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Because many episodes of ventricular fibrillation (VF) are believed to be triggered by ventricular tachycardia (VT), patients who present with VT or VF are usually grouped together in discussions of natural history and treatment. However, there are significant differences in the clinical profiles of these 2 patient groups, and some studies have suggested differences in their response to therapy. We examined arrhythmias occurring spontaneously in 449 patients assigned to implantable cardioverter-defibrillator (ICD) therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial to determine whether patients who receive an ICD after VT have arrhythmias during follow-up that are different from patients who present with VF. ICD printouts were analyzed both by a committee blinded to the patients' original presenting arrhythmia and by the local investigator. During 31 +/- 14 months of follow-up, 2,673 therapies were reported. Patients who were enrolled in the AVID trial after an episode of VT were more likely to have an episode of VT (73.5% vs 30.1%, p <0.001), and were less likely to have an episode of VF (18.3% vs 28.0%, p = 0.013) than patients enrolled after an episode of VF. Adjustment for differences in ejection fraction, previous infarction, and beta-blocker and antiarrhythmic therapy did not appreciably change the results. Ventricular arrhythmia recurrence during follow-up is different in patients who originally present with VT than in those who originally present with VF. These findings suggest there are important differences in the electrophysiologic characteristics of these 2 patient populations. [ABSTRACT FROM AUTHOR]

To understand predictors of cardiac arrest early in acute myocardial infarction (AMI), for the Thrombolytic Predictive Instrument, we developed a multivariable regression model predicting primary cardiac arrest using time-dependent variables based on a case-control study of emergency department (ED) patients with AMI: 65 cases with sudden cardiac arrest and 258 without cardiac arrest. Within the first hour of AMI symptom onset, adjusting for age, systolic blood pressure, serum potassium, and infarct size, increased risk of cardiac arrest was associated with electrocardiographic prolonged QTc interval and a greater sum of ST-segment elevation. After 1 hour, the effect of ST-segment elevation was much reduced and the effect of the QTc interval was reversed, so prolonged QTc appeared protective. Accordingly, for patients presenting 30 minutes after chest pain onset, compared with a QTc of 0.44, the risk for cardiac arrest for patients with QTc of 0.50 was more than doubled (odds ratio [OR] 2.20, 95% confidence intervals [CI] 1.17 to 4.13), whereas for those presenting after an hour, it was much lower (e.g., at 1.5 hours, OR 0.21, 95% CI 0.06 to 0.73). Patients presenting 30 minutes after chest pain onset with a sum of ST elevation of 20 mm had a threefold higher risk than patients with a sum of ST elevation of 5 mm (OR 3.37, 95% CI 1.83 to 6.20). However, if presenting 1.5 hours after chest pain onset, the risk was barely elevated (OR 1.18; 95% CI 1.09 to 1.29). Thrombolytic therapy was protective, halving the odds of cardiac arrest (OR 0.51, 95% CI 0.27 to 0.93). Thus, the relation of prolonged QTc interval and substantial ST segment elevation to cardiac arrest in AMI may be obscured because patients with these risks are more likely to die soon after AMI onset, before ED presentation, and are thereby unavailable for study. Those with prolonged QTc or substantial ST elevation who survive the initial 1.5-hour period are those less susceptible to these risks. [ABSTRACT FROM AUTHOR]

Background: Remote monitoring (RM) of pacemakers and implantable cardioverter-defibrillators (ICDs) is a Class 1, Level of Evidence A recommendation because of its multitude of clinical benefits. However, RM adherence rates are suboptimal, precluding patients from achieving these benefits. There is a need for direct-to-patient efforts to improve adherence., Methods: In this national randomized, controlled trial conducted in the Veterans Health Administration (VHA), 2120 patients with a pacemaker or ICD who had not sent an RM transmission for ≥1 year (and usually ≥3 years) while under VHA care for their device were randomly assigned to be mailed a postcard (n = 1076) or a detailed letter (n = 1044). The postcard described what RM does and its key benefits (reduced mortality and fewer in-person visits). The letter provided a similar message but included more details about RM benefits and the process. The primary outcome was an RM transmission sent within 90 days of mailing, and a secondary outcome was an RM transmission sent within 365 days., Results: The primary outcome was achieved in 121 (11.3%) in the postcard and 96 patients (9.2%) in the letter group (p = .12). The secondary outcome was achieved in 266 (24.7%) and 239 (22.9%), respectively (p = .32)., Conclusions: This randomized trial showed no significant difference in the proportion of chronically non-adherent patients who sent an RM transmission after receiving a low-cost postcard or a detailed, higher-cost letter encouraging their participation in RM. However, as only a minority of patients responded to either, further work is needed to engage patients in the life-saving benefits of RM., (Published 2023. This article is a U.S. Government work and is in the public domain in the USA.)

Background: Implantable loop recorders (ILRs) are increasingly placed for arrhythmia detection. However, historically, ≈75% of ILR alerts are false positives, requiring significant time and effort for adjudication. The LINQII and LUX-Dx are remotely reprogrammable ILRs with dual-stage algorithms using artificial intelligence to reduce false positives, but their utility in routine clinical practice has not been studied., Methods and Results: We identified patients with the LINQII and LUX-Dx who were monitored by the Veterans Affairs National Cardiac Device Surveillance Program between March and June 2022. ILR programming was customized on the basis of implant indication. All alerts and every 90-day scheduled transmissions were manually reviewed. ILRs were remotely reprogrammed, as appropriate, after false-positive alerts or 2 consecutive same-type alerts, unless there was ongoing clinical need for that alert. Outcomes were total number of transmissions and false positives. We performed medical record review to determine if patients experienced any adverse clinical events, including hospitalization and mortality. Among 117 LINQII patients, there were 239 total alerts, 43 (18.0%) of which were false positives. Among 105 LUX-Dx patients, there were 300 total alerts, 115 (38.3%) of which were false positives. LINQIIs were reprogrammed 22 times, resulting in a decrease in median alerts/day from 0.13 to 0.03. LUX-Dx ILRs were reprogrammed 52 times, resulting in a decrease from 0.15 to 0.01 median alerts/day. There were no adverse clinical events that could have been identified by superior or earlier arrhythmia detection., Conclusions: ILRs with artificial intelligence algorithms and remote reprogramming ability are associated with reduced alert burden because of higher true-positive rates than prior ILRs, without missing potentially consequential arrhythmias.

