Faculty Bibliography

Background: The rapid increase in the number and complexity of electrophysiology (EP) procedures performed annually requires improved strategies to safely enhance post procedural monitoring and early discharge.
Objective(s): To determine if a wearable device that continuously and non-invasively measures vital signs and hemodynamic parameters can predict post-procedure cardiovascular decompensation.
Method(s): Investigator initiated, prospective study of 21 patients receiving either atrial fibrillation ablation (N=16) or device implantation (N=5). Patients were monitored for the post-procedure time periods ranging from 8 to18 hours with two techniques: 1) sporadic measurements with a conventional vital sign monitor; and 2) continuous measurements with toSense's CoVaTM Monitoring System, an FDA-cleared wearable device measuring stroke volume (SV), cardiac output (CO), thoracic fluid index (TFI), heart rate (HR), and respiration rate (RR). CoVaTM-generated data were wirelessly analyzed to established markers of decompensation, defined as decline in systolic blood pressure of >20mmHg over 5 minutes or SpO2 values < 90%. Decompensation index (DI), a normalized index defined as: DI = mean{(norm d[HR]/dt) + (norm d[HRV]/dt) + (norm d[SV]/dt) + (norm d[RR]/dt) + (norm [TI]/dt)} was used to predict decompensation events.
Result(s): Patients continuously monitored for >8 hours with CoVaTM, who were also sporadically measured at least 5 times with the vital sign monitor (N=11) were analyzed. Agreement of the two parameters measured by both devices-HR and RR-was: DELTAHR = 6.5+/-0.3 bpm; DELTARR = 3.8+/-0.8 breaths/min. 55% of patients (N=6) experienced brief decompensation events. The vital sign monitor made sporadic measurements every 95+/-21.3 minutes. Using DI, CoVaTM predicted 78% of the total patient decompensations, with the average prediction being 22+/-23 minutes in advance.
Conclusion(s): Continuous measurements with a wearable device may detect post-procedure decompensation in patients receiving electrophysiology procedures or device implantations with greater accuracy and better temporal resolution as compared to sporadic measurements with conventional vital sign monitors.
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Background: Implantable loop recorder (ILR) based monitoring of patients with LQTS allows enhanced arrhythmia surveillance and can help distinguish life-threatening from benign arrhythmias.
Objective(s): We present a case of a child with LQTS and wide complex tachycardia detected by ILR.
Result(s): An asymptomatic 12 year old with LQT2 syndrome, positive for a G648S hERG mutation, with baseline QTc of 510-550ms despite maximally tolerated Nadolol (Figure 1A) was followed in our inherited arrhythmia center. His affected mother has had multiple syncopal events related to polymorphic ventricular tachycardia (VT) and appropriate ICD shocks. We elected to implant him with ILR to allow longitudinal monitoring and early detection of arrhythmia. He presented 6 months later with 2 alerts for asymptomatic polymorphic, wide complex tachycardia at ~200 bpm during sleeping (Figure 1B). Electrophysiology study (EPS) was performed to determine etiology of the arrhythmia. Dual AV node physiology was present. Sinus tachycardia at 200 bpm with left bundle branch block (LBBB) morphology was induced with Isoproterenol and atrio-fascicular pathway was excluded. Respiratory changes resulted in the tachycardia appearing as polymorphic on the ILR during the EPS.
Conclusion(s): This is the first reported case of sinus tachycardia with LBBB aberrancy in a child with LQTS. Pseudopolymorphic wide complex tachycardia was the result of aberrancy and respiratory artifact. Combined ILR monitoring and EP study provided a correct diagnosis, thus avoiding further interventions. [Figure presented]
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Background: Left atrial posterior wall (LAPW) isolation is associated with favorable outcomes for catheter ablation of persistent atrial fibrillation (AF) in several studies. Reported techniques for LAPW isolation include ablation at the periphery without ablation within the LAPW, and high density ablation of all sites of electrical activity within the LAPW. The proportion of LA isolated by the lesion set in various reports also varies greatly. The optimal technique to achieve LAPW isolation is not clear.
