Ventricular fibrillation/ventricular tachycardia within 72 h of VA-ECMO: incidence, outcomes, risk factors, and management.

AIMS: Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is an important technique for the treatment of refractory cardiogenic shock and cardiac arrest; however, the early management of ventricular fibrillation/ventricular tachycardia (VF/VT), within 72 h of VA-ECMO, and its effects on patient prognosis remain unclear. METHODS AND RESULTS: We retrospectively analysed patients at the First Affiliated Hospital of Nanjing Medical University who underwent VA-ECMO between January 2017 and March 2022. The patients were divided into two groups, VF/VT and nVF/VT, based on whether or not VF/VT occurred within 72 h after the initiation of VA-ECMO. We utilized logistic regression analysis to evaluate the independent risk factors for VF/VT in patients undergoing VA-ECMO and to ascertain whether the onset of VF/VT affected 28 day survival rate, length of intensive care unit stay, and/or other clinical prognostic factors. Subgroup analysis was performed for the VF/VT group to determine whether defibrillation affected prognosis. In the present study, 126 patients were included, 65.87% of whom were males (83/126), with a mean age of 46.89 ± 16.23, a 28 day survival rate of 57.14% (72/126), an incidence rate of VF/VT within 72 h of VA-ECMO initiation of 27.78% (35/126), and 80% of whom (28/35) received extracorporeal cardiopulmonary resuscitation. The incidence of VF/VT resulting from cardiac arrest at an early stage was significantly higher than that of refractory cardiogenic shock (80% vs. 20%; P = 0.022). The restricted cubic spline model revealed a U-shaped relationship between VF/VT incidence and initial heart rate (iHR), and multivariate logistic regression analysis showed that an iHR > 120 b.p.m. [odds ratio (OR) 6.117; 95% confidence interval (CI) 1.672-22.376; P = 0.006] and hyperlactataemia (OR 1.125; 95% CI 1.016-1.246; P = 0.023) within 1 h of VA-ECMO initiation were independent risk factors for the occurrence of VF/VT. VF/VT was not found to be associated with the 28 day survival of patients undergoing VA-ECMO support, nor did it affect other secondary endpoints. Defibrillation did not alter the overall prognosis in patients with VF/VT during VA-ECMO. CONCLUSIONS: An iHR > 120 b.p.m. and hyperlactataemia were independent risk factors for the occurrence of VF/VT within 72 h of VA-ECMO initiation. The occurrence of VF/VT does not affect, nor does defibrillation in these patients improve the overall patient prognosis. TRIAL REGISTRATION: ChiCTR1900026105.

Incidence, management, and prognostic impact of arrhythmias in patients with Takotsubo syndrome: a nationwide retrospective cohort study.

AIMS: Arrhythmia is a major complication of Takotsubo syndrome (TTS). However, its incidence, management, and prognostic impact remain to be elucidated in a large cohort. METHODS AND RESULTS: We retrospectively identified 16 713 patients hospitalized for TTS between July 2010 and March 2021 from the Japanese Diagnosis Procedure Combination database. Serious arrhythmias were defined as ventricular tachycardia/fibrillation (VT/VF), 2nd-/3rd-degree atrioventricular block (AVB), sick sinus syndrome (SSS), or unspecified arrhythmias requiring device treatment. Patient characteristics and outcomes were compared based on the occurrence of serious arrhythmias. The overall incidence proportion of serious arrhythmias was 6.2% (n = 1036; 449 VT/VF, 283 2nd-/3rd-degree AVB, 133 SSS, 55 multiple arrhythmias, 116 others), which remained stable over 11 years. The arrhythmia group was younger, more often male, and exhibited greater impairment in activities of daily living (ADLs) and consciousness than the non-arrhythmia group. Although crude in-hospital mortality was higher in the arrhythmia group (9.6% vs. 5.0%, P < 0.001), the significant association between arrhythmias and mortality disappeared after adjustment for confounders (odds ratio = 1.15, 95% confidence interval = 0.90-1.49). Meanwhile, age, sex, ADLs, consciousness level, and Charlson comorbidity index were significantly associated with mortality. In the arrhythmia group, 254 (24.5%) patients received pacemakers (18.4%) or defibrillators (6.1%), which were implanted at a median of 8 and 19 days after admission, respectively. CONCLUSION: Arrhythmias are not uncommon in TTS. Patients' background characteristics, rather than arrhythmia itself, may be associated with in-hospital mortality. Given the reversibility of cardiac dysfunction in TTS, there may be unnecessary device implantations for arrhythmias occurring as sequelae to TTS, warranting further investigations.

