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IntroductionThe assessment of the ventricular myocardial substrate critically depends on the size of mapping electrodes, their orientation with respect to wavefront propagation, and interelectrode distance. We conducted a dual-center study to evaluate the impact of microelectrode mapping in patients undergoing catheter ablation (CA) of ventricular tachycardia (VT). MethodsWe included 21 consecutive patients (median age, 68 [12], 95% male) with structural heart disease undergoing CA for electrical storm (n = 14) or recurrent VT (n = 7) using the QDOT Micro catheter and a multipolar catheter (PentaRay, n = 9). The associations of peak-to-peak maximum standard bipolar (BVc) and minibipolar (PentaRay, BVp) with microbipolar (BV mu Max) voltages were respectively tested in sinus rhythm with mixed effect models. Furthermore, we compared the features of standard bipolar (BE) and microbipolar (mu BE) electrograms in sinus rhythm at sites of termination with radiofrequency energy. ResultsBV(mu Max) was moderately associated with both BVc (beta = .85, p < .01) and BVp (beta = .56, p < .01). BV mu Max was 0.98 (95% CI: 0.93-1.04, p < .01) mV larger than corresponding BVc, and 0.27 (95% CI: 0.16-0.37, p < .01) mV larger than matching BVp in sinus rhythm, with higher percentage differences in low voltage regions, leading to smaller endocardial dense scar (2.3 [2.7] vs. 12.1 [17] cm(2), p < .01) and border zone (3.2 [7.4] vs. 4.8 [20.1] cm(2), p = .03) regions in microbipolar maps compared to standard bipolar maps. Late potentials areas were nonsignificantly greater in microelectrode maps, compared to standard electrode maps. At sites of VT termination (n = 14), mu BE were of higher amplitude (0.9 [0.8] vs. 0.4 [0.2] mV, p < .01), longer duration (117 [66] vs. 74 [38] ms, p < .01), and with greater number of peaks (4 [2] vs. 2 [1], p < .01) in sinus rhythm compared to BE. Conclusionmicroelectrode mapping is more sensitive than standard bipolar mapping in the identification of viable myocytes in SR, and may facilitate recognition of targets for CA.

Background Outcomes of catheter ablation (CA) among patients with non-paroxysmal atrial fibrillation (AF) are largely disappointing. Purpose We sought to evaluate the feasibility, effectiveness, and safety of a single-stage stepwise endo-/epicardial approach in patients with persistent/longstanding-persistent AF. Methods We enrolled 25 consecutive patients with symptomatic persistent (n=4) or longstanding-persistent (n=21) AF and at least one prior endocardial procedure, who underwent CA using an endo-/epicardial approach. Our anatomical stepwise protocol included multiple endocardial as well as epicardial (Bachmann's bundle [BB] and ligament of Marshall ablations) components, and entailed ablation of atrial tachycardias emerging during the procedure. The primary outcome was freedom from any AF/atrial tachycardia episode after a 3-month blanking period. The secondary outcome was patients' symptom status during follow-up. Results The stepwise endo-/epicardial approach allowed sinus rhythm restoration in 72% of patients, either directly (n=6, 24%) or after AF organization into atrial tachycardia (n=12, 48%). BB's ablation was commonly implicated in arrhythmia termination. After a median follow-up of 266 days (interquartile range, 96 days), survival free from AF/atrial tachycardia was 88%. Antiarrhythmic drugs could be discontinued in 22 patients (88%). As compared to baseline, more patients were asymptomatic at 9-month follow-up (0% vs- 56%, p=0.02). Five patients (20%) developed mild medical complications, whereas one subject (4%) had severe kidney injury requiring dialysis. Conclusion A single-stage endo-/epicardial CA resulted in favorable rhythm and symptom outcomes in a cohort of patients with symptomatic persistent/longstanding-persistent AF and one or more prior endocardial procedures. Epicardial ablation of BB was commonly implicated in procedural success. Funding Acknowledgement Type of funding sources: None.

