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Background: Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease, and sudden cardiac death represents an important mode of death in these patients. Data evaluating the implantable cardioverter defibrillator (ICD) in this patient population remain scarce. Methods: A Nationwide French Registry including all patients with tetralogy of Fallot with an ICD was initiated in 2010 by the French Institute of Health and Medical Research. The primary time to event end point was the time from ICD implantation to first appropriate ICD therapy. Secondary outcomes included ICD-related complications, heart transplantation, and death. Clinical events were centrally adjudicated by a blinded committee. Results: A total of 165 patients (mean age, 42.2±13.3 years, 70.1% males) were included from 40 centers, including 104 (63.0%) in secondary prevention. During a median (interquartile range) follow-up of 6.8 (2.5–11.4) years, 78 (47.3%) patients received at least 1 appropriate ICD therapy. The annual incidence of the primary outcome was 10.5% (7.1% and 12.5% in primary and secondary prevention, respectively; P =0.03). Overall, 71 (43.0%) patients presented with at least 1 ICD complication, including inappropriate shocks in 42 (25.5%) patients and lead dysfunction in 36 (21.8%) patients. Among 61 (37.0%) patients in primary prevention, the annual rate of appropriate ICD therapies was 4.1%, 5.3%, 9.5%, and 13.3% in patients with, respectively, 0, 1, 2, or ≥3 guidelines-recommended risk factors. QRS fragmentation was the only independent predictor of appropriate ICD therapies (hazard ratio, 3.47 [95% CI, 1.19–10.11]), and its integration in a model with current criteria increased the 5-year time-dependent area under the curve from 0.68 to 0.81 ( P =0.006). Patients with congestive heart failure or reduced left ventricular ejection fraction had a higher risk of nonarrhythmic death or heart transplantation (hazard ratio, 11.01 [95% CI, 2.96–40.95]). Conclusions: Patients with tetralogy of Fallot and an ICD experience high rates of appropriate therapies, including those implanted in primary prevention. The considerable long-term burden of ICD-related complications, however, underlines the need for careful candidate selection. A combination of easy-to-use criteria including QRS fragmentation might improve risk stratification. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03837574.

Background: Ventricular fibrillation (VF) storm after myocardial infarction (MI) is a life-threatening condition that necessitates multiple defibrillations. Catheter ablation is a potentially effective treatment strategy for VF storm refractory to optimal medical treatment. However, its impact on patient survival has not been verified in a large population. Methods: We conducted a multicenter, retrospective observational study involving consecutive patients who underwent catheter ablation of post-MI refractory VF storm without preceding monomorphic ventricular tachycardia. The target of ablation was the Purkinje-related ventricular extrasystoles triggering VF. The primary outcome was in-hospital and long-term mortalities. Univariate logistic regression and Cox proportional-hazards analysis were used to evaluate clinical characteristics associated with in-hospital and long-term mortalities, respectively. Results: One hundred ten patients were enrolled (age, 65±11years; 92 men; left ventricular ejection fraction, 31±10%). VF storm occurred at the acute phase of MI (4.5±2.5 days after the onset of MI during the index hospitalization for MI) in 43 patients (39%), the subacute phase (>1 week) in 48 (44%), and the remote phase (>6 months) in 19 (17%). The focal triggers were found to originate from the scar border zone in 88 patients (80%). During in-hospital stay after ablation, VF storm subsided in 92 patients (84%). Overall, 30 (27%) in-hospital deaths occurred. The duration from the VF occurrence to the ablation procedure was associated with in-hospital mortality (odds ratio for each 1-day increase, 1.11 [95% CI, 1.03–1.20]; P =0.008). During follow-up after discharge from hospital, only 1 patient developed recurrent VF storm. However, 29 patients (36%) died, with a median survival time of 2.2 years (interquartile range, 1.2–5.5 years). Long-term mortality was associated with left ventricular ejection fraction P =0.014), New York Heart Association class ≥III (hazard ratio, 2.68 [95% CI, 1.16–6.19]; P =0.021), a history of atrial fibrillation (hazard ratio, 3.89 [95% CI, 1.42–10.67]; P =0.008), and chronic kidney disease (hazard ratio, 2.74 [95% CI, 1.15–6.49]; P =0.023). Conclusions: In patients with MI presenting with focally triggered VF storm, catheter ablation of culprit triggers is lifesaving and appears to be associated with short- and long-term freedom from recurrent VF storm. Mortality over the long-term follow-up is associated with the severity of underlying cardiovascular disease and comorbidities in this specific patient population.

Background: Achieving bidirectional mitral isthmus (MI) block using radiofrequency catheter ablation (RFCA) alone is challenging, and MI reconnection is common. Adjunctive vein of Marshall (VOM) ethanol infusion (VOM-Et) can facilitate acute MI block. However, little is known about its long-term success. This study sought to evaluate the impact of adjunctive VOM-Et on MI block achievement and durability compared with RFCA alone. Methods: Patients undergoing the first attempt of posterior MI ablation were grouped according to their MI block index strategy: adjunctive VOM-Et and RFCA alone. Rates of acute MI block and MI reconnection observed during repeat procedures were compared between the 2 groups. Results: The VOM-Et group consisted of 152 patients (63.8±9.4 years) undergoing adjunctive VOM-Et for MI block. The RFCA group consisted of 110 patients (60.9±9.2 years) undergoing MI ablation using RFCA alone. Acute MI block was more frequently achieved in the VOM-Et group (98.7% [150/152] versus 63.6% [70/110]; P P P P =0.008). Conclusions: Beyond facilitating acute MI block, VOM-Et is associated with greater lesion durability as evidenced by higher rates of MI block during repeat procedures.

Background: Various strategies for ablation of ventricular tachycardia (VT) have been described, but their impact on ventricular fibrillation (VF) is largely unknown. The aim of our study was to assess the effect of substrate-based VT ablation targeting local abnormal ventricular activity (LAVA) on recurrent VF events in patients with structural heart disease. Methods: A retrospective 2-center study was performed on patients with structural heart disease and both VT and VF, with incident VT ablation procedures targeting LAVAs. Generalized estimating equations with a Poisson loglinear model were used to assess the impact of catheter ablation on VF episodes. The change in VF events before and after catheter ablation was compared with matched controls without ablation. Results: From a total of 686 patients with an incident VT ablation procedure targeting LAVAs, 21 patients (age, 57±14 years; left ventricular ejection fraction, 30±10%) had both VT and VF and met inclusion criteria. A total of 80 VF events were recorded in the implantable cardioverter-defibrillator logs the 6 months preceding ablation. Complete and partial LAVA elimination was achieved in 11 (52%) and 10 (48%) patients, respectively. Catheter ablation was associated with a highly significant reduction in VF recurrences ( P P =0.0003). Conclusions: Substrate-guided VT ablation targeting LAVAs may be associated with a significant reduction in recurrent VF, suggesting that VT and VF share overlapping arrhythmogenic substrates in patients with structural heart disease.

