Search

Introduction: Around 30% of patients do not respond to cardiac resynchronization therapy (CRT). Nonischemic cardiomyopathy has been identified as an independent predictor of response to CRT, probably due to the absence of compact scar., Methods and Results: The relationship between cardiac scar, ischemia, and hibernation (both at the left-ventricular pacing site and as a total burden) and response to CRT was studied in patients with ischemic cardiomyopathy using the perfusion-viability positron emission tomography (PET) test. Sixty-six patients with ischemic cardiomyopathy and traditional criteria for CRT were included. All patients underwent PET scan prior to CRT. Using PET, the amount and location of scarred, ischemic, and hibernating myocardium were characterized. No revascularization was indicated. Responders were defined by an improvement of left-ventricular ejection fraction (LVEF) >or= 5% and/or New York Heart Association (NYHA) class >or= 1 degree. During a mean follow-up of 26.2 +/- 22.2 months, there was a significant improvement in NYHA class and reverse remodeling in patients with the LV lead inserted remotely from the scar. However, reverse remodeling of a similar degree was present also in patients with extensive scarring including the lateral wall. The presence of ischemia, hibernation, or nontransmural scar at the pacing-site did not significantly modify the outcome of CRT as compared with viable myocardium. There were only 38% of CRT-nonresponders. Neither the extent of scar, ischemia, hibernation, or viability predicted outcome or mortality. Twenty patients died during the follow-up, one patient underwent heart transplant., Conclusions: At follow-up, response to CRT is observed regardless of the presence of extensive scarring. Left ventricular (LV) pacing at sites with ischemia, hibernation, or nontransmural scar does not appear to modify the effect of CRT as compared to viable tissue.

Background: Despite the recent advances in cardiac mapping, ablation of scar-related ventricular tachycardia (VT) still remains a clinical challenge. A detailed electroanatomical map is a prerequisite for accurate localization and ablation of the VT substrate., Objective: The purpose of this study was to evaluate the feasibility and accuracy of integrating the positron emission tomography (PET)/computed tomography (CT) with the electroanatomical map and compare the accuracy of the voltage-based scar with the biological scar., Methods: Patients undergoing radiofrequency ablation (n = 19) for scar-related VT were enrolled. CT angiography and PET scans were performed for all patients. Tomographic and volumetric data from both images were processed and coregistered using internally designed software. That image was segmented in an electrophysiology mapping system and registered to the electroanatomical map. Eight different thresholds were applied on the voltage map to define the scar. The surface areas of the biological and electrical dense scars at different thresholds were measured and compared., Results: The PET/CT image was well integrated with the electroanatomical map with a mean surface registration error of 5.1 +/- 2.1 mm. Of the eight different thresholds defining the scar, the surface area of the scar at a threshold of 0.9 mV (68.6 +/- 49.2 cm(2)) correlated best with the surface area of the PET-based scar (70.4 +/- 49.3 cm(2)) and had the least total area error (4.8 +/- 1.8 cm(2)) compared with the 0.5 threshold (29.7 +/- 23.9 cm(2))., Conclusion: Integrating PET/CT with the electroanatomical map is feasible and accurate. Based on the biological scar, readjustment of the voltage scar threshold to 0.9 mV is suggested. In view of the better accuracy of PET/CT in defining scar, the need for acquiring detailed voltage maps may be obviated.

Introduction: Evaluation of luminal temperature during left atrial ablation is used clinically; however, luminal temperature does not necessarily reflect temperature within the esophageal wall and poses a risk of atrioesophageal fistula. This animal study evaluates luminal esophageal temperature and its relation to the temperature of the external esophageal tissue during left atrial lesions using the 8 mm solid tip and the open irrigated tip catheters (OIC)., Methods and Results: A thermocouple was secured to the external surface of the esophagus at the level of the left atrium of the dogs. Luminal esophageal temperature was measured using a standard temperature probe. In four randomized dogs, lesions were placed using an 8 mm solid tip ablation catheter. In six randomized dogs, lesions were placed using the 3.5 mm OIC. The average peak esophageal tissue temperature when using the OIC was significantly higher than that of the 8 mm tip catheter (88.6 degrees C +/- 15.0 degrees C vs. 62.3 degrees C +/- 12.5 degrees C, P < 0.05). Both OIC and 8 mm tip catheter had significantly higher peak tissue temperatures than luminal temperatures (OIC: 88.6 degrees C +/- 15.0 degrees C vs 39.7 degrees C +/- 0.82 degrees C, P < 0.05) (8 mm: 62.3 degrees C +/- 12.5 degrees C vs 39.0 +/- 0.5 degrees C, P < 0.05). Both catheters achieved peak temperatures faster in the tissue as compared to the lumen of the esophagus, although the tissue temperature peaked significantly faster for the OIC (OIC: 25 seconds vs 90 seconds, P < 0.05) (8 mm: 63 seconds vs 105 seconds, P < 0.05)., Conclusion: Despite the significant difference in actual tissue temperatures, no significant difference was observed in luminal temperatures between the OIC and 8 mm tip catheter.

