Same-day discharge after transvenous lead extraction: feasibility and outcomes.

AIMS: Same-day discharge (SDD) is safe for patients undergoing electrophysiology procedures. There is no existing data regarding SDD for patients undergoing transvenous lead extraction (TLE). We report our experience with SDD for patients undergoing TLE. METHODS AND RESULTS: The study group included patients undergoing TLE between February 2020 and July 2021 without an infectious indication. A modified SDD protocol for device implants/ablations was applied to TLE patients. Patient characteristics, extraction details, outcomes, and complications were reviewed. Of 239 patients undergoing TLE, 210 were excluded (94 infections and 116 did not meet SDD criteria). Of the remaining 29 patients, seven stayed due to patient preference and 22 were discharged home the same day. The SDD group had an average age of 65.9 ± 12 (47-84), 41% female, and LVEF of 52.2 ± 18% (10-80). The indication for TLE was malfunction (20), upgrade (4), advisory lead (2), and magnetic resonance imaging compatibility (1). Extractions included four implantable cardioverter-defibrillators (ICDs), 17 pacemakers (PPM), and one cardiac resynchronization therapy (CRT)-P system. The leads were 9.6 years (1.5-21.7) old, and 1.8 leads were removed per patient (1-3); the lead extraction difficulty (LED) score was 11.6 ± 7. Twenty underwent cardiovascular implantable electronic device (CIED) re-implantation (2 ICD, 3 CRT-D, 13 PPM, and 2 CRT-P). For CIED re-implants, patients sent a remote transmission the next day, and all patients received a next-day call. There were no procedure or device-related issues, morbidities, or mortalities in the 30 days after discharge. CONCLUSION: Same-day discharge after TLE for non-infectious aetiologies is safe and feasible in a select group of patients with early procedure completion who meet strict SDD criteria.

Ablation of ectopic atrial foci for successful management of symptomatic bradycardia: A case series (bradycardia and ectopic atrial beats).

Atrial premature contractions (PACs) that block at the atrio-ventricular (AV) nodal level and occurring in a bigeminal frequency are recognized as a cause of symptomatic bradycardia. Appropriate suppression of the PACs often results in restoration of a regular rhythm with resolution of bradycardia-related symptoms. We report a series of three patients with non-conducted bigeminal PACs arising from the mitral annulus that resulted in symptomatic bradycardia and who were referred for consideration of cardiac pacing. Focal ablation suppressed PACs restoring a normal heart rate and resolution of symptoms without resorting to cardiac pacing.

Durable pulmonary vein isolation with diffuse posterior left atrial ablation using low-flow, median power, short-duration strategy.

INTRODUCTION: To target posterior wall isolation (PWI) in atrial fibrillation (AF) ablation, diffuse ablation theoretically confers a lower risk of conduction recovery compared to box set. We sought to assess the safety and efficacy of diffuse PWI with low-flow, medium-power, and short-duration (LF-MPSD) ablation, and evaluate the durability of pulmonary vein isolation (PVI) and PWI among patients undergoing repeat ablations. METHODS: We retrospectively studied patients undergoing LF-MPSD ablation for AF (PVI + diffuse PWI) between August 2017 and December 2019. Clinical characteristics were collected. Kaplan-Meier survival analysis was performed to study AF/atrial flutter (AFL) recurrence. Ablation data were analyzed in patients who underwent a repeat AF/AFL ablation. RESULTS: Of the 463 patients undergoing LF-MPSD AF ablation (PVI alone, or PVI + diffuse PWI), 137 patients had PVI + diffuse PWI. Acute PWI with complete electrocardiogram elimination was achieved in 134 (97.8%) patients. Among the 126 patients with consistent follow-up, 38 (30.2%) patients had AF/AFL recurrence during a median duration of 14 months. Eighteen patients underwent a repeat AF/AFL ablation after PVI + diffuse PWI, and 16 (88.9%) patients had durable PVI, in contrast to 10 of 45 (23.9%) patients who had redo ablation after LF-MPSD PVI alone. Seven patients (38.9%) had durable PWI, while 11 patients had partial electrical recovery at the posterior wall. The median percentage of area without electrical activity at the posterior wall was 70.7%. Conduction block across the posterior wall was maintained in 16 (88.9%) patients. CONCLUSION: There was a high rate of PVI durability in patients undergoing diffuse PWI and PVI. Partial posterior wall electrical recovery was common but conduction block across the posterior wall was maintained in most patients.

HeartMate 3: new challenges in ventricular tachycardia ablation.