Benefits of PVI in Patients with Atrial Flutter Background This study examined incidence of AF following cavotricuspid isthmus (CTI) ablation alone or CTI plus prophylactic pulmonary vein isolation (PVI) in patients presenting with isolated atrial flutter (AFL) with no history of AF. Methods and Results We enrolled 216 patients with isolated typical atrial flutter and randomized them to CTI alone (group 1, n = 108, 61.2 ± 9.7 year, 75% male) or CTI+PVI ablation (group 2, n = 108, 62.4 ± 9.3 year, 73% male). Insertible loop recorder (ILR) was implanted in 21 and 19 patients from groups 1 and 2, respectively. Remaining patients were monitored with event recorders, ECG, 7-day Holter. Follow-up period was for 18 ± 6 months. Compared to group 1, group 2 had significantly longer procedural duration (75.9 ± 33 min vs. 161 ± 48 min [P < 0.001]) and fluoroscopy time (15.9 ± 12.3 min vs. 56.4+21 min [P < 0.001]). At the end of follow-up, 65 (60.2%) in group 1 and 77 (71.3%) in group 2 were arrhythmia free off-AAD (log-rank P = 0.044). A subgroup analysis was performed with 55 year age cut-off. In the

Long-Term Outcome of AF Ablation in MMV PatientsIntroduction It is unclear whether extended pulmonary vein antrum isolation (PVAI) plus nonpulmonary vein (non-PV) trigger elimination prevents more arrhythmia recurrence than PVAI alone in patients with mechanical mitral valve (MMV) undergoing AF ablation. This study compared the efficacy and long-term outcome of 2 ablation strategies—PVAI alone versus extended PVAI plus non-PV trigger elimination—for the treatment of AF in patients with MMV. Methods and Results One hundred and nine consecutive AF patients with MMV were divided into 2 groups: standard PVAI was performed in group 1 (N = 45); in group 2 (N = 64) PVAI was extended to the LA posterior wall, LA septum, and CS; and all non-PV triggers were eliminated. Patients were followed up for 3 years. At the 12th month, 7 (15.6%) patients in group 1, and 39 (60.9%) patients in group 2 were arrhythmia free (log-rank P < 0.001). Four patients (8.9%; 3 cases of AT and 1 case of AF) from group 1, and 12 patients (18.8%; 9 cases of AT, and 3 cases of AFL) from group 2 experienced very late recurrence. At 36 ± 7 months follow-up, the cumulative recurrence after a single procedure was 42/45 (93.3%) in group 1, and 37/64 (57.8%) in group 2 (log-rank P < 0.001). Conclusion Compared with the standard PVAI alone, a strategy including extended PVAI and non-PV trigger elimination is associated with a higher 12-month and long-term arrhythmia-free survival in patients with MMV undergoing AF ablation. Very late recurrence may occur years after the initial procedure with focal AT as the most common type of recurrent arrhythmia.

MVI Block vs Trigger Ablation in PMFL. Introduction: Patients with previous ablation for atrial fibrillation (AF) may experience recurrence of perimitral flutter (PMFL). These arrhythmias are usually triggered from sources that may also induce AF. This study aims at determining whether ablation of triggers or completing mitral valve isthmus (MVI) block prevents more arrhythmia recurrences. Methods and Results: Sixty-five patients with recurrent PMFL after initial ablation of long standing persistent AF were included in this study. Thirty-two patients were randomized to MVI ablation only (Group 1) and 33 were randomized to cardioversion and repeat pulmonary vein (PV) isolation plus ablation of non-PV triggers (Group 2). MVI bidirectional block was achieved in all but 1 patient from Group 1. In Group 2, reconnection of 17 PVs was detected in 14 patients (42%). With isoproterenol challenge, 44 non-PV trigger sites were identified in 28 patients (85%, 1.57 sites per patient). At 18-month follow-up, 27 patients (84%) from Group 1 had recurrent atrial tachyarrhythmias, of whom 15 remained on antiarrhythmic drug (AAD); however, 28 patients from Group 2 (85%, P < 0.0001 vs Group 1) were free from arrhythmia off AAD. The ablation strategy used in Group 2 was associated with a lower risk of recurrence (hazard ratio = 0.10, 95% CI 0.04–0.28, P < 0.001) and an improved arrhythmia-free survival (log rank P < 0.0001). Conclusion: In patients presenting with PMFL after ablation for longstanding persistent AF, MVI block had limited impact on arrhythmia recurrence. On the other hand, elimination of all PV and non-PV triggers achieved higher freedom from atrial arrhythmias at follow-up. (J Cardiovasc Electrophysiol, Vol. 23, pp. 137-144, February 2012)

RV Scar by Electroanatomical Mapping and CMR. Introduction: Assessment of late gadolinium enhancement (LGE) at cardiac magnetic resonance is often used to detect scar in patients with arrhythmias of right ventricular (RV) origin. Recently, electroanatomic mapping (EAM) has been shown to reliably detect scars corresponding to different cardiomyopathic substrates. We compared LGE with EAM for the detection of scar in patients with arrhythmias of RV origin.