Focal atrial tachycardias originating from the left atrial appendage present unique anatomic challenges for successful ablation. We describe the role of minimally invasive percutaneous epicardial mapping and ablation in the management of two patients with ectopic atrial tachycardias arising from the left atrial appendage following failure of a conventional endocardial approach to achieve cure.

Introduction: The incidence of left atrial appendage (LAA) thrombus in patients with paroxysmal atrial fibrillation (PAF) who present for pulmonary vein antrum isolation procedure (PVAI) is unknown., Methods and Results: All consecutive patients from January 2000 to June 2004 who underwent a PVAI received a computed tomography (CT) to evaluate LAA thrombus before the procedure and 3 months post-PVAI. All patients were followed prospectively. One thousand two hundred twenty-one patients received a PVAI during the study dates. All patients received a CT pre-PVAI at 3 months, and 601 (49%) received a transesophageal echocardiography (TEE) pre-PVAI. Per protocol, all patients who had CT scans that were positive for LAA thrombus received a TEE. There were 9 patients who had LAA thrombus on CT scan, but only 3 had LAA thrombus on TEE. Using TEE as the gold standard, only 3 patients had an LAA thrombus before PVAI; of these patients, 2 had chronic AF with average ejection fraction (EF) of 48% and 1 patient had PAF with EF 25%. No patients with PAF and normal EF had LAA thrombus. Patients with LAA thrombus pre-PVAI had lower EF than patients without LAA thrombus (40% vs. 53%, P = 0.007) but had similar LA size (5.0 vs. 4.5 cm, P = 0.77). No other differences in baseline characteristics were noted., Conclusions: In this registry of 1,221 patients, we did not observe LA thrombus in PAF patients with normal EF who present for PVAI. Prescreening CT alone is likely to be sufficient in paroxysmal AF patients with normal EF, and the use of TEE may not be needed.

Background: The efficacy of radiofrequency ablation of atypical atrial flutter (AAFL) remains relatively low. This is probably related to the complex mechanism of this arrhythmia or may be due to an inability to deliver sufficient energy during ablation., Objective: The aim of this study is to assess whether an open-irrigation-tip catheter or an 8-mm-tip catheter is more effective for ablation of AAFL in patients with prior history of cardiac surgery and/or catheter ablation of atrial fibrillation., Methods: Seventy patients with AAFL after cardiac surgery/atrial fibrillation ablation were randomized for ablation with either an open-irrigation-tip catheter (Group 1, n=36) or an 8-mm-tip catheter (Group 2, n=34). Acute success was defined as the termination of AAFL by radiofrequency delivery and noninducibility by programmed pacing at the end of procedure. Patients' postoperative courses were followed up by means of intermittent standard electrocardiogram (ECG), transtelephonic ECG monitoring, and telephone interview. All patients underwent 48-hour Holter monitoring at their 3-, 6-, and 9-month follow-up after ablation., Results: Acute success was achieved in 34 patients (94.4%) in Group 1 and 26 patients (76.5%) in Group 2 (P<.05). As compared with the patients in Group 2, more patients in Group 1 remained in sinus rhythm without antiarrhythmic drugs at 90-day follow-up (22 vs 8, P<.05). After 10 months of follow-up, 91.7% of the patients from Group 1 were free of atrial tachyarrhythmias, whereas only 58.9% of the patients from Group 2 remained in sinus rhythm (P <.05). The fluoroscopy and radiofrequency times were significantly shorter when an open-irrigation-tip ablation catheter was used., Conclusion: In patients with a prior history of cardiac surgery or ablation for atrial fibrillation, an open-irrigation-tip catheter is superior to an 8-mm-tip catheter for radiofrequency ablation of scar-related AAFLs. Patients ablated with an open-irrigation-tip catheter seem to have higher acute success rate with less x-ray exposure and radiofrequency delivery, and have a more favorable long-term outcome with more patients maintaining sinus rhythm without antiarrhythmic drugs.