AIM: To describe clinical characteristics, procedural details, specific challenges, and outcomes in patients with HeartMate3™ (HM3), a left ventricular assist device system with a magnetically levitated pump, undergoing ventricular tachycardia ablation (VTA). METHODS AND RESULTS: Data were collected from patients with an HM3 system who underwent VTA in seven tertiary centres. Data included baseline patient characteristics, procedural data, mortality, and arrhythmia-free survival. The study cohort included 19 patients with cardiomyopathy presenting with ventricular tachycardia (VT) (53% with VT storm). Ventricular tachycardias were induced in 89% of patients and a total of 41 VTs were observed. Severe electromagnetic interference was present on the surface electrocardiogram. Hence, VT localization required analysis of intra-cardiac signals or the use of filter in the 40-20 Hz range. The large house pump HM3 design obscured the cannula inflow and therefore multi imaging modalities were necessary to avoid catheter entrapment in the cannula. A total of 32 VTs were mapped and were successfully ablated (31% to the anterior wall, 38% to the septum and only 9% to the inflow cannula region). Non-inducibility of any VT was reached in 11 patients (58%). Over a follow-up of 429 (interquartile range 101-692) days, 5 (26%) patients underwent a redo VT ablation due to recurrent VTA and 2 (11%) patients died. CONCLUSIONS: Ventricular tachycardia ablation in patients with HM3 is feasible and safe when done in the appropriate setup. Long-term arrhythmia-free survival is acceptable but not well predicted by non-inducibility at the end of the procedure.

Clinical predictors of heart block during atrioventricular nodal reentrant tachycardia ablation: A multicenter 18-year experience.

BACKGROUND: Catheter ablation is considered the first-line treatment of symptomatic atrioventricular nodal reentrant tachycardia (AVNRT). It has been associated with a risk of heart block (HB) requiring a pacemaker. This study aims to determine potential clinical predictors of complete heart block as a result AVNRT ablation. METHODS: Consecutive patients undergoing catheter ablation for AVNRT from January 2001 to June 2019 at two tertiary hospitals were included. We defined ablation-related HB as the unscheduled implantation of pacemaker within a month of the index procedure. Use of electroanatomic mapping (EAM), operator experience, inpatient status, age, sex, fluoroscopy time, baseline PR interval, and baseline HV interval was included in univariate and multivariate models to predict HB post ablation. RESULTS: In 1708 patients (56.4 ± 17.0 years, 61% females), acute procedural success was 97.1%. The overall incidence of HB was 1.3%. Multivariate analysis showed that age more than 70 (odds ratio [OR] 7.907, p ≤ .001, confidence interval [CI] 2.759-22.666), baseline PR ≥ 190 ms (OR 2.867, p = .026, CI 1.135-7.239) and no use of EAM (OR 0.306, p = .037, CI 0.101-0.032) were independent predictors of HB. CONCLUSION: Although the incidence of HB post AVNRT ablation is generally low, patients can be further stratified using three simple predictors.

Concomitant leadless pacemaker implantation and lead extraction during an active infection.

INTRODUCTION: The need for transvenous lead extractions due to cardiac implantable electronic device (CIED)-related infections continues to rise. Current guidelines recommend complete device removal in the setting of an active infection, which can be challenging in pacemaker-dependent patients. METHODS: We retrospectively reviewed all leadless pacemaker implants between January 2018 and November 2019 and identified a subset of patients who had undergone a concomitant CIED extraction in the setting of an active infection. Baseline characteristics, procedural details, and clinical follow-ups were recorded. RESULTS: Seventeen patients received a leadless pacemaker during the same procedure as the CIED extraction. There were no procedural complications. All patients were being treated for an active CIED infection at the time of the procedure. Fourteen patients (82.4%) were completely pacemaker-dependent and four patients (23.5%) had positive blood cultures at the time of the leadless pacemaker implantation. During a median follow-up of 143 days (interquartile range: 57, 181 days), there were no recurrent infections. CONCLUSION: Simultaneous leadless pacemaker implantation and CIED extraction are safe and feasible in the setting of an active infection. This strategy may be particularly useful in patients that are pacemaker-dependent.

Electrocardiographic localization of ventricular arrhythmias successfully ablated from the distal great cardiac vein.