Background: Ventricular tachycardia (VT) with structural heart disease is dependent on reentry within scar regions. We set out to assess the VT circuit in greater detail than has hitherto been possible, using ultra-high-density mapping. Methods: All ultra-high-density mapping guided VT ablation cases from 6 high-volume European centers were assessed. Maps were analyzed offline to generate activation maps of tachycardia circuits. Topography, conduction velocity, and voltage of the VT circuit were analyzed in complete maps. Results: Thirty-six tachycardias in 31 patients were identified, 29 male and 27 ischemic. VT circuits and isthmuses were complex, 11 were single loop and 25 double loop; 3 had 2 entrances, 5 had 2 exits, and 15 had dead ends of activation. Isthmuses were defined by barriers, which included anatomic obstacles, lines of complete block, and slow conduction (in 27/36 isthmuses). Median conduction velocity was 0.08 m/s in entrance zones, 0.29 m/s in isthmus regions ( P P =0.002). Median local voltage in the isthmus was 0.12 mV during tachycardia and 0.06 mV in paced/sinus rhythm. Two circuits were identifiable in 5 patients. The median timing of activation was 16% of diastole in entrances, 47% in the mid isthmus, and 77% in exits. Conclusions: VT circuits identified were complex, some of them having multiple entrances, exits, and dead ends. The barriers to conduction in the isthmus seem to be partly functional in 75% of circuits. Conduction velocity in the VT isthmus slowed at isthmus entrances and exits when compared with the mid isthmus. Isthmus voltage is often higher in VT than in sinus or paced rhythms.

Background: Biatrial tachycardia (BiAT) is a rare form of atrial macroreentrant tachycardia, in which both atria form a critical part of the circuit. We aimed to identify the characteristics and precise circuits of single-loop macroreentrant BiATs. Methods and Results: We identified 8 patients (median age, 59.5 years old) with 9 BiATs in a cohort of 336 consecutive patients from 2 institutions who had undergone AT catheter ablation using an automatic ultrahigh-resolution mapping system. Seven of the 8 patients had a history of persistent AF ablation, including septal or anterior left atrium ablation before developing BiAT. One of the 8 patients had a history of an atrial septal patch closure with a massively enlarged right atrium. Nine ATs (median cycle length, 334 ms; median 12 561 points in the left atrium; 8814 points in the right atrium) were diagnosed as single-loop macroreentrant BiATs. We observed 3 types of BiAT (1) BiAT with a perimitral and peritricuspid reentrant circuit (n=3), (2) BiAT using the right atrium septum and a perimitral circuit (n=3), and (3) BiAT using only the left atrium and right atrium septum (n=3). Catheter ablation successfully terminated 8 of the 9 BiATs. Conclusions: All patients who developed BiAT had an electric obstacle on the anteroseptal left atrium, primarily from prior ablation lesions. In this situation, mapping of both atria should be considered during AT. Because 3 types of single-loop BiAT were observed, ablation strategies should be adjusted to the type of BiAT circuit.

Background: Long-term results of substrate modification for ablation of ventricular tachycardia (VT) have not been reported. We report long-term outcomes of substrate elimination targeting local abnormal ventricular activities (LAVA) for post–myocardial infarction VT. Methods and Results: One hundred fifty-nine consecutive patients undergoing first ablation were included (65±11 years, 92% implantable cardioverter defibrillators, 54% storms, and 73% appropriate shocks). LAVA were identified in 92% and VT was inducible in 73%. Complete LAVA elimination and noninducibility after ablation were achieved in 64% and 85%. During a median follow-up of 47 months (interquartile range, 34–82), single-procedure ventricular arrhythmia (VA)–free survival was 55% (10% storms and 19% shocks). The VA-free survival was 73%, 68%, 61%, 55%, and 49% after 1, 2, 3, 4, and 5 years, respectively. Complete LAVA elimination was associated with improved outcomes: VA-free survival of 82% at 1 year and 61% at 5 years. In the subgroup treated with multielectrode mapping and real-time image integration, VA-free survival was 86% and 65% at 1 year and 4 years, respectively. Including repeat procedures in 18% of pts (1.3±0.6 ablations/pt) outcomes improved to 69% VA-free survival (2% storms and 9% shocks) during median 46-month follow-up. Overall survival was 91% at 1 year and 77% at 5 years of follow-up. Conclusions: In this monocentric study, substrate modification targeting LAVA for post–myocardial infarction VT resulted in a substantial reduction of VT storm and implantable cardioverter defibrillator shocks and up to 49% of patients free from arrhythmia at 5 years after a single procedure. Complete LAVA elimination, multielectrode mapping, and real-time integration were associated with improved VA-free survival.

Background— Ventricular tachycardia recurrence can occur after ventricular tachycardia ablation because of incomplete and nontransmural ventricular lesion formation. We sought to compare the lesions made by a novel irrigated needle catheter to conventional radiofrequency lesions. Methods and Results— Thirteen female sheep (4.6±0.7 years, 54±8 kg) were studied. In 7 sheep, 60-s radiofrequency applications were performed using an irrigated needle catheter. In 6 sheep, conventional lesions were made using a 4-mm irrigated catheter. 1.5T in vivo and high-density magnetic resonance imaging (9.4T) were performed on explanted hearts from animals receiving needle radiofrequency. Conventional lesion volume was calculated as (1/6)×π×(A×B 2 +C×D 2 /2). Needle lesion volume was measured as Σ(π×r 2 )/2 with a slice thickness of 1 mm. The dimensions of all lesions were also measured on gross pathology. Additional histological analysis of the needle lesions was performed. One hundred twenty endocardial left ventricular ablation lesions (conventional, n=60; needle, n=60) were created. At necropsy, more lesions were found using needle versus conventional radiofrequency (90% versus 75%; P 3 ; P P P Conclusions— Irrigated needle ablation is associated with more frequent, larger, deeper, and more often transmural lesions compared with conventional irrigated ablation. This technology might be of value to treat intramural or epicardial ventricular tachycardia substrates resistant to conventional ablation.

Background— Left ventricular assist devices (LVADs) are increasingly used as a bridge to cardiac transplantation or as destination therapy. Patients with LVADs are at high risk for ventricular arrhythmias. This study describes ventricular arrhythmia characteristics and ablation in patients implanted with a Heart Mate II device. Methods and Results— All patients with a Heart Mate II device who underwent ventricular arrhythmia catheter ablation at 9 tertiary centers were included. Thirty-four patients (30 male, age 58±10 years) underwent 39 ablation procedures. The underlying cardiomyopathy pathogenesis was ischemic in 21 and nonischemic in 13 patients with a mean left ventricular ejection fraction of 17%±5% before LVAD implantation. One hundred and ten ventricular tachycardias (VTs; cycle lengths, 230–740 ms, arrhythmic storm n=28) and 2 ventricular fibrillation triggers were targeted (25 transseptal, 14 retrograde aortic approaches). Nine patients required VT ablation Conclusions— Catheter ablation of VT among LVAD recipients is feasible and reasonably safe even soon after LVAD implantation. Intrinsic myocardial scar, rather than the apical cannula, seems to be the dominant substrate.

