Elimination of local abnormal ventricular activities: a new end point for substrate modification in patients with scar-related ventricular tachycardia.

BACKGROUND: Catheter ablation of ventricular tachycardia (VT) is effective and particularly useful in patients with frequent defibrillator interventions. Various substrate modification techniques have been described for unmappable or hemodynamically intolerable VT. Noninducibility is the most frequently used end point but is associated with significant limitations, so the optimal end point remains unclear. We hypothesized that elimination of local abnormal ventricular activities (LAVAs) during sinus rhythm or ventricular pacing would be a useful and effective end point for substrate-based VT ablation. As an adjunct to this strategy, we used a new high-density mapping catheter and frequently used epicardial mapping. METHODS AND RESULTS: Seventy patients (age, 67±11 years; 7 female) with VT and structurally abnormal ventricle(s) were prospectively enrolled. Conventional mapping was performed in sinus rhythm in all, and a high-density Pentaray mapping catheter was used in the endocardium (n=35) and epicardially. LAVAs were recorded in 67 patients (95.7%; 95% confidence interval, 89.2-98.9). Catheter ablation was performed targeting LAVA with an irrigated-tip catheter placed endocardially via a transseptal or retrograde aortic approach or epicardially via the subxiphoid approach. LAVAs were successfully abolished or dissociated in 47 of 67 patients (70.1%; 95% confidence interval, 58.7-80.1). In multivariate analysis, LAVA elimination was independently associated with a reduction in recurrent VT or death (hazard ratio, 0.49; 95% confidence interval, 0.26-0.95; P=0.035) during long-term follow-up (median, 22 months). CONCLUSIONS: LAVAs can be identified in most patients with scar-related VT. Elimination of LAVAs is feasible and safe and is associated with superior survival free from recurrent VT.

Positron emission tomography in patients with suspected pacing system infections may play a critical role in difficult cases.

BACKGROUND: A pacemaker recipient may be hospitalized recurrently with an infection of unknown origin despite detailed investigations. OBJECTIVE: The purpose of this study was to investigate whether (18)F-fluorodeoxyglucose positron emission tomography/computerized tomography (FDG-PET/CT) scanning has a role in identifying pacing material infection in these difficult cases. METHODS: Ten patients who presented with fever of unknown origin despite detailed investigations including transesophageal echocardiography underwent FDG-PET/CT scanning. Identification of increased FDG uptake along a pacing lead prompted the removal of the entire pacing system, whereas in the absence of increased FDG uptake the pacing material was left in place. Forty control pacemaker recipients underwent FDG-PET/CT scanning as part of investigation of malignancy. RESULTS: Among the 40 patients in the control group, FDG-PET/CT scanning was normal in 37 (92.5%) patients. Among the 10 patients who presented with suspected pacing system infections, FDG-PET/CT scanning showed increased FDG uptake along a lead in six patients; as a result of this finding, these patients subsequently underwent complete removal of the implanted material. Cultures of the leads were positive in all six patients, confirming involvement of the leads in the infectious process. In the other four patients, the pacing system was left in place without objective signs of active lead endocarditis during follow-up. CONCLUSION: This study demonstrates the potential value of FDG-PET/CT scanning in the diagnosis of pacing lead endocarditis in difficult cases. Increased FDG uptake along a lead in this clinical context appears to be a reliable sign of active infection.

Long-term outcomes after pocket or scar revision and reimplantation of pacemakers with preerosion.

INTRODUCTION: Cardiac pacemakers with preerosion are often reimplanted. Preerosion may be caused by an evolving local infectious process affecting the entire pacing system or by mechanical migration of the device causing ischemic necrosis of the skin tissues. We examined the long-term outcome of 33 patients who underwent pocket or scar revision and submuscular reimplantation of cardiac pacemakers in our institution. METHODS: Before undergoing pocket or scar revision and reimplantation, all patients (1) had negative serial blood cultures, (2) had no vegetation on transesophageal echocardiography, (3) had a normal blood C-reactive protein concentrations, (4) were afebrile, (5) had no cutaneous breakthrough, and (6) presented with preerosion of the pulse generator or granulomatous-like scar abnormality. RESULTS: THE mean follow-up was 37 ± 12 months. Among 16 patients presenting with preerosion associated with signs of local cutaneous inflammation, 62.5% developed an infection of the pacing system requiring later explantation. Of eight patients presenting initially with migration of the pulse generator and mechanical protrusion, none required subsequent explantation of the system. Among nine patients presenting initially with granulomatous-like scar abnormalities, 55.6% underwent explantation of the pacing system during follow-up for management of documented local infection. CONCLUSIONS: The reimplantation of pulse generators with preerosion in the presence of local inflammatory manifestations or granulomatous-like changes of the scar is complicated by documented cardiac pacemaker infection in >50% of cases. In these patients, the explantation of the pacing system is recommended before the development of prognostically much more serious spread of infection to the leads and cardiac tissues.