An in-silico assessment of efficacy of two novel intra-cardiac electrode configurations versus traditional anti-tachycardia pacing therapy for terminating sustained ventricular tachycardia.

The implanted cardioverter defibrillator (ICD) is an effective direct therapy for the treatment of cardiac arrhythmias, including ventricular tachycardia (VT). Anti-tachycardia pacing (ATP) is often applied by the ICD as the first mode of therapy, but is often found to be ineffective, particularly for fast VTs. In such cases, strong, painful and damaging backup defibrillation shocks are applied by the device. Here, we propose two novel electrode configurations: "bipolar" and "transmural" which both combine the concept of targeted shock delivery with the advantage of reduced energy required for VT termination. We perform an in silico study to evaluate the efficacy of VT termination by applying one single (low-energy) monophasic shock from each novel configuration, comparing with conventional ATP therapy. Both bipolar and transmural configurations are able to achieve a higher efficacy (93% and 85%) than ATP (45%), with energy delivered similar to and two orders of magnitudes smaller than conventional ICD defibrillation shocks, respectively. Specifically, the transmural configuration (which applies the shock vector directly across the scar substrate sustaining the VT) is most efficient, requiring typically less than 1 J shock energy to achieve a high efficacy. The efficacy of both bipolar and transmural configurations are higher when applied to slow VTs (100% and 97%) compared to fast VTs (57% and 29%). Both novel electrode configurations introduced are able to improve electrotherapy efficacy while reducing the overall number of required therapies and need for strong backup shocks.

Disparities in the Management of Newly Diagnosed Paroxysmal Supraventricular Tachycardia for Women Versus Men in the United States.

Background Information on differences in paroxysmal supraventricular tachycardia (PSVT) diagnosis, healthcare resource use, expenditures, and treatment among women versus men is limited. Methods and Results Study participants identified in the IBM MarketScan Commercial Research Databases were aged 18 to 40 years with newly diagnosed PSVT (International Classification of Diseases, Ninth Revision [ICD-9]: 427.0; International Classification of Diseases, Tenth Revision [ICD-10]: I47.1) from October 1, 2012, through September 30, 2016, observable 1 year preindex and postindex diagnosis. Study outcomes were mean annual per-patient healthcare resource use and expenditures before and after diagnosis. Among 5466 patients newly diagnosed with PSVT, most (66.9%) were women. Compared with men, women with PSVT tended to have higher rates of anxiety (13.9% versus 10.9%; P<0.01) and chronic pulmonary disease (10.9% versus 8.3%; P<0.01). Following diagnosis, mean annual per-patient expenditures increased for all patients, but were significantly lower for women ($26 922 versus $33 112; P<0.05), reflecting lower spending for services billed as a result of a PSVT diagnosis ($8471 versus $11 405; P<0.05). After diagnosis, nearly half of all patients had at least 1 emergency department visit (women versus men, 49.6% versus 44.5%; P<0.01) and more had hospital admissions (women versus men, 24.7% versus 20.0%; P<0.01). Fewer women were treated with cardiac ablation (12.6% versus 15.3%; P<0.01), and more were treated with medical therapy, including ß blockers or calcium channel blockers (odds ratio, 1.15; 95% CI, 1.02-1.31). Conclusions Among patients aged 18 to 40 years, ≈2 of 3 patients diagnosed with PSVT were women. After diagnosis, spending was significantly lower for women, reflecting lower ablation rates and less spending on services with a PSVT diagnosis.

Cost-effectiveness of ablation of ventricular tachycardia in ischaemic cardiomyopathy: limitations in the trial evidence base.