Background— Therapy strategies for atrial fibrillation based on electric characterization are becoming viable personalized medicine approaches to treat a notoriously difficult disease. In light of these approaches that rely on high-density surface mapping, this study aims to evaluate the presence of 3-dimensional electric substrate variations within the transmural wall during acute episodes of atrial fibrillation. Methods and Results— Optical signals were simultaneously acquired from the epicardial and endocardial tissue during acute fibrillation in ovine isolated left atria. Dominant frequency, regularity index, propagation angles, and phase dynamics were assessed and correlated across imaging planes to gauge the synchrony of the activation patterns compared with paced rhythms. Static frequency parameters were well correlated spatially between the endocardium and the epicardium (dominant frequency, 0.79±0.06 and regularity index, 0.93±0.009). However, dynamic tracking of propagation vectors and phase singularity trajectories revealed discordant activity across the transmural wall. The absolute value of the difference in the number, spatial stability, and temporal stability of phase singularities between the epicardial and the endocardial planes was significantly >0 with a median difference of 1.0, 9.27%, and 19.75%, respectively. The number of wavefronts with respect to time was significantly less correlated and the difference in propagation angle was significantly larger in fibrillation compared with paced rhythms. Conclusions— Atrial fibrillation substrates are dynamic 3-dimensional structures with a range of discordance between the epicardial and the endocardial tissue. The results of this study suggest that transmural propagation may play a role in atrial fibrillation maintenance mechanisms.

Background— Epicardial ventricular tachycardia (VT) ablation is associated with risks of coronary artery (CA) and phrenic nerve (PN) injury. We investigated the role of multidetector computed tomography in visualizing CA and PN during VT ablation. Methods and Results— Ninety-five consecutive patients (86 men; age, 57±15) with VT underwent cardiac multidetector computed tomography. The PN detection rate and anatomic variability were analyzed. In 49 patients undergoing epicardial mapping, real-time multidetector computed tomographic integration was used to display CAs/PN locations in 3-dimensional mapping systems. Elimination of local abnormal ventricular activities (LAVAs) was used as ablation end point. The distribution of CAs/PN with respect to LAVA was analyzed and compared between VT etiologies. Multidetector computed tomography detected PN in 81 patients (85%). Epicardial LAVAs were observed in 44 of 49 patients (15 ischemic cardiomyopathy, 15 nonischemic cardiomyopathy, and 14 arrhythmogenic right ventricular cardiomyopathy) with a mean of 35±37 LAVA points/patient. LAVAs were located within 1 cm from CAs and PN in 35 (80%) and 18 (37%) patients, respectively. The prevalence of LAVA adjacent to CAs was higher in nonischemic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy than in ischemic cardiomyopathy (100% versus 86% versus 53%; P P Conclusions— The epicardial electrophysiological VT substrate is often close to CAs and PN in patients with nonischemic cardiomyopathy. High-resolution image integration is potentially useful to minimize risks of PN and CA injury during epicardial VT ablation.

Background— Although the Task Force Criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC) have recently been updated, the diagnosis remains challenging in the early stages. The aim of this study was to evaluate the diagnostic value of β-adrenergic stimulation in ARVC. Methods and Results— We evaluated 412 consecutive patients (213 men, age 41.5±16 years) referred for premature ventricular contractions evaluation or suspected ARVC. Isoproterenol testing was performed with continuous infusion of isoproterenol (45 μg/min) for 3 minutes. It was considered positive if there were either (1) polymorphic premature ventricular contractions with ≥1 couplet or (2) sustained or nonsustained ventricular tachycardia with left bundle branch block excluding right ventricular outflow tract ventricular tachycardia. ARVC was diagnosed in 35 patients at initial evaluation (23 men, aged 42±15 years). Isoproterenol testing was positive in 32 of 35 (91.4%) patients with ARVC and in 42 of 377 (11.1%) patients without ARVC ( P P Conclusions— Ventricular arrhythmogenicity during isoproterenol testing is highly sensitive (sensitivity, 91.4%) for the diagnosis of ARVC, particularly in its early stages.

Background— Rapid pulmonary vein (PV) activity has been shown to maintain paroxysmal atrial fibrillation (AF). We evaluated in persistent AF the cycle length (CL) gradient between PVs and the left atrium (LA) in an attempt to identify the subset of patients where PVs play an important role. Methods and Results— Ninety-seven consecutive patients undergoing first ablation for persistent AF were studied. For each PV, the CL of the fastest activation was assessed over 1 minute (PV fast ) using Lasso recordings. The PV to LA CL gradient was quantified by the ratio of PV fast to LA appendage (LAA) AF CL. Stepwise ablation terminated AF in 73 patients (75%). In the AF termination group, the PV fast CL was much shorter than the LAA CL resulting in lower PV fast /LAA ratios compared with the nontermination group (71±10% versus 92±7%; P fast /LAA ratios were notably lower if AF terminated after PV isolation or limited adjunctive substrate ablation compared with patients who required moderate or extensive ablation (63±6% versus 75±8%; P fast /LAA ratio fast /LAA ratios P Conclusions— The PV to LA CL gradient may identify the subset of patients in whom persistent AF is likely to terminate after PV isolation or limited substrate ablation and better long-term outcomes are achieved.

Background— Implantable cardioverter-defibrillator indications in Brugada syndrome remain controversial, especially in asymptomatic patients. Previous outcome data are limited by relatively small numbers of patients or short follow-up durations. We report the outcome of patients with Brugada syndrome implanted with an implantable cardioverter-defibrillator in a large multicenter registry. Methods and Results— A total of 378 patients (310 male; age, 46±13 years) with a type 1 Brugada ECG pattern implanted with an implantable cardioverter-defibrillator (31 for aborted sudden cardiac arrest, 181 for syncope, and 166 asymptomatic) were included. Fifteen patients (4%) were lost to follow-up. During a mean follow-up of 77±42 months, 7 patients (2%) died (1 as a result of an inappropriate shock), and 46 patients (12%) had appropriate device therapy (5±5 shocks per patient). Appropriate device therapy rates at 10 years were 48% for patients whose implantable cardioverter-defibrillator indication was aborted sudden cardiac arrest, 19% for those whose indication was syncope, and 12% for the patients who were asymptomatic at implantation. At 10 years, rates of inappropriate shock and lead failure were 37% and 29%, respectively. Inappropriate shock occurred in 91 patients (24%; 4±4 shocks per patient) because of lead failure (n=38), supraventricular tachycardia (n=20), T-wave oversensing (n=14), or sinus tachycardia (n=12). Importantly, introduction of remote monitoring, programming a high single ventricular fibrillation zone (>210–220 bpm), and a long detection time were associated with a reduced risk of inappropriate shock. Conclusions— Appropriate therapies are more prevalent in symptomatic Brugada syndrome patients but are not insignificant in asymptomatic patients (1%/y). Optimal implantable cardioverter-defibrillator programming and follow-up dramatically reduce inappropriate shock. However, lead failure remains a major problem in this population.

