The BLISTER Score: A Novel, Externally Validated Tool for Predicting Cardiac Implantable Electronic Device Infections, and Its Cost-Utility Implications for Antimicrobial Envelope Use.

BACKGROUND: Antimicrobial envelopes reduce the incidence of cardiac implantable electronic device infections, but their cost restricts routine use in the United Kingdom. Risk scoring could help to identify which patients would most benefit from this technology. METHODS: A novel risk score (BLISTER [Blood results, Long procedure time, Immunosuppressed, Sixty years old (or younger), Type of procedure, Early re-intervention, Repeat procedure]) was derived from multivariate analysis of factors associated with cardiac implantable electronic device infection. Diagnostic utility was assessed against the existing PADIT score (Prior procedure, Age, Depressed renal function, Immunocompromised, Type of procedure) in both standard and high-risk external validation cohorts, and cost-utility models examined different BLISTER and PADIT score thresholds for TYRX (Medtronic; Minneapolis, MN) antimicrobial envelope allocation. RESULTS: In a derivation cohort (n=7383), cardiac implantable electronic device infection occurred in 59 individuals within 12 months of a procedure (event rate, 0.8%). In addition to the PADIT score constituents, lead extraction (hazard ratio, 3.3 [95% CI, 1.9-6.1]; P<0.0001), C-reactive protein >50 mg/L (hazard ratio, 3.0 [95% CI, 1.4-6.4]; P=0.005), reintervention within 2 years (hazard ratio, 10.1 [95% CI, 5.6-17.9]; P<0.0001), and top-quartile procedure duration (hazard ratio, 2.6 [95% CI, 1.6-4.1]; P=0.001) were independent predictors of infection. The BLISTER score demonstrated superior discriminative performance versus PADIT in the standard risk (n=2854, event rate: 0.8%, area under the curve, 0.82 versus 0.71; P=0.001) and high-risk validation cohorts (n=1961, event rate: 2.0%, area under the curve, 0.77 versus 0.69; P=0.001), and in all patients (n=12 198, event rate: 1%, area under the curve, 0.8 versus 0.75, P=0.002). In decision-analytic modeling, the optimum scenario assigned antimicrobial envelopes to patients with BLISTER scores ≥6 (10.8%), delivering a significant reduction in infections (relative risk reduction, 30%; P=0.036) within the National Institute for Health and Care Excellence cost-utility thresholds (incremental cost-effectiveness ratio, £18 446). CONCLUSIONS: The BLISTER score (https://qxmd.com/calculate/calculator_876/the-blister-score-for-cied-infection) was a valid predictor of cardiac implantable electronic device infection, and could facilitate cost-effective antimicrobial envelope allocation to high-risk patients.

The Impact of Known Heart Disease on Long-Term Outcomes of Catheter Ablation in Patients with Atrial Fibrillation and Left Ventricular Systolic Dysfunction: A Multicenter International Study.

BACKGROUND: Catheter ablation for AF is an effective treatment for patients with AF and systolic LV dysfunction; however, the clinical outcome is variable. We evaluated the impact of cardiomyopathy etiology on long-term outcomes post-catheter ablation. METHODS: Patients undergoing AF ablation across 3 centers (2 Australian, 1 UK) from 2002 to 2014, with LVEF<45% were evaluated. Patients were stratified into those with known heart disease as a cause of cardiomyopathy (KHD), and those with idiopathic dilated cardiomyopathy (IDCM). RESULTS: One hundred and one patients (IDCM = 77, KHD = 24) with AF and LVEF <45% underwent AF ablation. The KHD group (ischemic HD in 67%) were older (61 ± 7 vs. 55 ± 11 years, P = 0.005), with a higher CHADS2 score (2.0 ± 0.8 vs. 1.6 ± 0.7, P = 0.016), but otherwise well matched. After mean follow-up of 36 ± 23 months, AF control was greater in the IDCM group (82% vs. 50% in KHD, P < 0.001). On multivariate analysis IDCM was associated with long-term AF control (P = 0.033). The IDCM group had less functional impairment at follow-up (NYHA class 1.5 ± 0.7 vs. 2.0 ± 0.8, P = 0.005) and improved LVEF (50 ± 11% vs. 38 ± 10%, P < 0.001). Super responders (EF improvement >15%) were overwhelmingly in the IDCM group (94% vs. 6%, P < 0.001) with greater AF control (89% vs. 61%, P < 0.001). All-cause mortality was significantly higher in the KHD group (17% vs. 1.3%, P = 0.002). CONCLUSION: IDCM was associated with greater AF control, and improvement in symptoms and LVEF compared to patients with KHD post-AF ablation. AF is an important reversible cause of HF in patients with an unexplained CM and catheter ablation an effective treatment option.