Objective(s): To assess impact of ablation lesion density within the LAPW and dimensions of LAPW isolation region on arrhythmia recurrence in catheter ablation of persistent AF.
Method(s): LAPW lesion density, and LAPW isolation surface area relative to total LA surface area were calculated using electroanatomic maps of 110 consecutive patients undergoing LAPW isolation for persistent AF (CARTO 3, Biosense Webster, Inc.) LAPW isolation lesion sets were created at the discretion of 5 experienced operators after LA voltage mapping. LAPW and PV entrance block and exit block were confirmed. Arrhythmia recurrence at one year was assessed by the Kaplan-Meier method.
Result(s): LAPW lesion density ranged from 0% - 99%. Proportion of LA surface area isolated ranged from 35% - 75%. There was no significant difference in arrhythmia-free survival by quartile of LAPW ablation density (81% vs. 68% vs. 85% vs. 78%, p=0.8), or by quartile of LA surface area proportion isolated (85% vs. 75% vs. 79% vs. 74%, p=0.3). Voltage map guided LAPW isolation resulted in no significant difference in incidence of recurrent arrhythmia by quartile of total LA surface area (81% vs. 78% vs. 78% vs. 74%, p=0.5).
Conclusion(s): Neither the density of ablation within the LAPW nor the dimensions of the isolated region predicted arrhythmia-free survival LAPW isolation for catheter ablation of persistent AF. Voltage map guided LAPW isolation resulted in similar ablation efficacy regardless of LA size.
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Background: Left ventricular outflow tract (LVOT) obstruction is associated with adverse outcomes in hypertrophic cardiomyopathy (HCM). AV sequential pacing has not demonstrated benefit for patients with medication-refractory LVOT obstruction in prospective, randomized clinical trials, although these trials did not include transthoracic echocardiogram (TTE) guided optimization or concomitant pharmacotherapy with disopyramide.
Objective(s): To evaluate efficacy of a standardized TTE guided AV optimization protocol for patients with persistent LVOT obstruction despite AV sequential pacing for reduction in LVOT gradient.
Method(s): Outcomes of 20 consecutive HCM patients with medication refractory LVOT gradients who were not surgical candidates and underwent AV sequential pacing from 8/2014 to 6/2017 were analyzed. ECG guided AV intervals were determined by the implanting cardiac electrophysiologist at the time of implant. Patients with incomplete response to initial settings underwent Doppler TTE guided AV optimization.
Result(s): All patients received maximally tolerated disopyramide and beta or calcium channel blockade. Following initial implant, 8 of 20 (40%) of patients had complete elimination of LVOT gradient with, and 12 of 20 (60%) had incomplete response and underwent TTE guided optimization. Compared to initial ECG guided programming, the TTE optimized sensed AV delays were shorter in all patients (mean reduction 51 +/- 48ms). Following TTE guided AV optimization, 9 of 12 patients had elimination of LVOT gradient, and 3 of 12 patients had 82.6 +/- 5.2% reduction in LVOT gradient. Patients undergoing TTE optimization had significant reduction in NYHA heart failure class (1.0 +/- 0 vs. 2.2 +/- 0.7, p=0.004).
Conclusion(s): TTE guided AV optimization shows promise as a means of improving outcomes in patients with incomplete response to medical therapy including disopyramide and AV sequential pacing for reduction of LVOT gradient in HCM.
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Background: Increased catheter stability during AF ablation is associated with higher ablation success rates. Rapid cardiac pacing and high frequency jet ventilation (HFJV) have both been independently shown to improve catheter stability. Simultaneous modulation of cardiac and respiratory motion has not been previously studied.
Objective(s): To study the effects of modulating heart rate and respiratory rate simultaneously on catheter stability.
Method(s): Forty paroxysmal AF patients were randomized to four study conditions. Ablation lesions were created at 15 prespecified locations. Twenty patients received atrial pacing (500 msec) during the first half of each lesion; twenty patients were paced during the second half of each lesion. Within each group, half received HFJV and half received standard ventilation. Contact force (CF) variability, defined as CF standard deviation, was compared between study groups.
