Implantable Cardioverter-defibrillator Therapy For Ventricular Arrhythmia Research Articles

Ventricular activation time as a marker for complex ventricular arrhythmias, sudden cardiac death and ICD implantation in hypertrophic cardiomyopathy

Abstract Background Identification of patients with hypertrophic cardiomyopathy (HCM) who are at high risk of sudden cardiac death (SCD) is essential, as life-threatening ventricular arrhythmias (VAs) can be effectively prevented with an implantable cardioverter defibrillator (ICD). Risk stratification using HCM Risk-SCD score is recommended in the 2014 ESC guidelines for the management of patients with HCM. However, the role of electrocardiogram (ECG) in risk stratification is less well established. Purpose We investigated the association between the ventricular activation time (VAT), an ECG marker of the duration of ventricular depolarization, with the HCM Risk-SCD score, the presence of complex VAs, the implantation of an ICD and ICD-therapy for VAs. Methods Patients with a history of HCM, documented by echocardiography, were studied. The 12-lead ECG and echocardiography were performed on the same day. On ECG, we evaluated the VAT in milliseconds, between the onset of the QRS complex to the peak of R wave on V5 or V6 precordial ECG leads. A careful personal and family history for unexplained syncope and SCD was obtained, respectively. The presence of non-sustained ventricular tachycardia (NSVT) and ICD therapy were assessed either with 48h ECG recording or ICD interrogation. HCM Risk-SCD score was calculated by the corresponding ESC online calculator. Statistical analysis was performed using the SPSS software. Results Thirty-three patients with HCM were included (mean age 51±12 years, 78.8% male). According to the HCM Risk-SCD score, HCM patients were divided into three groups: low-risk (<4, 45.5%), intermediate-risk (4 to <6, 24.2%) and high-risk (>6, 30.3%) for SCD. Approximately half of the HCM patients had episodes of NSVT (48.5%) and an ICD (48.5%). Ventricular activation time was significantly prolonged in high-risk group compared either with intermediate-risk (74±24.5 vs 48.7±16.4, p=0.006) or low-risk (74±24.5 vs 44.3±12.6, p<0.001). HCM patients with NSVT had a significantly prolonged VAT compared with those without NSVT (62.19±25.2 vs 47.06±15.3, p=0.022). Moreover, HCM patients with an ICD had a higher VAT than those without an ICD (62.1±25.2 vs 47±15.3, p=0.003). VAT was also significantly prolonged in the group with appropriate ICD therapy for VAs compared with that without ICD therapy (82.8±22.1 vs 52.2±16.4, p=0.007). Finally, there was a significant positive correlation between VAT and NSVT (r=0.352, p=0.044), history of syncope (r=0.604, p<0.001), HCM risk-SCD score (r=0.493, p=0.004), ICD implantation (r=0.508, p=0.003) and ICD therapy (r=0.648, p=0.007) for VAs while there was not a correlation with the family history of SCD. Conclusion Prolongation of VAT is associated with NSVT, HCM risk score for SCD, ICD implantation and ICD therapy for VAs in patients with HCM and it seems to be a novel, easy to measure, ECG marker for risk stratification. Funding Acknowledgement Type of funding sources: None.

Underrepresentation of women in implantable cardioverter defibrillator trials

There are sex differences in the epidemiology and presentation of ventricular arrhythmias. Sudden cardiac death (SCD) is less common in women than in men. Women have been under-represented in implantable cardioverter defibrillator (ICD) trials evaluating the benefit of ICD therapy for primary and secondary prevention of SCD. Following ICD implantation, women are less likely to experience appropriate ICD therapy for ventricular arrhythmias, consistent with epidemiological findings of a lower rate of SCD in women. Sex differences in ICD implantation rates have also been noted for primary and secondary prevention of SCD in registries and large observational cohort studies. Reasons for these differences are unclear. Age and comorbidities at the time of presentation may be partially responsible, although sex bias, patient preference, or contribution of social determinants of health cannot be excluded. There are many unanswered questions regarding reasons for sex differences in ICD usage and under-representation of women in clinical device trials. Additional investigation is needed to better understand these differences to improve outcome of all patients who are at risk for sudden cardiac arrest.