Objective: Catheter ablation is an important treatment for ventricular tachycardia (VT) that reduces the frequency of episodes of VT. We sought to evaluate the cost-effectiveness of catheter ablation versus antiarrhythmic drug (AAD) therapy. Methods: A decision-analytic Markov model was used to calculate the costs and health outcomes of catheter ablation or AAD treatment of VT for a hypothetical cohort of patients with ischaemic cardiomyopathy and an implantable cardioverter-defibrillator. The health states and input parameters of the model were informed by patient-reported health-related quality of life (HRQL) data using randomised clinical trial (RCT)-level evidence wherever possible. Costs were calculated from a 2018 UK perspective. Results: Catheter ablation versus AAD therapy had an incremental cost-effectiveness ratio (ICER) of £144 150 (€161 448) per quality-adjusted life-year gained, over a 5-year time horizon. This ICER was driven by small differences in patient-reported HRQL between AAD therapy and catheter ablation. However, only three of six RCTs had measured patient-reported HRQL, and when this was done, it was assessed infrequently. Using probabilistic sensitivity analyses, the likelihood of catheter ablation being cost-effective was only 11%, assuming a willingness-to-pay threshold of £30 000 used by the UK's National Institute for Health and Care Excellence. Conclusion: Catheter ablation of VT is unlikely to be cost-effective compared with AAD therapy based on the current randomised trial evidence. However, better designed studies incorporating detailed and more frequent quality of life assessments are needed to provide more robust and informed cost-effectiveness analyses.

Non-invasive assessment of the arrhythmogenic substrate in Brugada syndrome using signal-averaged electrocardiogram: clinical implications from a prospective clinical trial.

AIMS: Brugada syndrome (BrS) represents a major cause of sudden cardiac death in young individuals. The risk stratification to forecast future life-threatening events is still controversial. Non-invasive assessment of late potentials (LPs) has been proposed as a risk stratification tool. However, their nature in BrS is still undetermined. The purpose of this study is to assess the electrophysiological determinants of non-invasive LPs. METHODS AND RESULTS: Two hundred and fifty consecutive patients with (Group 1, n = 96) and without (Group 2, n = 154) BrS-related symptoms were prospectively enrolled in the registry. Signal-averaged electrocardiogram (SAECG) was performed in all subjects before undergoing epicardial mapping. Group 1 patients exhibited larger arrhythmogenic substrates (AS; 5.8 ± 2.8 vs. 2.6 ± 2.1 cm2, P < 0.001) with more delayed potentials (220.4 ± 46.0 vs. 186.7 ± 42.3 ms, P < 0.001). Late potentials were present in 82/96 (85.4%) Group 1 and in 31/154 (20.1%) Group 2 individuals (P < 0.001). Patients exhibiting LPs had more frequently a spontaneous Type 1 pattern (30.1% vs. 10.9%, P < 0.001), SCN5A mutation (34.5% vs. 21.2%, P = 0.02), and exhibited a larger AS with longer potentials (5.8 ± 2.7 vs. 2.2 ± 1.7 cm2; 231.2 ± 37.3 vs. 213.8 ± 39.0 ms; P < 0.001, respectively). Arrhythmogenic substrate dimension was the strongest predictor of the presence of LPs (odds ratio 1.9; P < 0.001). An AS area of at least 3.5 cm2 identified patients with LPs (area under the curve 0.88, 95% confidence interval 0.843-0.931; P < 0.001) with a sensitivity of 86%, specificity 88%, positive predictive value 85%, and negative predictive value 89%. CONCLUSION: The results of this study support the role of the epicardial AS as an electrophysiological determinant of non-invasive LPs, which may serve as a tool in the non-invasive assessment of the BrS substrate, as SAECG-LPs could be considered an expression of the abnormal epicardial electrical activity.ClinicalTrials.gov number (NCT02641431; NCT03106701).

Impact of first documented rhythm on cost-effectiveness of extracorporeal cardiopulmonary resuscitation.