Result(s): Compared to sinus rhythm and standard ventilation, rapid pacing (5.45 g vs. 5.86 g; p=0.006) and HFJV (5.10 g; p=0.003) each significantly reduced mean CF standard deviation. Simultaneous pacing and HFJV produced even greater reduction of mean CF standard deviation (4.29 g; p<0.001) (Figure). Pacing and HFJV alone had similar effects on mean CF variability (p=0.2).
Conclusion(s): Rapid pacing and HFJV synergistically improve catheter stability during AF ablation. Simultaneous pacing with HFJV further optimizes catheter stability over pacing or HFJV alone and may improve ablation outcomes. [Figure presented]
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Background: Despite the increased prevalence of atrial fibrillation (AF) in hypertrophic cardiomyopathy (HCM), the efficacy of radiofrequency ablation (RFA) has been characterized over limited follow-up intervals (~1 year). Several large meta-analyses note that patients with HCM have substantially higher rates of arrhythmia recurrence after RFA, compared to patients without HCM. The implication of confirmed HCM mutations on ablation efficacy has similarly only been assessed in small-scale studies.
Objective(s): To assess arrhythmia recurrence after RFA in patients with HCM and paroxysmal AF (PAAF) or persistent AF (PEAF) as well as its relation to their genetic background and LVOT gradient.
Method(s): Arrhythmia recurrence after RFA was assessed in 66 HCM patients and compared to 343 patients without HCM. AF recurrence was defined as AF on EKG or >30s of AF on ICD/pacemaker interrogation or on monitoring devices after a 3-month blanking period. Kaplan-Meier analysis was performed to compare arrhythmia recurrence rate and timing.
Result(s): The EF of HCM patients was higher than that of the non-HCM patients in both the PAAF and PEAF groups (65.5 and 63.0% vs 61.4 and 53.3%, respectively, p<0.001); within the HCM group, the clinical characteristics of the genetically (+) HCM group (n=14) did not differ from those of the genetically (-) group (n=12). Arrhythmia recurrence at 1 year in PAAF and PEAF was not significantly different between HCM and non-HCM patients (18% vs 11%, p=0.2, and 33% vs 26%, p=1), nor was mean time to arrhythmia recurrence (PAAF 193+/-48 vs 181+/-59 days, p=0.8, and PEAF 175+/-58 vs 168+/-20 days, p=0.6). Recurrence rates over the entire follow-up period of the HCM patients were 54 and 85% in the PAAF and PEAF groups (1076+/-187 and 1050+/- 201 days of follow-up), respectively. Amongst HCM patients with LVOT gradients >70mmHg (PAAF, n = 8, and PEAF, n = 3) longer-term rates of arrhythmia recurrence were similar at 88% and 67% (p=0.9).
Conclusion(s): Arrhythmia recurrence at 1 year following AF ablation in HCM patients is similar to that of non-HCM AF patients regardless of the type of AF. Absolute rates of atrial arrhythmia recurrence in HCM patients at >3 years post ablation are considerable. Confirmed HCM mutations and severe LVOT gradients do not modify the outcome of AF ablation.
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PURPOSE/OBJECTIVE:Elimination of pace-capture along pulmonary vein isolation (PVI) lesion sets reduces atrial fibrillation (AF) recurrence in catheter ablation of paroxysmal AF. Pacing from the RF ablation electrode during RF application is prevented within the CARTO electroanatomic mapping system (Biosense Webster, Inc.) due to theoretical safety considerations. We evaluated a method of pacing the distal ablation electrode during RF application in the CARTO system, thus avoiding repeated activation and inactivation of the pacing channel and facilitating immediate recognition of pace-capture loss. We investigated the safety, feasibility, and utility of simultaneous pace-ablate (SPA) during AF ablation with the CARTO-3 system and a contact-force sensing RF ablation catheter. METHODS:Safety of feasibility of SPA was evaluated in 250 patients undergoing first-time AF ablation. Frequency and regional distribution of pace-capture following PVI was evaluated in a cohort of 50 consecutive patients undergoing catheter ablation of paroxysmal AF. RESULTS:SPA was successfully performed in all 250 patients without adverse event. At least one pace-capture site was noted in 22 of 50 PAF patients (44%), and pace-capture following PVI was most common at anterior and superior left atrial sites. There were 2.0 ± 3.3 RF applications during pacing via the distal ablation electrode per patient, and all lesions sets were successfully rendered unexcitable. CONCLUSIONS:Pace-capture along the completed PVI lesion set remains common despite utilization of contact-force sensing RF ablation catheters and automated lesion annotation. Simultaneous pace-ablate in AF ablation using the CARTO system may be safely used to render atrial lesion sets unexcitable.