Background: Remote monitoring (RM) of pacemakers and implantable cardioverter-defibrillators (ICDs) reduces morbidity and mortality. However, many patients are not adherent to RM., Objective: To test the effect of informational postcards on RM adherence., Design/patients: Stepped-wedge randomized controlled trial among Veterans with pacemakers and ICDs., Intervention: In wave 1, Veterans who had sent at least 1 transmission within the past 2 years but had become non-adherent were randomly assigned to receive a postcard or no postcard. Those receiving postcards were randomized to 1 of 2 messages: (1) a"warning" postcard describing risks of non-adherence or (2) an "encouraging" postcard describing benefits of adherence. In wave 2, Veterans who had either not received a postcard in wave 1 or had since become non-adherent were mailed a postcard (again, randomized to 1 of 2 messages). Patients who did not send an RM transmission within 1 month were mailed a second, identical postcard., Main Measures: Transmission within 70 days., Key Results: Overall, 6351 Veterans were included. In waves 1 and 2, postcards were mailed to 5657 Veterans (2821 "warning" messages and 2836 "encouraging" messages). Wave 1 included 2178 Veterans as controls (i.e., not mailed a postcard), some of whom received a postcard in wave 2 if they remained non-adherent. In wave 2, 3473 postcards were sent. Of the 5657 patients mailed a postcard, 2756 (48.7%) sent an RM transmission within 70 days, compared to 530 (24.3%) of 2178 controls (absolute difference 24.4%, 95% confidence interval [CI] 22.2%, 26.6%). Of those who sent a transmission, 71.8% did so after the first postcard. Transmission rates at 70 days did not significantly differ between "warning" and "encouraging" messages (odds ratio 1.04, 95% CI 0.92, 1.18)., Conclusions: Informational postcards led to a 24.4% absolute increase in adherence at 70 days among Veterans with pacemakers and ICDs who were non-adherent to RM., (© 2023. The Author(s).)

Competing Interests: Disclosures Dr Kizer reports stock ownership in Abbott, Bristol Myers Squibb, Johnson & Johnson, Medtronic, Merck, and Pfizer. The other authors have no conflicts of interest.

Background: The Heart Rhythm Society strongly recommends remote monitoring (RM) of cardiovascular implantable electronic devices (CIEDs) because of the clinical outcome benefits to patients. However, many patients do not adhere to RM and, thus, do not achieve these benefits. There has been limited study of patient-level barriers and facilitators to RM adherence; understanding patient perspectives is essential to developing solutions to improve adherence., Objective: We sought to identify barriers and facilitators associated with adherence to RM among veterans with CIEDs followed by the Veterans Health Administration., Methods: We interviewed 40 veterans with CIEDs regarding their experiences with RM. Veterans were stratified into 3 groups based on their adherence to scheduled RM transmissions over the past 2 years: 6 fully adherent (≥95%), 25 partially adherent (≥65% but <95%), and 9 nonadherent (<65%). As the focus was to understand challenges with RM adherence, partially adherent and nonadherent veterans were preferentially weighted for selection. Veterans were mailed a letter stating they would be called to understand their experiences and perspectives of RM and possible barriers, and then contacted beginning 1 week after the letter was mailed. Interviews were structured (some questions allowing for open-ended responses to dive deeper into themes) and focused on 4 predetermined domains: knowledge of RM, satisfaction with RM, reasons for nonadherence, and preferences for health care engagement., Results: Of the 44 veterans contacted, 40 (91%) agreed to participate. The mean veteran age was 75.3 (SD 7.6) years, and 98% (39/40) were men. Veterans had been implanted with their current CIED for an average of 4.4 (SD 2.8) years. A total of 58% (23/40) of veterans recalled a discussion of home monitoring, and 45% (18/40) reported a good understanding of RM; however, when asked to describe RM, their understanding was sometimes incomplete or not correct. Among the 31 fully or partially adherent veterans, nearly all were satisfied with RM. Approximately one-third recalled ever being told the results of a remote transmission. Among partially or nonadherent veterans, only one-fourth reported being contacted by a Department of Veterans Affairs health care professional regarding not having sent a remote transmission; among those who had troubleshooted to ensure they could send remote transmissions, they often relied on the CIED manufacturer for help (this experience was nearly always positive). Most nonadherent veterans felt more comfortable engaging in RM if they received more information or education. Most veterans were interested in being notified of a successful remote transmission and learning the results of their remote transmissions., Conclusions: Veterans with CIEDs often had limited knowledge about RM and did not recall being contacted about nonadherence. When they were contacted and troubleshooted, the experience was positive. These findings provide opportunities to optimize strategies for educating and engaging patients in RM., (©Sanket S Dhruva, Merritt H Raitt, Scott Munson, Hans J Moore, Pamela Steele, Lindsey Rosman, Mary A Whooley. Originally published in JMIR Cardio (https://cardio.jmir.org), 21.11.2023.)

Background: Remote monitoring (RM) of patients with cardiovascular implantable electronic devices (CIEDs) (pacemakers and implantable cardioverter-defibrillators) has a Class 1, Level of Evidence A Heart Rhythm Society recommendation. Yet RM adherence varies widely across settings, and factors associated with variation are not understood., Objective: The purpose of this study was to identify strategies for supporting RM across Veterans Health Administration (VHA) facilities., Methods: In a national evaluation, we surveyed and interviewed 27 nurses, medical instrument technicians, and advanced practice providers across 26 VHA facilities (following approximately 15,000 CIED patients). Participants were selected based on overall patient adherence by facility, which ranged from 46%-96%. Questions covered RM adherence strategies, manufacturer resources, organizational characteristics, and workflows for optimizing adherence., Results: All clinicians reported that RM adherence was extremely important (53.8%), very important (34.6%), or important (11.5%) for improving patient outcomes. High performing facilities prioritized consistent patient education about RM and evaluated nonadherence using dashboards and manufacturer web sites. High performing facilities instituted clear standard operating procedures that defined staff responsibilities and facilitated efficient contact with nonadherent patients and then family members by phone and then mail. Clinicians based at high performing facilities spent twice as many hours per week (9.1) on average managing RM adherence compared to other facilities (4.5). Effective communication (internally and with non-VHA care partners) and use of CIED manufacturer resources were essential. Facilities that were not high performing rarely used these strategies., Conclusion: Clinicians can support high RM adherence by emphasizing patient education, regularly assessing and addressing nonadherence using staff protocols, and engaging CIED manufacturers.