OBJECTIVES: Recommendations for extracorporeal cardiopulmonary resuscitation (ECPR) state that appropriate patient selection is important for the sake of efficacy and cost-effectiveness of ECPR. It is not known whether first documented rhythm plays a prominent role in economic outcomes of patients with cardiac arrest who received ECPR. METHODS AND RESULTS: We reviewed the medical records of 120 consecutive patients who received extracorporeal membrane oxygenation (ECMO) assisted CPR due to refractory circulatory collapse between 2008 and 2016 in Urasoe General Hospital. The patients presented with ventricular fibrillation or pulseless ventricular tachycardia (VF/VT; n = 59, 49.2%) or with asystole or pulseless electric activity (ASY/PEA; n = 61, 50.8%) as the first documented rhythm. Multivariate logistic regression analysis identified shorter duration from collapse to ECMO initiation (odds ratio, 1.95 per 10 min; 95% confidence interval, 1.32-2.89, p = 0.001), bystander CPR (odds ratio, 5.53; 95% confidence interval, 1.36-22.5, p = 0.017), and first documented rhythm of VF/VT (odds ratio, 3.93; 95% confidence interval, 1.30-11.8, p = 0.015) as clinical predictors for neurologically intact survival. Total hospital cost per life saved by ECPR for ASY/PEA was approximately twice that for VF/VT ($213,656 vs. $101,669). ECPR yielded Quality adjusted life years (QALYs) of 3.32 at a mean total cost of $39,634 for VF/VT and QALYs of 1.17 at a mean cost of $35,609 for ASY/PEA. The cost per QALYs was $11,081 for VF/VT and $29,447 for ASY/PEA. The incremental cost-effectiveness ratio of ECPR vs. conventional CPR was estimated to be $ 16,246 per QALY gained. CONCLUSION: ECPR for patients presenting with VF/VT was found to be highly cost-effective and ECPR for patients presenting with ASY/PEA was borderline cost-effective.

Health Care Utilization After Ventricular Tachycardia Ablation: A Propensity Score-Matched Cohort Study.

BACKGROUND: Catheter ablation of ventricular tachycardia (VT) can reduce the burden of ventricular arrhythmia (VA) but its effect on health care utilization and costs after such therapy is poorly known. We sought to compare the rates of cardiovascular (CV)-related hospitalizations, survival, and health care costs in patients with recurrent VT treated either with VT ablation or with medical therapy. METHODS: One-hundred implantable cardioverter-defibrillator patients with structural heart disease who underwent VT ablation were included. Propensity score-matched patients with recurrent VT treated with medical therapy were identified from a prospective registry of approximately 7000 de novo implantable cardioverter-defibrillator patients. Outcomes and costs were ascertained using health administrative databases. RESULTS: Among patients who underwent VT ablation, the cumulative rates of VA-related hospitalizations were lower in the 2 years after their ablation procedure compared with the year before (rate ratio, 0.3; 95% confidence interval [CI], 0.22-0.43). Rates of CV-related hospitalization and hospitalization because of VA post index date were similar between the VT ablation and medical therapy groups (hazard ratio [HR], 0.94; 95% CI, 0.57-1.54 and HR, 1.04; 95% CI, 0.57-1.91, respectively). Health care costs in the VT ablation patients were not increased post-ablation compared with the medical management group. The risk of all-cause mortality was lower among patients in the VT ablation group relative to the medical therapy group (HR, 0.64; 95% CI, 0.4-0.99). CONCLUSIONS: Patients who underwent VT ablation experienced a significant reduction in their rate of VA-related hospitalizations. Patients treated with VT ablation had similar rates of CV-related hospitalization compared with those treated with medical therapy without increased health care-related costs.

Use of Antiarrhythmic Medications in Medicare Part D Patients With an Implantable Cardioverter-Defibrillator and Ventricular Tachycardia.

Ventricular tachycardia (VT) is common in cardiomyopathy patients with an implantable cardioverter-defibrillator. This analysis evaluated antiarrhythmic medication use and change in use over time in patients with VT and structural heart disease. Query of Medicare claims identified patients with an implantable cardioverter-defibrillator and VT. Patients with atrial fibrillation or supraventricular tachycardia were excluded. Two cohorts were created of patients enrolled in Medicare Part D for the 12 months before 2007 and 2012. Patients were identified through a search for antiarrhythmic medication fills with a supply covering January 1 of the cohort year. Adjusted logistic regression modeling evaluated the association between patient characteristics and antiarrhythmic medication use. The 2007 (n = 2,334) and 2012 (n = 3,892) Medicare Part D cohorts had similar demographics: median age 76 years, 64%-67% male, and 87%-89% white. Of the 2007 cohort, 1,380 (59%) patients were on a beta blocker, and 484 (20.7%) were on an antiarrhythmic medication (70% amiodarone and 20% sotalol). Between 2007 and 2012, there was a statistically significant higher use of any antiarrhythmic medication (p = 0.014), beta blockers (p <0.0001), mexiletine (p = 0.005), and ranolazine (p <0.0001), while amiodarone use remained unchanged (p = 0.53). After multivariable adjustment, male gender and renal disease were associated with higher antiarrhythmic medication use. In conclusion, although antiarrhythmic medication and beta blocker use in patients with VT increased over time, <1 in 4 patients were on an antiarrhythmic medication and only 65% of the patients were on a beta blocker.