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

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

Disparate evolution of right and left atrial rate during ablation of long-lasting persistent atrial fibrillation.

OBJECTIVES: The purpose of this study was to assess whether additional ablation in the right atrium (RA) improves termination rate in long-lasting persistent atrial fibrillation (PsAF). BACKGROUND: Prolongation of atrial fibrillation (AF) cycle length (CL) measured from the left atrial appendage predicts favorable outcome during catheter ablation of PsAF. However, in some patients, despite prolongation of AF CL in the left atrium (LA) with ablation, AF persists. We hypothesized that this persistence is due to RA drivers, and that these patients may benefit from RA ablation. METHODS: In all, 148 consecutive patients undergoing catheter ablation of PsAF (duration 25 +/- 32 months) were studied. AF CL was monitored in both atria during stepwise ablation commencing in the LA. Ablation was performed in the RA when all LA sources in AF had been ablated and an RA-LA gradient existed. The procedural end point was AF termination. RESULTS: Two distinct patterns of AF CL change emerged during LA ablation. In 104 patients (70%), there was parallel increase of AF CL in LA and RA culminating in AF termination (baseline: LA 153 ms [range 140 to 170 ms], RA 155 ms [range 143 to 171 ms]; after ablation: LA 181 ms [range 170 to 200 ms], RA 186 ms [range 175 to 202 ms]). In 24 patients (19%), RA AF CL did not prolong, creating a right-to-left frequency gradient (baseline: LA 142 ms [range 143 to 153 ms], RA 145 ms [range 139 to 162 ms]; after ablation: LA 177 ms [range 165 to 185 ms], RA 152 ms [range 147 to 175 ms]). These patients had a longer AF history (23 months vs. 12 months, p = 0.001), and larger RA diameter (42 mm vs. 39 mm, p = 0.005), and RA ablation terminated AF in 55%. In the remaining 20 patients, biatrial ablation failed to terminate AF. CONCLUSIONS: A divergent pattern of AF CL prolongation after LA ablation resulted in a right-to-left gradient, demonstrating that the right atrium is driving AF in approximately 20% of PsAF.

Biventricular stimulation improves right and left ventricular function after tetralogy of Fallot repair: acute animal and clinical studies.

BACKGROUND: Optimal treatment of right ventricular (RV) dysfunction observed in patients after tetralogy of Fallot (TOF) repair is unclear. Studies of biventricular (BiV) stimulation in patients with congenital heart disease have been retrospective or have included patients with heterogeneous disorders. OBJECTIVE: The purpose of this study was to determine the effects on cardiac function of stimulating at various cardiac sites in an animal model of RV dysfunction and dyssynchrony and in eight symptomatic adults with repaired TOF. METHODS: Pulmonary stenosis and regurgitation as well as RV scars were induced in 15 piglets to mimic repaired TOF. The hemodynamic effects of various configurations of RV and BiV stimulation were compared with sinus rhythm (SR) 4 months after surgery. In eight adults with repaired TOF, RV and left ventricular (LV) dP/dt(max) were measured invasively during SR, apical RV stimulation, and BiV stimulation. RESULTS: At 4 months, RV dilation, dysfunction, and dyssynchrony were present in all piglets. RV stimulation caused a decrease in LV function but no change in RV function. In contrast, BiV stimulation significantly improved LV and RV function (P < .05). Echocardiography and epicardial electrical mapping showed activation consistent with right bundle branch block during SR and marked resynchronization during BiV stimulation. In patients with repaired TOF, BiV stimulation increased significantly RV and LV dP/dt(max) (P < .05). CONCLUSION: In this swine model of RV dysfunction and in adults with repaired TOF, BiV stimulation significantly improved RV and LV function by alleviating electromechanical dyssynchrony.