Background: Implantable cardioverter defibrillators (ICDs) are typically programed with both ventricular tachycardia (VT) and ventricular fibrillation (VF) treatment zones. Biotronik and Abbott ICDs do not increment the VT counter when the tachycardia accelerates to the VF zone, which could result in a prolonged delay in tachycardia detection., Methods: Patients with Biotronik and Abbott ICDs receiving care at Veterans Affairs facilities in Northern California were identified. Patient information and device tracings for patients with any ICD therapies were examined to assess for possible delayed tachycardia detection., Results: Among 52 patients with Biotronik ICDs, 8 (15%) experienced appropriate ICD therapy over a median follow-up of 29 months. Among 68 patients with Abbott ICDs, 26 (38%) experienced appropriate ICD therapy over a median follow-up of 83 months. Three of the patients with Biotronik ICDs who received appropriate therapy experienced a delay in VT/VF detection due to the tachycardia rate oscillating between the VT and VF treatment zones (longest 31.2 s on detection), compared with four of the patients with Abbott ICDs (longest 4.1 s on the detection and 8 s on redetect). One of the patients with a Biotronik ICD experienced recurrent syncope associated with delayed detection and another died on the day of delayed detection. One of the patients with an Abbott ICD experienced syncope., Conclusions: Because contemporary Biotronik and Abbott ICDs freeze the VT counters when tachycardia is in the VF zone, ICD therapies can be markedly delayed when the tachycardia oscillates between the VT and VF zone., (© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Background: Current methods to identify cardiovascular implantable electronic device lead failure include postapproval studies, which may be limited in scope, participant numbers, and attrition; studies relying on administrative codes, which lack specificity; and voluntary adverse event reporting, which cannot determine incidence or attribution to the lead., Objective: The purpose of this study was to determine whether adjudicated remote monitoring (RM) data can address these limitations and augment lead safety evaluation., Methods: Among 48,191 actively monitored patients with a cardiovascular implantable electronic device, we identified RM transmissions signifying incident lead abnormalities and, separately, identified all leads abandoned or extracted between April 1, 2019, and April 1, 2021. We queried electronic health record and Medicare fee-for-service claims data to determine whether patients had administrative codes for lead failure. We verified lead failure through manual electronic health record review., Results: Of the 48,191 patients, 1170 (2.4%) had incident lead abnormalities detected by RM. Of these, 409 patients had administrative codes for lead failure, and 233 of these 409 patients (57.0%) had structural lead failure verified through chart review. Of the 761 patients without administrative codes, 167 (21.9%) had structural lead failure verified through chart review. Thus, 400 patients with RM transmissions suggestive of lead abnormalities (34.2%) had structural lead failure. In addition, 200 patients without preceding abnormal RM transmissions had leads abandoned or extracted for structural failure, making the total lead failure cohort 600 patients (66.7% with RM abnormalities, 33.3% without). Patients with isolated right atrial or left ventricular lead failure were less likely to have lead replacement and administrative codes reflective of lead failure., Conclusion: RM may strengthen real-world assessment of lead failure, particularly for leads where patients do not undergo replacement., (Published by Elsevier Inc.)

Competing Interests: Funding Support and Author Disclosures This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Boston Scientific provided engineering information related to this manuscript. Dr Friday is an employee of Boston Scientific. No direct or indirect funding was provided by Boston Scientific. The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Background: Professional societies strongly recommend remote monitoring (RM) of all cardiac implantable electronic devices, and higher RM adherence is associated with improved patient outcomes. However, adherence with RM is suboptimal., Objective: The purpose of this study was to better understand factors associated with RM adherence., Methods: We linked RM data from the Veterans Affairs National Cardiac Device Surveillance Program to clinical data for patients monitored between October 25, 2018, and October 24, 2020. RM adherence was defined as the percentage of days covered by an RM transmission during the study period. Patients were classified into 3 categories: complete (100% of days covered by an RM transmission), intermediate (above median in patients with <100% adherence), and low (below median in patients with <100% adherence) adherence. We used multivariable logistic regression to examine patient, device, and facility characteristics associated with adherence., Results: In 52,574 patients, average RM adherence was 71.9%. Only 30.9% (16,224) of patients had complete RM adherence. Black or African American patients had a lower odds of complete RM adherence than white patients (odds ratio 0.88; 95% confidence interval 0.82-0.94), and Hispanic or Latino patients had a lower odds of complete RM adherence (odds ratio 0.79; 95% confidence interval 0.70-0.89) than non-Hispanic or Latino patients. Dementia, depression, and posttraumatic stress disorder were associated with a lower odds of RM adherence., Conclusion: There are significant disparities in RM adherence by race, ethnicity, and neuropsychiatric comorbidities. These findings can inform strategies to improve health equity and ensure that all patients with cardiac implantable electronic devices receive the evidence-based clinical benefits of RM., (Published by Elsevier Inc.)

Background: Implantable cardioverter-defibrillators (ICDs) reduce the risk of sudden cardiac death among patients with persistently reduced (≤35 %) left ventricular ejection fraction (LVEF) at least 40 days following acute myocardial infarction (AMI). Few prior studies have used LVEF measured after the 40-day waiting period to examine primary prevention ICD placement., Methods: We sought to determine factors associated with ICD placement among patients who met LVEF criteria post-MI within a large integrated health care system in the U.S by conducting a retrospective cohort study of Veteran patients hospitalized for AMI from 2004 to 2017 who had documented LVEF ≤35 % from echocardiograms performed between 40 and 455 (90 days +1 year) days post-MI. We used multivariable logistic regression to examine factors associated with ICD placement., Results: Of 12,893 patients with LVEF ≤35 % at least 40 days post-MI, 2176 (16.9 %) received an ICD between 91- and 455-days post-MI. Younger age, fewer comorbidities, revascularization with PCI, and greater use of GDMT were associated with increased odds of receiving an ICD. However, half of patients treated with a beta-blocker, ACE inhibitor or angiotensin receptor blocker, and mineralocorticoid receptor antagonist prior to LVEF assessment did not receive an ICD. Eligible Black patients were less likely (odds ratio 0.80, 95 % confidence interval 0.69-0.92) to receive an ICD than White patients., Conclusion: Many factors affect ICD placement among Veteran patients with a confirmed LVEF ≤35 % at least 40 days post-MI. Greater understanding of factors influencing ICD placement would help clinicians ensure guideline-concordant care., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dr. Dhruva reports financial support was provided by VHA Health Services Research & Development. Dr. Whooley reports financial support was provided by VHA Health Services Research & Development. Dr. Dhruva reported research support from the Food and Drug Administration; the National Heart, Lung, and Blood Institute of the National Institutes of Health; the Greenwall Foundation; Arnold Ventures; National Institute for Health Care Management; and the National Evaluation System for health Technology Coordinating Center.

To describe health related quality of life (HRQOL) and symptoms in the SPIRIT trial and determine effects of implantable cardioverter defibrillator (ICD) shocks on HRQOL over 24 months. Ninety participants aged 66 ± 10 years, 96% men, 75% with NYHA class II, with an ICD were randomized to spironolactone 25 mg ( N  = 44) or placebo ( N  = 46). HRQOL was measured every 6 months for 24 months using: Patient Concerns Assessment (PCA), Short Form Health Survey-Veterans Version (SF-36V), and Kansas City Cardiomyopathy Questionnaire (KCCQ). Linear mixed modeling compared changes in HRQOL over-time and ANCOVA compared HRQOL between those getting an ICD shock or not. Over 24-months, there were no differences in HRQOL between the spironolactone versus placebo groups. Those with at least one ICD shock reported significantly lower HRQOL and more symptoms at 6- and 24-months. Patients receiving one or more ICD shocks reported significant reductions in HRQOL and higher symptoms.