BACKGROUND: Idiopathic ventricular arrhythmias (IVAs) from the left ventricular (LV) summit may be successfully ablated from the distal great cardiac vein (dGCV). Using a 12-lead electrocardiogram (ECG) to localize IVAs that can be ablated from the dGCV is valuable for ablation planning. OBJECTIVE: To determine if a "w" wave, a notch in the Q wave in lead I, and other ECG features can identify IVAs that can be successfully ablated from the dGCV. METHODS: We reviewed outflow tract premature ventricular contraction (PVC) ablations performed at two centers between September 2010 and June 2018. Successful PVC ablations, in which the PVCs were mapped from the right ventricular outflow tract, coronary cusps, commissures, endocardial LV, and the coronary venous system including the dGCV were included. ECG characteristics were compared between patients with successful ablations in the dGCV and non-dGCV sites. RESULTS: Of the 120 patients (age 56.8 ± 13.8 years, 45% female) that met the inclusion criteria, the dGCV was the successful ablation site in 18 patients (15%). Multivariate analysis with binary logistic regression showed that a "w" in lead I in combination with an early precordial pattern break and a maximum deflection index (MDI) ≥ 0.5 had sensitivity and specificity for a successful ablation in the dGCV of 94.4% and 96.1%, respectively. CONCLUSION: Combining a "w" wave in lead I with an early precordial pattern break and an MDI ≥ 0.5 is highly sensitive and specific for identifying the dGCV as a successful ablation site for PVCs.

Outcomes in patients with cardiac amyloidosis and implantable cardioverter-defibrillator.

AIMS: Cardiac amyloidosis (CA) is associated with increased mortality due to arrhythmias, heart failure, and electromechanical dissociation. However, the role of an implantable cardioverter-defibrillator (ICD) remains unclear. We conducted case-control study to assess survival in CA patients with and without a primary prevention ICD and compared outcomes to an age, sex, and device implant year-matched non-CA group with primary prevention ICD. METHODS AND RESULTS: There were 91 subjects with CA [mean age= 71.2 ± 10.2, female 22.0%, 49 AL with Mayo Stage 2.9 ± 1.0, 41 transthyretin amyloidosis (ATTR), 1 other] followed by Vanderbilt Amyloidosis centre. Patients with ICD (n = 23) were compared with those without (n = 68) and a non-amyloid group with ICD (n = 46). All subjects with ICD had implantation for primary prevention. Mean left ventricular ejection fraction was 36.2% ± 14.4% in CA with ICD, 41.0% ± 10.6% in CA without ICD, and 33.5% ± 14.4% in non-CA patients. Over 3.5 ± 3.1 years, 6 (26.1%) CA, and 12 (26.1%) non-CA subjects received ICD therapies (P = 0.71). Patients with CA had a significantly higher mortality (43.9% vs. 17.4%, P = 0.002) compared with the non-CA group. Mean time from device implantation to death was 21.8 months in AL and 22.8 months in ATTR patients. There was no significant difference in mortality between CA patients who did and did not receive an ICD (39.0% vs. 46.0%, P = 0.59). CONCLUSIONS: Despite comparable event rates patients with CA had a significantly higher mortality and ICDs were not associated with longer survival. With the emergence of effective therapy for AL amyloidosis, further study of ICD is needed in this group.

Mechanical Circulatory Support During Catheter Ablation of Ventricular Tachycardia: Indications and Options.

Mapping of scar-related ventricular tachycardia (VT) in structural heart disease is fundamentally driven by identifying the critical isthmus of conduction that supports re-entry in and around myocardial scar. Mapping can be performed using activation and entrainment techniques during VT, or by substrate mapping performed in stable sinus or paced rhythm. Activation and entrainment mapping requires the patient to be in continuous VT, which may not be haemodynamically tolerated, or, if tolerated, may lead to adverse sequelae related to impaired end organ perfusion. Mechanical circulatory support (MCS) devices may facilitate haemodynamic stability and preserve end organ perfusion during sustained VT to permit mapping for long periods. Available options for haemodynamic support include an intra-aortic balloon pump (IABP), TandemHeart left atrial to femoral artery bypass system (CardiacAssist Inc., Pittsburgh, PA, USA), Impella left ventricle (LV) to aorta flow-assist system (Abiomed, Danvers, MA, USA), and extracorporeal membrane oxygenation (ECMO); the bypass and assist devices provide far better augmentation of cardiac output than IABP. MCS has potential key advantages including maintenance of vital organ perfusion, reduction of intra-cardiac filling pressures, reduction of LV volumes, wall stress, and myocardial consumption of oxygen, and improvement of coronary perfusion during prolonged periods of VT induction and/or mapping. Observational studies show MCS allows for longer duration of mapping, and increased likelihood of VT termination, without an increased risk of peri-procedural mortality or VT recurrence in follow-up, despite being used in a significantly sicker cohort of patients. However, MCS has increased risk of complications related to vascular access, bleeding, thromboembolic risk, mapping system interference, increase procedural complexity and increased cost. Acute haemodynamic decompensation occurs in ∼11% of patients undergoing VT ablation, and is associated with increased mortality. Prospectively identifying patients at risk of acute haemodynamic decompensation in the peri-procedural period may allow prophylactic MCS. Although observational studies of MCS in patients at high risk of haemodynamic decompensation are encouraging, its benefit needs to be proven in randomised trials. This review will summarise the indication for MCS, forms of MCS, procedural outcomes, complications and utility of MCS during VT ablation.