It is unclear whether extended pulmonary vein antrum isolation (PVAI) plus nonpulmonary vein (non-PV) trigger elimination prevents more arrhythmia recurrence than PVAI alone in patients with mechanical mitral valve (MMV) undergoing AF ablation. This study compared the efficacy and long-term outcome of 2 ablation strategies--PVAI alone versus extended PVAI plus non-PV trigger elimination--for the treatment of AF in patients with MMV.One hundred and nine consecutive AF patients with MMV were divided into 2 groups: standard PVAI was performed in group 1 (N = 45); in group 2 (N = 64) PVAI was extended to the LA posterior wall, LA septum, and CS; and all non-PV triggers were eliminated. Patients were followed up for 3 years. At the 12th month, 7 (15.6%) patients in group 1, and 39 (60.9%) patients in group 2 were arrhythmia free (log-rank P0.001). Four patients (8.9%; 3 cases of AT and 1 case of AF) from group 1, and 12 patients (18.8%; 9 cases of AT, and 3 cases of AFL) from group 2 experienced very late recurrence. At 36 ± 7 months follow-up, the cumulative recurrence after a single procedure was 42/45 (93.3%) in group 1, and 37/64 (57.8%) in group 2 (log-rank P0.001).Compared with the standard PVAI alone, a strategy including extended PVAI and non-PV trigger elimination is associated with a higher 12-month and long-term arrhythmia-free survival in patients with MMV undergoing AF ablation. Very late recurrence may occur years after the initial procedure with focal AT as the most common type of recurrent arrhythmia.

Introduction: Transseptal puncture (TSP) is the conventional approach to assess the left atrial chamber. This technique has been widely used in interventional cardiology and, in the last years, this approach is mostly applied to electrophysiologic procedures. For atrial fibrillation (AF) ablation, two or more transseptal sheaths are often positioned in the left atrium in the majority of centers, therefore requiring two or more transseptal punctures. Theoretically, double puncture could bear additional risks or could increase the risk of persistence of septal defects. We reported the results of a retrospective analysis of a single transseptal puncture as a simplified approach for positioning multiple catheters in the left atrium during AF ablation. Methods: Between November 2003 and November 2005, 1,150 consecutive patients (mean age 54 ± 8 years, 75% men) were considered for AF ablation and underwent single transseptal puncture for positioning multiple catheters in the left atrium. Results: In only 6 of 1,150 (0.5%) cases a second transseptal puncture was required to position the ablation catheter in the left atrium. Neither acute complications related to transseptal catheterization such as atrial or aortic perforations, pericardial tamponade, thrombotic formation, or air embolism, nor complications due to the attempts of crossing the septum with the ablation catheter were reported. In all cases, each mapping catheter was properly maneuvered at different sites in the left atrium and at the pulmonary veins. In no patient was a residual septal atrial defect after the transseptal maneuvers detected during a mean follow up of 14 ± 2 months. Conclusions: This retrospective study on a large cohort of patients shows that single transseptal puncture for positioning two or more catheters in the left atrium for AF ablation is a highly successful and safe maneuver with a very low morbidity in the majority of patients. This may avoid potential complications related to a second transseptal puncture.

Heart Rate Turbulence in Myotonic Dystrophy. Introduction: Myotonic dystrophy type 1 (MD1) is the most common muscular dystrophy of adult life. Cardiac involvement is characterized by disorders of atrioventricular conduction, ventricular arrhythmias, and sudden death. Heart rate turbulence (HRT) is a noninvasive risk predictor in patients affected by ischemic heart disease. The aim of our study is to assess the prognostic value of HRT in MD1 patients. Methods and Results: We performed HRT analysis by 24-hour Holter recording to calculate turbulence onset (TO) and turbulence slope (TS) in 29 MDl patients (mean age 52 ± 10 years), and in 30 patients (mean age 52 ± 13 years) with frequent ventricular arrhythmias and structurally normal heart (VANH). An electrophysiological study (EPS) tested ventricular arrhythmias inducibility in 22 MD1 patients. TO was significantly different between MD1 and VANH patients (-1.66 ± 2.04 and -2.98 ± 1.79%, respectively, P 0.01), while no difference was observed in TS between MDl and VANH patients (11.12 ± 6.46 and 9.12 ± 6 msec/beat, respectively). On EPS, sustained ventricular arrhythmias (SVA) were induced in six MD1 patients. TO was significantly different in inducible MDl patients (0.88 ± 1.95%), as compared with both noninducible (-2.49 ± 1.43%, P < 0.001) or no eligible to EPS (-1.93 ± 1.63%, P < 0.005) MD1 patients and to VANH patients (-2.98 ± 1.79%, P < 0.001). Conclusions: An impairment of TO, a measure of HRT, suggesting impaired cardiac parasympathetic activity, may be a useful, noninvasive predictor of arrhythmic risk in MDl patients.