Background: Dexmedetomidine (Dex) is an attractive agent for procedural sedation due to its unique pharmacodynamic profile, specifically affording predictable sedation without concurrent respiratory depression. However, Dex has previously been reported to prevent or terminate arrhythmias. The purpose of this study was to investigate paroxysmal supraventricular tachycardia (PSVT) inducibility and homeostatic stability during electrophysiology studies (EPSs) and ablation when a standardized Dex protocol was used as the primary sedation agent., Methods: We performed a retrospective review of 163 consecutive procedures for PSVT ablation that received Dex as the primary sedative with adjunct fentanyl and midazolam boluses (DEX-FENT-MIDAZ). This cohort was compared to 163 consecutive control procedures wherein strictly fentanyl and midazolam were used for sedation. The primary outcome reviewed was PSVT inducibility assessed before ablation. Reviewed secondary outcomes included level of sedation and intraprocedure hemodynamics and oxygenation., Results: The arrhythmia profiles of the DEX-FENT-MIDAZ and control cohorts were very similar. The overall incidence of a "negative" EPSs in which arrhythmia was not induced was 24% in the DEX-FENT-MIDAZ group and 26% in the control group (P = .7). Unintended deep sedation was significantly less with DEX-FENT-MIDAZ (4.3% vs 27%; P ≤ .0001). However, DEX-FENT-MIDAZ use was associated with a higher incidence of intraprocedure hypotension., Conclusions: Dex sedation during EPSs is not associated with a reduction in PSVT inducibility. The therapeutic utility of Dex during EPS arises from the predictable sedation Dex affords but is associated with an increased incidence of intraprocedure hypotension.

Background: It is unclear whether physiologic pacing by either cardiac biventricular pacing (BiVP) or His bundle pacing (HisBP) may prevent adverse structural and functional consequences known to occur among some patients who receive right ventricular pacing (RVP)., Aim: Our analysis sought to review existing literature to determine if BiVP and/or HisBP might prevent adverse remodeling and be associated with structural, functional, and clinical advantages compared with RVP among patients without severe left ventricular dysfunction (>35%) who required permanent pacing because of heart block., Methods: A literature search was conducted using MEDLINE (through PubMed) and Embase to identify randomized trials and observational studies comparing the effects of BiVP or HisBP versus RVP on measurements of left ventricular dimensions, left ventricular ejection fraction (LVEF), heart failure functional classification, quality of life, 6-minute walk, hospitalizations, and mortality. Data from studies that met the appropriate population, intervention, comparator, and outcomes of interest were abstracted for meta-analysis. Studies that reported pooled outcomes among patients with LVEF both above and below 35% could not be included in the meta-analysis because of strict relationships with industry procedures that preclude retrieval of industry-retained unpublished data on the subset of patients with preserved left ventricular function., Results: Evidence from 8 studies, including a total of 679 patients meeting the prespecified criteria for inclusion, was identified. Results were compared for BiVP versus RVP, HisBP versus RVP, and BiVP+HisBP versus RVP. Among patients who received physiologic pacing with either BiVP or HisBP, the LV end-diastolic and end-systolic volumes were significantly lower (mean duration of follow-up: 1.64 years; -2.77 mL [95% CI -4.37 to -1.1 mL]; p=0.001; and -7.09 mL [95% CI -11.27 to -2.91; p=0.0009) and LVEF remained preserved or increased (mean duration of follow-up: 1.57 years; 5.328% [95% CI: 2.86%-7.8%; p<0.0001). Data on clinical impact such as functional status and quality of life were not definitive. Data on hospitalizations were unavailable. There was no effect on mortality. Several studies stratified results by LVEF and found that patients with LVEF >35% but ≤52% were more likely to receive benefit from physiologic pacing. Patients with chronic atrial fibrillation who underwent atrioventricular node ablation and pacemaker implant demonstrated clear improvement in LVEF with BiVP or HisBP versus RVP., Conclusion: Among patients with LVEF >35%, the LVEF remained preserved or increased with either BiVP or HisBP compared with RVP. However, patient-centered clinical outcome improvement appears to be limited primarily to patients who have chronic atrial fibrillation with rapid ventricular response rates and have undergone atrioventricular node ablation., (Copyright © 2019 American College of Cardiology Foundation, the American Heart Association, Inc., and the Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Dual external direct current cardioversion (dual-DCCV) is a rhythm control strategy for persistent atrial fibrillation (AF), involving simultaneous delivery of two shocks from two defibrillators. The long-term effectiveness of this approach has not been studied in the biphasic cardioversion era., Methods: Seventy-seven consecutive patients at a single center were identified to receive dual-DCCV at the time of their initial cardioversion for AF, when maximum output standard external direct current cardioversion failed in two vectors. Logistic regression was used to analyze risk factors for dual-DCCV in a historical control group of 77 patients undergoing standard cardioversion and Cox proportional hazard models were used to compare time to AF recurrence., Results: The dual-DCCV group had a significantly larger body mass index (BMI), but similar AF duration and left atrial size as controls. Multivariable logistic regression revealed that BMI and absence of prior paroxysmal AF were risk factors for dual-DCCV (P < 0.05). There was no difference observed between dual-DCCV and control groups (adjusted hazard ratio = 0.57; P = .12) after adjusting for number of shocks and age. Transient hypoxia was the only acute complication in either group (P > .999)., Conclusion: Dual-DCCV appears to be a safe and effective cardioversion strategy for patients with AF. The need for dual-DCCV in the treatment of AF appears to be influenced more by body habitus than atrial substrate., (© 2019 Wiley Periodicals, Inc.)