Background: Elimination of vagal inputs into the left atrium (LA) may be necessary for successful catheter ablation of atrial fibrillation (AF). These vagal inputs are clustered in autonomic ganglia (AG) that are close to the pulmonary vein antrum (PVA) borders, but whether standard intracardiac echocardiography (ICE)-guided PVA isolation (PVAI) affects these inputs is unknown., Objective: The purpose of this study was to assess whether standard ICE-guided PVAI affects vagal responses induced by endocardial AG stimulation in the LA., Methods: Twenty consecutive patients undergoing first-time PVAI (group 1) and 20 consecutive patients undergoing repeat PVAI for AF recurrence (group 2) were enrolled in the study. Before ablation, electrical stimulation (20 Hz, pulse duration 10 ms, voltage range 12-20 V) was performed through an 8-mm-tip ablation catheter. Based on prior data, regions around all four PVA borders were carefully mapped and stimulated to localize AG inputs. A positive stimulated vagal response was defined as atrioventricular (AV) block, asystole, or increase in mean RR interval by >50%. Locations of positive vagal responses were recorded wth biplane fluoroscopy and CARTO. All patients then underwent standard ICE-guided PVAI by an operator blinded to the locations of vagal responses. Stimulation of the AG locations was then repeated postablation., Results: Patients (age 54 +/- 11 years, 30% female, ejection fraction 54% +/- 7%) had a history of paroxysmal (75%) and persistent (25%) AF. In group 1, vagal responses were induced in all 20 patients around a mean of 3.8 +/- 0.4 PVAs per patient. The most common response was asystole (53%), mean RR slowing >50% (28%), and AV block (20%). Postablation, vagal responses could no longer be induced in all 20 patients. A diminished response was induced (RR slowing <50%) in 2/20 patients around one PVA each. In group 2, vagal responses were not induced in any of the 20 repeat patients. Stimulation capture postablation was confirmed because transient, nonsustained (<30 seconds) AF or atrial flutter was induced in all 40 patients with stimulation, whether vagal responses were induced or not., Conclusions: Standard ICE-guided PVAI eliminates vagal responses induced by AG stimulation. Responses are not seen in patients presenting for repeat PVAI, despite clinical recurrence of AF.

Objectives: We aimed at assessing the feasibility and efficacy of remote magnetic navigation (MN) and ablation in patients with atrial fibrillation (AF)., Background: This novel MN system could facilitate standardization of the procedures, reducing the importance of the operator skill., Methods: After becoming familiar with the system in 48 previous patients, 45 consecutive patients with AF were considered for ablation using the Niobe II remote magnetic system (Stereotaxis, St. Louis, Missouri) in a stepwise approach: circumferential pulmonary vein ablation (CPVA), pulmonary vein antrum isolation (PVAI), and, if failed, PVAI using the conventional approach. Remote navigation was done using the coordinate or the wand approach. Ablation end point was electrical disconnection of the pulmonary veins (PVs)., Results: Using the coordinate approach, the target location was reached in only 60% of the sites, whereas by using the wand approach 100% of the sites could be reached. After step 2 ablation, only 1 PV in 4 patients (8%) could be electrically isolated. Charring on the ablation catheter tip was seen in 15 (33%) of the cases. In 23 patients, all PVs were isolated with the conventional thermocool catheter, and in 22 patients only the right PVs were isolated with the conventional catheter. After a mean follow-up period of 11 +/- 2 months, recurrence was seen in 5 patients (22%) with complete PVAI and in 20 patients (90%) with incomplete PVAI., Conclusions: Remote navigation using a magnetic system is a feasible technique. With the present catheter technology, effective lesions cannot be achieved in most cases. This appears to impact the cure rate of AF patients.

Background: Studies examining AF recurrences post-PVAI base recurrence on patient reporting of symptoms. However, whether asymptomatic recurrences are common is not well known., Objective: To assess the incidence of atrial tachycardia/fibrillation post-PVAI as detected by a PPM and whether these recurrences correlate to symptomatic recurrence., Methods: Eighty-six consecutive patients with symptomatic AF and PPMs with programmable mode-switch capability underwent PVAI. Mode switching was programmed post-PVAI to occur at an atrial-sensed rate of >170 bpm. Patients were followed with clinic visits, ECG, and PPM interrogation at 1, 3, 6, and 9 months post-PVAI. The number and duration of mode-switching episodes (MSEs) were recorded at each visit and is presented as median (interquartile range)., Results: The patients (age 57 +/- 8 years, EF 54 +/- 10%) had paroxysmal (65%) and persistent (35%) AF pre-PVAI. Sensing, pacing, and lead function were normal for all PPMs at follow-up. Of the 86 patients, 20 (23%) had AF recurrence based on symptoms. All 20 of these patients had appropriate MSEs detected. Of the 66 patients without symptomatic recurrence, 21 (32%) had MSEs detected. In 19 of these patients, MSEs were few in number, compared with patients with symptomatic recurrence (16 [4-256] vs 401 [151-2,470], P < 0.01). The durations were all <60 seconds. All of these nonsustained MSEs occurred within the first 3 months post-PVAI, gradually decreasing over time. The other 2 of 21 remaining patients had numerous (1,343 [857-1,390]) and sustained (18 +/- 12 minutes) MSEs that also persisted beyond 3 months (1 beyond 6 months). Therefore, the incidence of numerous, sustained MSEs in asymptomatic patients post-PVAI was 2 of 66 (3%)., Conclusions: Detection of atrial tachyarrhythmias by a PPM occurred in 30% of patients without symptomatic AF recurrence. Most of these episodes were <60 seconds and waned within 3 months. Sustained, asymptomatic episodes were uncommon.