Safety of deferring the reimplantation of pacing systems after their removal for infectious complications in selected patients: a 1-year follow-up study.

INTRODUCTION: Recent expert consensus guidelines mention that one of the principles for infected device replacement following removal is to "reevaluate carefully if there is a continued need for a new cardiac device replacement." This is a Class I recommendation, which nevertheless suffers from a very low level of evidence (level of evidence C), since no study has revisited the systematic practice of reimplanting the same device based on a meticulous clinical reassessment. In the present paper, we examined the safety of withholding the implantation of pacing systems in selected patients. METHODS AND RESULTS: Between January 2005 and December 2007, 188 consecutive patients underwent extractions of infected pacing systems at 2 medical centers. "Low-risk" patients were identified by (1) a spontaneous heart rate >45 bpm, (2) no symptomatic asystole during monitoring, (3) QRS duration <120 ms when history of AV block was noted, (4) no high-degree AV block during continuous monitoring. They remained device-free, unless an adverse clinical event occurred mandating the reimplantation. The primary study endpoint was rate of sudden death and syncope after a 12-month follow-up. Among the 74 (39.4%) "low-risk" patients, a single patient suffered a bradycardia-related syncopal event corresponding to a 1.3% (95% CI, 0.0-3.9) rate of primary endpoint. Pacing systems were also reimplanted in 24 patients (32.4%) for syncope (n = 1), nonsevere bradycardia-reated symptoms (n = 17), cardiac resynchronization (n = 2), and for reassurance in 4 asymptomatic patients. CONCLUSION: After removal of infected pacing systems, these preliminary data demonstrated that a strategy of nonsystematic device reimplantation associated with close surveillance was safe in "low-risk" patients, allowing the administration of antimicrobials in a device-free state.

Performance of a radiation protection cabin during implantation of pacemakers or cardioverter defibrillators.

INTRODUCTION: Pacemaker implants are associated with a high cumulative exposure of the operators to radiation. Standard radiation protection with lead aprons is incomplete and the cause of spine disorders. A radiation protection cabin offers complete protection by surrounding the operator, without requiring a lead apron. METHODS: We randomly and evenly assigned 60 patients undergoing implantations of permanent pacemakers or cardioverter defibrillators (ICD) with (a) a radiation protection cabin (cabin group, n = 30) versus (b) standard protection with a 0.5 mm lead-equivalent apron (control group, n = 30). Radiation exposure was measured using personal electronic dosimeters placed on the thorax, back, and head of the operator. RESULTS: The patient, procedural, and device characteristics of the 2 study groups were similar. All procedures in the cabin group were performed as planned without increase in duration or complication rate compared with the control group. The mean radiation dose to the head, normalized for fluoroscopy duration, was significantly lower in the cabin (0.040 +/- 0.032 microSv/min) than in the control (1.138 +/- 0.560 microSv/min) group (p < 0.0001). The radiation doses to the thorax (0.043 +/- 0.027 vs 0.041 +/- 0.040 microSv/min) and back (0.038 +/- 0.029 vs 0.033 +/- 0.018 microSv/min) in the cabin versus control group (under the apron) were similar. CONCLUSIONS: The use of a radiation protection cabin markedly decreased the exposure of the operator to radiation, and eliminated the need to wear a lead apron, without increasing the procedural time or complication rate during implantation of pacemaker and ICD.

Long-term follow-up of persistent atrial fibrillation ablation using termination as a procedural endpoint.

AIMS: Catheter ablation of long-lasting persistent atrial fibrillation (AF) has been performed with varying results using a combination of different techniques. Whether arrhythmia termination during ablation is associated with an improved clinical outcome is controversial. METHODS AND RESULTS: In this prospective study, 153 consecutive patients (56 +/- 10 years) underwent catheter ablation of persistent AF (25 +/- 33 months) using a stepwise approach with the desired procedural endpoint being AF termination. Repeat ablation was performed for patients with recurrent AF or atrial tachycardia (AT) after a 1 month blanking period. A minimum follow-up of 12 months with repeated Holter monitoring was performed. Atrial fibrillation was terminated in 130 patients (85%). There was a lower incidence of AF in those patients in whom AF was terminated during the index procedure compared with those who had not (5 vs. 39% P < 0.0001, mean follow-up 32 +/- 11 months). Seventy-nine patients underwent repeat procedures: 64/130 in the termination group (6 AF, 58 AT) and 15 in the non-termination group (9 AF, 7 AT). After repeat ablation, sinus rhythm was maintained in 95% in whom AF was terminated compared with 52% in those in whom AF could not be terminated. CONCLUSION: Procedural termination of long-lasting AF by catheter ablation alone is associated with an improved outcome.