Periprocedural stroke risk in patients undergoing catheter ablation for atrial fibrillation on uninterrupted warfarin.

BACKGROUND: Catheter ablation is an effective treatment for symptomatic individuals with atrial fibrillation (AF) but is associated with a risk of periprocedual stroke. Recent data suggest that this risk may be abolished if catheter ablation is performed with uninterrupted warfarin (UW). We sought to compare the incidence, severity and timing of periprocedural stroke between 2 periprocedural anticoagulation protocols: bridging low-molecular-weight heparin (LMWH) and UW. METHODS AND RESULTS: Periprocedural stroke (≤14 days) was assessed in 2,855 ablations performed in 1,813 patients. Thromboembolic stroke occurred in 11/1,653 (0.7%) procedures with bridging LMWH and in 5/1,202 (0.4%) procedures on UW (P = 0.5). Four of the 5 strokes (80%) on UW occurred despite a therapeutic INR and a mean activated clotting time of ≥300 seconds and 4/5 strokes (80%) occurred in patients with a CHADS2 score of 0. Eleven of 16 (69%) strokes overall occurred within 24 hours of the procedure. All 4 strokes resulting in major neurological deficit occurred in the LMWH group. Major bleeding complications occurred in 6.0% of patients in the bridging LMWH group compared to 4.0% in the UW group (P = 0.02). CONCLUSIONS: In contrast to existing data, periprocedural stroke still occurs despite therapeutic anticoagulation throughout the operative period. The optimal strategy to protect patients against thromboembolic stroke remains unclear.

Utility of mapping signals to improve precision of atrioventricular node ablation.

BACKGROUND: Atrioventricular node (AVN) ablation is effective for rate control in atrial fibrillation. This may require multiple radiofrequency applications to achieve complete atrioventricular block (CAB). In this retrospective study, we tested the hypothesis that mapping the AVN utilizing electrograms (EGMs) on both proximal and distal bipoles of the mapping catheter may improve the likelihood of CAB. METHODS: Lesion characteristics and EGM components on the proximal and distal bipoles of the ablation catheter in first-time AVN ablation procedures were analyzed. Outcomes of each lesion, including presence of CAB, acute recurrence of AVN conduction, new-onset right bundle branch block (RBBB), and junctional escape rhythm, were analyzed. Multivariate binary logistic regression analysis was performed to identify EGM characteristics that independently predicted the outcomes of interest. Lesions with these EGM characteristics were then identified and their outcomes compared with the whole cohort. RESULTS: A total of 441 ablation lesions were analyzed. EGM characteristics that independently predicted outcomes were the presence of His and atrial EGMs on the distal bipole and the absence of ventricular EGM on the proximal bipole. Among the 25 lesions with all these characteristics, 18 (72%) resulted in CAB compared to the overall cohort rate of 38% (P = 0.001). There was no new-onset RBBB. The likelihood of acute recurrent AVN conduction and junctional escape rhythm were similar. CONCLUSION: Combining proximal and distal bipole EGM characteristics of the ablation catheter can improve the accuracy of AVN localization during AVN ablation and avoid right bundle branch injury.

Epicardial catheter ablation for ventricular tachycardia in heparinized patients.

