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Background Patients on rivaroxaban have variable international normalized ratios (INRs) but it is uncertain if INR impacts procedural heparin requirement during left atrial ablation. We sought to examine the determinants of heparin dosing in this patient population. Methods We reviewed consecutive patients who received rivaroxaban within 24 hours of left atrial ablation and compared them to patients on uninterrupted warfarin. The determinants of heparin requirement were evaluated using regression analysis. We then tested a weight-based heparin dose prospectively in rivaroxaban patients. Results There were 258 patients on rivaroxaban and 213 on warfarin. The mean INR was 1.4 in the rivaroxaban group and 2.3 in the warfarin group (P < 0.01). To achieve an activated clotting time (ACT) >350 seconds, rivaroxaban patients required significantly more heparin (166.9 vs. 78.3 units/kg, P < 0.001). In the rivaroxaban group, body weight was the strongest predictor of heparin dose (r = 0.52), while INR was weakly correlated (r = −0.21). In the prospective group, 25 patients were given an initial heparin dose of 120 units/kg with 22/25 (88%) achieving an ACT > 300 seconds. There were seven and three cases of pericardial effusion in rivaroxaban and warfarin patients, respectively (P = 0.41). The average volume drained in the rivaroxaban group was elevated (988.6 vs. 275.0 mL, P = 0.21). Conclusions Body weight is the strongest predictor of procedural heparin requirement during left atrial ablation in patients on uninterrupted rivaroxaban, even in those with an elevated INR. A heparin dose of 120 units/kg achieves an ACT > 300 seconds in the majority of patients. In cases of pericardial effusion, bleeding may be prolonged. [ABSTRACT FROM AUTHOR]

VT Recurrence as Related to Scar Ablation Sites Introduction Magnetic resonance (MR)-imaging has shown that infarct scars causing ventricular tachycardia (VT) can extend deep to and beyond bipolar low-voltage areas (LVAs) and may be a source of ablation failure. We hypothesized that the size of the unipolar LVA 'penumbra' beyond the overlying bipolar scar may predict outcome of endocardial VT ablation. Methods Twenty consecutive patients with ischemic cardiomyopathy who underwent endocardial VT ablation were retrospectively reviewed. Bipolar (30-500 Hz) LVA defined as <1.5 mV and unipolar (0.5-500 Hz) LVA defined as <8.3 mV were reviewed on an electroanatomic mapping system. VT isthmus sites were identified from entrainment mapping, VT termination by ablation, or pace-mapping with abolition of VT inducibility by ablation. Results All bipolar LVAs (70.5 ± 20 cm2) had unipolar LVAs that surrounded the bipolar LVA (147 ± 47 cm2). Only 58% of the induced VTs could be mapped and ablated. During a 3-month follow-up 8/20 patients had VT recurrence. The size of the LVA penumbra was not different for those with (88 ± 47 cm2) versus without (69 ± 35 cm2) recurrences. However, all (8/8) of the group that recurred had isthmus/exits in the bipolar LVA border compared to only 3/12 that did not recur (100% vs. 25%; P < 0.05). Furthermore, 5/8 patients who recurred harbored VT isthmuses in the unipolar LVA penumbra than 1/12 who did not recur (63% vs. 8%; P = 0.01). Conclusion In ischemic cardiomyoapthy, unipolar LVA penumbra of varying size surrounds endocardial bipolar LVA, indicating intramural/epicardial scar. Although the size of this area did not predict early recurrence after endocardial ablation, frequent recurrences after VT ablation at scar periphery suggests deeper substrate toward the infarct border. [ABSTRACT FROM AUTHOR]

