Direct current cardioversion practices following percutaneous left atrial appendage closure.

INTRODUCTION: Among patients with non-valvular atrial fibrillation (AF) and percutaneous left atrial appendage closure (LAAC) undergoing direct current cardioversion (DCCV), the need for and use of LAA imaging and oral anticoagulation (OAC) is unclear. OBJECTIVE: The purpose of this study is to evaluate the real-world use of transesophageal echocardiography (TEE) or cardiac computed tomography angiography (CCTA) before DCCV and use of OAC pre- and post-DCCV in patients with AF status post percutaneous LAAC. METHODS: This retrospective single center study included all patients who underwent DCCV after percutaneous LAAC from 2016 to 2022. Key measures were completion of TEE or CCTA pre-DCCV, OAC use pre- and post-DCCV, incidence of left atrial thrombus (LAT) or device-related thrombus (DRT), incidence of peri-device leak (PDL), and DCCV-related complications (stroke, systemic embolism, device embolization, major bleeding, or death) within 30 days. RESULTS: A total of 76 patients with AF and LAAC underwent 122 cases of DCCV. LAAC consisted of 47 (62%), 28 (37%), and 1 (1%) case of Watchman 2.5, Watchman FLX, and Lariat, respectively. Among the 122 DCCV cases, 31 (25%) cases were identified as "non-guideline based" due to: (1) no OAC for 3 weeks and no LAA imaging within 48 h before DCCV in 12 (10%) cases, (2) no OAC for 4 weeks following DCCV in 16 (13%) cases, or (3) both in 3 (2%) cases. Among the 70 (57%) cases that underwent TEE or CCTA before DCCV, 16 (23%) cases had a PDL with a mean size of 3.0 ± 1.1 mm, and 4 (6%) cases had a LAT/DRT on TEE resulting in cancellation. There were no DCCV-related complications within 30 days. DISCUSSION: There is a widely varied practice pattern of TEE, CCTA, and OAC use with DCCV after LAAC, with a 6% rate of LAT/DRT. LAA imaging before DCCV appears prudent in all cases, especially within 1 year of LAAC, to assess for device position, PDL, and LAT/DRT.

Cardiac magnetic resonance imaging for left atrial appendage closure planning.

BACKGROUND: Transesophageal echocardiography (TEE) and cardiac computed tomography angiography (CCTA) are currently utilized for left atrial appendage closure (LAAC) planning. During the recent global iodine contrast media shortage in 2022, cardiac magnetic resonance imaging (CMR) was utilized for the first time for LAAC planning. This study sought to assess the utility of CMR versus TEE for LAAC planning. METHODS: This single center retrospective study consisted of all patients who underwent preoperative CMR for LAAC with Watchman FLX or Amplatzer Amulet. Key measures were accuracy of LAA thrombus exclusion, ostial diameter, depth, lobe count, morphology, accuracy of predicted device size, and devices deployed per case. Bland-Altman Analysis was used to compare CMR versus TEE measurements of LAA ostial diameter and depth. RESULTS: 25 patients underwent preoperative CMR for LAAC planning. A total of 24 (96%) cases were successfully completed with 1.2 ± 0.5 devices deployed per case. Among the 18 patients who underwent intraoperative TEE, there was no significant difference between CMR versus TEE in LAA thrombus exclusion (CMR 83% vs. TEE 100% cases, p = .229), lobe count (CMR 1.7 ± 0.8 vs. TEE 1.4 ± 0.6, p = .177), morphology (p = .422), and accuracy of predicted device size (CMR 67% vs. TEE 72% cases, p = 1.000). When comparing the difference between CMR and TEE measurements, Bland-Altman analysis demonstrated no significant difference in LAA ostial diameter (CMR-TEE bias 0.7 mm, 95% CI [-1.1, 2.4], p = .420), but LAA depth was significantly larger with CMR versus TEE (CMR-TEE bias 7.4 mm, 95% CI [1.6, 13.2], p = .015). CONCLUSIONS: CMR is a promising alternative for LAAC planning in cases where TEE or CCTA are contraindicated or unavailable.