Temporal trends in safety and complication rates of catheter ablation for atrial fibrillation.

INTRODUCTION: Atrial fibrillation (AF) ablation is increasingly common, but is associated with potential major complications. Technology, experience, and protocols have evolved significantly in recent times, and may have impacted procedural safety. We sought to compare AF ablation safety profiles, including complication rates and fluoroscopy times in a "modern" versus "historical" cohort. METHODS AND RESULTS: We evaluated consecutive patients undergoing AF ablation from a modern cohort (MC) from 2014 to 2015 and a historic cohort (HC) from 2009 to 2011 for complications. Major complications were categorized according to Heart Rhythm Society guidelines. We included 1,425 patients, 726 in the HC and 699 in the MC. The MC was older, had more OSA and less valvular AF. Fifty-two (3.5%) procedures suffered major complications across the cohorts, with significantly fewer in the MC (5.0% vs. 2.3%, P  =  0.007). The largest reductions were seen in vascular, hemorrhagic, ischemic stroke, and perforation/tamponade related complications. Periprocedural antiplatelets drugs (aHR 2.1 [95 CI 1.1-3.9], P  =  0.02) and force-sensing catheters (aHR 0.4 [95 CI 0.2-0.9], P  =  0.03) were independently related to major complication rates. Direct oral anticoagulants and uninterrupted anticoagulation were not associated with complications. There was a decrease in both fluoroscopy (-17.4 minutes [95 CI 19.2-15.6], P < 0.0001) and radiofrequency ablation times (-561 seconds [95CI -750 to -371], P < 0.0001). CONCLUSIONS: The safety profile of AF ablation has improved significantly in less than a decade.

Family history of atrial fibrillation as a predictor of atrial substrate and arrhythmia recurrence in patients undergoing atrial fibrillation catheter ablation.

Aims: A commonly held notion is that patients with a family history of atrial fibrillation (AF) have worse atrial substrate and higher rates of arrhythmia recurrence following ablation. We sought to examine differences in atrial substrate and catheter ablation outcomes in patients with a 1st degree family member with paroxysmal or persistent AF (PeAF) compared to those without. Methods and results: A total of 256 consecutive patients undergoing their 1st ablation for AF (123 paroxysmal, 133 persistent) with >1 year follow up were included. The presence of one 1st-degree family relative was defined as a 'positive family history'. Clinical characteristics, electroanatomic map findings, ablation characteristics and outcomes were compared in patients with and without a positive family history of AF. Patients with paroxysmal fibrillation with a positive family history (n = 57; 46%) had similar clinical characteristics and arrhythmia recurrence after catheter ablation as those without. Of those that recurred, patients with a positive family history were more likely to have progressed to PeAF (P = 0.05). Patients with PeAF with a positive family history (n = 75; 56%) had similar clinical characteristics, electroanatomic mapping findings and ablation characteristics, but worse long term arrhythmia free survival (P = 0.04). Conclusion: The presence of a 1st-degree family member with AF does not impact the clinical outcomes of catheter ablation for paroxysmal AF. However, a positive family history is associated with worse arrhythmia free survival in patients with PeAF. This finding is not explained by differences in clinical characteristics, atrial substrate assessed by voltage maps or ablation characteristics.

Downstream overdrive pacing and intracardiac concealed fusion to guide rapid identification of atrial tachycardia after atrial fibrillation ablation.