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.

Differences Between Access to Follow-Up Care and Inappropriate Shocks Based on Insurance Status of Implantable Cardioverter Defibrillator Recipients.

Differences in implantable cardioverter defibrillator (ICD) utilization based on insurance status have been described, but little is known about postimplant follow-up patterns associated with insurance status and outcomes. We collected demographic, clinical, and device data from 119 consecutive patients presenting with ICD shocks. Insurance status was classified as uninsured/Medicaid (uninsured) or private/Health Maintenance Organization /Medicare (insured). Shock frequencies were analyzed before and after a uniform follow-up pattern was implemented regardless of insurance profile. Uninsured patients were more likely to present with an inappropriate shock (63% vs 40%, p = 0.01), and they were more likely to present with atrial fibrillation (AF) as the shock trigger (37% vs 19%, p = 0.04). Uninsured patients had a longer interval between previous physician contact and index ICD shock (147 ± 167 vs 83 ± 124 days, p = 0.04). Patients were followed for a mean of 521 ± 458 days after being enrolled in a uniform follow-up protocol, and there were no differences in the rate of recurrent shocks based on insurance status. In conclusion, among patients presenting with an ICD shock, underinsured/uninsured patients had significantly longer intervals since previous physician contact and were more likely to present with inappropriate shocks and AF, compared to those with private/Medicare coverage. After the index shock, both groups were followed uniformly, and the differences in rates of inappropriate shocks were mitigated. This observation confirms the importance of regular postimplant follow-up as part of the overall ICD management standard.

A propensity matched case-control study comparing efficacy, safety and costs of the subcutaneous vs. transvenous implantable cardioverter defibrillator.

BACKGROUND: Subcutaneous implantable cardioverter defibrillators (S-ICD) have become more widely available. However, comparisons with conventional transvenous ICDs (TV-ICD) are scarce. METHODS: We conducted a propensity matched case-control study including all patients that underwent S-ICD implantation over a five-year period in a single tertiary centre. Controls consisted of all TV-ICD implant patients over a contemporary time period excluding those with pacing indication, biventricular pacemakers and those with sustained monomorphic ventricular tachycardia requiring anti-tachycardia pacing. Data was collected on device-related complications and mortality rates. A cost efficacy analysis was performed. RESULTS: Sixty-nine S-ICD cases were propensity matched to 69 TV-ICD controls. During a mean follow-up of 31±19 (S-ICD) and 32±21months (TV-ICD; p=0.88) there was a higher rate of device-related complications in the TV-ICD group predominantly accounted for by lead failures (n=20, 29% vs. n=6, 9%; p=0.004). The total mean cost for each group, including the complication-related costs was £9967±4511 ($13,639±6173) and £12,601±1786 ($17,243±2444) in the TV-ICD and S-ICD groups respectively (p=0.0001). Even though more expensive S-ICD was associated with a relative risk reduction of device-related complication of 70% with a HR of 0.30 (95%CI 0.12-0.76; p=0.01) compared to TV-ICDs. CONCLUSIONS: TV-ICDs are associated with increased device-related complication rates compared to a propensity matched S-ICD group during a similar follow-up period. Despite the existing significant difference in unit cost of the S-ICD, overall S-ICD costs may be mitigated versus TV-ICDs over a longer follow-up period.

Benefit of the Wearable Cardioverter-Defibrillator in Protecting Patients After Implantable-Cardioverter Defibrillator Explant: Results From the National Registry.