AIMS: In patients undergoing epicardial catheter ablation of ventricular tachycardia (VT), current guidelines recommend obtaining pericardial access prior to heparinization to minimize bleeding complications. Consequently, access is obtained before endocardial mapping (leading to unnecessary punctures) or during an additional procedure. We present our experience of obtaining pericardial access during the index procedure in heparinized patients. METHODS AND RESULTS: Patients undergoing catheter ablation of VT in whom pericardial access was performed after heparinization were included. Clinical and procedural data and complications were recorded. Electrocardiograms (ECGs) were analysed for published criteria suggesting an epicardial ablation target and compared with patients (matched for substrate) undergoing successful endocardial ablation. Seventeen patients (13 males, age 58 ± 16 years, 8 (47%) ischaemic) were evaluated. Pericardial access was achieved in 16 (94%), including 2 patients with prior epicardial ablation. The mean activated clotting time was 273 ± 36 s. No bleeding complications occurred. In three patients, inadvertent puncture of the right ventricle caused no adverse consequences. An epicardial ablation target was found in nine of which three (33%) had ECG criteria, suggesting an epicardial circuit. In comparison 5 of 17 patients undergoing successful endocardial ablation had at least one ECG criterion suggesting an epicardial ablation target. CONCLUSION: Obtaining pericardial access for epicardial catheter ablation for VT appears to be safe in heparinized patients. Electrocardiogram criteria suggesting an epicardial ablation target lack the sensitivity and specificity accurately to predict which patients might need epicardial ablation. Performing pericardial access in heparinized patients therefore may reduce unnecessary punctures and reduce the number of additional procedures in some patients.

The Prevalence of Low Left Atrial Appendage Emptying Velocity and Thrombus in Patients Undergoing Catheter Ablation for Atrial Fibrillation on Uninterrupted Peri-procedural Warfarin Therapy.

Introduction: The 2012 HRS/EHRA/ECAS guidelines encourage pre-procedural transesophageal echocardiography (TEE) prior to ablation for atrial fibrillation (AF), but acknowledge a lack of consensus in patients maintained on therapeutic warfarin before, during and after the procedure. This is partly because the incidence of left atrial appendage (LAA) thrombus is so low, that it is hard to draw clear conclusion regarding the characteristics of patients who develop thrombus. We hypothesize that the presence of low LAA emptying velocities, which predisposes to thrombus, and/or thrombus itself can be predicted in patients undergoing ablation, based upon clinical characteristics and transthoracic echocardiography (TTE). Methods: In this multicentre study, we undertook TTE and transesophageal echocardiograms (TEE) in 586 patients (age 59.9±0.4 years old, 64.5% male) undergoing catheter ablation for AF who were anticoagulated on warfarin (target international normalized ratio 2-3.5) for ≥3 consecutive weeks prior to procedure and maintained on warfarin for the procedure. Results: Low peak LAA emptying velocities (<40cm/s) were identified in 111 (24.7%) patients and LAA thrombus was identified in 3 patients (0.5%) despite having therapeutic INRs. The 3 patients with thrombus had LAA emptying velocities of 23, 29 and 31 cm/s. None of the remaining patients had a peri-procedural stroke. Patients with peak LAA emptying velocities <40cm/s or thrombus on TEE had significantly (p<0.05) higher CHA2DS2-VASc scores (1.7± 0.1 v's 1.4±0.1), and were more likely to have impaired LVSF (odds ratio [95% CI]: 2.66 [1.52-4.66]), a LA diameter >4.6cm on TTE (2.40 [2.13-5.41]), or persistent AF (2.60 [1.63-4.14]) compared to those with a higher LAA velocity without thrombus. Conclusion: In patients on uninterrupted warfarin therapy, a CHA2DS2-VASc score ≥1 or LA diameter >4.6cm on TTE identifies 91.5% of those at risk of developing thrombus with LAA emptying velocity of <40 cm/s and 100% of those with thrombus in our cohort.

Routine transthoracic echocardiography to assess pericardial collections in patients after extensive left atrial catheter ablation: a prospective study.