Objectives: We sought to test how catheter ablation using an open irrigation catheter (OIC) compares with standard catheters for pulmonary vein antrum isolation., Background: Open irrigation catheters have the advantage of delivering greater power without increasing the temperature of the catheter tip, which enables deeper and wider lesions without the formation of coagulum on catheters., Methods: Catheter ablation was performed using an 8-mm catheter (8MC) or an OIC. Patients were randomized to 3 groups: 8MC; OIC-1, OIC with a higher peak power (50 W); and OIC-2, OIC with lower peak power (35 W)., Results: A total of 180 patients were randomized to the 3 treatment strategies. Isolation of pulmonary vein antra was achieved in all patients. The freedom from atrial fibrillation was significantly greater in the 8MC and OIC-1 groups compared with the OIC-2 group (78%, 82%, and 68%, respectively, p = 0.043). Fluoroscopy time was lower in OIC-1 compared with OIC-2 and 8MC (28 +/- 1 min, 53 +/- 2 min, and 46 +/- 2 min, respectively, p = 0.001). The mean left atrium instrumentation time was lower in the OIC-1 compared with the OIC-2 and 8MC groups (59 +/- 3 min, 90 +/- 5 min, and 88 +/- 4 min, respectively, p = 0.001). However, there was a greater incidence of "pops" in the OIC-1 (100%, 0%, 0%, p < 0.001) along with higher incidences of pericardial effusion (20%, 0%, 0%, p < 0.001) and gastrointestinal complaints (17% in OIC-1, 3% in 8MC, and 5% in OIC-2, p = 0.031)., Conclusions: Although there was a decrease in fluoroscopy and left atrium instrumentation time with the use of OIC at higher power, this setting was associated with increased cardiovascular and gastrointestinal complications.

Introduction: Image integration is being used in ablation procedures. However, the success of this approach is dependent on the accuracy of the image integration process. This study aims to evaluate the in vivo accuracy and reliability of the integrated image., Methods and Results: One hundred twenty-four patients undergoing radiofrequency (RF) ablation catheter ablation for atrial fibrillation (AF) were recruited for this study from three different centers. Cardiac computerized tomography (CT) was performed in all patients and a 3D image of the left atrium (LA) and pulmonary veins (PVs) was extracted for registration after segmentation using a software program (CartoMerge, Biosense Webster, Inc.). Different landmarks were selected for registration and compared. Surface registration was then done and the impact on integration and the landmarks was evaluated. The best landmark registration was achieved when the posterior points on the pulmonary veins were selected (5.6 +/- 3.2). Landmarks taken on the anterior wall, left atrial appendage (LAA) or the coronary sinus (CS) resulted in a larger registration error (9.1 +/- 2.5). The mean error for surface registration was 2.17 +/- 1.65. However, surface registration resulted in shifting of the initially registered landmark points leading to a larger error (from 5.6 +/- 3.2 to 9.2 +/- 2.1; 95% CI 4.2-3.05)., Conclusion: Posterior wall landmarks at the PV-LA junction are the most accurate landmarks for image integration in respect to the target ablation area. The concurrent use of the present surface registration algorithm may result in shifting of the initial landmarks with loss of their initial correlation with the area of interest.

Background: Recent data have shown that the septum and anterior left atrial (LA) wall may contain "rotor" sites required for AF maintenance. However, whether adding ablation of such sites to standard ICE-guided PVAI improves outcome is not well known., Objective: To determine if adjuvant anterior LA ablation during PVAI improves the cure rate of paroxysmal and permanent AF., Methods: One hundred AF patients (60 paroxysmal, 40 persistent/permanent) undergoing first-time PVAI were enrolled over three months to receive adjuvant anterior LA ablation (Group I). These patients were compared with 100 randomly selected, matched first-time PVAI controls from the preceding three months who did not receive adjuvant ablation (Group II). All 200 patients underwent ICE-guided PVAI during which all four PV antra and SVC were isolated. In group I, a decapolar lasso catheter was used to map the septum and anterior LA wall during AF (induced or spontaneous) for continuous high-frequency, fractionated electrograms (CFAE). Sites where CFAE were identified were ablated until the local EGM was eliminated. A complete anterior line of block was not a requisite endpoint. Patients were followed up for 12 months. Recurrence was assessed post-PVAI by symptoms, clinic visits, and Holter at 3, 6, and 12 months. Patients also wore rhythm transmitters for the first 3 months. Recurrence was any AF/AFL >1 min occurring >2 months post-PVAI., Results: Patients (age 56 +/- 11 years, 37% female, EF 53%+/- 11%) did not differ in baseline characteristics between group I and II by design. Group I patients had longer procedure time (188 +/- 45 min vs 162 +/- 37 min) and RF duration (57 +/- 12 min vs 44 +/- 20 min) than group II (P < 0.05 for both). Overall recurrence occurred in 15/100 (15%) in group I and 20/100 (20%) in group II (P = 0.054). Success rates did not differ for paroxysmal patients between group I and II (87% vs 85%, respectively). However, for persistent/permanent patients, group I had a higher success rate compared with group II (82% vs 72%, P = 0.047)., Conclusions: Adjuvant anterior LA ablation does not appear to impact procedural outcome in patients with paroxysmal AF but may offer benefit to patients with persistent/permanent AF.