Burden of Ventricular Arrhythmias in Cardiac Resynchronization Therapy Defibrillation and Implantable Cardioverter-Defibrillator Recipients with Recovered Left Ventricular Ejection Fraction: The Additive Role of Speckle-Tracking Echocardiography

Patients with heart failure undergoing cardiac resynchronization therapy with or without defibrillator function may exhibit recovery of left ventricular ejection fraction (LVEF) during follow-up. Mechanical dispersion (MD; the SD of time to peak longitudinal strain by two-dimensional speckle-tracking echocardiography) is a known predictor of life-threatening ventricular arrhythmias (VAs). Relationships among LVEF recovery, changes in MD, and incidence of VA are still not extensively investigated. In this retrospective study, recipients of cardiac resynchronization therapy defibrillation (n=183) or implantable cardioverter-defibrillators only (n=87) underwent conventional and speckle-tracking echocardiography, both at baseline and after 10 to 12months, and were followed clinically. Both a ≥10% increase in LVEF and a final LVEF > 35% defined echocardiographic response (EchoResp). Reduction in MD ≥10 msec defined MD response (MDResp). Risk for appropriate implantable cardioverter-defibrillator therapy for VAs was assessed using a multivariable Cox hazard model. The prevalence of EchoResp+ and MDResp+ was 39% and 46%, respectively. During follow-up (49.8±33.5months), 74 VA events occurred. The incidence rate (per 100 patient-years) of VAs was lowest in the EchoResp+/MDResp+group (1.66%; 95% CI, 0.69%-3.99%), highest in the EchoResp-/MDResp- group (12.8%; 95% CI, 9.53%-17.2%; P<.0001), and intermediate in the EchoResp-/MDResp+ (5.5%; 95% CI, 3.3%-9.4%) or EchoResp+/MDResp- (5.3%; 95% CI, 3.0%-9.4%) group. Multivariable analysis showed that higher MD at follow-up (>71.4 msec) was associated with VAs independent of whether final LVEF was below or above the guideline-reported cutoff of 35% (P<.05). Among ICD recipients, improvements in both left ventricular function and MD are associated with reduced risk for VAs. In patients whose follow-up LVEFs improved to >35%, risk for VAs, although substantially decreased, remained elevated in the presence of still elevated MD.

Risk of ventricular arrhythmia in cardiac resynchronization therapy responders and super-responders: a systematic review and meta-analysis

Response to cardiac resynchronization therapy (CRT) is associated with improved survival, and reduction in heart failure hospitalization, and ventricular arrhythmia (VA) risk. However, the impact of CRT super-response [CRT-SR, increase in left ventricular ejection fraction (LVEF) to ≥ 50%] on VA remains unclear. We undertook a meta-analysis aimed at determining the impact of CRT response and CRT-SR on risk of VA and all-cause mortality. Systematic search of PubMed, EMBASE, and Cochrane databases, identifying all relevant English articles published until 31 December 2019. A total of 34 studies (7605 patients for VA and 5874 patients for all-cause mortality) were retained for the meta-analysis. The pooled cumulative incidence of appropriate implantable cardioverter-defibrillator therapy for VA was significantly lower at 13.0% (4.5% per annum) in CRT-responders, vs. 29.0% (annualized rate of 10.0%) in CRT non-responders, relative risk (RR) 0.47 [95% confidence interval (CI) 0.39-0.56, P < 0.0001]; all-cause mortality 3.5% vs. 9.1% per annum, RR of 0.38 (95% CI 0.30-0.49, P < 0.0001). The pooled incidence of VA was significantly lower in CRT-SR compared with CRT non-super-responders (non-responders + responders) at 0.9% vs. 3.8% per annum, respectively, RR 0.22 (95% CI 0.12-0.40, P < 0.0001); as well as all-cause mortality at 2.0% vs. 4.3%, respectively, RR 0.47 (95% CI 0.33-0.66, P < 0.0001). Cardiac resynchronization therapy super-responders have low absolute risk of VA and all-cause mortality. However, there remains a non-trivial residual absolute risk of these adverse outcomes in CRT responders. These findings suggest that among CRT responders, there may be a continued clinical benefit of defibrillators.

Impact of Exercise Restriction on Arrhythmic Risk Among Patients With Arrhythmogenic Right Ventricular Cardiomyopathy.