INTRODUCTION: Little is known about the incidence and timing of reactive pericardial collections developing after left atrial catheter ablation (LACA), and when and if transthoracic echocardiography (TTE) should be performed routinely in these patients postprocedure. METHODS AND RESULTS: Two hundred consecutive LACA patients for persistent atrial fibrillation (AF) (107), paroxysmal AF (75) or atrial tachycardia (AT) (18) underwent on-table TTE at the end of the procedure, and the next day prior to discharge. One patient developed tamponade at the time of transseptal puncture. Thirty-three percent of the remaining 199 who underwent on-table TTE, had a pericardial collection. On next day TTE, there were significantly more pericardial collections (53%, P < 0.0001). Persistent rather than paroxysmal arrhythmia at the time of the procedure was the only predictor of a pericardial collection, either on-table (χ(2)= 9.64; P = 0.002) or next day (χ(2)= 5.95; P = 0.02). Eight patients had collections on next day TTE ≥ 1.5 cm. One needed drainage because of clinical tamponade. Repeated TTEs in the other 7 patients demonstrated resolution of collections over 1-2 weeks. CONCLUSION: Pericardial collections are common in LACA patients. Almost all are not associated with clinical compromise. The only predictor of collection size is arrhythmia type at ablation, which may correspond to ablation at sites specific to persistent rather than paroxysmal arrhythmias. Performing on-table TTE routinely may help guide immediate anticoagulation protocols, but even larger on-table collections are not associated with tamponade and resolve spontaneously. TTE does not need to be performed routinely unless there are clinical signs of tamponade.

Catheter ablation for atrial fibrillation on uninterrupted warfarin: can it be done without echo guidance?

INTRODUCTION: Catheter ablation for atrial fibrillation is an effective treatment for symptomatic patients who have failed drug therapy. Recent studies using intracardiac echocardiography have demonstrated that ablation can be performed safely on uninterrupted warfarin and may be superior to bridging low molecular weight heparin (LMWH). We sought to assess the safety of an uninterrupted warfarin protocol using a simplified ablation protocol in a prospective controlled study. METHODS: Two anticoagulation regimes for patients undergoing catheter ablation for atrial fibrillation were evaluated--a bridging LMWH group and an uninterrupted warfarin group. Bleeding complications were compared between the 2 groups. RESULTS: In total 198 patients were evaluated (109 bridging LMWH, 89 uninterrupted warfarin). The preprocedure INR in the LMWH group (mean age 60.6 years, 72% male) was 1.2 ± 0.3 compared to 2.3 ± 0.5 in the uninterrupted warfarin group (mean age 60.9 years, 69% male). The primary outcome (a composite of major and minor bleeding complications) was observed in 78% in the LMWH group compared to 56% in the warfarin group (P = 0.001), mainly due to increased pain at the venous access site (41% vs 16%, P = 0.001). Two patients undergoing ablation on warfarin required pericardiocentesis for cardiac tamponade. Drug costs were lower in the warfarin group ($64.77 ± 31.86 vs $20.76 ± 15.60, P = 0.005), but the overall cost of treatment per patient (including bed occupancy costs) was similar in the LMWH group compared to the warfarin group ($883.96 ± 278.78 vs $816.59 ± 182.72, P = 0.06). CONCLUSION: Catheter ablation for atrial fibrillation can be performed safely on uninterrupted warfarin without intracardiac echocardiography, with a reduced risk of bleeding complications.

A randomized trial to compare atrial fibrillation ablation using a steerable vs. a non-steerable sheath.

AIMS: Catheter positioning and stability are recognized challenges in catheter ablation of atrial fibrillation (AF). This prospective randomized study assessed whether routinely using a steerable sheath affects procedure outcomes. METHODS AND RESULTS: Fifty-six AF patients were randomized to ablation using either an Agilis NXT (St Jude Medical, St Paul, MN, USA) steerable sheath or a fixed-curve Mullins sheath (Cook Medical Inc., Bloomington, IN, USA) for the ablation catheter. A mapping system with CT integration was used to isolate the pulmonary veins (PVs) in pairs and further ablation performed if AF persisted. There was no significant difference in time to gain trans-septal access, CT registration time, time to isolate PVs, fluoroscopy time for PV isolation, total procedure time, or total fluoroscopy time. A learning curve was seen for the steerable sheath, and after correcting for this, CT registration time and right PV isolation were quicker in this group. One patient crossed over from fixed-curve to steerable. Acute, 3-, and 6-month single procedure success were similar in both groups. CONCLUSION: Allowing for the usage learning curve, a steerable sheath reduced time for some elements of AF ablation. Although this did not result in improved success, it may be useful for inexperienced operators, but at increased procedure cost.