Background— Atrial tachycardias (AT) during or after ablation of atrial fibrillation frequently pose a diagnostic challenge. We hypothesized that both the patterns and the timing of coronary sinus (CS) activation could facilitate AT mapping. Methods and Results— A total of 140 consecutive postpersistent atrial fibrillation ablation patients with sustained AT were investigated by conventional mapping. CS activation pattern was defined as chevron or reverse chevron when the activations recorded on both the proximal and the distal CS dipoles were latest or earliest, respectively. The local activation of mid-CS was timed with reference to P peak –P peak (P–P) interval in lead V1. A ratio, mid-CS activation time to AT cycle length, was computed. Of 223 diagnosed ATs, 124 were macroreentrant (56%) and 99 were centrifugal (44%). When CS activation was chevron/reverse chevron (n=44; 20%), macroreentries were mostly roof dependent. With reference to P–P interval, mid-CS activation timing showed specific consistency for peritricuspid and perimitral AT. Proximal to distal CS activation pattern and mid-CS activation at 50% to 70% of the P–P interval (n=30; 13%) diagnosed peritricuspid AT with 81% sensitivity and 89% specificity. Distal to proximal CS activation and mid-CS activation at 10% to 40% of the P–P interval (n=44; 20%) diagnosed perimitral AT with 88% sensitivity and 75% specificity. Conclusions— The analysis of the patterns and timing of CS activation provides a rapid stratification of most likely macroreentrant ATs and points toward the likely origin of centrifugal ATs. It can be included in a stepwise diagnostic approach to rapidly select the most critical mapping maneuvers.

Background— A majority of patients undergoing ablation of ventricular tachycardia have implanted devices precluding substrate imaging with delayed-enhancement MRI. Contrast-enhanced multidetector computed tomography (MDCT) can depict myocardial wall thickness with submillimetric resolution. We evaluated the relationship between regional myocardial wall thinning (WT) imaged by MDCT and arrhythmogenic substrate in postinfarction ventricular tachycardia. Methods and Results— We studied 13 consecutive postinfarction patients undergoing MDCT before ablation. MDCT data were integrated with high-density 3-dimensional electroanatomic maps acquired during sinus rhythm (endocardium, 509±291 points/map; epicardium, 716±323 points/map). Low-voltage areas (R =0.82; P =0.001), but no such correlation was found in the epicardium. The WT 2 [Q1–Q3, 46–92] versus 71 cm 2 [Q1–Q3, 59–124]; P =0.001). Among a total of 13 060 electrograms reviewed in the whole study population, 538 LAVA were detected and analyzed. LAVA were located within the WT 100 ms after QRS complex) were almost exclusively detected within the thinnest area (93% in the WT Conclusions— Regional myocardial WT correlates to low-voltage regions and distribution of LAVA critical for the generation and maintenance of postinfarction ventricular tachycardia. The integration of MDCT WT with 3-dimensional electroanatomic maps can help focus mapping and ablation on the culprit regions, even when MRI is precluded by the presence of implanted devices.

Background— Contact force (CF) is an important determinant of lesion formation for atrial endocardial radiofrequency ablation. There are minimal published data on CF and ventricular lesion formation. We studied the impact of CF on lesion formation using an ovine model both endocardially and epicardially. Methods and Results— Twenty sheep received 160 epicardial and 160 endocardial ventricular radiofrequency applications using either a 3.5-mm irrigated-tip catheter (Thermocool, Biosense-Webster, n=160) or a 3.5 irrigated-tip catheter with CF assessment (Tacticath, Endosense, n=160), via percutaneous access. Power was delivered at 30 watts for 60 seconds, when either catheter/tissue contact was felt to be good or when CF>10 g with Tacticath. After completion of all lesions, acute dimensions were taken at pathology. Identifiable lesion formation from radiofrequency application was improved with the aid of CF information, from 78% to 98% on the endocardium ( P P =0.02). The mean total force was greater on the endocardium (39±18 g versus 21±14 g for the epicardium; P 3 versus 209±131 mm 3 ; P =0.02) probably because of the absence of the heat sink effect of the circulating blood and covered a greater area (41±27 mm 2 versus 29±17 mm 2 ; P =0.03) because of catheter orientation. Conclusions— In the absence of CF feedback, 22% of endocardial radiofrequency applications that are thought to have good contact did not result in lesion formation. Epicardial ablation is associated with larger lesions.

Background— The remote magnetic navigation system (MNS) has been used with a nonirrigated magnetic catheter for atrial fibrillation (AF) ablation. The objective of this study was to evaluate the feasibility and efficiency of the newly available irrigated tip magnetic catheter for index pulmonary vein isolation (PVI) in patients with paroxysmal AF (PAF). Methods and Results— Between January 2008 and June 2009, 30 consecutive patients with drug-resistant PAF underwent circular mapping catheter-guided PVI with MNS (MNS group). The outcomes were compared retrospectively with those of a conventional hand-controlled ablation technique during the same period in 44 consecutive patients (manual group). All 4 pulmonary veins were successfully isolated in both groups except in 4 patients in the MNS group. Radiofrequency and procedure duration were higher in the MNS group (60±27 versus 43±16 minutes; P =0.0019) than in the manual group (246±50 versus 153±51 minutes; P P =0.0002). At 12-month follow-up after a single procedure, 69.0% of the patients in MNS group and 61.8% of patients in manual group were free of atrial tachyarrhythmia without antiarrhythmic drugs. There was no significant difference in the atrial tachyarrhythmia-free survival between the 2 groups ( P =0.961). Cardiac tamponade occurred in 1 patient in the manual group. Conclusions— In patients with PAF, MNS-guided PVI with the newly available irrigated tip magnetic catheter backed up with manual ablation whenever required is feasible. However, it requires longer ablation, fluoroscopy, and procedural times than the conventional approach in the early experience stage.

Background— The mainstay of treatment for atrial fibrillation (AF) remains pharmacological; however, catheter ablation has increasingly been used over the last decade. The relative merits of each strategy have not been extensively studied. Methods and Results— We conducted a randomized multicenter comparison of these 2 treatment strategies in patients with paroxysmal AF resistant to at least 1 antiarrhythmic drug. The primary end point was absence of recurrent AF between months 3 and 12, absence of recurrent AF after up to 3 ablation procedures, or changes in antiarrhythmic drugs during the first 3 months. Ablation consisted of pulmonary vein isolation in all cases, whereas additional extrapulmonary vein lesions were at the discretion of the physician. Crossover was permitted at 3 months in case of failure. Echocardiographic data, symptom score, exercise capacity, quality of life, and AF burden were evaluated at 3, 6, and 12 months by the supervising committee. Of 149 eligible patients, 112 (18 women [16%]; age, 51.1±11.1 years) were enrolled and randomized to ablation (n=53) or “new” antiarrhythmic drugs alone or in combination (n=59). Crossover from the antiarrhythmic drugs and ablation groups occurred in 37 (63%) and 5 patients (9%), respectively ( P =0.0001). At the 1-year follow-up, 13 of 55 patients (23%) and 46 of 52 patients (89%) had no recurrence of AF in the antiarrhythmic drug and ablation groups, respectively ( P Conclusion— This randomized multicenter study demonstrates the superiority of catheter ablation over antiarrhythmic drugs in patients with AF with regard to maintenance of sinus rhythm and improvement in symptoms, exercise capacity, and quality of life.