Background: Biophysical markers of effective lesion formation during radiofrequency (RF) ablation include impedance decline, stable catheter-tissue contact and local unipolar electrogram change suggesting lesion transmurality The interactions between these factors as well as the implications of lesion sequence are not well understood. Objective: To analyze the impact of catheter stability and lesion sequence on markers of lesion formation during atrial fbrillation (AF) ablation. Methods: Sequential or time-spaced paired RF lesions with goal force-time integral (FTI) 400 gs were placed in prespecifed locations in 20 patients undergoing frst time RF ablation for paroxysmal AF. Custom developed software (MATLAB, Mathworks, USA) was used to extract and analyze lesion data, and 3D catheter position sampled at 60Hz from the CARTO3 mapping system (Biosense Webster, Inc.). All cases were performed using jet ventilation and irrigated force-sensing catheters. Results: 282 ablation lesions were studied, with mean FTI 410.8+/-18.2 gs. Mean impedance decline was greater for the frst lesion in a given pair, 13.6+/-7.9OMEGA vs. 10.7+/-4.6OMEGA, (p < 0.01). Compared to time-spaced lesions, sequential lesions resulted in signifcantly smaller impedance decline (9.8+/-3.8OMEGA vs. 11.8+/-5.2OMEGA, p<0.01), but increased probability of achieving transmurality, as evident by unipolar signal change (68% vs 42% p=0.01). Mean catheter excursion for a single lesion was 0.67+/-0.54mm and maximal catheter excursion was 1.64+/-1.3mm. Ablation catheter spatial stability was found to be inversely related to both amplitude (rho=0.51, p<0.0001) and maximal rate (dI/dT) of impedance decline (rho=0.32, p<0.0001). Conclusion: Lesion sequence and catheter spatial stability were major modifers of impedance change and unipolar electrographic evidence of lesion transmurality during RF ablation. Sequential ablation resulted in transmural lesions more frequently, despite lesser impedance decline. In contrast to previously reported positive association between contact-force and impedance decline, increased ablation catheter spatial stability was associated with lesser impedance decline

Background: Recent studies suggest RF ablation at high power for short durations may be safer and more effcient than using conventional power levels. Comparative data exploring the kinetics and safety of lesion formation at high power/short duration vs. conventional methods is lacking. Objective: The goal of this study is to compare lesion formation and safety across study conditions in an intracardiac model. Methods: Canines (n=24) were anesthetized and intracardiac RF energy was applied in both ventricles over a wide range of conditions (20-50 W, 5-60 s, 5-40 g) in a quasi-random fashion using a contact force, irrigated RF ablation catheter. Hearts were then stained with 1% TTC and formalin fxed Hearts were sectioned and lesions measured A common regression model for lesion width, depth and steam pop likelihood was created, and subsequently realized for three RF powers (see fgure). With these models, the time to achieve target lesion sizes and the relative steam pop risk were compared. Results: Of the 228 lesions created, 227 were found (99%). At 50 W, the maximum lesion width growth rate was 1.4 mm/s, vs. 0.9 mm/s (40 W) and 0.7 mm/s (30 W). Steam pop risk grew by 0.25%/s when ablating at 30 W vs. 1.1%/s at 50 W. Comparable lesions could be created at 30 W and 50 W power with similar steam pop risk (e.g., 30 W took 42 s to create a 10 mm wide lesion vs. 10 s at 50 W with similar risk). Conclusion: In this study, RF ablation lesions can be created about two times faster when using 50 W vs. 30 W; however the steam pop risk increased 4.4 fold. Though lesions are created more effciently, there is a much lower margin for error when ablating at 40-50 W. [Figure Presented]