Acute and chronic pulmonary vein reconnection after atrial fibrillation ablation: a prospective characterization of anatomical sites.

BACKGROUND: Arrhythmia recurrence after atrial fibrillation (AF) ablation is often associated with pulmonary vein reconnection (PVR). We prospectively examined anatomical sites of both acute and chronic PVR. METHODS: One hundred and fifty AF patients underwent PV wide encirclement and sites where immediate electrical isolation (EI) occurred were tagged using electroanatomic mapping/CT integration (Cartomerge, Biosense Webster, Diamond Bar, CA, USA). After 30 minutes PVs were checked and acute PVR sites marked at reisolation. Chronic PVR sites were marked at the time of repeat procedures. RESULTS: On the left, immediate EI sites were predominantly on the intervenous ridge (IVR) and PV-left atrial appendage (PV-LAA) ridge. On the right they were at the roof, IVR, and floor of the PVs. Ninety-eight of one hundred and fifty patients had PVs checked after >30 minutes. Thirty-two of ninety-eight had acute PVR. This was mostly on the IVR and PV-LAA ridge on the left (88%), and on the roof and IVR on the right (78%). At repeat procedure, 38/39 patients had chronic PVR, predominantly on the IVR (61%) and PV-LAA ridge (21%) on the left, and on the roof, IVR, and floor of the right PVs (79%). There was minimal acute or chronic PVR posteriorly. Acutely PVR occurred close to the immediate EI site 60% of the time, but only 30% of the time chronically. CONCLUSION: Acute and chronic PVR sites have a preferential distribution. This may be determined by anatomical and technical factors. Knowledge of immediate EI sites may be beneficial acutely, but with chronic PVR a careful survey is required. These findings may help target ablation, improving safety and success.

The impact of image integration on catheter ablation of atrial fibrillation using electroanatomic mapping: a prospective randomized study.

AIMS: A detailed appreciation of the left atrial/pulmonary venous (LA/PV) anatomy may be important in improving the safety and success of catheter ablation for AF. The aim of this randomized study was to determine the impact of computed tomographic (CT) integration into an electroanatomic mapping (EAM) system on clinical outcome in patients undergoing catheter ablation for atrial fibrillation (AF). METHODS AND RESULTS: Eighty patients with AF were randomized to undergo first-time wide encirclement of ipsilateral PV pairs using EAM alone (40 patients) or with CT (40 patients, Cartomerge). Wide encirclement of the pulmonary veins was performed using irrigated radiofrequency ablation with the electrophysiological endpoint of electrical isolation (EI). The primary endpoint was single-procedure success at 6 month follow up. Acute and long-term procedural outcomes were also determined. There was no significant difference in single procedure success between EAM (56%) and cavotricuspid isthmus image (CTI) (50%) groups (P = 0.9). Acute procedural outcomes (EI, PV reconnection, sinus rhythm restored by ablation in persistent AF), fluoroscopy, and procedure durations (EI of right PVs, EI of left PVs, total) did not differ significantly between EAM and CTI groups. CONCLUSION: Image integration to guide catheter ablation for AF did not significantly improve the clinical outcome. Achieving PV EI is the critical determinant of procedural success rather than the mapping tools used to achieve it.

Validation of computed tomography image integration into the EnSite NavX mapping system to perform catheter ablation of atrial fibrillation.