Protection of the esophagus during catheter ablation of atrial fibrillation.

Esophageal injury still occurs with high frequency during ablation of atrial fibrillation (AF). The purpose of this study is to provide a review of methods to protect the esophagus from injury during AF ablation. Despite advances in imaging and ablation, the potential risk of esophageal injury during AF ablation remains an important concern with a high occurrence of esophageal injury (≈15%). There have been numerous studies evaluating varied techniques for esophageal protection including active cooling and displacement of the esophagus. These techniques are reviewed in this manuscript as well as the role of esophageal protection in managing patients undergoing AF ablation procedure.

Esophageal deviation with vacuum suction and mechanical deflection during ablation of atrial fibrillation: First in man evaluation.

Deviation of the esophagus during atrial fibrillation (AF) ablation can reduce esophageal injury. This study reports upon a novel esophageal retractor that utilizes vacuum suction and mechanical deflection to deviate the esophagus. The device was used in seven patients undergoing cryoballoon AF ablation. The esophagus was deviated 31.9 ± 4.4 mm to the right and 28.2 ± 5.9 mm to the left. Endoscopy at 4.4 ± 1.5 days postablation showed no esophageal injury. This study demonstrates the safe and effective deviation of the esophagus without a trailing edge with an esophageal retractor utilizing vacuum suction and mechanical deflection.

A 10 J shock impedance in sinus rhythm correlates with a 65 J defibrillation impedance during subcutaneous defibrillator implantation using an intermuscular technique.

INTRODUCTION: Defibrillation testing (DT) is recommended during the subcutaneous defibrillator (S-ICD) placement. We sought to compare 10 J shock impedance in sinus rhythm (SR) with 65 J defibrillation impedance and evaluate device position on a postimplant chest X-ray (CXR) using an intermuscular (IM) technique. METHODS: Consecutive S-ICD implantations between 12/2019 and 12/2020 at The Ohio State University were reviewed. All implantations were performed using a two-incision IM technique. Standard DT with 65 J shock and 10 J shock in SR were performed unless contraindicated. The PRAETORIAN score was calculated based on CXR. RESULTS: A total of 37 patients (age: 47.2 ± 15.8 years old, male: n = 26 [70.3%], body mass index: 30.1 ± 6.7 kg/m2 ) underwent IM S-ICD implantation, and of those, 27 (73%) underwent both 65 J shock and 10 J shock in SR. The coefficient of determination (R2 ) between 10 J shock impedance and 65 J shock impedance was 0.84. The mean of an impedance difference was 1.6 ± 4.8 Ω (minimum - 11 and maximum 8). Postimplant CXR was available for 33 out of 37 patients (89.2%). The PRAETORIAN score was less than 90 in all patients and the mean score was 32.7 ± 8.8. CONCLUSION: We demonstrated that 10 J shock impedance in SR correlated well with 65 J defibrillation impedance during IM S-ICD implantation. An IM implantation technique provides excellent generator location on postimplant CXR. The IM technique combined with 10 J shock in SR may be sufficient to predict and ensure the defibrillation efficacy of the S-ICD.

Incidence of pacing-induced cardiomyopathy in pacemaker-dependent patients is lower with leadless pacemakers compared to transvenous pacemakers.

INTRODUCTION: Frequent right AQ4ventricular pacing (≥40%) with a transvenous pacemaker (TVP) is associated with the risk of pacing-induced cardiomyopathy (PICM). Leadless pacemakers (LPs) have distinct physical and mechanical differences from TVP. The risk of PICM with LP is not known. To identify incidence, predictors, and long-term outcomes of PICM in LP and TVP patients. METHODS: The study comprised all pacemaker-dependent patients with LP or TVP who had left ventricular ejection fraction (LVEF) of ≥50 from 2014 to 2019. The incidence of PICM (≥10% LVEF drop) was assessed with an echocardiogram. Predictors for PICM were identified using multivariate analysis. Long-term outcomes after cardiac resynchronization (CRT) were assessed in both groups. RESULTS: A total of 131 patients with TVP and 67 with LP comprised the study. All patients in the TVP group and the majority in the LP group underwent atrioventricular node ablation. The mean follow-up duration in TVP and LP groups was 592 ± 549 and 817 ± 600 days, respectively. A total of 18 (13.7%) patients in TVP and 2 (3%) in LP developed PICM after a median duration of 254 (interquartile range: 470) days. The incidence of PICM was significantly higher with TVP compared with LP (p = .02). TVP as pacing modality was a positive (odds ratio [OR]: 1.07) while age was negative (OR: 0.94) predictor for PICM on multivariable analysis. Both patients in LP and all except two in the TVP group responded to CRT. CONCLUSION: Incidence of PICM is significantly lower with LP compared with TVP in pacemaker-dependent patients. Age and TVP as pacing modality were predictors for PICM.