Complex fractionated atrial electrogram (CFAE) ablation is one successful approach for treating patients with persistent atrial fibrillation (AF), along with strategies that incorporate pulmonary vein isolation and linear lesions. In this issue of Circulation: Arrhythmia and Electrophysiology , Oral et al1 investigate the effect of right atrial CFAE focused ablation in patients with long-lasting persistent fibrillation. All patients had CFAE ablation in the left atrium and coronary sinus, and patients who did not convert to either sinus rhythm or atrial tachycardia were randomized to either additional right atrial CFAE ablation or to no further ablation. Patients were followed up for more than 1 year with similar outcomes in both groups, which suggests that right atrial CFAE ablation has no incremental benefit to targeting CFAE in the left atrium in persistent AF. Oral et al1 do acknowledge some limitations in their study design, which may have given a false-negative result. Page 6 Does the right atrial substrate play an important role in persistent AF, and how do we distinguish patients in whom the right atrium needs to be targeted as part of a catheter ablation strategy from those in whom the right atrium is unimportant? The Heart Rhythm Society/European Heart Rhythm Association/European Cardiac Arrhythmia Society expert consensus document2 on catheter and surgical ablation of AF suggests that areas with CFAEs potentially represent AF substrate sites, ie, the atrial, venous, and ganglionic tissue that is critical in perpetuating or “driving” AF. Is this widely held assumption that CFAEs are related to the substrate correct? CFAEs are defined as electrograms displaying >2 deflections that are fractionated or have a short cycle length

▪ Abstract Atrial fibrillation is frequently disabling and resistant to antiarrhythmic drugs. Curative treatment by catheter-based ablation has been shown to be feasible either by achieving long linear lesions, mainly in the left atrium, or by targeting the initiating focus, most frequently in the pulmonary veins. This paper reviews the different ablation approaches, their results, potential complications, and relative merits.

Background— There are no reports describing the technique, electrophysiological evaluation, and clinical consequences of complete linear block at roofline joining the superior pulmonary veins (PVs) in patients with paroxysmal atrial fibrillation (AF). Methods and Results— Ninety patients with drug-refractory paroxysmal AF undergoing radiofrequency ablation were prospectively randomized into 2 ablation strategies: (1) PV isolation (n=45) or (2) PV isolation in combination with linear ablation joining the 2 superior PVs (roofline; n=45). In both groups, the cavotricuspid isthmus, fragmented peri-PV-ostial electrograms, and spontaneous non-PV foci were ablated. Roofline ablation was performed at the most cranial part of the left atrium (LA) with complete conduction block demonstrated during LA appendage pacing by the online mapping of continuous double potential and an activation detour propagating around the PVs to activate caudocranially the posterior wall of the LA. The effect of ablation at the LA roof was evaluated by the change in fibrillatory cycle length, termination and noninducibility of AF, and clinical outcome. PV isolation was achieved in all patients with no significant differences in the radiofrequency duration, fluoroscopy, or procedural time between the groups. Roofline ablation required 12±6 (median 11, range 3 to 25) minutes of radiofrequency energy delivery with a fluoroscopic duration of 7±2 minutes and was performed in 19±7 minutes. Complete block was confirmed in 43 patients (96%) and resulted in an activation delay that was shorter circumventing the left than the right PVs during LA appendage pacing (138±15 versus 146±25 ms, respectively; P =0.01). Roofline ablation resulted in a significant increase in the fibrillatory cycle length (198±38 to 217±44 ms; P =0.0005), termination of arrhythmia in 47% (8/17), and subsequent noninducibility of AF in 59% (10/17) of the patients inducible after PV isolation. However, LA flutter, predominantly perimitral, could be induced in 10 patients (22%) after roofline ablation. At 15±4 months, 87% of the roofline group and 69% with PV isolation alone are arrhythmia free without antiarrhythmics ( P =0.04). Conclusions— This prospective randomized study demonstrates the feasibility of achieving complete linear block at the LA roof. Such ablation resulted in the prolongation of the fibrillatory cycle, termination of AF, and subsequent noninducibility and is associated with an improved clinical outcome compared with PV isolation alone.

Background— Isolated atrial fibrillation (AF) is associated with mild enlargement of the left atrium (LA) and left ventricular (LV) diastolic dysfunction. The impact of ablation of isolated AF on left chamber size and function is unclear, and whether diastolic dysfunction is the cause or the consequence of AF remains unknown. The objective of this prospective study was to evaluate the impact of sinus rhythm restoration by catheter ablation on LV diastolic dysfunction, LA morphology, and mechanical function. Methods and Results— Forty-eight patients with isolated AF were studied by serial echocardiographic studies at baseline and at 1-, 3-, 6-, 9-, and 12-month intervals after radiofrequency ablation. LA dimensions and mechanical function and LV systolic and diastolic functions were evaluated at each time interval. Diastolic function was assessed with conventional Doppler parameters and new indexes such as tissue Doppler imaging, mitral flow propagation velocity, and combined criteria. LV diastolic dysfunction was present in paroxysmal and chronic AF patients with a reduction of tissue Doppler imaging lateral early diastolic peak velocity in 37% ( P P P P P P Conclusions— This study demonstrates reverse morphological remodeling of the LA and improvement of LV diastolic and systolic functions after restoration of sinus rhythm by ablation for isolated AF. Because patients with isolated AF have none of the traditional causes of LV diastolic dysfunction, our findings suggest that AF may be partly the cause rather than the consequence of diastolic dysfunction.

Background— The modification of atrial fibrillation cycle length (AFCL) during catheter ablation in humans has not been evaluated. Methods and Results— Seventy patients undergoing ablation of prolonged episodes of AF were randomized to pulmonary vein (PV) isolation or additional ablation of the mitral isthmus. Mean AFCL was determined at a distance from the ablated area (coronary sinus) at the following intervals: before ablation, after 2- and 4-PV isolations, and after linear ablation. Inducibility of sustained AF (≥10 minutes) was determined before and after ablation. Spontaneous sustained AF (715±845 minutes) was present in 30 patients and induced in 26 (AFCL, 186±19 ms). PV isolation terminated AF in 75%, with the number of PVs requiring isolation before termination increasing with AF duration ( P =0.018). PV isolation resulted in progressive or abrupt AFCL prolongation to various extents, depending on the PV: to 214±24 ms ( P P =0.002) when AF persisted. The increase in AFCL (30±17 versus 14±11 ms; P =0.005) and the decrease in fragmentation (30.0±26.8% to 10.3±14.5%; P P =0.08). Sustained AF was noninducible in 57% after PV isolation and in 77% after linear ablation. At 7±3 months, 74% with PV isolation and 83% with linear ablation were arrhythmia free without antiarrhythmics, which was significantly associated with noninducibility ( P =0.03) with a recurrence rate of 38% and 13% in patients with and without inducibility, respectively. Conclusions— AF ablation results in a decline in AF frequency, with a magnitude correlating with termination of AF and prevention of inducibility that is predictive of subsequent clinical outcome.