INTRODUCTION: The complex anatomy of the left atrium (LA) makes location of ablation catheters difficult using fluoroscopy alone, and therefore 3D mapping systems are now routinely used. We describe the integration of a CT image into the EnSite NavX System with Fusion and its validation in patients undergoing atrial fibrillation (AF) or left atrial tachycardia (AT) catheter ablation. METHODS AND RESULTS: Twenty-three patients (61 +/- 9.2 years, 16 male) with paroxysmal (14) and persistent (8) AF and persistent (1) AT underwent ablation using CT image integration into the EnSite NavX mapping system with the EnSite Fusion Dynamic Registration software module. In all cases, segmentation of the CT data was accomplished using the EnSite Verismo segmentation tool, although repeat segmentation attempts were required in seven cases. The CT was registered with the NavX-created geometry using an average of 24 user-defined fiducial pairs (range 9 to 48). The average distance from NavX-measured lesion positions to the CT surface was 3.2 +/- 0.9 mm (median 2.4 mm). A large, automated, retrospective test using registrations with random subsets of each patient's fiducial pairs showed this average distance decreasing as the number of fiducial pairs increased, although the improvement ceased to be significant beyond 15 pairs. In confirmation, those studies which had used 16 or more pairs had a smaller average lesion-to-surface distance (2.9 +/- 0.7 mm) than those using 15 or fewer (4.3 +/- 0.8 mm, P < 0.02). Finally, for the 13 patients who underwent left atrial circumferential ablation (LACA), there was no significant difference between the circumference computed using NavX-measured positions and CT surface positions for either the left pulmonary veins (178 +/- 64 vs. 177 +/- 60 mm; P = 0.81) or the right pulmonary veins (218 +/- 86 vs. 207 +/- 81 mm; P = 0.08). CONCLUSION: CT image integration into the EnSite NavX Fusion system was successful in all patients undergoing catheter ablation. A learning curve exists for the Verismo segmentation tool; but once the 3D model was created, the registration process was easily accomplished, with a registration error that is comparable with registration errors using other mapping systems with CT image integration. All patients went on to have subsequent successful ablation procedures. Where LACA was performed (13 patients), only four patients required segmental ostial lesions to achieve electrical isolation.

Electrophysiologic and anatomic characterization of sites resistant to electrical isolation during circumferential pulmonary vein ablation for atrial fibrillation: a prospective study.

BACKGROUND: Catheter ablation (CA) by wide encirclement of pulmonary veins (WEPV) restores sinus rhythm in up to 95%. Complex PV-left atrial (LA) connections make achieving electrical isolation (EI) challenging. We examined anatomical and technical features associated with resistance to EI during WEPV in a prospective study. METHODS: One hundred one consecutive patients with symptomatic AF underwent first-time CA guided by electroanatomic mapping and CT integration (Cartomerg). Following double-transseptal access, WEPV was performed. After completion of PV encirclement, the line was mapped and where no signal could be obtained, CA was performed inside the WE line at the site of earliest PV breakthrough on the circular mapping catheter. Sites of EI were tagged. Anatomic studies of corresponding regions of the venoatrial junction in 24 adult hearts were performed. RESULTS: Sites resistant to EI were located at the inferior quadrant (P < 0.001) for the RSPV, superior quadrant (P < 0.001) for the RIPV, and the inferior and anterior quadrants (P < 0.001) for the LSPV. EI was significantly less frequent at the posterior quadrant (P < 0.001) for the LIPV. To achieve EI, CA was necessary inside the WE on the intervenous ridge on the right in 51% and on the left in 41%. The LPV/LAA ridge was investigated by anatomic studies that demonstrated considerable variation in the narrowest width (3-23.7 mm) and transmural thickness (1-5 mm). CONCLUSION: Sites of EI after WEPV have a preferential distribution determined by anatomic features. CA on the intervenous ridge is required in a significant proportion of patients to achieve EI. Atrial folds and ridges increase myocardial thickness creating technical and anatomic challenges for achieving transmural lesions.

Current case mix and results of catheter ablation of regular supraventricular tachycardia: are we giving unrealistic expectations to patients?

AIMS: Catheter ablation (CA) has become the treatment of choice for regular supraventricular tachycardia (SVT). The purpose of this study was to investigate whether the current clinical results in a large single centre are as good as success rates quoted to patients from published trials and national cardiology society websites. METHODS AND RESULTS: We recorded and analysed prospectively the acute and follow-up (FU) results of all CA procedures performed for SVT at our institution over a 2-year period. We compared our results with the success rates of 90-98% for CA quoted in the literature. We performed a total of 547 CA at our institution over 2 years, of which 389 (71%) were for regular SVT. Of these, 71 procedures (18%) were redo procedures. The overall acute procedural success rate was 96.1% (374/389). Follow-up data were available for 367 of 389 (94.3%) procedures. The overall 6-week success rate varied between 74.7 and 91.3% depending on the SVT type (average 83.9%). The FU success rates were lower for redo procedures (47/66, 71.2%) when compared with first ablation (de novo) procedures (261/301, 86.7%), P = 0.003. CONCLUSION: Published success rates are much better than current success rates in a large single centre. It is possible that the information regarding outcome given to patients during the consent process is not accurate.