OBJECTIVES: This study reports on the time course of reimplantation and benefits of the wearable cardioverter-defibrillator (WCD) in patients post implantable cardioverter-defibrillator (ICD) explantation. BACKGROUND: The WCD is used to treat patients at high risk for ventricular tachycardia (VT) and ventricular fibrillation (VF), including patients with ICD-related infections who undergo device removal and cannot be immediately reimplanted. METHODS: This retrospective study included consecutive patients from 2002 to 2014 who underwent ICD removal because of device-related infection and were prescribed a WCD. WCD-stored electrocardiograms were reviewed. Event outcome was assessed through either the manufacturer WCD registry or the Social Security death index search. RESULTS: A total of 8,058 patients (mean age 62 ± 14 years, 75% male) were included in the analysis. Median time to reimplantation of an ICD was 50 days (interquartile range: 24 to 83 days). While wearing the WCD, 334 patients (4%) experienced 406 VT/VF events, of which 348 events were treated. Shocks were averted in 54 events by conscious patients. The overall 24-h survival, both treated and nontreated, was 93% (312 of 334). VT/VF occurrence was the highest in the initial weeks after ICD removal (0.9%, 0.7%, and 0.7% per week for weeks 1, 2, and 3, respectively). The 12-month cumulative event rate was 10%. For all patients, the 30-day post-event survival was 81%. An ICD was reimplanted in 80% of patients. CONCLUSIONS: The risk of VT/VF reaches 4% during the first 2 months and 10% at 1 year after ICD removal. WCD demonstrated a high efficacy for protecting patients from VT/VF. Clinicians may use the WCD as an ICD alternative when reimplantation is medically delayed.

Lead Integrity Alert Is Useful for Assessment of Performance of Biotronik Linox Leads.

INTRODUCTION: Medtronic's Lead Integrity Alert (LIA) software algorithm is useful for detecting abnormal parameters across various ICD-lead families. However, its utility in the assessment of the Biotronik Linox™ family of high-voltage (HV) leads is unknown. METHODS: We conducted a retrospective cohort study to assess the performance of the LIA algorithm to detect abnormalities and lead failure in Linox ICD-leads. All LIA-enabled Medtronic devices connected to an active Linox lead were included. The alerts were adjudicated by 2 blinded electrophysiologists and correlated with clinical data. RESULTS: Between 2008 and 2012, data from 208 patients with 564 patient-years of follow-up were available for analysis. The median follow-up duration was 32 (IQR 21-41 months). Twenty-one LIA triggers were noted in 20 different patients. The median delay until a positive LIA was 32 months (IQR 21-41 months) postimplant with a 5-year lead survival free from LIA of 76%. Ninety-five percent (19/20) LIA alerts were true lead failures. The most common LIA triggers were short V-V intervals (85%) and nonsustained ventricular tachycardia (85%). Abrupt changes of the ICD-lead impedance occurred in 5/20 triggers. Inappropriate ICD-shocks were strongly associated with a positive LIA (30% vs. 7.4%; P = 0.006). Of the explanted Linox leads 53% had visible abnormalities. The sensitivity, specificity, and positive predictive value for lead failure in the presence of a LIA trigger were 87%, 99.5%, and 95.2%, respectively. CONCLUSIONS: A positive LIA trigger in Biotronik Linox ICD-leads is highly predictive of lead failure. LIA is useful in ongoing surveillance of lead performance.

Inappropriate shocks in the subcutaneous ICD: Incidence, predictors and management.

BACKGROUND: The entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) eliminates the need for transvenous leads, and therefore has the potential to improve lead-longevity and reduce lead-related complications. The S-ICD has a morphology-based sensing algorithm of which inappropriate shocks have been reported. METHODS: We analyzed the incidence, predictors and management of inappropriate shocks in the EFFORTLESS S-ICD Registry, which collects S-ICD implantation information and follow-up data from clinical centers in Europe and New Zealand. RESULTS: During a follow-up of 21 ± 13 months, 48 out of 581 S-ICD patients (71% male, age 49 ± 18 years) experienced 101 inappropriate shocks (8.3%). The most common cause was cardiac signal oversensing (73%), such as T-wave oversensing. Eighteen shocks (18%) were due to supraventricular tachycardias (SVT), of which 15 occurred in the shock-only zone. Cox-proportional hazard modeling using time-dependent covariates demonstrated that patients with a history of atrial fibrillation (HR 2.4) and patients with hypertrophic cardiomyopathy (HR 4.6) had an increased risk for inappropriate shocks, while programming the primary vector for sensing (from xyphoid to V6) reduced the risk. Reprogramming or optimization of SVT treatment after the first clinical event of inappropriate shock was successful in preventing further inappropriate shocks for cardiac oversensing and SVT events. CONCLUSIONS: Inappropriate shocks, mainly due to cardiac oversensing, occurred in 8.3% of the S-ICD patients. Patients with hypertrophic cardiomyopathy or a history of atrial fibrillation were at increased risk, warranting specific attention for sensing and programming in this population.