Background: Device-detected atrial fibrillation (AF) is associated with increased risk of stroke; however, there are no clearly defined thresholds of AF burden at which to initiate oral anticoagulation (OAC). We sought to describe OAC prescription practice variation in response to new device-detected AF and the association with outcomes., Methods: We performed a retrospective cohort study using data from the Veterans Health Administration linked to remote monitoring data that included day-level AF burden. We included patients with cardiac implantable electronic devices and remote monitoring from 2011 to 2014, CHA 2 DS 2 -VASc score ≥2, and no prior stroke or OAC receipt in the preceding 2 years. We determined the proportion of patients prescribed OAC within 90 days after new device-detected AF across a range of AF thresholds (≥6 minutes to >24 hours) and examined site variation in OAC prescription. We used multivariable Cox proportional hazards regressions to determine the association of OAC prescription with stroke by device-detected AF burden., Results: Among 10 212 patients with cardiac implantable electronic devices, 4570 (45%), 3969 (39%), 3263 (32%), and 2469 (24%) had device-detected AF >6 minutes, >1 hour, >6 hours, and >24 hours, respectively. For device-detected AF >1 hour, 1712 patients met inclusion criteria (72±10 years; 1.5% female; CHA 2 DS 2 -VASc score 4.0±1.4; HAS-BLED score 2.6±1.1). The proportion receiving OAC varied based on device-detected AF burden (≥6 minutes: 272/2101 [13%]; >1 hour: 273/1712 [16%]; >6 hours: 263/1279 [21%]; >24 hours: 224/818 [27%]). Across 52 sites (N=1329 patients), there was substantial site-level variation in OAC prescription after device-detected AF >1 hour (median, 16%; range, 3%-67%; median odds ratio, 1.56 [95% credible interval, 1.49-1.71]). In adjusted models, OAC prescription after device-detected AF >24 hours was associated with reduced stroke risk (hazard ratio, 0.28; 95% CI, 0.10-0.81; P=0.02), although the propensity-adjusted model was significant when AF lasted at least 6 minutes., Conclusions: Among veterans with cardiac implantable electronic devices, device-detected AF is common. There is large practice variation in 90-day OAC initiation after new device-detected AF, with low rates of treatment overall, even for episodes that last >24 hours. The strongest association of OAC with reduction in stroke was observed after device-detected AF >24 hours. Randomized trials are needed to confirm these observational findings.

Background: Previous studies have suggested that aldosterone blockade can reduce the incidence of ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients with heart failure. The SPIronolactone to Reduce ICD Therapy (SPIRIT) trial was designed to test the hypothesis that spironolactone reduces the incidence of VT/VF in patients with implantable cardioverter-defibrillators (ICDs) who are at moderately high risk for recurrent VT/VF., Methods and Results: Ninety patients who had ICDs who were at moderately high risk for recurrent VT/VF and who were not candidates for spironolactone by current heart failure guidelines were randomized to receive spironolactone 25 mg daily or placebo in a double-blind fashion. All patients had previously received ICD therapy (shock or antitachycardia pacing) for VT/VF within 2 years of randomization or an ICD for secondary prevention of VT/VF within 6 months of randomization. The primary end point was time to first recurrence of VT/VF requiring ICD therapy. After a median follow-up of 35 months, the Kaplan-Meier probability estimates for VT/VF requiring ICD therapy were 68.7% in the placebo group and 84.7% in the spironolactone group. Compared with placebo, spironolactone was associated with a similar risk of VT/VF (hazard ratio, 1.01; 95% CI, 0.64-1.83; P=0.71). There was no significant difference between the median times to first VT/VF recurrence requiring ICD therapy in the 2 groups., Conclusions: In patients with ICDs who were at moderately high risk for recurrent VT/VF on account of a recent VT/VF event that was either sustained or treated by the ICD and who were not candidates for spironolactone by current heart failure guidelines, spironolactone did not delay the first recurrence of VT/VF or reduce the risk of recurrent VT/VF.

Background: Implantable cardioverter-defibrillator (ICD) shocks are associated with an increased risk of death. It is unclear whether ICD shocks are detrimental per se or a marker of higher risk patients., Objective: We aimed to assess the association between ICD shocks and time to death after correction for baseline mortality based on the Seattle Heart Failure Model (SHFM)., Methods: The primary analysis compared time-to-death between patients receiving no shocks and patients receiving shocks of any type adjusted for SHFM score at time of implantation and other comorbidities. Subgroup analyses were performed to further describe the relationship between shocks and mortality risk., Results: Over a median follow-up of 41 months (interquartile range 23-64), one or more shock episodes occurred in 59% of 425 patients and 40% of the patients died. Patients receiving shocks of any type had increased risk of death (hazard ratio 1.55; 95% confidence interval 1.07-2.23; P = .02) versus patients receiving no shocks. While patients with 1-5 days with shock (shock days) did not show evidence of increased risk of death (1.30 [0.88-1.94]; P = 0.19), those with 6-10 shock days (2.22 [1.21-4.08]; P <.01) and >10 shock days (3.66 [1.86-7.19]; P <.01) had increasingly higher risk. There was no increased hazard for death (0.73 [0.34-1.57]; P = .41) in patients treated only with antitachycardia pacing (ATP)., Conclusion: ICD shocks were associated with increased mortality risk after adjustment for SHFM-predicted mortality, and the burden of shocks played a role in this association. ATP did not increase mortality risk, suggesting that shocks may themselves be detrimental., (Published by Elsevier Inc.)

Aims: To determine the effects of omega-3 polyunsaturated fatty acids (omega-3 PUFAs) from fish on the incidence of recurrent ventricular arrhythmia in implantable cardioverter defibrillator (ICD) patients by combining results from published trials., Methods and Results: We searched in the Medline, EMBASE, and Cochrane databases and performed a meta-analysis on all three available trials on fish oil and ventricular arrhythmia. Furthermore, we pooled individual data of two of these randomized, double-blind, placebo-controlled trials (Raitt et al. Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial. JAMA 2005;293:2884-2891 and Brouwer et al. Effect of fish oil on ventricular tachyarrhythmia and death in patients with implantable cardioverter defibrillators: the Study on Omega-3 Fatty Acids and Ventricular Arrhythmia (SOFA) randomized trial. JAMA 2006;295:2613-2619). The main outcome was time to first confirmed ventricular fibrillation (VF) or ventricular tachycardia (VT) combined with death for the meta-analysis, and time to first spontaneous confirmed VF or VT for the pooled analysis. The meta-analysis (n = 1148) showed no convincing protective effect of fish oil (RR 0.90; 95% CI 0.67-1.22). The hazard ratio for the subgroup of patients with coronary artery disease at baseline (0.79; 0.60-1.06) tended towards a protective effect. The pooled analysis (n = 722) showed that time to appropriate ICD intervention was similar for fish oil and placebo treatment (log-rank P = 0.79)., Conclusion: These findings do not support a protective effect of omega-3 PUFAs from fish oil on cardiac arrhythmia in all patients with an ICD. Current data neither prove nor disprove a beneficial or a detrimental effect for subgroups of patients with specific underlying pathologies.