Comparison of noncontact and electroanatomic mapping to identify scar and arrhythmia late after the Fontan procedure.

BACKGROUND: The right atrium late after the Fontan procedure is characterized by multiple complex arrhythmia circuits. We performed simultaneous electroanatomic and noncontact mapping to assess the accuracy of both systems to identify scar and arrhythmia. METHODS AND RESULTS: Mapping was performed in 26 patients aged 26.8+/-8.9 years, 18.7+/-4.4 years after Fontan surgery. The area and site of abnormal endocardium defined by electroanatomic mapping (bipolar contact electrogram <0.5 mV) were compared with those defined by noncontact mapping during sinus rhythm and by dynamic substrate mapping. Contact and reconstructed unipolar electrograms at a known distance from the multielectrode array, recorded by the noncontact system simultaneously at 452 endocardial sites, were compared for morphological cross correlation, timing difference, and amplitude. Mapping of arrhythmias was performed with both systems when possible. The median patient abnormal endocardium as defined by electroanatomic mapping covered 38.0% (range 16.7% to 97.8%) of the right atrial surface area, as opposed to 60.9% (range 21.3% to 98.5%) defined by noncontact mapping during sinus rhythm and 11.9% (range 0.4% to 67.3%) by dynamic substrate mapping. A significant decrease in electrogram cross correlation (P=0.003), timing (P=0.012), and amplitude (P=0.003) of reconstructed electrograms, but not of contact electrograms (P=0.742), was seen at endocardial sites >40 mm from the multielectrode array. Successful arrhythmia mapping by electroanatomic versus noncontact mapping was superior in 15 patients (58%), the same in 6 (23%), and inferior in 5 (19%; P=0.044). CONCLUSIONS: Electroanatomic mapping is the superior modality for arrhythmia mapping late after the Fontan procedure. Noncontact mapping is limited by a significant reduction in reconstructed electrogram correlation, timing, and amplitude >40 mm from the multielectrode array and cannot accurately define areas of scar and low-voltage endocardium.

Can atrial fibrillation with a coarse electrocardiographic appearance be treated with catheter ablation of the tricuspid valve-inferior vena cava isthmus? Results of a multicentre randomised controlled trial.

OBJECTIVE: To see if strategy of ablating the tricuspid annulus-inferior vena cava isthmus (TV-IVC) is superior to electrical cardioversion to prevent recurrences in patients with coarse atrial fibrillation. DESIGN: Prospective randomised controlled multicentre study. SETTING: Four tertiary referral hospitals in the UK. PATIENTS: 57 patients with persistent coarse atrial fibrillation (irregular P waves > or =0.15 mV in > or =1 ECG lead). INTERVENTIONS: Patients were randomised to receive external cardioversion (group A, n = 30) or TV-IVC ablation +/- DC cardioversion (group B, n = 27). MAIN OUTCOME MEASURES: Cardiac rhythm, scores on quality of life and symptom questionnaires were assessed at 4, 16 and 52 weeks after the procedure. RESULTS: 20 (67%) patients in group A and 19 (70%) patients in group B were in sinus rhythm immediately after their index procedure. At 4, 16 and 52 weeks, the number of patients in sinus rhythm were 5, 3 and 2 in group A and 3, 3 and 1 in group B (p = NS). The quality of life and symptom questionnaire scores were similar in the two groups at each period of follow-up, although they were significantly better for sinus rhythm than for atrial fibrillation at each follow-up visit. CONCLUSIONS: As a first-line strategy, TV-IVC ablation offers no advantages over direct current cardioversion for the management of coarse atrial fibrillation.