Background— The left superior vena cava (LSVC) is the embryological precursor of the ligament of Marshall, which has been implicated in the initiation and maintenance of atrial fibrillation (AF). Rarely, the LSVC may persist and has been associated with some organized arrhythmias, though not with AF. We report 5 patients in whom the LSVC was a source of ectopy, initiating AF. Methods and Results— In 5 patients (4 men; age, 46±11 years) with symptomatic drug-refractory AF, ectopy from the LSVC resulting in AF was observed after pulmonary vein isolation. The ectopics were spontaneous in 2 and induced by isoproterenol in the others and preceded P-wave onset by 67±13 ms. During multielectrode or electroanatomic mapping, venous potentials were recorded circumferentially at the proximal LSVC near its junction with the coronary sinus (CS), but at the mid-LSVC level, they were recorded only on part of the circumference. The LSVC was electrically connected to the lateral left atrium (LA) and through the CS to the right atrium, with 4.1±2.3 CS-LSVC and 1.6±0.5 LA-LSVC connections per patient. Catheter ablation in the LSVC targeting these connections resulted in electrical isolation in 4 of the 5 patients without complications. After 15±10 months, the 4 patients with successful isolation, including 1 who had successful reablation for LA flutter, remained in sinus rhythm without drugs. Conclusions— The LSVC can be the arrhythmogenic source of AF with connections to the CS and LA. Ablation of these connections resulted in electrical isolation.

Background— Symptomatic prolonged sinus pauses on termination of atrial fibrillation (AF) are an indication for pacemaker implantation. We evaluated sinus node function and clinical outcome in patients with prolonged sinus pauses on termination of arrhythmia who underwent ablation of paroxysmal AF. Methods and Results— Twenty patients with paroxysmal AF and prolonged sinus pauses (≥3 seconds) on termination of AF underwent ablation between May 1995 and November 2002. Patients with sinus pauses independent of episodes of AF were excluded from the analysis. The procedure included pulmonary vein and linear atrial ablation. After ablation, sinus node function was assessed during the first week and at 1, 3, and 6 months, by 24-hour ambulatory monitoring to determine the mean heart rate and heart rate range, and by exercise testing to determine the maximal heart rate. Corrected sinus node recovery time was determined at the completion of ablation and at 24.0±11.3 months at 600 and 400 ms. After AF ablation, there was a significant improvement of sinus node function, with an increase in the mean heart rate ( P =0.001), maximal heart rate ( P P P =0.016) and 400 ms ( P =0.019). At 26.0±17.6 months, 18 patients (85%) had no recurrence of AF (in the absence of medication), with no symptoms attributable to bradycardia or sinus pauses on ambulatory monitoring. Two patients had infrequent episodes of AF, 1 requiring pacemaker implantation. Conclusion— Prolonged sinus pauses after paroxysms of AF may result from depression of sinus node function that can be eliminated by curative ablation of AF. This is accompanied by improvement in parameters of sinus node function, suggesting reverse remodeling of the sinus node.

Background— The long-QT and Brugada syndromes are important substrates of malignant ventricular arrhythmia. The feasibility of mapping and ablation of ventricular arrhythmias in these conditions has not been reported. Methods and Results— Seven patients (4 men; age, 38±7 years; 4 with long-QT and 3 with Brugada syndrome) with episodes of ventricular fibrillation or polymorphic ventricular tachycardia and frequent isolated or repetitive premature beats were studied. These premature beats were observed to trigger ventricular arrhythmias and were localized by mapping the earliest endocardial activity. In 4 patients, premature beats originated from the peripheral right (1 Brugada) or left (3 long-QT) Purkinje conducting system and were associated with variable Purkinje-to-muscle conduction times (30 to 110 ms). In the remaining 3 patients, premature beats originated from the right ventricular outflow tract, being 25 to 40 ms ahead of the QRS. The accuracy of mapping was confirmed by acute elimination of premature beats after 12±6 minutes of radiofrequency applications. During a follow-up of 17±17 months using ambulatory monitoring and defibrillator memory interrogation, no patients had recurrence of symptomatic ventricular arrhythmia but 1 had persistent premature beats. Conclusion— Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes. These can be eliminated by focal radiofrequency ablation.

Background — Despite extensive proximal ablation, all potentials frequently cannot be eliminated from the left pulmonary veins (PV). Methods and Results — PV electrograms were analyzed during sinus rhythm, coronary sinus, and left atrial appendage (LAA) pacing, and PV and LAA angiography performed. During pacing, an initial low-amplitude slow potential was recorded on the anterior aspect of the left superior PV and anticipated with shortest activation time by LAA pacing. Its timing coincided with posterior LAA activation, shown to be immediately adjacent to the left superior PV by angiography. In the left inferior PV, the first potential was smaller and less sharp, coinciding with adjacent low LA activation. Angiographically, the LAA was at least 15 mm from the left inferior PV. The second sharper potential in both left PVs was eliminated by proximal ablation. Conclusion — Far field LAA activity consistently adds to PV myocardial electrograms in the left superior PV whereas lower, less sharp extravenous potentials in the left inferior PV originate from the inferior LA. They can be identified by LAA and coronary sinus pacing.

Background —Because complete linear conduction block is necessary to minimize the recurrence of reentrant tachycardias such as typical atrial flutter, we investigated a simple technique to recognize a persistent gap or complete linear block. Methods and Results —We prospectively evaluated cavotricuspid isthmus conduction in 50 patients (age 63±8 years, 43 men) after radiofrequency ablation. The distal and proximal bipoles of a quadripolar catheter placed close to the ablation line were successively stimulated during recording from the ablation line. We hypothesized that because the initial and terminal components of local potentials reflected activation at the ipsilateral and contralateral borders of the ablation lesion, a change to a more proximal pacing site without moving the catheter would prolong the stimulus to the initial component timing, whereas the response of the terminal component would depend on the presence of block or persistent conduction. A shortening or no change in timing of the terminal component would indicate block, whereas lengthening would indicate persistent gap conduction. The results were compared with previously described criteria for isthmus block. Ninety-two sites were assessed: 17 before and 75 after the achievement of complete isthmus block. The timing of the initial component was delayed by 19±9 ms, and the terminal component was advanced by 13±8 ms after block and delayed by 12±9 ms in case of persisting conduction. The sensitivity, specificity, and positive and negative predictive values for linear block were 100%, 75%, 94%, and 100%, respectively. Conclusions —An accurate assessment of isthmus block or persistent isthmus conduction is possible with this technique of differential pacing.