T-peak to T-end interval for prediction of ventricular tachyarrhythmia and mortality in a primary prevention population with systolic cardiomyopathy.

BACKGROUND: The electrocardiographic T-wave peak to T-wave end interval (Tpe) correlates with dispersion of ventricular repolarization (DVR). Increased DVR increases propensity toward electrical reentry that can cause ventricular tachyarrhythmia. The baseline rate-corrected Tpe (Tpec) has been shown to predict ventricular tachyarrhythmia and death in multiple patient populations but not among cardiomyopathic patients undergoing insertion of an implantable cardioverter-defibrillator (ICD) for primary prevention. OBJECTIVE: The purpose of this study was to assess the risk stratification ability of the Tpec in patients with systolic cardiomyopathy without prior ventricular tachyarrhythmia (ie, the primary prevention population). METHODS: We performed prospective follow-up of 305 patients (73% men; left ventricular ejection fraction [LVEF] 23 ± 7%) with LVEF ≤35% and an ICD implanted for primary prevention. Baseline ECGs were analyzed with automated algorithms. Endpoints were ventricular tachycardia (VT)/ventricular fibrillation (VF), death, and a combined endpoint of VT/VF or death, assessed by device follow-up and Social Security Death Index query. RESULTS: The average Tpec was 107 ± 22 ms. During device clinic follow-up of 31 ± 23 months, 82 patients (27%) had appropriate ICD therapy for VT/VF, and during mortality follow-up of 49 ± 21 months, 91 patients (30%) died. On univariable analysis, Tpec predicted VT/VF, death, and the combined endpoint of VT/VF or death (P < .05 for each endpoint). Multivariable analysis included univariable predictors among demographics, clinical data, laboratory data, medications used, and electrocardiography parameters. After correction, Tpec remained predictive of VT/VF (hazard ratio [HR] per 10-ms increase 1.16, P = .009), all-cause mortality (HR per 10 ms 1.13, P = .05), and the combined endpoint (HR per 10 ms 1.17, P = .001). CONCLUSION: Tpec independently predicts both VT/VF and overall mortality in patients with systolic dysfunction and ICDs implanted for primary prevention.

Sex Differences in Device Therapies for Ventricular Arrhythmias or Death in the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT) Trial.

INTRODUCTION: Studies suggest that women with ischemic heart disease are less likely to experience appropriate ICD therapies for ventricular arrhythmias (VT/VF). We evaluated the influence of sex on arrhythmic events or death in subjects enrolled in MADIT-CRT. METHODS AND RESULTS: Arrhythmic event rates, defined as VT/VF treated with defibrillator therapy or all-cause death, were determined among 1,790 subjects enrolled in MADIT-CRT with documented 3-year follow-up. Predictors of VT/VF/death were identified using multivariate analysis. Ninety-one (21%) women and 466 (35%) men experienced VT/VF/death over the follow-up period. The overall probability of VT/VF/death was significantly lower in women versus men (HR 0.62; P < 0.001). The probability of VT/VF/death was the lowest in women with ischemic heart disease (HR 0.51; P = 0.003). In ICD subjects, the 3-year risk of VT/VF was lower in ischemic women versus men (P = 0.021), and in nonischemic women versus men (P = 0.049). The probability of VT/VF/death was significantly lower in women (HR 0.52; P = 0.007) and men (HR 0.74; P = 0.018) with LBBB who received CRT-D. Appropriate shock therapy strongly correlated with increased risk of death during postshock follow-up in women (HR 5.18; P = 0.001) and men (HR 1.63; P = 0.033); interaction P value of 0.034. CONCLUSION: In this substudy of MADIT-CRT, sex, etiology of heart disease and type of device implanted significantly influenced subsequent risk for VT/VF or death. Women with ischemic heart disease and women with LBBB who received CRT-D had the lowest incidence of VT/VF or death when compared to men. Appropriate shock therapy was a strong predictor of death, particularly in women.