Objectives: We present the clinical course and management outcomes of patients with total pulmonary vein occlusion (PVO)., Background: Pulmonary vein occlusion is a rare complication that can develop after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The long term follow-up data of patients diagnosed with PVO are minimal., Methods: Data from 18 patients with complete occlusion of at least one pulmonary vein (PV) were prospectively collected. All patients underwent RFA for AF using different strategies between September 1999 and May 2004. Pulmonary vein occlusion was diagnosed using computed tomography (CT) and later confirmed by angiography when intervention was warranted. Lung perfusion scans were performed on all patients before and after intervention. The percent stenoses of the veins draining each independent lung were added together to yield an average cumulative stenosis of the vascular cross-sectional area draining the affected lung (cumulative stenosis index [CSI])., Results: The patients' symptoms had a positive correlation with the CSI (r = 0.843, p < 0.05) and a negative one with the lung perfusion (r = -0.667, p < 0.05). A CSI > or =75% correlated well with low lung perfusion (<25%; r = -0.854, p < 0.01). Patients with a CSI > or =75% appeared to improve mostly when early (r = -0.497) and repeat dilation/stenting (r = 0.0765) were performed., Conclusions: Patients with single PVO are mostly asymptomatic and should undergo routine imaging. On the other hand, patients with concomitant ipsilateral PV stenosis/PVO and a CSI > or =75% require early and, when necessary, repeated pulmonary interventions for restoration of pulmonary flow and prevention of associated lung disease.

Objectives: The aims of this study were to demonstrate the safety and the feasibility of the robotic catheter remote control system (CCS) in endocardial navigation in all cardiac chambers, as well as facilitation of the transseptal puncture., Background: CCS has been developed to facilitate control and precise positioning of catheters within the cardiovascular system., Methods: CCS consists of a remote catheter manipulator, a set up joint, a physician workstation, and a steerable guide catheter (SGC) and sheath. A conventional 4-mm tip catheter was inserted through the SGC to perform mapping of five predefined targets in each cardiac chamber. Seven mongrel dogs were used in this study. Intracardiac echocardiography and three-dimensional (3-D) electroanatomical mapping were integrated with CCS to facilitate catheter manipulation and to guide transseptal puncture. The time to complete the transseptal puncture and the time to complete access to the predefined targets in each cardiac chamber were measured. Gross and microscopic examinations of the accessed and ablation sites were performed to evaluate safety., Results: Transseptal puncture was performed successfully in all animals with a mean time of 7 +/- 3 minutes. Procedure times to access the five targets in the right atrium, right ventricle, left atrium, and left ventricle were 5.6 +/- 1.7, 4.6 +/- 1.5, 13.5 +/- 11.0, 7.0 +/- 2.9 minutes, respectively. There were no intracardiac damages associated with catheter manipulation noted in the excised hearts., Conclusions: Endocardial catheter navigation and mapping using the robotic catheter remote control is safe and feasible. Moreover, the CCS could be used to perform transseptal puncture and left atrial instrumentation.

Background: Premature ventricular contractions (PVCs) and ventricular tachycardia may arise from the coronary cusps. Navigation, mapping, and ablation in the coronary cusps can be challenging. Remote magnetic navigation may offer an alternative to conventional manually operated catheters., Objective: We report a case of left coronary cusp ventricular tachycardia ablation using remote magnetic navigation., Methods: Right ventricular outflow tract and coronary cusp mapping, and ablation of the left coronary cusp using a remote magnetic navigation and three-dimensional (3-D) mapping system was performed in a 28-year-old male with frequent, symptomatic PVCs and ventricular tachycardia., Results: Successful ablation of left coronary cusp ventricular tachycardia was performed using remote magnetic navigation., Conclusions: Remote magnetic navigation may be used to map and ablate PVCs and ventricular tachycardia originating from the coronary cusps.

Background: Cerebrovascular events are an important complication during pulmonary vein antrum isolation (PVAI). Microembolic signals (MES) have been associated with stroke and neurological impairment. However, the incidence of MES during PVAI, and their relationship to microbubble formation and radiofrequency (RF) parameters are unknown., Objectives: We sought to assess the relationship between MES, microbubble detection, and neurological outcome and the impact of RF titration strategy on these parameters., Methods: We studied 202 patients in two groups undergoing PVAI using an intracardiac echocardiography (ICE)-guided technique. MES were detected by transcranial Doppler (TCD) using insonation of the middle cerebral arteries. The number of microbubbles on ICE were qualitatively labeled as FEW, MODERATE, and SHOWER. In group I (n = 107), RF output was titrated to avoid microbubble formation and in group II (n = 95), standard power-limited RF output was used., Results: TCD detected MES in all 202 patients during PVAI with an average of 1,793 +/- 547 per patient; 90% were detected during left atrial ablation. Over 85% of MES occurred after microbubbles. Group I patients had significantly lower numbers of MES (1,015 +/- 438 per patient) compared to group II patients (2,250 +/- 864 per patient) (P < 0.05). Group II also had a 3.1% incidence of acute neurological complications versus 0.9% in group I (P = 0.10). Patients with clinical events had significantly higher numbers of MES. There were no significant correlations between RF power, temperature, or impedence and MES number., Conclusions: MES directly correlate to the amount of microbubble formation on ICE, and may result in cerebroembolic complications. Titration of RF according to microbubble formation by ICE during PVAI may be important for minimizing the occurrence of MES and possibly acute neurological complications.