Evaluation of a novel esophageal retractor utilizing vacuum suction and mechanical force for deviating the esophagus.

BACKGROUND: Deviation of the esophagus prevents esophageal injury during atrial fibrillation ablation. OBJECTIVES: This study is to evaluate, in animals, safety and effectiveness of a novel esophageal retractor that utilizes vacuum suction and mechanical force to deviate the esophagus. METHODS: Following general anesthesia, a radiopaque ruler was placed behind the animal perpendicular to the esophagus. The esophageal retractor was inserted and esophagram was completed. Suction force (280-300 mm Hg) was applied to the distal aspect of the device that resulted in adherence of the esophagus in a circumferential manner. Then movement of a deflecting arm was used to deviate the esophagus. Four animal studies completed: (a) deviation distance and presence of trailing edge; (b) effect of 1 hour continuous suction and deviation upon esophageal cellular architecture; (c) impact on luminal esophageal temperature (LET) during high power ablation; and (d) compatibility of esophageal retractor with electroanatomic mapping system. RESULTS: The distance of deviation to the right (26.6 ± 2.5 mm) was higher than to the left (18.7 ± 2.3 mm; P < .01). There was no esophageal trailing edge in 65/68 deviations (96%). With continuous suction for 1 hour, pathology revealed small, <1mm, circular area of hyperemia in the esophageal mucosa. During high power ablation, the maximum increase in LET was 0.2°C. Finally, there was no interference between the device and electro-anatomical mapping system. CONCLUSION: In animal models, the esophageal retractor utilizing vacuum suction was successful at deviating the esophagus without significant trailing edge and with minor (1 mm) injury with prolonged continuous suction.

Subclinical atrial fibrillation detection with a floating atrial sensing dipole in single lead implantable cardioverter-defibrillator systems: Results of the SENSE trial.

INTRODUCTION: Subclinical atrial fibrillation (AF), in the form of cardiac implantable device-detected atrial high rate episodes (AHREs), has been associated with increased thromboembolism. An implantable cardioverter-defibrillator (ICD) lead with a floating atrial dipole may permit a single lead (DX) ICD system to detect AHREs. We sought to assess the utility of the DX ICD system for subclinical AF detection in patients, with a prospective multicenter, cohort-controlled trial. METHODS AND RESULTS: One hundred fifty patients without prior history of AF (age 59 ± 13 years; 108 [72%] male) were enrolled into the DX cohort and implanted with a Biotronik DX ICD system at eight centers. Age-, sex-, and left ventricular ejection fraction-matched single- and dual-chamber ICD cohorts were derived from a Cornell database and from the IMPACT trial, respectively. The primary endpoint were AHRE detection at 12 months. During median 12 months follow-up, AHREs were detected in 19 (13%) patients in the DX, 8 (5.3%) in the single-chamber, and 19 (13%) in the dual-chamber cohorts. The rate of AHRE detection was significantly higher in the DX cohort compared to the single-chamber cohort (P = .026), but not significantly different compared to the dual-chamber cohort. There were no inappropriate ICD therapies in the DX cohort. At 12 months, only 3.0% of patients in the DX cohort had sensed atrial amplitudes less than 1.0 mV. CONCLUSION: Use of a DX ICD lead allows subclinical AF detection with a single lead DX system that is superior to that of a conventional single-chamber ICD system.