A deductive mapping strategy for atrial tachycardia following atrial fibrillation ablation: importance of localized reentry.

BACKGROUND: Atrial tachycardia (AT) occurring following catheter ablation of persistent atrial fibrillation (AF) may be challenging to map and ablate because their mechanism and location is unpredictable and may be multiple in an individual patient. METHODS AND RESULTS: A prospective cohort of 128 consecutive patients presenting 246 AT in the context of prior AF ablation was investigated. Using activation and entrainment mapping and applying the consensus definition of AT, we evaluated a deductive diagnostic approach based on up to three steps: (1) cycle length regularity, (2) search for macroreentry (i.e., involving >2 separate atrial segments), and (3) if macroreentry excluded, search for focal origin giving a centrifugal activation of the atria. A total of 238/246 (97%) sustained AT (mean cycle length [CL] 284 +/- 87 ms) were successfully mapped (single AT, 51 pts; multiple AT, 77 pts) with a diagnostic time of 10 +/- 8 min per tachycardia. AT were macroreentrant in 109 (46%) and focal in 129 (54%). Of the latter, only 34 focal AT originated from a discrete point site fulfilling the consensus criteria, while a distinct mechanism, localized reentry (AT that was neither macro reentry nor focal), was identified in 95. Localized reentry was defined by (1) electrograms covering >or=75% of the cycle length of AT within an area covering a single or 2 contiguous segments, (2) postpacing interval (PPI) < 30 ms at the site, (3) an identifiable zone of slow conduction, and (4) centrifugal activation of the atrium from the area. CONCLUSIONS: This prospective study demonstrates the feasibility of rapid and accurate identification of all types of postablation AT in a large cohort of patients and describes the dominant role of localized reentry as a novel mechanism of AT.

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

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

Imaging in catheter ablation for atrial fibrillation: enhancing the clinician's view.

Catheter ablation is an effective treatment for symptomatic atrial fibrillation. A thorough understanding of the left atrium anatomy and its adjacent structures is critical for the success of the procedure and for avoiding complications. Pre-procedural imaging aims at determining left atrial size, anatomy, and function and is also used to rule out an atrial thrombus. During the procedure, while fluoroscopy remains the gold standard imaging modality for guiding transseptal catheterization and catheter ablation, numerous other imaging modalities have been developed to improve 3D navigation and ablation. Finally, post-operative imaging intends to monitor heart function and to search for potential complications like pulmonary vein stenosis or the rare but dramatic atrio-oesophageal fistula. This review discusses the relative merits of all imaging modalities available in the context of catheter ablation of atrial fibrillation.

Haemodynamic impact of the left ventricular pacing site during graded ischaemia in an open-chest pig model.

AIMS: In post-operative setting after cardiac surgery, the choice of the optimal ventricular pacing site remains an issue, particularly in patients with ischaemic cardiomyopathy. We aimed to investigate the impact of the left ventricular (LV) pacing site in an animal model of incremental myocardial ischaemia. METHODS AND RESULTS: Three epicardial LV pacing leads were implanted in 10 pigs [LV1 in the territory of the left anterior descending (LAD) artery, LV2 in the lateral border of this territory, LV3 in an anatomically opposed position]. A two-dimensional strain echocardiogram was performed at baseline and during two levels of incremental ischaemia, corresponding to 30 and 70% reduction of coronary flow in the LAD, during spontaneous sinus rhythm (SR) and during LV1, LV2, LV3, and multi-LV (LV1 + LV2 + LV3) pacing. At baseline (n = 10), LV + dP/dt(max) was decreased (P < 0.01) during LV1, LV2, LV3, and multi-LV pacing compared with SR. At first level of ischaemia (n = 7; 3 animals died from ventricular fibrillation), LV1 pacing (ischaemic area) induced a significant decrease in LV + dP/dt(max) compared with SR, LV2, LV3, and multi-LV pacing (P < 0.05). At second level of ischaemia (n = 6), LV1 pacing induced a significant decrease in LV + dP/dt(max) associated with an increase in the extent of myocardium with echocardiographic post-systolic shortening compared with SR, LV2, LV3, or multi-LV pacing (P < 0.05). In contrast, multi-LV pacing induced a significant haemodynamic improvement compared with SR, LV1, LV2, and LV3 (P < 0.05). CONCLUSIONS: Pacing within an ischaemic area has detrimental impact on acute global and regional LV function. More studies are needed to assess the impact of multi-LV pacing in chronic ischaemic conditions.