BackgroundPrior studies have shown a close link between exercise and development of arrhythmogenic right ventricular cardiomyopathy. How much exercise restriction reduces ventricular arrhythmia (VA), how genotype modifies its benefit, and whether it reduces risk sufficiently to defer implantable cardioverter‐defibrillator (ICD) placement in arrhythmogenic right ventricular cardiomyopathy are unknown.Methods and ResultsWe interviewed 129 arrhythmogenic right ventricular cardiomyopathy patients (age: 34.0±14.8 years; male: 60%) with ICDs (36% primary prevention) about exercise participation. Exercise change was defined as annual exercise duration and dose in the 3 years before clinical presentation minus that after presentation. The primary outcome was appropriate ICD therapy for VA. During the 5.1 years (interquartile range: 2.7–10.8 years) after presentation, 74% (95/129) patients reduced exercise dose and 85 (66%) patients experienced the primary outcome. In multivariate analyses, top tertile reduction in exercise duration and dose were both associated with less VA (duration: hazard ratio: 0.23 [95% confidence interval, 0.07–0.81]; dose: hazard ratio: 0.14 [95% confidence interval, 0.04–0.44]). Greater reduction in exercise dose conferred greater reduction in VA (P=0.01 for trend). Patients without desmosomal mutations and those with primary‐prevention ICDs benefited more from exercise reduction (P=0.16 and P=0.06 for interaction); however, 58% (18/31) of athletes who reduced exercise dose by >80% still experienced VA.ConclusionsExercise restriction should be recommended to all arrhythmogenic right ventricular cardiomyopathy patients with ICDs. Patients who are “gene‐elusive” and those with primary‐prevention devices may particularly benefit. Exercise reduction is unlikely to reduce arrhythmia sufficiently in high‐risk patients to alter decision‐making regarding ICD implantation.

Predictors and outcomes of cardiac resynchronization therapy extended to the second generator

A proportion of patients who receive cardiac resynchronization therapy with defibrillator (CRT-D) live to receive a second generator. Controversy exists on whether an implantable cardioverter-defibrillator (ICD) should be offered to patients who have normalized or near-normalized left ventricular ejection fraction (LVEF) at the time of generator replacement (GR). The purpose of this study was to evaluate incidence of appropriate ICD therapy after CRT-D GR. This series involved 1026 consecutive patients who underwent CRT-D implant between January 1, 2002 and December 31, 2012. Echocardiography was assessed before the initial device implant and before GR. ICDs were monitored at our device clinic in person or remotely, or both. Of the cohort, 227 patients (22.1%) underwent CRT-D GR at our institution. Approximately 48% of the patients who received new CRT-D generators were no longer meeting the guidelines indication for ICD use at the time of GR. These patients received subsequent appropriate ICD therapies at a significantly lower rate than those with LVEF <35% (12% vs 35%; P < .001). Of these patients, 47 (20.7%) had LVEF improvement to ≥50% at the time of GR. ICD therapy for ventricular arrhythmia in the ischemic group was 18.2%, while no patient in the nonischemic group received ICD therapy from the second generator after GR. Improvement in LVEF after CRT-D GR is associated with significantly reduced incidence of appropriate ICD therapy. Ventricular arrhythmia is less likely to develop with normalized LVEF in nonischemic cardiomyopathy.

Clinical decision tool for CRT-P vs. CRT-D implantation: Findings from PROSE-ICD.