RIsk Stratification prior to lead Extraction and impact on major intraprocedural complications (RISE protocol).

BACKGROUND: An internal risk stratification algorithm was developed to decrease the risk of major adverse cardiac events (MACEs) during lead extractions (LEs). OBJECTIVE: To report upon the impact of a risk stratification algorithm (RISE [RIsk Stratification prior to lead Extraction] protocol) on outcomes of LEs in a high-volume center. METHODS: A retrospective review of a prospectively maintained LEs database was performed to identify features associated with MACEs. On the basis of the retrospective data, the RISE protocol differentiated LEs procedures into "High" and "Low" risk for occurrence of MACEs. High-risk LEs included dual-coil defibrillator lead (≥3 years), pacemaker and single-coil lead (≥5 years), and any StarFix coronary sinus lead. During the prospective evaluation of the RISE protocol, "High-risk" LEs were performed in an operating room (OR) or hybrid laboratory with the cardiac anesthesiologist, OR nursing team, perfusionist in the room, and a cardiac surgeon on the premises. "Low-risk" LEs were performed in the electrophysiology (EP) laboratory with anesthesia provided by EP nursing team. The preintervention (pre-RISE) and postintervention (post-RISE) group spanned 19 and 40 months and consisted of 449 (632 leads) and 751 patients (1055 leads), respectively. The primary outcome of MACEs in the two groups was compared. RESULTS: Protocol compliance was 100%. The primary outcome of MACEs occurred in 15 patients (3.34%) before and 12 (1.6%) after implementation of the RISE protocol (P = .04). CONCLUSION: RISE identified a low-risk group where minimal resources are needed and allowed for rapid intervention in the high-risk group that reduced the consequences of MACEs.

Comprehensive strategy to reduce the incidence of lead dislodgement for cardiac implantable electronic devices.

BACKGROUND: Lead dislodgement (LD) is a well-recognized complication during implantation of cardiac implantable electronic devices (CIEDs). An intraprocedural protocol, referred to as reduction of LD protocol, was developed to reduce the risk of LD. METHODS: The protocol involved (1) inserting a straight stylet down the right atrial lead and applying forward pressure while monitoring for fluoroscopic stability, (2) visualizing all leads during deep inspiration to determine if there is adequate lead redundancy, and (3) having the patient take a deep breath and cough while pacing just at capture threshold to assess for loss of capture in each lead. Any intraprocedural change in the parameters fulfilling the predefined criteria for inadequate lead implantation prompted lead repositioning. Data regarding demographic factors, clinical characteristics, and incidence of LD in the first 30 days after implant was obtained from intramural CIED database. The preintervention (control) group spanned 27 months and consisted of a total of 4,294 leads while the postintervention (intervention) group spanned 17 months and consisted of 2,361 leads implanted. RESULTS: There was no significant difference in the demographic factors and clinical characteristics in the two groups. Protocol compliance was > 90%. There were 44 occurrences of LD (1.02%) before and 10 (0.4%) after implementation of the protocol. The protocol significantly reduced the incidence of LD during the 30 days after implant (P = 0.014). No clinical characteristic predicted the risk of LD. CONCLUSION: Intraprocedural maneuvers performed to assess the adequacy of lead implantation results in reduced risk of LD.

Implantation of subcutaneous defibrillator is feasible and safe with monitored anesthesia care.