Risk factors related to infections of implanted pacemakers and cardioverter-defibrillators: results of a large prospective study.

BACKGROUND: The Prospective Evaluation of Pacemaker Lead Endocarditis study is a multicenter, prospective survey of the incidence and risk factors of infectious complications after implantation of pacemakers and cardioverter-defibrillators. METHODS AND RESULTS: Between January 1, 2000, and December 31, 2000, 6319 consecutive recipients of implantable systems were enrolled at 44 medical centers and followed up for 12 months. All infectious complications were recorded, and their occurrence was related to the baseline demographic, clinical, and procedural characteristics. Among 5866 pacing systems, 3789 included 2 and 117 had >2 leads; among 453 implantable cardioverter-defibrillators, 178 were dual-lead systems. A total of 4461 de novo implantations occurred and 1858 pulse generator or lead replacements. Reinterventions were performed before hospital discharge in 101 patients. Single- and multiple-variable logistic regression analyses were performed to identify risk factors; adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were calculated. At 12 months, device-related infections were reported in 42 patients (0.68%; 95% CI, 0.47 to 0.89). The occurrence of infection was positively correlated with fever within 24 hours before the implantation procedure (aOR, 5.83; 95% CI, 2.00 to 16.98), use of temporary pacing before the implantation procedure (aOR, 2.46; 95% CI, 1.09 to 5.13), and early reinterventions (aOR, 15.04; 95% CI, 6.7 to 33.73). Implantation of a new system (aOR, 0.46; 95% CI, 0.24 to 0.87) and antibiotic prophylaxis (aOR, 0.4; 95% CI, 0.18 to 0.86) were negatively correlated with risk of infection. CONCLUSIONS: This study identified several factors of risk of device infection and confirmed the efficacy of antibiotic prophylaxis in recipients of new or replacement pacemakers or implantable cardioverter-defibrillators.

Flutter localized to the anterior left atrium after catheter ablation of atrial fibrillation.

INTRODUCTION: Organized atrial arrhythmias following atrial fibrillation (AF) ablation are typically due to recovered pulmonary vein (PV) conduction or reentry at incomplete ablation lines. We describe the role of nonablated anterior left atrium (LA) in arrhythmias observed after AF ablation. METHODS: A total of 275 consecutive patients with paroxysmal (n = 200) or chronic (n = 75) AF had PV isolation with/without additional linear ablation at the mitral isthmus (n = 106), LA roof (n = 23), or both (n = 88). Organized arrhythmias occurring after ablation were evaluated utilizing activation and entrainment mapping. RESULTS: Fourteen patients (11 female, 65 +/- 13 years, 10 chronic AF, 10 structural heart disease) demonstrated tachycardia localized to the anterior LA, an area not targeted by prior ablation. Eight had ECG features during sinus rhythm suggestive of impaired anterior LA conduction at baseline. These arrhythmias demonstrated a distinctive ECG flutter morphology in 7 of 10 (70%) with discrete -/+ or +/-/+ aspect in inferior leads. Mapping the anterior LA revealed electrograms spanning the entire tachycardia cycle length (325 +/- 125 msec). Entrainment was possible in all with a postpacing interval exceeding the tachycardia cycle length by 9 +/- 10 msec. Electroanatomic mapping in 6 demonstrated small reentrant circuits rotating clockwise in 4 and counterclockwise in 2. Low-amplitude, fractionated mid-diastolic potentials with long duration (200 +/- 80 msec) occupying 63 +/- 22% of the cycle length were targeted for ablation resulting in termination and subsequent noninducibility. CONCLUSION: Organized arrhythmias occurring after AF ablation can be due to reentrant circuits localized to the anterior LA, predominantly in females with chronic AF, structural heart disease, and abnormal atrial conduction. They are characterized by a distinctive surface ECG and highly responsive to RF ablation at the slow conduction area.

