoing catheter ablation of AF were studied. The CS was targeted if AF persisted after ablation of pulmonary veins and selected left atrial tissue. CS ablation was commenced endocardially by dragging along the inferior paramitral left atrium. Ablation was continued from within the vessel (epicardial) if CS electrograms had cycle lengths shorter than that of the left atrial appendage. RF energy was limited to 35 W endocardially and 25 W epicardially. The impact of ablation was evaluated on CS electrogram cycle length (CSCL) and activation sequence, atrial fibrillatory cycle length measured in the left atrial appendage (AFCL) and on perpetuation of AF. RESULTS: Endocardial ablation significantly prolonged CSCL by 17 +/- 5 msec and organized the CS activation sequence (from 13% of patients before to 51% after ablation); subsequent epicardial ablation further increased local CSCL by 32 +/- 27 msec (P < 0.001). AFCL prolonged significantly both during endocardial and epicardial ablation (median: 152 to 167 msec P = 0.03) and was associated with AF termination in 16 (35%) patients (46% of paroxysmal and 30% of persistent AF). AFCL prolongation > or =5 msec and/or AF termination was associated with more rapid activity in the CS region originally: P < or = 0.04. CONCLUSION: Catheter ablation targeting both the endocardial and epicardial aspects of the CS region significantly prolongs fibrillatory cycle length and terminates AF persisting after PV isolation in 35% of patients.