Aims: Atrial tachycardia (AT) related to atrial fibrillation (AF) ablation frequently poses a diagnostic challenge. Downstream overdrive pacing (DOP) can be used to rapidly detect reentry and assess proximity of a pacing site to an AT circuit or focus. We hypothesized that systematic DOP using multielectrode catheters would facilitate AT mapping. Methods and results: DOP identified constant fusion when the post-pacing interval (PPI)-tachycardia cycle length (TCL) <40 ms and stimulus to adjacent upstream atrial electrogram interval >75% of TCL. Mapping was performed as follows: (i) CS DOP, (ii) DOP at left atrial (LA) roof, (iii) DOP at selected LA sites based on prior DOP attempts, and (iv) mapping and ablation at regions of fractionated electrograms in region of AT. Activation mapping was performed at operator discretion. AT diagnosis was confirmed by successful ablation or additional mapping when ablation was unsuccessful. Fifty consecutive patients with sustained AT underwent mapping of 68 ATs, of whom 42 (62%) were macroreentrant, 19 were locally reentrant (28%), and 7 (10%) were focal. AT was correctly identified with a median of three DOP attempts. All macroreentrant ATs were identified with ≤6 DOP attempts. One AT (1.6%) was terminated by DOP, and three ATs (4.8%) required activation mapping. Intracardiac concealed fusion was seen in 26 ATs (38%), each of which was successfully ablated. Conclusion: Reentry could be demonstrated in a substantial majority of AF ablation-related AT. A stepwise diagnostic approach using DOP and recognition of intracardiac concealed fusion can be used to rapidly identify and ablate reentrant AT.

Sinus Node and Atrial Arrhythmias.

Although sinus node dysfunction (SND) and atrial arrhythmias frequently coexist and interact, the putative mechanism linking the 2 remain unclear. Although SND is accompanied by atrial myocardial structural changes in the right atrium, atrial fibrillation (AF) is a disease of variable interactions between left atrial triggers and substrate most commonly of left atrial origin. Significant advances have been made in our understanding of the genetic and pathophysiologic mechanism underlying the development and progression of SND and AF. Although some patients manifest SND as a result of electric remodeling induced by periods of AF, others develop progressive atrial structural remodeling that gives rise to both conditions together. The treatment strategy will thus vary according to the predominant disease phenotype. Although catheter ablation will benefit patients with predominantly AF and secondary SND, cardiac pacing may be the mainstay of therapy for patients with predominant fibrotic atrial cardiomyopathy. This contemporary review summarizes current knowledge on sinus node pathophysiology with the broader goal of yielding insights into the complex relationship between sinus node disease and atrial arrhythmias.

Catheter Ablation of Atypical Atrioventricular Nodal Reentrant Tachycardia.

BACKGROUND: Because of its low prevalence, data on atypical atrioventricular nodal reentrant tachycardia (AVNRT) are scarce, and the optimal ablation method has not been established. Our study aimed at assessing the efficacy and safety of conventional slow pathway ablation, as applied for typical cases, in atypical AVNRT. METHODS: We studied 2079 patients with AVNRT subjected to slow pathway ablation. In 113 patients, mean age 48.5±18.1 years, 68 female, atypical AVNRT or coexistent atypical and typical AVNRT without other concomitant arrhythmia was diagnosed. Ablation data and outcomes were compared with a group of age- and sex-matched control patients with typical AVNRT. RESULTS: Fluoroscopy and radiofrequency current delivery times were not different in the atypical and typical groups, 20.3±12.2 versus 20.8±12.9 minutes (P=0.730) and 5.9±5.0 versus 5.5±4.5 minutes (P=0.650), respectively. Slow pathway ablation was accomplished from the right septum in 110 patients, and from the left septum in 3 patients, in the atypical group. There was no need for additional ablation lesions at other anatomic sites, and no cases of atrioventricular block were encountered. Recurrence rates of the arrhythmia were 5.6% in the atypical (6/108 patients) and 1.8% in the typical (2/111 patients) groups in the next 3 months following ablation (P=0.167). CONCLUSIONS: Conventional ablation at the anatomic area of the slow pathway is the therapy of choice for symptomatic AVNRT, regardless of whether the typical or atypical form is present.

Association of Antitachycardia Pacing or Shocks With Survival in 69,000 Patients With an Implantable Defibrillator.