Catheter Ablation of Atrial Arrhythmias Background Management of atrial arrhythmias (AA) in orthotopic heart transplant (OHT) patients is challenging. Objective The purpose of this study was to define the mechanisms of these arrhythmias and to evaluate the role of ablation. Methods Patients with OHT referred for ablation of AA from 1999 to 2011 were included (n = 15). Entrainment and anatomic 3-D mapping were utilized to identify AA mechanism and guide ablation. Results The median time from OHT to ablation was 8 years (range: 1 month-16 years). AA types included 1 (7%) AVNRT, 5 (33%) cavotricuspid isthmus (CTI) dependent donor atrial flutter (AFl), 3 (20%) non-CTI-dependent donor AFL (n = 3), focal atrial tachycardia (AT) (n = 2) and in 4 (27%) recipient to donor atria conduction (RDC) that involved the right atrial anastomosis in 3 and left atrial anastamosis in 1 patient. In RDC tachycardia, ablation was performed at the site of earliest donor atrial activation on the suture line. AA in the recipient atria were not targeted. This resulted in acute success in all cases. In most patients 12/15 (80%) only right atrial ablation was necessary. Regardless of surgical technique (bicaval vs biatrial) right-sided AA was most common. Acute success occurred in 14/15 (93%) patients and 3/15 (20%) required repeat Abl for recurrence. There were no major complications. Conclusion AA after OHT are most commonly due to atrial macroreentry, but focal arrhythmias and RDC atrial conduction also occur. Ablation of organized AA is usually successful with low risk, warranting early consideration in preference to medical treatment. [ABSTRACT FROM AUTHOR]

Ablation Multiform Fascicular Tachycardia. Introduction: Fascicular tachycardia (FT) is an uncommon cause of monomorphic sustained ventricular tachycardia (VT). We describe 6 cases of FT with multiform QRS morphologies. Methods and Results : Six of 823 consecutive VT cases were retrospectively analyzed and found attributable to FT with multiform QRS patterns, with 3 cases exhibiting narrow QRS VT as well. All underwent electrophysiology study including fascicular potential mapping, entrainment pacing, and electroanatomic mapping. The first 3 cases describe similar multiform VT patterns with successful ablation in the upper mid septum. Initially, a right bundle branch block (RBBB) VT with superior axis was induced. Radiofrequency catheter ablation (RFCA) targeting the left posterior fascicle (LPF) resulted in a second VT with RBBB inferior axis. RFCA in the upper septum just apical to the LBB potential abolished VT in all cases. Cases 4 and 5 showed RBBB VT with alternating fascicular block compatible with upper septal dependent VT, resulting in bundle branch reentrant VT (BBRT) after ablation of LPF and left anterior fascicle (LAF). Finally, Cases 5 and 6 demonstrated spontaneous shift in QRS morphology during VT, implicating participation of a third fascicle. In Case 6, successful ablation was achieved over the proximal LAF, likely representing insertion of the auxiliary fascicle near the proximal LAF. Conclusions : Multiform FTs show a reentrant mechanism using multiple fascicular branches. We hypothesize that retrograde conduction over the septal fascicle produces alternate fascicular patterns as well as narrow VT forms. Ablation of the respective fascicle was successful in abolishing FT but does not preclude development of BBRT unless septal fascicle is targeted and ablated. (J Cardiovasc Electrophysiol, Vol. 24, pp. 297-304, March 2013) [ABSTRACT FROM AUTHOR]

Criteria for Epicardial Origin in Ischemic VT. Objectives: We tested proposed algorithms for idiopathic and nonischemic tachycardias for their ability to identify epicardial LV-VT origins. Backgroud: Several ECG features have been reported to identify epicardial origins for left ventricular tachycardias (LV-VTs) in the absence of myocardial infarction. Only limited data exist in postinfarction patients. Methods: The QRS features of 24 VTs that were ablated from the epicardium and 39 left ventricular VTs ablated from the endocardium were retrospectively analyzed for various 12-lead ECG features previously reported. Results: No ECG feature consistently predicted an epicardial LV-VT origin in infarct-related tachycardias, with epicardial VTs showing slightly longer QRS durations (189 ± 32 ms in epicardial vs 179 ± 37 ms in endocardial, P = 0.28). Pseudo-delta duration was 38 ± 27 versus 47 ± 27 ms (P = 0.2), intrinsicoid deflection time 93 ± 35 versus 86 ± 32 ms (P = 0.4), shortest RS 97 ± 38 versus 99 ± 32 ms (P = 0.77), and median deflection index 0.82 ± 0.25 versus 0.87 ± 0.22 (P = 0.43). The finding of a Q wave in lead I and the absence of a Q wave in the inferior leads failed to predict an epicardial origin in superior LV-VT sites. Q waves in any inferior lead and aVR/aVL-ratio<1 were not specific for an epicardial origin in inferior sites (all P = ns). Furthermore, all inferior LV-VTs showed a Q wave in the inferior leads which correlated with pre-existing Q-waves in sinus rhythm (P = 0.045). Conclusion : Proposed 12-lead ECG features for differentiation of epicardial versus endocardial sites for nonischemic LV-VTs do not reliably identify VTs that require ablation from the epicardium. Endocardial mapping should be the first approach to catheter ablation for VTs in patients with ischemic heart disease. (J Cardiovasc Electrophysiol, Vol. 23, pp. 188-193, February 2012) [ABSTRACT FROM AUTHOR]