BackgroundCardiac resynchronization therapy (CRT) devices reduce mortality through pacing-induced cardiac resynchronization and implantable cardioverter defibrillator (ICD) therapy for ventricular arrhythmias (VAs). Whether certain factors can predict if patients will benefit more from implantation of CRT pacemakers (CRT-P) or CRT defibrillators (CRT-D) remains unclear.Methods and resultsWe followed 305 primary prevention CRT-D recipients for the two primary outcomes of HF hospitalization and ICD therapy for VAs. Serum biomarkers, electrocardiographic and clinical variables were collected prior to implant. Multivariable analysis using Cox-proportional hazards model was used to fit the final models. Among 282 patients with follow-up outcome data, 75 (26.6%) were hospitalized for HF and 31 (11%) received appropriate ICD therapy. Independent predictors of HF hospitalization were atrial fibrillation (HR = 1.8 (1.1,2.9)), NYHA class III/IV (HR = 2.2 (1.3,3.6)), ejection fraction <20% (HR = 1.7 (1.1,2.7)), HS-IL6 >4.03pg/ml (HR = 1.7 (1.1,2.9)) and hemoglobin (<12g/dl) (HR = 2.2 (1.3,3.6)). Independent predictors of appropriate therapy included BUN >20mg/dL (HR = 3.0 (1.3,7.1)), HS-CRP >9.42mg/L (HR = 2.3 (1.1,4.7)), no beta blocker therapy (HR = 3.2 (1.4,7.1)) and hematocrit ≥38% (HR = 2.7 (1.03,7.0)). Patients with 0–1 risk factors for appropriate therapy (IR 1 per 100 person-years) and ≥3 risk factors for HF hospitalization (IR 23 per 100-person-years) were more likely to die prior to receiving an appropriate ICD therapy.ConclusionsClinical and biomarker data can risk stratify CRT patients for HF progression and VAs. These findings may help characterize subgroups of patients that may benefit more from the use of CRT-P vs. CRT-D systems.Trial registrationClinicalTrials.gov NCT00733590

Abstract 17176: Prognostic Importance of Defibrillator Appropriate Shocks and Anti Tachycardia Pacing in Mild Heart Failure Patients

Background: Previous studies had shown that patients with heart failure (HF) who receive implantable cardioverter-defibrillator (ICD) for primary prevention are at increased risk for mortality if they receive a shock. However, information about the prognostic importance of therapies [both shock and anti-tachycardia pacing (ATP)] delivered for a different ventricular arrhythmia (VA) rate is limited. Methods: We evaluated the risk for death among 1790 ICD implanted patients from the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy using a time dependent analysis. Patients were categorized to mutually exclusive groups by either the rate of the treated VA (categorized at 200 bpm) or the type of the therapy and VA rate (ATP or shock both categorized at 200 bpm), the reference group was patients that had no device therapy. Results: During a median follow-up time of 4 years 423 patients had appropriate ICD therapy, with 163 receiving therapy for VA&lt; 200 bpm only, and 260 for VA≥200 bpm. ICD therapy for VA≥200 was associated with significant increased mortality (HR=2.27 CI 1.48-3.48, p&lt;.001), while therapy for VA&lt;200 was not different from the no therapy group (HR=1.45 CI=0.86-2.44, p=0.162). Accordingly, in a second model both shocks and ATPs for VA≥200 were associated with increased mortality (HR=2.96 CI 1.91-4.60 p&lt;.001 and HR=2.22 CI 0.96-5.14, p=0.063 respectively), while shocks and ATPs for VA&lt;200 did not differ from the no therapy group (HR=1.43 CI 0.52-3.92 p=0.489 and HR=1.43 CI 0.80-2.56, p=0.232 respectively). Conclusions: In mild HF patients, who receive ICD for primary prevention, mortality is associated with the rate of the arrhythmia rather than the device rendered therapy.

The prognostic impact of pre-implantation hyponatremia on morbidity and mortality among patients with left ventricular dysfunction and implantable cardioverter-defibrillators

Hyponatremia is commonly observed among patients with left ventricular (LV) dysfunction and is a marker for adverse outcomes. We aimed to determine the prognostic significance of pre-implant hyponatremia on the outcomes of death, acute decompensated heart failure (ADHF) and appropriate implantable cardioverter-defibrillator (ICD) therapy for ventricular arrhythmias among patients with ICDs. The study population consisted of patients with an ejection fraction ≤40% undergoing ICD implantation (n = 911) for the primary or secondary prevention of sudden cardiac death from 1997 to 2007. The predictive value of the severity of pre-implantation hyponatremia stratified into mild hyponatremia (n = 268, sodium 134-136 mmol/L), moderate hyponatremia (n = 105, sodium 131-133 mmol/L), and severe hyponatremia (n = 31, sodium ≤130 mmol/L) on the risk of death, ADHF, and appropriate ICD therapy for ventricular arrhythmias as compared with patients a normal serum sodium (n = 507, sodium ≥ 137 mmol/L), was calculated using multivariable Cox proportional hazards analyses. During a mean follow-up of 775 ± 750 days as the severity of hyponatremia (from a normal sodium to severe hyponatremia) increased an incremental incidence of death (25% to 61%, P < 0.001) and ADHF (11% to 26%, P = 0.004) was observed with a reduced incidence of ICD therapy for ventricular tachycardia/ventricular fibrillation (37-29%, P = 0.037). Compared with the normal sodium cohort, patients with severe hyponatremia demonstrated an increased risk of death [adjusted hazard ratio (AHR) 2.69 (95% confidence interval, CI 1.57-4.59), P = 0.004] and ADHF [AHR 2.98 (95% CI 1.41-6.30), P = 0.004], with a lower probability of appropriate ICD therapy [AHR 0.68 (95% CI 0.27-0.88), P = 0.031]. Hyponatremia is commonly observed among ICD recipients with LV dysfunction. Patients with an increasing severity of hyponatremia are at increased risk of death and HF related morbidity with a reduced incidence of appropriate ICD therapy particularly among patients with severe hyponatremia.