Background: Patients with heart failure who receive an implantable cardioverter-defibrillator (ICD) for primary prevention (i.e., prevention of a first life-threatening arrhythmic event) may later receive therapeutic shocks from the ICD. Information about long-term prognosis after ICD therapy in such patients is limited., Methods: Of 829 patients with heart failure who were randomly assigned to ICD therapy, we implanted the ICD in 811. ICD shocks that followed the onset of ventricular tachycardia or ventricular fibrillation were considered to be appropriate. All other ICD shocks were considered to be inappropriate., Results: Over a median follow-up period of 45.5 months, 269 patients (33.2%) received at least one ICD shock, with 128 patients receiving only appropriate shocks, 87 receiving only inappropriate shocks, and 54 receiving both types of shock. In a Cox proportional-hazards model adjusted for baseline prognostic factors, an appropriate ICD shock, as compared with no appropriate shock, was associated with a significant increase in the subsequent risk of death from all causes (hazard ratio, 5.68; 95% confidence interval [CI], 3.97 to 8.12; P<0.001). An inappropriate ICD shock, as compared with no inappropriate shock, was also associated with a significant increase in the risk of death (hazard ratio, 1.98; 95% CI, 1.29 to 3.05; P=0.002). For patients who survived longer than 24 hours after an appropriate ICD shock, the risk of death remained elevated (hazard ratio, 2.99; 95% CI, 2.04 to 4.37; P<0.001). The most common cause of death among patients who received any ICD shock was progressive heart failure., Conclusions: Among patients with heart failure in whom an ICD is implanted for primary prevention, those who receive shocks for any arrhythmia have a substantially higher risk of death than similar patients who do not receive such shocks., (2008 Massachusetts Medical Society)

Objectives: This study investigated whether defibrillation threshold (DFT) testing during implantable cardioverter-defibrillator (ICD) implantation predicts clinical outcomes., Background: Defibrillation testing is often performed during insertion of ICDs to confirm shock efficacy. There are no prospective data to suggest that this procedure improves outcomes when modern ICDs are implanted for primary prevention of sudden death., Methods: The analysis included the 811 patients who were randomized to the ICD arm of the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) and had the device implanted. The DFT testing protocol in SCD-HeFT was designed to limit shock testing in a primary prevention heart failure population., Results: Baseline DFT data were available for 717 patients (88.4%). All 717 patients had a DFT of < or =30 J, the maximum output of the device in this study. The DFT was < or =20 J in 97.8% of patients. There was no survival difference between patients with a lower DFT (< or =10 J, n = 547) and a higher DFT (>10 J, n = 170) (p = 0.41). First shock efficacy was 83.0% for the first clinical ventricular tachyarrhythmia event; there were no differences in shock efficacies when the cohort was subdivided by baseline DFT., Conclusions: Low baseline DFTs were obtained in patients with stable, optimally treated heart failure during ICD implantation for primary prevention of sudden death. First shock efficacy for ventricular tachyarrhythmias was high regardless of baseline DFT testing results. Baseline DFT testing did not predict long-term mortality or shock efficacy in this study.

Background: A reliable predictor of an imminent episode of ventricular tachyarrhythmia that could be incorporated in an implantable defibrillator capable of preventive therapy would have important clinical utility., Method: A test set of 208 R-R records saved by defibrillators spanning a mean of 1.6 hours before sustained tachyarrhythmia were used to derive criteria that would improve the specificity of the previously identified monotonic heart rate acceleration predictor. Additional criteria were used, namely two such patterns need to occur within a period of 1.8 hour and the heart rate during these accelerations exceeds 86 bpm (700 ms). The specificity was tested using R-R records matched in duration from 26 control patients with defibrillators during normal periods., Results: The basic acceleration pattern was found during sinus rhythm in the 1.8-hour period prior to 83% of episodes of ventricular tachyarrhythmia. It was also found in 43% of the matched set of non-arrhythmic records, corresponding to a specificity of 57%. With the two extra requirement of multiplicity within 1.8 hour and peak heart rate, the sensitivity of the proposed predictor is reduced to 53%, but the specificity is increased to 91%, which corresponds to an average false positive rate of 0.8 event/day across the patient population., Conclusion: A ventricular tachyarrhythmia predictor based on a pattern of heart rate acceleration has been proposed that can yield sensitivity from 53% to 69%, with specificity up to 91%. Instances of this predictor increase significantly prior to an episode of tachyarrhythmia.

Background: The early recurrence of atrial fibrillation (AF) after cardioversion and the need for frequent cardioversions to maintain sinus rhythm are important clinical features of AF management., Methods: We evaluated patients in the AFFIRM study whose qualifying episode of AF lasted > or = 48 hours and was terminated by cardioversion. Clinical, electrocardiographic, and echocardiographic risk factors associated with AF recurrence within 2 months of cardioversion and > or = 2 cardioversions during the first year were identified using multivariate analysis in 1293 eligible patients., Results: The risk factors for the recurrence of AF within 2 months of cardioversion were no coronary artery disease and an electrocardiographic lead II P-wave duration of > 135 milliseconds. In the subset of patients not taking antiarrhythmic drug therapy, the multivariate risk factors were no coronary artery disease, second or greater episode of AF, left ventricular ejection fraction < 0.50, and mitral valve thickening. Significant risk factors for the need for > 2 cardioversions in the first year in patients taking antiarrhythmic medication were left atrial diameter > 4.5 cm and mitral valve thickening. The overall sensitivity and specificity of these parameters for recurrence and repeated cardioversion are low., Conclusion: There are several risk factors for difficulty maintaining sinus rhythm after cardioversion of persistent AF. The clinical predictive value of these factors is low, and they probably should not be used to justify withholding rhythm control efforts in patients who might benefit from sinus rhythm.

Context: Clinical studies of omega-3 polyunsaturated fatty acids (PUFAs) have shown a reduction in sudden cardiac death, suggesting that omega-3 PUFAs may have antiarrhythmic effects., Objective: To determine whether omega-3 PUFAs have beneficial antiarrhythmic effects in patients with a history of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF)., Design and Setting: Randomized, double-blind, placebo-controlled trial performed at 6 US medical centers with enrollment from February 1999 until January 2003., Patients: Two hundred patients with an implantable cardioverter defibrillator (ICD) and a recent episode of sustained VT or VF., Intervention: Patients were randomly assigned to receive fish oil, 1.8 g/d, 72% omega-3 PUFAs, or placebo and were followed up for a median of 718 days (range, 20-828 days)., Main Outcome Measures: Time to first episode of ICD treatment for VT/VF, changes in red blood cell concentrations of omega-3 PUFAs, frequency of recurrent VT/VF events, and predetermined subgroup analyses., Results: Patients randomized to receive fish oil had an increase in the mean percentage of omega-3 PUFAs in red blood cell membranes from 4.7% to 8.3% (P<.001), with no change observed in patients receiving placebo. At 6, 12, and 24 months, 46% (SE, 5%), 51% (5%), and 65% (5%) of patients randomized to receive fish oil had ICD therapy for VT/VF compared with 36% (5%), 41% (5%), and 59% (5%) for patients randomized to receive placebo (P = .19). In the subset of 133 patients whose qualifying arrhythmia was VT, 61% (SE, 6%), 66% (6%), and 79% (6%) of patients in the fish oil group had VT/VF at 6, 12, and 24 months compared with 37% (6%), 43% (6%), and 65% (6%) of patients in the control group (P = .007). Recurrent VT/VF events were more common in patients randomized to receive fish oil (P<.001)., Conclusion: Among patients with a recent episode of sustained ventricular arrhythmia and an ICD, fish oil supplementation does not reduce the risk of VT/VF and may be proarrhythmic in some patients.