Background: Long-term outcomes after ventricular tachycardia (VT) ablation are sparsely described., Objectives: The purpose of this study was to describe long-term prognosis after VT ablation in patients with no structural heart disease (no SHD), ischemic cardiomyopathy (ICM), and nonischemic cardiomyopathy (NICM)., Methods: Consecutive patients (N = 695: no SHD, 98; ICM, 358; NICM, 239) ablated for sustained VT were followed for a median of 6 years. Acute procedural parameters (complete success [noninducibility of any VT]) and outcomes after multiple procedures were reported., Results: Compared with patients with no SHD or NICM, patients with ICM were the oldest, were more likely to be men, lowest left ventricular ejection fraction, highest drug failures, VT storms, and number of inducible VTs. Complete procedure success was highest in patients with no SHD than in patients with ICM and those with NICM (79%, 56%, 60%, respectively; P < .001). At 6 years, ventricular arrhythmia (VA)-free survival was highest in patients with no SHD (77%) than in patients with ICM (54%) and those with NICM (38%) (P < .001), and overall survival was lowest in patients with ICM (48%), followed by patients with NICM (74%) and patients with no SHD (100%) (P < .001). Age, left ventricular ejection fraction, presence of SHD, acute procedural success (noninducibility of any VT), major complications, need for nonradiofrequency ablation modalities, and VA recurrence were independently associated with all-cause mortality., Conclusion: Long-term follow-up after VT ablation shows excellent prognosis in the absence of SHD, highest VA recurrence, and transplantation in patients with NICM and highest mortality in patients with ICM. The extremely low mortality for those without SHD suggests that VT in this population is rarely an initial presentation of a myopathic process., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: As the population ages, recurrent ventricular tachycardia (VT) is increasingly encountered in elderly patients with ischemic heart disease. Radiofrequency catheter ablation is useful for reducing VT therapy in patients with an implantable defibrillator. The utility of radiofrequency catheter ablation in the elderly is not well defined., Objective: The purpose of this study was to evaluate the prognosis and safety of radiofrequency catheter ablation of postinfarct VT in elderly patients., Methods: Radiofrequency catheter ablation was performed in 285 consecutive patients with recurrent postinfarct VT refractory to antiarrhythmic drugs. Mortality and outcomes were compared for an elderly group (age >or=75 years, n = 72) and a younger group (age <75 years, n = 213)., Results: The groups were similar with regard to baseline characteristics, except for a greater number of females in the elderly group (20.8% vs 10.8%, P = .03). Inducible VTs were abolished or modified in 79.2% of the elderly group and 87.8% of the younger group (P = .12). Major complications occurred in 5.6% of elderly patients and 2.3% of younger patients (P = .48). Periprocedural mortality was similar between both groups (2/72 in elderly and 9/213 in younger group, P = .74). During mean follow-up of 42 +/- 33 months, 50.0% of the elderly group and 35.2% of the younger group died (P = .08). No VT was observed in 63.9% of the elderly patients and 60.1% of the younger patients, respectively (mean follow-up 18 +/- 24 months, P = .80)., Conclusion: Outcomes of catheter ablation are similar for selected elderly and younger patients. Advanced age should not preclude ablation when recurrent VT is adversely affecting quality of life in elderly patients who otherwise have a reasonable expectation for survival., (Copyright (c) 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)