Introduction: It is unknown if identification of scar border zones by electroanatomical mapping correlates with successful ablation sites determined from mapping during ventricular tachycardia (VT) post-myocardial infarction (MI). We sought to assess the relationship between successful ablation sites of hemodynamically stable post-MI VTs determined by mapping during VT with the scar border zone defined in sinus rhythm., Methods and Results: Forty-six patients presenting with hemodynamically stable, mappable monomorphic VT post-MI and who had at least one such VT successfully ablated were prospectively included in the study. In each patient, VT was ablated by targeting regions during VT that exhibited early activation, +/- isolated mid-diastolic potentials, and concealed entrainment suggesting a critical isthmus site. Prior to ablation, a detailed sinus-rhythm CARTO voltage map of the left ventricle was obtained. A voltage <0.5 mV defined dense scar. Successful VT ablation sites were registered on the sinus voltage map to assess their relationship to the scar border zone. Of the 86 VTs, 68% were successfully ablated at sites in the endocardial border zone. The remaining VTs had ablation sites within the scar in (18%), in normal myocardium (4%), and on the epicardial surface (10%). There were no significant differences in VT recurrence amongst the different groups., Conclusion: Successful ablation sites of hemodynamically stable, monomorphic VTs post-MI are often located in the scar border zone as defined by substrate voltage mapping. However, in a sizable minority, ablation sites are located within endocardial scar, epicardially, and even in normal myocardium.

Objectives: The aim of this study was to assess the incidence of atrial flutter (AFL) after pulmonary vein antrum isolation (PVAI) in patients with previous cardiac surgery (PCS) in comparison to patients without PCS and to assess the need for AFL ablation in both groups., Background: Atrial fibrillation (AF) and AFL often co-exist. Pulmonary vein antrum isolation may be sufficient to control both arrhythmias. However, in patients with PCS, atrial incisions, cannulations, and scar areas may cause AFL recurrence despite elimination of pulmonary vein triggers., Methods: Data from 1,345 patients who had PVAI were analyzed. Patients with a history of AFL ablation and patients who had concomitant AFL ablation during PVAI were excluded from analysis. Sixty-three patients constituted the PCS group (Group 1, age 57 +/- 13 years, 12 female) and 1,062 patients constituted the non-PCS group (Group 2, age 55 +/- 12 years, 212 female). Patients in Group 1 had larger left atria, higher incidence of AFL pre-PVAI, and lower ejection fraction., Results: There was no significant difference in post-PVAI AF recurrence between Groups 1 and 2, but AFL incidence after PVAI was higher in Group 1 (33% vs. 4%, p < 0.0001). Ablation of AFL in Group 1 patients resulted in an 86% acute success rate and 11% recurrence over a mean follow-up of 357 +/- 201 days., Conclusions: In patients with PCS, post-PVAI AF recurrence is similar to patients without PCS. However, history of PCS is associated with a higher recurrence of AFL after PVAI. In a significant number of patients with PCS, AFL ablation is required to achieve a cure.

Introduction: Left atrial flutter (LAFL) is a known complication of pulmonary vein isolation. Treatment of this arrhythmia currently involves both linear lesions as well as re-isolation. However, it is unknown if re-isolation alone is sufficient to prevent recurrence. This study reviews the incidence of LAFL following segmental PV antrum isolation (PVAI) in a large patient population and evaluates if re-isolation alone is sufficient to prevent recurrence., Methods and Results: Seven hundred thirty-seven patients underwent PVAI. Twenty-three patients (3.1%) developed post-PVAI LAFL. All patients underwent a second procedure in which only repeat PVAI was done. During the second procedure, all flutter circuits were electroanatomically mapped. All patients were followed at 3, 6, and 12 months. All 23 patients demonstrated recovery in one or more PV. After repeat isolation of the PVs, 61% of patients were arrhythmia free off all antiarrhythmic drugs. A relationship between the presence/absence of pre-existing left atrial (LA) scar was observed. Of the 11 patients with pre-existing LA scar, 36% remained arrhythmia free off antiarrhythmic drugs. In contrast, of the 12 patients without pre-existing LA scar, 83% remained arrhythmia free off antiarrhythmic drugs (P = 0.03)., Conclusion: Among patients with LAFL following PVAI, re-isolation alone is sufficient in preventing recurrence in patients without pre-existing LA scar. Patients with pre-existing LA scar tend to have recurrence requiring further ablation including linear lesions, and continue to need antiarrhythmic medications.