Introduction: In animals, atrial fibrillation results in reversible atrial electrical remodeling manifested as shortening of the atrial effective refractory period, slowing of intra-atrial conduction, and prolongation of sinus node recovery time. There is limited information on changes in these parameters after cardioversion in patients with persistent atrial fibrillation., Methods and Results: Thirty-eight patients who had been in atrial fibrillation for 1 to 12 months underwent electrophysiologic testing 10 minutes and 1 hour after cardioversion. At 1 week, 19 patients still in sinus rhythm returned for repeat testing. Reverse remodeling of the effective refractory period was not uniform across the three atrial sites tested. At the lateral right atrium, there was a highly significant increase in the effective refractory period between 10 minutes and 1 hour after cardioversion (drive cycle length 400 ms: 204 +/- 17 ms vs 211 +/- 20 ms, drive cycle length 550 ms: 213 +/- 18 ms vs 219 +/- 23 ms, P < 0.001). The effective refractory period at the coronary sinus and distal coronary sinus did not change in the first hour but had increased by 1 week. The corrected sinus node recovery time did not change in the first hour but was shorter at 1 week (606 +/- 311 ms vs 408 +/- 160 ms, P = 0.009). P wave duration also was shorter at 1 week (135 +/- 18 ms vs 129 +/- 13 ms, P = 0.04) consistent with increasing atrial conduction velocity., Conclusion: The atrial effective refractory period increases, sinus node function improves, and atrial conduction velocity goes up in the first week after cardioversion of long-standing atrial fibrillation in humans. Reverse electrical remodeling of the effective refractory period occurs at different rates in different regions of the atrium.

Patients with recurrence of persistent atrial fibrillation within 30 days of cardioversion had slower atrial conduction, a slower sinus rate, no difference in the absolute value of the effective refractory period, greater early reverse remodeling of the effective refractory period, and more premature atrial contractions than those who did not. These findings highlight the role of slow conduction and premature atrial contractions in the pathophysiology of atrial fibrillation and suggest a possible proarrhythmic effect of reverse remodeling.

Introduction: The implantable cardioverter defibrillator (ICD) is commonly used to treat patients with documented sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Arrhythmia recurrence rates in these patients are high, but which patients will receive a therapy and the forms of arrhythmia recurrence (VT or VF) are poorly understood., Methods and Results: The therapy delivered by the ICD was examined in 449 patients randomized to ICD therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. Events triggering ICD shocks or antitachycardia pacing (ATP) were reviewed for arrhythmia diagnosis, clinical symptoms, activity at the onset of the arrhythmia, and appropriateness and results of therapy. Both shock and ATP therapies were frequent by 2 years, with 68% of patients receiving some therapy or having an arrhythmic death. An appropriate shock was delivered in 53% of patients, and ATP was delivered in 68% of patients who had ATP activated. The first arrhythmia treated in follow-up was diagnosed as VT (63%), VF (13%), supraventricular tachycardia (18%), unknown arrhythmia (3%), or due to ICD malfunction or inappropriate sensing (3%). Acceleration of an arrhythmia by the ICD occurred in 8% of patients who received any therapy. No physical activity consistently preceded arrhythmias, nor did any single clinical factor predict the symptoms of the arrhythmia., Conclusion: Delivery of ICD therapy in AVID patients was common, primarily due to VT. Inappropriate ICD therapy occurred frequently. Use of ICD therapy as a surrogate endpoint for death in clinical trials should be avoided.

Objectives: We sought to determine the value of electrophysiology (EP) testing in patients with ventricular fibrillation (VF), ventricular tachycardia (VT) with syncope, or sustained VT in the setting of left ventricular dysfunction., Background: Traditionally, EP testing is part of the workup of patients with sustained VT or VF. Recently, some have suggested that EP testing is unnecessary in these patients, many of whom are likely to receive an implantable cardioverter-defibrillator (ICD)., Methods: Within a multicenter trial (Antiarrhythmics Versus Implantable Defibrillators) designed to evaluate whether drugs or ICD resulted in a better outcome, data were analyzed regarding EP testing. Although this testing was not required, it was performed in >50% of patients. Information regarding the results of EP testing was correlated to baseline clinical characteristics and outcome., Results: Of 572 patients subjected to an EP test, 384 (67%) had inducible sustained VT or VF. Inducible patients were more likely to have coronary artery disease, previous infarction, and VT as their index arrhythmic event. Inducibility of VT or VF did not predict death or recurrent VT or VF., Conclusions: Information derived from EP testing in this patient population, particularly those with VF, is of limited value and may not be worth the risks and costs of the procedure, particularly in those patients likely to receive an ICD.

Objectives: This study evaluated the prognosis of patients resuscitated from ventricular tachycardia (VT) or ventricular fibrillation (VF) with a transient or correctable cause suspected as the cause of the VT/VF., Background: Patients resuscitated from VT/VF in whom a transient or correctable cause has been identified are thought to be at low risk for recurrence and often receive no primary treatment for their arrhythmias., Methods: In the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial, patients with a potentially transient or correctable cause of VT/VF were not eligible for randomization. The mortality of these patients was compared with the mortality of patients with a known high risk of recurrence of VT/VF in the AVID registry., Results: Compared with patients having high risk VT/VF, those with a transient or correctable cause for their presenting VT/VF were younger and had a higher left ventricular ejection fraction. These patients were more often treated with revascularization as the primary therapy, more commonly received a beta-blocker, less often required therapy for congestive heart failure and less commonly received either an antiarrhythmic drug or an implantable cardioverter defibrillator. Nevertheless, subsequent mortality of patients with a transient or correctable cause of VT/VF was no different or perhaps even worse than that of the primary VT/VF population., Conclusions: Patients identified with a transient or correctable cause for their VT/VF remain at high risk for death. Further research is needed to define truly reversible causes of VT/VF. Meanwhile, these patients may require more aggressive evaluation, treatment and follow-up than is currently practiced.