BACKGROUND: The perioperative anesthesia care during subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation is still evolving. OBJECTIVE: To assess the feasibility and safety of S-ICD implantation with monitored anesthesia care (MAC) versus general anesthesia (GA) in a tertiary care center. METHODS: This is a single-center retrospective study of patients undergoing S-ICD implantation between October 2012 and May 2019. Patients were categorized into MAC and GA group based on the mode of anesthesia. Procedural success without escalation to GA was the primary endpoint of the study, whereas intraprocedural hemodynamics, need of pharmacological support for hypotension and bradycardia, length of the procedure, stay in the post-anesthesia care unit, and postoperative pain were assessed as secondary endpoints. RESULTS: The study comprises 287 patients with MAC in 111 and GA in 176 patients. Compared to MAC, patients in GA group were younger and had a higher body mass index. All patients had successful S-ICD implantation. Only one patient (0.9%) in the MAC group was converted to GA. Despite a similar baseline heart rate (HR) and mean arterial blood pressure (MAP) in both groups, patients with GA had significantly lower HR and MAP during the procedure and more frequently required pharmacological hemodynamic support. Length of the procedure, stay in the postanesthesia care unit, and postoperative pain was similar in both groups. CONCLUSION: This retrospective experience suggests that implantation of S-ICD is feasible and safe with MAC. Use of GA is associated with more frequent administration of hemodynamic drugs during S-ICD implantation.

Feasibility of concomitant vacuum-assisted removal of lead-related vegetations and cardiac implantable electronic device extraction.

BACKGROUND: Cardiac implantable electronic device (CIED) infections associated with large, mobile vegetation adds to the complexity of lead extraction and is associated with significant patient morbidity and mortality. OBJECTIVE: To show the feasibility of concomitant cardiovascular implantable electronic device extraction and vacuum-assisted removal of lead-related vegetations. METHODS: This is a single-center retrospective case series of consecutive patients with persistent bacteremia, sepsis, or endocarditis despite medical therapy who have vegetations >2 cm and subsequently underwent immediate CIED lead extraction after debulking with vacuum-assisted suction. RESULTS: Eight patients underwent successful removal of 17 leads immediately after debulking of vegetations with vacuum-assisted device suction. Debulking procedure was not successful in 1 patient due to inability to direct the vacuum suction device into proper position. There were no intraprocedure complications related to the vacuum-assisted debulking. One patient required open sternotomy for tear of the coronary sinus ostium related to extraction of a left ventricular pacing electrode. There was no mortality within 30 days of the procedure. CONCLUSIONS: Based upon these clinical results, it is feasible for patients with infected CIED systems that have large right-sided vegetations to undergo vacuum-assisted debulking then immediately followed by percutaneous CIED removal in whom surgical removal is considered high risk.

Clinical experience with wearable cardioverter defibrillators at a tertiary electrophysiology program.

BACKGROUND: A wearable cardioverter defibrillator (WCD) is an alternative for patients who are not immediate candidates for an implantable cardioverter defibrillator (ICD). METHODS: Retrospective analysis of 242 patients prescribed a WCD from January 2014 through March 2015 with 1-year follow-up. RESULTS: A WCD was prescribed to 242 patients during the 15-month period. Forty-one patients were excluded due to lack of complete follow-up. The remaining 201 patients received a WCD for primary or secondary prevention of SCD. Seventy-nine percent of WCDs were prescribed by nonelectrophysiologists. Underlying etiologies for the WCD prescription included: 38% nonischemic cardiomyopathy, 25% recent myocardial infarction, 16% newly diagnosed ischemic cardiomyopathy, 12% documented ventricular arrhythmia, 6% ICD lead extraction, and 3% had high risk conditions for sudden cardiac death. During 1-year follow-up, 96 patients (48%) received an ICD and five patients (2.5%) received appropriate shocks and one patient (0.5 %) received an inappropriate shock. Other 105 (52%) patients subsequently did not require an ICD due to either improvement in ejection fraction, refusal of ICD therapy, or death. CONCLUSIONS: About half of patients prescribed a WCD subsequently receive an ICD and the rate of appropriate shock therapy from the WCD is 2.5%.

Anesthesia for subcutaneous implantable cardioverter-defibrillator implantation: Perspectives from the clinical experience of a U.S. panel of physicians.