Objectives: The goal of this study was to assess the impact of left atrial scarring (LAS) on the outcome of patients undergoing pulmonary vein antrum isolation (PVAI) for atrial fibrillation (AF)., Background: Left atrial scarring may be responsible for both the perpetuation and genesis of AF., Methods: A total of 700 consecutive patients undergoing first-time PVAI were studied. Before ablation, extensive voltage mapping of the left atrium (LA) was performed using a multipolar Lasso catheter guided by intracardiac echocardiography (ICE). Patients with LAS were defined by a complete absence of electrographic recording by a circular mapping catheter in multiple LA locations, and this was validated by electroanatomic mapping. All four pulmonary vein antra and the superior vena cava were isolated using an ICE-guided technique. Patients were followed at least nine months for late AF recurrence. Univariate and multivariate analyses were performed to assess the predictive value of LAS and other variables on outcome., Results: Of 700 patients, 42 had LAS, which represented 21 +/- 11% of the LA surface area by electroanatomic mapping. Patients with LAS had a significantly higher AF recurrence (57%) compared with non-LAS patients (19%, p = 0.003). Also, LAS was associated with a significantly larger LA size, lower ejection fraction, and higher C-reactive protein levels. Univariate analysis revealed age, nonparoxysmal AF, and LAS as predictors of recurrence. Multivariate analysis showed LAS as the only independent predictor of recurrence (hazard ratio 3.4, 95% confidence interval 1.3 to 9.4; p = 0.01)., Conclusions: Pre-existent LAS in patients undergoing PVAI for AF is a powerful, independent predictor of procedural failure. Left atrial scarring is associated with a lower EF, larger LA size, and increased inflammatory markers.

Introduction: Electrical storm (ES) is characterized by either refractory ventricular tachycardia (VT) or ventricular fibrillation (VF). However, little is known about the prevalence, predictors, and mortality implications of the causative arrhythmia in ES. We sought to assess the prevalence, predictors, and survival significance of VT and VF as the causative arrhythmia of ES in implantable cardioverter defibrillator (ICD) patients., Methods and Results: Consecutive patients from January 2000 to December 2002 who presented to the ICD clinic with > or = 2 separate ventricular arrhythmic episodes requiring shock within 24 hours were included in the study. ICD interrogation confirmed the number of shocks and provided electrograms for interpretation of the causative arrhythmia. Patients were grouped as VF or VT according to the causative arrhythmia. Their prevalence, predictors, and mortality rates were compared. Of 2,028 patients assessed in the ICD clinic, 208 (10%) presented with ES. VF was the cause of ES in 99 of 208 patients, for an overall prevalence of 48%. Original ICD indication, coronary artery disease, and amiodarone therapy were predictive for the causative arrhythmia. There was no mortality difference between the VT and VF groups; however, both groups had significantly increased mortality compared to a control ICD population without ES., Conclusion: VF is the causative arrhythmia for a sizable proportion of patients with ES. The initial ICD indication, coronary artery disease, and amiodarone therapy are predictors of the causative arrhythmias in ES. There does not appear to be any mortality difference between ES patients with VT and VF, but mortality is increased in patients with ES versus control ICD patients without ES.

Objectives: In patients with atrial flutter (AFL) and postoperative right atrial incisional scars, we sought to assess if the use of additional ablative lesions that targeted all potential re-entrant circuits, regardless of the presenting type of flutter, would prevent long-term recurrence., Background: Patients with AFL and incisional scars have a complex atrial substrate that may promote multiple mechanisms of intra-atrial re-entry., Methods: Twenty-nine patients with single right atrial incisional scars undergoing ablation for scar-dependent (n = 15) and cavotricuspid isthmus (CTI)-dependent (n = 14) flutter were studied., Results: In the scar-dependent group, 9 of 15 (60%) patients had inducible or spontaneous CTI-dependent flutter immediately after ablation. In the group with CTI flutter, 7 of 14 (50%) patients had scar-related flutter immediately after ablation. If a second type of flutter was found during the initial ablation, a second ablation was performed either along the isthmus (scar-dependent group) or from the scar to another anatomic boundary (isthmus-dependent group). Patients were followed for 24 +/- 5 months and 18 +/- 6 months in the scar- and CTI-dependent groups, respectively. In the scar-dependent group, five of six (83%) who underwent only a single flutter line had recurrence at 3 +/- 1 months. In the isthmus-dependent group, three of seven (42%) patients who had only one flutter line performed had recurrence at 5 +/- 3 months. There was no flutter recurrence in patients who initially received two different flutter lines or in patients who subsequently underwent a second flutter line at follow-up., Conclusions: In patients with postoperative right atrial incisional scar and flutter, multiple ablation lines that target both scar-related and classic isthmuses appear necessary to prevent long-term recurrence.