AIMS: Antitachycardia pacing (ATP) is an effective treatment for ventricular tachycardia (VT) and can reduce the frequency of shocks in patients with an implantable cardioverter defibrillator (ICD). The association between survival and ATP, as compared to a shock, has not been confirmed in a large patient population. This study aims to determine if patients with an ICD receiving ATP have lower mortality, as compared to those receiving shock. METHODS: Sixty-nine thousand three hundred and sixty-eight patients underwent ICD implantation between October 2008 and May 2013 and were enrolled in the remote monitoring network Merlin.net™ (St. Jude Medical, St. Paul, MN, USA). Patients were categorized into three groups based on the type of ICD therapy received during follow-up: no therapy (N = 47,927), ATP (N = 8,049), and shock (N = 13,392) groups. Survival was determined by linking implant records to the Social Security Death Index. RESULTS: The no therapy (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.56-0.64, P < 0.001) and ATP (HR 0.70, 95% CI 0.64-0.77, P < 0.001) groups were associated with a lower mortality risk than the shock group. These results were unaffected by age, gender, device type, atrial fibrillation (AF) burden, or ventricular rate. ATP was effective in 85% of episodes and ATP effectiveness was dependent on the ventricular rate. CONCLUSIONS: Mortality rates were higher in ICD patients who received only ATP compared to no therapy, but ICD patients who received a shock had higher mortality compared to both groups. Furthermore, the data suggest that age, gender, device type, AF burden, and rate of arrhythmia do not change the trend of higher mortality in patients receiving ICD shock compared to ATP alone.

A Comparison of Women and Men Undergoing Catheter Ablation for Sustained Monomorphic Ventricular Tachycardia.

INTRODUCTION: Women are underrepresented in clinical studies on catheter ablation (CA) for ventricular tachycardia (VT). The role of gender as a predictor for VT recurrence after CA is unclear and complication rates have not been compared in a large cohort. METHODS AND RESULTS: We analyzed data of consecutive patients undergoing CA for sustained monomorphic VT at our center between 2005 and 2015. A total of 948 patients underwent 1314 ablation procedures: 114 patients without structural heart disease (SHD) (48% female), 486 with coronary artery disease (CAD) (9% female), 301 with nonischemic cardiomyopathy (NICM) (22% female), and 46 with arrhythmogenic right ventricular cardiomyopathy (ARVC) (17% female). Women with CAD and NICM were younger than men at first ablation (63 years vs. 68 years, P = 0.05; resp. 53 years vs. 59 years, P = 0.026) with no other significant differences in baseline characteristics. Age, LVEF, NYHA-class, and VT-recurrence but not gender were independently associated with increased mortality in CAD and NICM. Mortality rates in patients with no SHD and ARVC are low in men (0%, 2.6%) and women (1.8%, 0%). CONCLUSIONS: Although heart disease tends to present later in women, our data do not suggest that women are referred later than men. Women with CAD or NICM and VT present for ablation at younger age with disease severity comparable to men. VT ablation in women can be accomplished with success- and complication rates comparable to male patients in both those with and without SHD.

Beyond the Storm: Comparison of Clinical Factors, Arrhythmogenic Substrate, and Catheter Ablation Outcomes in Structural Heart Disease Patients With versus Those Without a History of Ventricular Tachycardia Storm.

AIMS: Catheter ablation can be lifesaving in ventricular tachycardia (VT) storm, but the underlying substrate in patients with storm is not well characterized. We sought to compare the clinical factors, substrate, and outcomes differences in patients with sustained monomorphic VT who present for catheter ablation with VT storm versus those with a nonstorm presentation. METHODS: Consecutive ischemic (ICM; n = 554) or nonischemic cardiomyopathy patients (NICM; n = 369) with a storm versus nonstorm presentation were studied (ICM storm 186; NICM storm 101). RESULTS: In ICM, storm compared with nonstorm patients had significantly lower left ventricular (LV) ejection fraction (EF), greater number of antiarrhythmic drug (AAD) failures, slower VTs, greater number of scarred LV segments, higher incidence of anterior, septal, and apical endocardial LV scar (all P < 0.05). However, outcomes in follow-up were similar (12-month ventricular arrhythmia [VA]-free survival: 51% vs. 52%, P = 0.6; survival free of death/transplant 75% vs. 87%, P = 0.7). In addition to the above differences, NICM storm patients were also older; however, the extent and distribution of scar was similar except for a higher incidence of lateral endocardial scar in storm patients (P = 0.05). VA-free survival (36% vs. 47%, P = 0.004) and survival free of death/transplant, however, were worse in NICM storm than nonstorm patients (72% vs. 88%, P = 0.001). NICM storm patients had worse VA-free survival than ICM storm patients. CONCLUSION: There are differences in clinical factors and scar patterns in patients undergoing VT ablation who present with VT storm versus those with a nonstorm presentation. Clinical outcomes are worse in NICM storm patients.

Determinants of Heparin Dosing and Complications in Patients Undergoing Left Atrial Ablation on Uninterrupted Rivaroxaban.

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.