Background —Typical right atrial isthmus–dependent flutters have been described in detail, but very little is known about left atrial (LA) flutters. Methods and Results —We performed conventional and 3D mapping of the LA for 22 patients with atypical flutters. Complete maps in 17 patients demonstrated macroreentrant circuits (n=15) with 1 to 3 loops rotating around the mitral annulus, the pulmonary veins, and a zone of block or a silent area. In 2 patients, a small reentry circuit with a zone of markedly slow conduction was identified. Linear ablation performed across the most accessible part of the circuit cured 16 patients (73%) with a follow-up of 15±7 months. Conclusions —LA reentrant tachycardias are related to individually varying circuits and are amenable to mapping guided radiofrequency ablation.

Background —The end point for catheter ablation of pulmonary vein (PV) foci initiating atrial fibrillation (AF) has not been determined. Methods and Results —Ninety patients underwent mapping during spontaneous or induced ectopy and/or AF initiation. Ostial PV ablation was performed by use of angiograms to precisely define targeted sites. Success defined by elimination of AF without drugs was correlated with the procedural end point of the abolition of distal PV potentials. A total of 197 arrhythmogenic PV foci (97%)—single in 31% and multiple in 69%—and 6 atrial foci were identified. A discrete radiofrequency (RF) application eliminated the PV potentials in 9 PV foci, whereas 2 foci from the same PV required RF applications at separate sites in 19 cases. In others, a wider region was targeted with progressive elimination of ectopy. In 49 patients, multiple sessions were necessary owing to recurrent or new ectopy. The clinical success rates were 93%, 73%, and 55% in patients with 1, 2, and ≥3 arrhythmogenic PV foci. Recovery of local PV potential and the inability to abolish it were significantly associated with AF recurrences (90% success rate with versus 55% without PV potential abolition). PV stenosis was noted acutely in 5 of 6 cases, remained unchanged at restudy, and was associated with RF power >45 W. Conclusions —Multiple PV foci are involved in initiation of AF, and elimination of PV muscle conduction is associated with clinical success.

Background —Dual-loop atrial reentrant tachycardias have not been clinically described. Methods and Results —Five patients (3 men, 2 women; mean age, 48±16 years) were studied 24±15 years after surgical closure of an ostium secundum atrial septal defect for drug-resistant atrial tachycardia. Complete tachycardia mapping was performed in the right atrium with multipolar catheters and a 3-dimensional electroanatomic mapping system (Biosense), followed by linear radiofrequency ablation of the narrowest part of each complete loop. Six tachycardias with a typical flutter morphology, a cycle length of 262±40 ms, and a superior f-wave axis (−77±11°) were mapped, 4 with a Biosense map including 106±32 points. Five figure-8 tachycardias had a counterclockwise loop around the tricuspid valve sharing a common anterior channel with a clockwise loop around the lateral atriotomy scar. One tachycardia was thought to have 2 counterclockwise loops around the same obstacles. Radiofrequency delivery in the cavotricuspid isthmus in each case transformed the tachycardia without any pause in a different morphology tachycardia with an inferior P-wave axis (50±42°) and nearly the same cycle length (272±39 ms) but with the periatriotomy loop alone. This arrhythmia required ablation of a second isthmus: between the lower end of the atriotomy and the inferior vena cava in 4 and the superior tricuspid annulus in 1. After a follow-up of 19±6 months, there were no recurrences. Conclusions —Figure-8 double-loop tachycardias mimicking the ECG pattern of a common atrial flutter occur in some patients after a surgical atriotomy. Ablation of 1 loop produces a sudden transformation to a new reentrant tachycardia formed of the remaining loop that requires ablation at a second isthmus.

Background —During ventricular echoes, reentrant excitation is supposed to involve 2 functionally distinct pathways in the atrioventricular (AV) nodal area. The exact pathway of reentrant excitation is unknown. The objectives of this study were to analyze electrical activity in the AV nodal area after ventricular stimulation and during ventricular echoes and to assess the role of perinodal atrial tissue in AV nodal reentry. Methods and Results —In 16 isolated, blood-perfused canine hearts, multiterminal electrodes were used to map electrical activity in Koch’s triangle after ventricular stimulation and during ventricular echoes. The subendocardial cell layers were chemically destroyed in 3 hearts. Incisions in the posterior approach to the compact node were made in 6 hearts. The apex of the triangle of Koch was surgically dissociated from the perinodal atrial tissue in 5 hearts. Retrograde atrial activation occurred via 2 distinct endocardial exit sites. Ventricular echoes could be induced in all hearts irrespective of the atrial activation pattern. Simultaneous retrograde activation of both exit sites often preceded reciprocation. Ventricular echoes were demonstrable after chemical destruction of the endocardium and after surgical dissociation of the perinodal atrial tissue from the AV node. Conclusions —Our data show that the reentrant pathway during ventricular echoes is confined to the AV node. The tissue that connects the node to the endocardial exit sites has to be excluded from the reentrant circuit responsible for single echoes.

Background The full circuit of common atrial flutter using conventional methods of sequential or multielectrode activation mapping is not completely understood. Methods and Results We performed three-dimensional right atrial endocardial activation mapping during common counterclockwise atrial flutter in 17 patients (16 men, 1 woman; mean age, 53±11 years) by using the Cordis-Biosense EP Navigation system and assessed the distribution of estimated conduction velocities and double and fractionated potentials. ECG flutter wave morphologies were compared with activation patterns. Points (91±29) were sequentially acquired covering 88±11% of the flutter cycle length of 239±22 ms. A wide and variable posterior zone of double and fractionated potentials coincided with blocking and colliding wave fronts and formed the posterior limit of the circuit. A progressively widening septal (sep) wave front ascending from just beyond the coronary sinus ostium, passed cranially as a broad front anterior to the superior vena cava (SVC) in 14 patients, whereas fusion around the SVC formed the superior (sup) limb of the circuit in 3. Bounded anteriorly by the tricuspid valve, the wave front descended down the lateral (lat) aspect of the right atrium before completing the circuit in all cases through the inferior vena cava–tricuspid annulus isthmus. The estimated conduction velocity in the medial isthmus (0.6±0.3 m/s) was lower than in the other limbs of the circuit (sup=1±0.5 m/s, lat=1±0.5 m/s, sep=0.9±0.4 m/s, P =.05). Double and fractionated potentials were constant and more prevalent in the posterior right atrium. ECG flutter wave morphology did not correlate with three-dimensional activation maps. Conclusions Interindividual variations occur in the right atrial circuit of common atrial flutter, with constant activation through the cavotricuspid isthmus. A variable zone of block forms the posterior limit. Fusion around the SVC can occur, and ascending medial septal activation does not follow a consistent pattern.