Emerging evidence suggests that atrial fibrillation is not a benign arrhythmia. It is associated with increased risk of death. The magnitude of association is controversial and potential causes remain unknown. Patients in the registry of the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial form the basis for this report. Baseline variables, in particular the presence or absence of a history of atrial fibrillation/flutter, were examined in relation to survival. Multivariate Cox regression was used to adjust for differences in important baseline co-variables using 27 pre-selected variables. There were 3762 subjects who were followed for an average of 773+/-420 days; 1459 (39 %) qualified with ventricular fibrillation and 2303 (61 %) with ventricular tachycardia. A history of atrial fibrillation/flutter was present in 24.4 percent. There were many differences in baseline variables between those with and those without a history of atrial fibrillation/flutter. After adjustment for baseline differences, a history of atrial fibrillation/flutter remained a significant independent predictor of mortality, (relative risk=1.20; 95 % confidence intervals=1.03-1.40; p=0.020). Antiarrhythmic drug use, other than amiodarone or sotalol, was also a significant independent predictor of mortality (relative risk 1.34; 95 % confidence intervals 1.07-1.69, p=0.011. Atrial fibrillation/flutter is a significant independent risk factor for increased mortality in patients presenting with ventricular tachyarrhythmias. This risk may have been overestimated in previous studies that could not adjust for the proarrhythmic effects of antiarrhythmic drugs other than amiodarone or sotalol.

Objectives: The goal of this study was to identify subgroups of arrhythmia patients who do not benefit from use of the implantable cardiac defibrillator (ICD)., Background: Treatment of serious ventricular arrhythmias has evolved toward more common use of the ICD. Since estimates of the cost per year of life saved by ICD therapy vary from $25,000 to perhaps $125,000, it is important to identify patient subgroups that do not benefit from the ICD., Methods: Data for 491 ICD patients enrolled in the Antiarrhythmics Versus Implantable Defibrillators Study were used to create a hazards model relating baseline factors to time to first recurrent arrhythmia. The model was used to predict the hazard for recurrent arrhythmia among all trial patients. A priori cut points provided lower and higher recurrent arrhythmia risk strata. For each stratum the incremental years of life due to ICD versus antiarrhythmic drug therapy were calculated., Results: Factors that predicted recurrent arrhythmia were: ventricular tachycardia as the index arrhythmia, history of cerebrovascular disease, lower left ventricular ejection fraction, a history of any tachyarrhythmia before the index event and the absence of revascularization after the index event. Survival times (over a follow-up of three years) were identical in each arm of the lowest risk sextile (survival advantage 0.03 +/- 0.12 [se] years), while the survival advantage for patients above the first sextile was 0.27 +/- 0.07 (se) years (two-sided p = 0.05)., Conclusions: Patients presenting with an isolated episode of ventricular fibrillation in the absence of cerebrovascular disease or history of prior arrhythmia who have undergone revascularization or who have moderately preserved left ventricular function (left ventricular ejection fraction > 0.27) are not likely to benefit from ICD therapy compared with amiodarone therapy.

Background: Sustained ventricular tachycardia (VT) can be unstable, can be associated with serious symptoms, or can be stable and relatively free of symptoms. Patients with unstable VT are at high risk for sudden death and are best treated with an implantable defibrillator. The prognosis of patients with stable VT is controversial, and it is unknown whether implantable cardioverter-defibrillator therapy is beneficial., Methods and Results: Screening for the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial identified patients with both stable and unstable VT. Both groups were included in a registry, and their clinical characteristics and discharge treatments were recorded. Mortality data were obtained through the National Death Index. The mortality in 440 patients with stable VT tended to be greater than that observed in 1029 patients presenting with unstable VT (33.6% versus 27.6% at 3 years; relative risk [RR]=1.22; P:=0.07). After adjustment for baseline and treatment differences, the RR was little changed (RR=1.25, P:=0.06)., Conclusions: Sustained VT without serious symptoms or hemodynamic compromise is associated with a high mortality rate and may be a marker for a substrate capable of producing a more malignant arrhythmia. Implantable cardioverter-defibrillator therapy may be indicated in patients presenting with stable VT.

Thirty-two patients had signal-averaged P wave duration measured after electrical cardioversion of AF, and were followed for 1 year or until there was a recurrence. The use of antiarrhythmic medications was left to the discretion of the attending physician. Among 20 patients not taking antiarrhythmic medication, the 11 patients who had a recurrence of AF within 3 months of cardioversion had a significantly longer signal-averaged P wave duration compared to the 9 patients who did not (148 +/- 17 vs 135 +/- 20 ms, P = 0.005). There was no difference in clinical parameters or left atrial diameter. A signal-averaged P wave duration cutoff anywhere between 130 and 135 ms correctly classified 85% of patients with a sensitivity of 81% and a specificity of 89%. In patients taking antiarrhythmic medications, signal-averaged P wave duration did not correlate with the risk of recurrence. In patients not taking antiarrhythmic medications, signal-averaged P wave duration can be used to predict the risk of an early recurrence of AF after cardioversion. The poor predictive value in patients taking antiarrhythmics may be due to changes in the atrial refractory period, which are not reflected in P wave duration.

The historical time of acute symptom onset is not always an accurate indication of the timing of onset of an acute myocardial infarction (AMI). Consideration of electrocardiographic (ECG) timing parameters could supplement historical timing alone as a clinical guide for decisions regarding the use of reperfusion therapy. Three hundred ninety-five patients from 4 trials of thrombolytic therapy conducted in the northwestern United States and western Canada are included in the present study. A total of 316 patients received either streptokinase or tissue plasminogen activator, and 79 received no reperfusion therapy. Historical time of symptom onset was acquired by emergency or cardiology department personnel and recorded on patient report forms. An ECG method for estimating the timing of the AMI, the Anderson-Wilkins (AW) acuteness score, was calculated from the initial standard 12-lead recording by investigators blinded to the knowledge of symptom duration or any other study variables. Tomographic thallium-201 imaging 7 weeks after hospital admission was used to measure final AMI size. The ECG timing method achieved a relation with final AMI size similar to that previously reported for historical timing. The AW acuteness score proved most useful for anterior AMI location when there was a > or = 2 hour delay following symptom onset, but was most useful for the inferior AMI location when there was a < 2 hour delay. Despite a longer delay, patients with high AW acuteness scores had 50% lower final anterior AMI size than those with low scores; and despite a shorter delay, those with low ECG acuteness scores had 50% greater final inferior AMI size than those with high scores. The AW acuteness score combined with the historical estimation of symptom duration should provide a more accurate basis for predicting the potential for limitation of final AMI size than either method alone. These results could potentially provide the basis for developing a new method for noninvasive guidance of clinical decisions regarding administration of reperfusion therapy in the initial evaluation of patients with AMI.