BACKGROUND AND OBJECTIVE: Worldwide adoption of the subcutaneous implantable cardioverter-defibrillator (S-ICD) for preventing sudden cardiac death continues to increase, as longer-term evidence demonstrating the safety and efficacy of the S-ICD expands. As a relatively new technology, comprehensive anesthesia guidance for the management of patients undergoing S-ICD placement is lacking. This article presents advantages and disadvantages of different periprocedural sedation and anesthesia options for S-ICD implants including general anesthesia, monitored anesthesia care, regional anesthesia, and nonanesthesia personnel administered sedation and analgesia. METHODS: Guidance, for approaches to anesthesia care during S-ICD implantation, is presented based upon literature review and consensus of a panel of high-volume S-ICD implanters, a regional anesthesiologist, and a cardiothoracic anesthesiologist with significant S-ICD experience. The panel developed suggested actions for perioperative sedation, anesthesia, surgical practices, and a decision algorithm for S-ICD implantation. CONCLUSIONS: While S-ICD implantation currently requires higher sedation than transvenous ICD systems, the panel consensus is that general anesthesia is not required or is obligatory for the majority of patients for the experienced S-ICD implanter. The focus of the implanting physician and the anesthesia services should be to maximize patient comfort and take into consideration patient-specific comorbidities, with a low threshold to consult the anesthesiology team.

Initiation and outcomes with Class Ic antiarrhythmic drug therapy.

BACKGROUND: Expert opinion recommends performing exercise testing with initiation of Class Ic antiarrhythmic medication. OBJECTIVE: To evaluate the rate and reason for discontinuation of Ic agent within the first year of follow up, with particular attention to rate of proarrhythmia and the value of routine treadmill testing. METHODS: This is a single center retrospective cohort study including consecutive patients with atrial arrhythmias who were initiated on a Class Ic agent from 2011 to 2016. Data was collated from chart review and pharmacy database. RESULTS: The study population included 300 patients (55% male, mean age 61; mean ejection fraction, 56%) started on flecainide (n = 153; 51%) and propafenone (n = 147; 49%). Drug initiation was completed while hospitalized on telemetry and the staff electrophysiologists directed dosing. There was one proarrhythmic event during initiation (0.3%). The primary reason for not being discharged on Ic agent was due to detection of proarrhythmia (n = 15) or ischemia (n = 1) with treadmill testing (5.3%). Exercise testing was the single significant variable to affect the decision to discontinue Ic drug, p < 0.0001 (95% CI: 1.89-6.08%). During follow up, the primary reason for discontinuation of Ic agent was lack of efficacy, 32%. CONCLUSIONS: With proper screening, initiation of Class Ic agent is associated with very low rate of proarrhythmia. Treadmill testing is of incremental value and should be completed in all patients after loading Class Ic antiarrhythmic.

Eleven-year trends of inpatient pacemaker implantation in patients diagnosed with sick sinus syndrome.

BACKGROUND: Pacemakers (PM) are used for managing sick sinus syndrome (SSS). This study evaluates predictors and trends of PM implantation for SSS. METHODS: Patients were identified from the National Inpatient Sample dataset (2003-2013). Included patients were ≥18 years old, had a diagnosis of sinus node dysfunction and atrial arrhythmia (i.e., SSS). Patients who died, transferred out, who had prior device, or had a defibrillator or resynchronization therapy device implanted were excluded. Included patients were then stratified by if a PM was implanted. Data regarding SSS, trends of PM utilization, and multivariable models of factors associated with PM implantation are presented. RESULTS: Note that 328,670 patients satisfied study criteria. This study compared patients who underwent (87.4%) PM implantation to those who did not undergo (12.6%) PM implantation. The annual trends for hospitalization with SSS and PM placement have been decreasing (P <0.001). Variables associated with lower likelihood for PM implantation include young age, female sex, non-Caucasian race, chronic heart failure, Charlson Comorbidity Score ≥1, emergency room and weekend admission, hospital stay ≤3 days, and high cardiology inpatient volume. Greater likelihood for PM implantation was associated with hyperlipidemia, hypertension, and hospitals that were either private, large, Northeastern location, or with high cardiac procedural volume. CONCLUSIONS: Analyzing 11-year data from a national inpatient database demonstrate a number of relevant variables that impact PM utilization that include not only clinical but also nonclinical variables such as socioeconomic status, gender, and hospital features. Racial and gender bias toward PM implantation are unchanged and persist through 2013.

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.