Long-term evaluation of atrial fibrillation ablation guided by noninducibility.

BACKGROUND: Pulmonary vein (PV) isolation and linear lesions are effective in eliminating paroxysmal atrial fibrillation (AF), but linear lesions probably are not required in all patients. Noninducibility of AF has been shown to be associated with freedom from arrhythmia in 87% of patients. OBJECTIVES: The purpose of this study was to prospectively evaluate the role of noninducibility in guiding a stepwise approach tailored to the patient. METHODS: In 74 patients (age 53 +/- 8 years) with paroxysmal AF, PV isolation was performed during induced or spontaneous AF. If AF was inducible after PV isolation, one to two additional linear lesions were placed at the mitral isthmus and/or left atrial roof, with the endpoint of noninducibility of AF or atrial flutter. Inducibility (AF/atrial flutter, lasting > or = 10 minutes) was assessed using burst pacing at an output of 20 mA down to refractoriness from the coronary sinus and both atrial appendages. RESULTS: In 42 patients (57%), PV isolation restored sinus rhythm and rendered AF noninducible. In the 32 patients with persistent or inducible AF after PV isolation, a single linear lesion achieved noninducibility in 20, whereas two linear lesions were required in 12 and resulted in conversion to sinus rhythm and noninducibility in 10. Using this stepwise approach, a total of 69 patients (93%) were rendered noninducible. During follow-up of 18 +/- 4 months, 67 patients (91%) were free from arrhythmia without antiarrhythmic drugs. Repeat procedures were performed in 23 patients: repeat ablation was required to consolidate prior targets in 15 patients (20%), and "new" linear lesions, which were not predicted by inducibility during the index procedure, were required in 8 (11%). CONCLUSION: Noninducibility can be used as an endpoint for determining the subset of patients with paroxysmal AF who require additional linear lesions after PV isolation. This tailored approach is effective in 91% of patients while preventing delivery of unnecessary linear lesions.

[Catheter ablation for atrial fibrillation]. / Méthodes ablatives dans la fibrillation atriale.

Atrial fibrillation, the most common cardiac arrhythmia, is frequently disabling and drug-resistant, and can be associated with major complications such as thromboembolic events. Non drug approaches, including surgery and catheter-based ablation, are used to treat the most severely symptomatic patients. These new treatment strategies have drastically improved our knowledge of the pathophysiology of this arrhythmia and, importantly, have shown that atrial fibrillation is curable. Since 1994, two main approaches have been used to modify the substrate responsible for AF maintenance, namely the creation of linear lesions, and ablation of triggers located within the pulmonary veins (about 90% of cases). Most teams worldwide now use approaches centered on PV isolation, which, although imperfect, are sufficiently effective to be offered routinely to selected patients in experienced centers. The importance of PVs in the initiation of AF has been clearly demonstrated, and there is also evidence of a role in AF maintenance. However, the existence of non venous foci or a prominent substrate for AF maintenance limits the success rate to about 70%. We are now using a combination of PV isolation and a linear lesion delivered to the mitral isthmus, from the mitral annulus to the ostium of the left inferior pulmonary vein. This more complex procedure carries a significantly higher success rate, about 82% of patients being cured and drug-free. The main problem is to identify patients requiring mitral isthmus ablation in addition to PV isolation. At present, AF ablation is restricted to symptomatic patients in whom at least two antiarrhythmic drugs have failed, but future technical improvements are likely to broaden the indications of ablation therapy for AF.

Reduction of fluoroscopy exposure and procedure duration during ablation of atrial fibrillation using a novel anatomical navigation system.