Introduction: Sick sinus syndrome is commonly associated with tachyarrhythmias and bradyarrhythmias that often are symptomatic. The aim of this study was to assess the effect of pulmonary vein isolation in patients with sick sinus syndrome and atrial fibrillation (AF)., Methods and Results: Three hundred fourteen consecutive patients who underwent pulmonary vein isolation between December 2000 and January 2002 were included in the study. Thirty-one patients had sick sinus syndrome, which was defined as a preprocedural history of symptomatic sinus bradycardia or pauses. Endpoints included AF recurrence, change in the frequency of sinus pauses, and symptoms of presyncope or syncope, as well as mean heart rate and percentage of atrial pacing in patients with pacemakers implanted prior to the pulmonary vein isolation. Patients had AF for an average of 6 +/- 3 years. Patients were 58 +/-8 years old and had ejection fractions of 55 +/- 4%. Sixty-one percent had implanted pacemakers. AF recurred within 6 months in 4 patients. Two had a successful second pulmonary vein isolation procedure. There were no recurrences of presyncopal events (P < 0.05) or documented sinus pauses (P < 0.05) after successful pulmonary vein isolation in the patients without permanent pacemakers. Patients with pacemakers had a 13-fold reduction in the percentage of atrial pacing (P < 0.05). Both groups showed a significant increase in average heart rates at 6-month follow-up., Conclusion: Cure of AF by pulmonary vein isolation helped resolve the clinical manifestations of sick sinus syndrome, suggesting that the occurrence of AF and/or the associated treatment could be partially responsible for sick sinus syndrome.

Objectives: We report on the initiation of ventricular fibrillation (VF) storm in patients with ischemic cardiomyopathy (ICM) and the results of targeted ablation to treat VF storm., Background: Monomorphic premature ventricular contractions (PVCs) have been shown to initiate VF in patients without structural heart disease., Methods: A total of 29 patients with ICM and documented VF initiation were identified. In 21 patients, VF storm was controlled with antiarrhythmic drugs and/or treatment of heart failure. Eight patients with VF (mean 52 +/- 25 episodes) refractory to medical management required ablation. All patients underwent three-dimensional electroanatomical mapping using CARTO (Biosense-Webster Inc., Diamond Bar, California), and PVCs were mapped when present. Scarred areas were identified using voltage mapping., Results: Monomorphic PVCs initiated VF in all 29 identified patients. Five of eight patients requiring ablation had frequent PVCs that allowed PVC mapping. The earliest activation site was consistently located in the scar border zone. The PVCs were always preceded by a Purkinje-like potential (PLP). Ablation was successfully performed at these sites. In three patients, infrequent PVCs prevented mapping, but PLPs were recorded around the scar border. Ablation targeting these potentials along the scar border was successfully performed. During follow-up (10 +/- 6 months), one patient had a single VF episode and another developed sustained, monomorphic ventricular tachycardia. There was no recurrence of VF storm., Conclusions: Ventricular fibrillation in ICM is triggered by monomorphic PVCs originating from the scar border zone with preceding PLPs; targeting these PVCs may prevent VF recurrence. In the absence of PVCs, both substrate mapping and ablation appear to be equally effective.

Introduction: A retrospective analysis was performed to define the impact of age on the outcomes and complications in patients undergoing pulmonary vein isolation (PVI). PVI is an evolving technique for the management of atrial fibrillation (AF). The impact of age on the risks, outcomes, and complications of PVI has not been well defined., Methods and Results: A total of 323 patients (259 men and 64 women; age 18-79 years) underwent PVI for treatment of drug-refractory symptomatic AF. An ostial isolation of the pulmonary veins was done using a cooled-tip ablation catheter guided by circular mapping. The patients were divided into three groups based on age (group I: <50 years, group II: 51-60 years, group III: >60 years) and the results were compared. There were 106 patients in group I, 114 patients in group II, and 103 patients in group III (mean age 41.3 +/- 7.8 years, 55.4 +/- 2.75 years, and 66.6 +/- 4.18 years, respectively) who underwent PVI for paroxysmal (53.8%), persistent (10.8%), or permanent (35.3%) AF. Baseline characteristics were similar except for a higher prevalence of hypertension and/or structural heart disease in groups II and III (58% and 63% vs 33% in group I, respectively). The procedural variables were similar in all age groups. The overall risk of complications was similar in the three groups, except that the risk of stroke was significantly higher in patients >60 years of age (3% vs 0%; P < 0.05). The recurrence rates of AF were similar in the three age groups (15.1%, 16.7%, and 18.4%, respectively; P > 0.05). The risk of severe pulmonary vein stenosis (1.8%, 2.6%, and 0.9%, respectively) was low and did not vary with age., Conclusion: PVI is a safe and effective treatment for patients with drug-refractory symptomatic AF, and its benefits extend to all age groups. The risk of procedural complications, especially thromboembolic events, appears to be higher in the elderly age group. This observation needs to be considered while assessing potential candidates for the procedure.