Background Despite verification of bidirectional conduction block after radiofrequency (RF) catheter ablation in the inferior vena cava (IVC)–tricuspid annulus (TA) isthmus, recurrence of common atrial flutter is relatively common. Although complete linear reablation is usually performed, we evaluated a simplified electrophysiological strategy selectively targeting recovered conducting isthmus tissue. Methods and Results Twenty-one patients (18 men and 3 women, age, 54±10 years) with a recurrence of typical atrial flutter 6±7 months after an apparently successful catheter ablation in the IVC-TA isthmus prospectively underwent electrophysiologically targeted reablation during flutter. Sites with narrow electrograms or fractionated electrograms interposed between adjacent sites with double potentials considered to represent gaps were ablated without movement of the catheter. Mapping showed that 18 of 21 patients had a single gap. Successful ablation required a single application in 14 patients and, in the group as a whole, a median of one application (mean, 2±2; range, 1 to 11) with resultant bidirectional block in 13 of 16. A single narrow electrogram (duration, 48±6 ms; amplitude, 0.1±0.05 mV) was noted at the successful site in 11, whereas a fractionated electrogram (97±32 ms, 0.05±0.04 mV, P Conclusions Transmural ablation lesions in the isthmus can be recognized during flutter by double potentials separated by an isoelectric interval. Postablation recurrent flutter is usually due to a single discrete recovered gap; this is represented by a single or a fractionated potential spanning the isoelectric interval of adjacent double potentials, which can be selectively targeted to minimize repeat ablation.

Our aim is to propose an inovative non-invasive analysis of heart contraction energetics, to be used for diagnosis and therapeutics follow-up in human heart pathologies. The analysis is based on the combination of non-invasive 31P-NMR and IRM techniques and the analytical background of metabolic modular control analysis (MoCA). Metabolic control analysis’ based approaches have been used by us and others to overcome the complexity of intra-cellular regulations and to describe and quantify controls and regulations in complex systems. We previously demonstrated that MoCA does bring new informations on the interplay between ATP demand and supply in heart contraction energetics. In the present study, MoCA was applied to beating Langendorff perfused guinea pig heart to describe qualitatively and quantitatively the global action of various inotropic effectors effector modifying (Adrenaline) or not (Levosimendan, a calcium-sensitizer; Frank-Starling effect) cytosolic calcium transients. MoCA allows to describe the relative importance of the different routes within the heart by which the inotropic effects are transmitted. The results show that in the absence of calcium transient changes, an energetic feed-back control occurs at the expense of total energy, like in skeletal muscle, while parallel activation of both supply and demand occurs after adrenaline addition, maintaining energy homeostasis (heart energetic paradigm). In conclusion, clinical application of System’s biology to the study of contraction energetics in patients may help to the understanding of the links between molecular events in pathologies and whole organ function / dysfunction.

A 60-year-old man with obesity and severe left ventricular dysfunction and left atrial dilatation underwent catheter ablation of symptomatic, drug-refractory, persistent atrial fibrillation. After pulmonary vein isolation and electrogram-based ablation, atrial fibrillation was cardioverted successfully. Mitral isthmus ablation was undertaken during distal coronary sinus (CS) 1 to 2 pacing. CS blood flow was occluded by inflating a 1-cm spherical balloon distally. During ongoing radiofrequency application using an irrigated ablation catheter (average power, 34 W; temperature, 39°C) on the endocardial mitral isthmus line, conduction delay between the bipoles CS 1 to 2 (pacing site) …

Background —The extent of ostial ablation necessary to electrically disconnect the pulmonary vein (PV) myocardial extensions that initiate atrial fibrillation from the left atrium has not been determined. Methods and Results —Seventy patients underwent PV mapping with a circumferential 10-electrode catheter during sinus rhythm or left atrial pacing. After assessment of perimetric distribution and activation sequence of PV potentials, ostial ablation was performed at segments showing earliest activation, with the end point of PV disconnection. A total of 162 PVs (excluding right inferior PVs) were ablated. PV potentials were present at 60% to 88% of their perimeter, but PV muscle activation was always sequential from a segment with earliest activation (breakthrough). Radiofrequency (RF) application at this breakthrough eliminated all PV potentials in 34 PVs, whereas a secondary breakthrough required RF applications at separate segments in 77; in others, >2 segments were ablated. A median of 5, 6, and 4 bipoles from the circular catheter were targeted in the right superior, left superior, and inferior PVs, respectively, to achieve PV disconnection. Early recurrence of arrhythmia was observed in 31 patients as a result of new venous or atrial foci or recovery of previously targeted PVs, most related to a single recovered breakthrough that was reablated with local RF application. Conclusions —Although PV muscle covers a large extent of the PV perimeter, there are specific breakthroughs from the left atrium that allow ostial PV disconnection by use of partial perimetric ablation.

A 38-year-old man with a history of arrhythmogenic right ventricular cardiomyopathy and right ventricular hypokinesia was referred for catheter ablation of an incessant symptomatic ventricular tachycardia resistant to antiarrhythmic drugs. Twelve-lead electrogram during tachycardia revealed wide QRS complexes negative in V1 and positive in inferior leads, suggesting a right ventricular outflow tract origin. An electrophysiological study was performed, and surprisingly, endocardial activation of the tachycardia was earliest in the left ventricle, on the lateral wall. The earliest recorded endocardial potential was 20 ms before …

A 47-year-old woman with a patent secundum atrial septal defect (maximal diameter, 14 mm), a persistent left superior vena cava (LSVC), and a 24-month history of symptomatic paroxysmal atrial fibrillation that was not responsive to antiarrhythmic medication was referred for catheter ablation. During the index procedure, she underwent radiofrequency isolation guided by a circumferential mapping catheter (Lasso, Biosense Webster, Diamond Bar, Calif) of 4 normally situated pulmonary veins, and ablation of the cavotricuspid …

A 59-year-old man underwent radiofrequency catheter ablation for symptomatic drug refractory atrial fibrillation (AF). Prior ablations for AF had included pulmonary vein (PV) electrical isolation and additional substrate modification involving linear ablation joining the 2 superior PVs (roofline) and the anterior mitral annulus with the roofline (anterior line). Despite significant clinical improvement, further mapping and ablation was performed because of recurrent arrhythmia. At the time of the procedure, the ECG demonstrated AF with intermittent termination that was followed by immediate re-initiations, …

Pulmonary vein isolation for treatment of atrial fibrillation sometimes requires extensive use of fluoroscopy, with inherent risk to the patient, operator, and laboratory staff. The LocaLisa system (Medtronic) is a nonfluoroscopic, noncontact mapping system that uses regular catheters as sensors for a high-frequency thoracic electrical field generated by the system to create a real-time, 3D image. The Data Supplement Movie demonstrates the utility of LocaLisa during a pulmonary vein disconnection procedure. The left screen is the LocaLisa system display, and the right screen shows the intracardiac recordings. The LocaLisa screen shows the Lasso (Biosense Webster)and ablation catheter in the right superior pulmonary vein as if viewed from within …