AIMS: Catheter ablation of atrial fibrillation (AF) is centred on pulmonary vein (PV) ablation with or without additional atrial substrate modification. These procedures may be prolonged with significant fluoroscopy exposure. This study evaluates a new non-fluoroscopic navigation system during ablation of AF. METHODS AND RESULTS: Seventy-two patients undergoing catheter ablation of symptomatic drug refractory AF were prospectively randomized to ablation with (n=35; study group) or without (n=37; control group) non-fluoroscopic navigation. PV isolation was performed in all patients. In patients with persistent or inducible sustained AF after PV isolation linear ablation was performed by joining the superior PVs. PV isolation was achieved in all patients; fluoroscopy (15.4+/-3.4 vs. 21.3+/-6.4 min; P<0.001) and procedural (52+/-12 vs. 61+/-17 min; P=0.02) durations were significantly reduced in the study group. Linear block was achieved in 37 of the 39 patients; with a significant reduction in fluoroscopy (5.6+/-2.2 vs. 9.9+/-4.8 min; P=0.003) and procedural (14.7+/-5.5 vs. 26.6+/-16.9 min; P=0.007) durations in the study group. After a follow-up of 6.9+/-2.9 months (range 3-10), 26 (74%) patients in the non-fluoroscopic navigation group and 29 (78%) patients in the control group were arrhythmia-free after the first procedure. CONCLUSION: This prospectively randomized study demonstrates significant reduction of fluoroscopy exposure and procedural duration using supplementary non-fluoroscopic imaging system for AF ablation.

Fever as a precipitant of idiopathic ventricular fibrillation in patients with normal hearts.

INTRODUCTION: Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death. The clinical precipitants of sudden cardiac death due to idiopathic VF are poorly characterized. Emerging evidence implicates triggers originating predominantly from the distal Purkinje arborization and the right ventricular outflow tract. METHODS AND RESULTS: We report three patients without structural heart disease or repolarization abnormalities in whom a febrile illness was the only concurrent disease associated with unexpected sudden cardiac death due to VF storm. An automated defibrillator was implanted in all three patients. In one patient with persistent recurrent VF episodes, mapping demonstrated the origin of these triggers was from the Purkinje arborization of the anterior wall of the right ventricle. Ablation at a site of earliest activation during ectopy, where pace mapping was concordant and Purkinje potential preceded the onset of ventriculogram, resulted in suppression of all arrhythmias. After follow-up of 22, 9, and 18 months in the three patients, no ventricular arrhythmias have been recorded. CONCLUSION: We present a series of patients in whom an apparently benign febrile illness was associated with malignant ventricular arrhythmias in the absence of cardiac disease or other factors known to precipitate sudden cardiac death. Physicians should be aware of this possible phenomenon in cases of febrile illness associated with syncope.

Pulmonary vein disconnection using the LocaLisa three-dimensional nonfluoroscopic catheter imaging system.

INTRODUCTION: Catheter ablation for atrial fibrillation (AF) is associated with prolonged fluoroscopy times. We prospectively evaluated the use of the LocaLisa three-dimensional nonfluoroscopic catheter imaging system with the aim of reducing fluoroscopy times during pulmonary vein (PV) disconnection. METHODS AND RESULTS: Fifty-two patients with AF (47 men and 5 women, mean age 53 +/- 9 years) underwent disconnection of all four PVs guided by a circumferential mapping catheter. The LocaLisa navigation system was used for real-time three-dimensional nonfluoroscopic imaging of the circumferential mapping catheter and ablation catheter electrodes in 26 patients. Procedural parameters were compared with those of a control group consisting of 26 patients in whom only standard fluoroscopy was used. PV disconnection was performed similarly in both groups by circumferential ablation around the ostia, with the endpoint of disconnecting left atrium to PV breakthroughs. The cumulative duration of radiofrequency (RF) energy delivery, procedural time, and fluoroscopy time required for PV disconnection were compared. Successful disconnection was achieved in all PVs, without acute complications. There was no significant difference in cumulative RF energy delivery: 34.8 +/- 11.4 minutes for the nonfluoroscopic imaging group versus 38.2 +/- 10.5 minutes for the control group. The fluoroscopy time required for disconnection of all four PVs was significantly lower in the LocaLisa group than in the control group: 8.4 +/- 4.3 minutes versus 23.7 +/- 9.7 minutes (P < 0.0001). There also was a significant difference in the mean time taken for PV disconnection: 46.5 +/- 12.0 minutes for the nonfluoroscopic imaging group versus 66.3 +/- 18.9 minutes for the control group (P < 0.0001). CONCLUSION: By allowing continuous three-dimensional monitoring of ablation and mapping catheter position and orientation, the LocaLisa nonfluoroscopic imaging system significantly reduces fluoroscopy and PV disconnection times.