Association Between Left Ventricular Ejection Fraction Post-Cardiac Resynchronization Treatment and Subsequent Implantable Cardioverter Defibrillator Therapy for Sustained Ventricular Tachyarrhythmias

Although cardiac resynchronization therapy (CRT) can improve left ventricular ejection fraction (LVEF), it is not known whether a specific level of improvement will predict future implantable cardioverter defibrillator (ICD) therapy. CRT-defibrillator (CRT-D) was implanted in 423 patients at 1 institution between October 2, 2001 and January 19, 2007. A retrospective analysis was performed to evaluate the relationship between post-CRT-D LVEF and ICD therapy for ventricular tachyarrhythmias. A landmark population of 270 patients, with post-CRT-D LVEF measured and no ICD therapy within 1 year of device implantation, was followed for subsequent outcomes. Of these, 22 patients (8.2%) had subsequent appropriate ICD therapy over a median follow-up of 1.5 years. The estimated 2-year risk of appropriate ICD therapy is 3.0% (95% confidence interval [95% CI], 0%-6.3%), 2.1% (95% CI, 0%-5.0%), and 1.5% (95% CI, 0%-3.9%) for post-CRT-D LVEF of 45%, 50%, and 55%, respectively. In patients with a primary prevention indication for CRT-D, the estimated 2-year risk is 3.3% (95% CI, 0%-7.3%), 2.5% (95% CI, 0%-6.1%), and 1.9% (95% CI, 0%-5.1%) for post-CRT-D LVEF of 45%, 50%, and 55%, respectively. When a CRT responder demonstrates near normalization in LVEF to ≥45%, the incidence of ICD therapy for ventricular arrhythmias becomes low. Future studies are needed to determine whether an ICD is still needed in some of these patients at the time of generator replacement.

Abstract 18694: Connexin-43 Gene Variants are Associated with Risk of Ventricular Arrhythmias in Patients with a Depressed Ejection Fraction

Background: Despite the life-saving benefits of implantable cardioverter defibrillator (ICD) therapy, only a minority of primary prevention patients ultimately receive ICD therapy for ventricular arrhythmias. Genetic risk factors may improve current risk stratification models. Connexin-43 is the predominant component of gap junctions in ventricular myocardium. Accordingly, we hypothesized that common genetic variants in connexin-43 are associated with risk of ventricular arrhythmias in patients with reduced ejection fraction. Methods: Caucasian individuals with an impaired ejection fraction (&lt; 35%) who had received a primary prevention ICD were identified from the Duke Electrophysiology Genetic Studies (EPGEN) database (N=252). Six connexin-43 single-nucleotide polymorphisms (SNPs) were genotyped using Taqman. Association with ventricular arrhythmia, defined as an appropriate ICD shock or anti-tachycardia pacing for ventricular tachycardia or fibrillation, was tested using univariate and multivariable logistic regression models adjusted for sex, age, hypertension, hyperlipidemia, smoking, diabetes and coronary artery disease status. Results: Over a mean follow-up of 2.3 years, there were 42 cases of ventricular arrhythmia. In univariate analyses, two SNPs in complete linkage disequilibrium, rs11961755 and rs10456940, were associated with risk of ventricular arrhythmia (19% of cases vs. 44% of controls carried at least one copy of the minor allele, p=0.003 in the dominant genetic model). In multivariable models, these SNPs were associated with an odds ratio for ventricular arrhythmia of 0.27 (95% confidence interval 0.11-0.62, p=0.002). These relationships were not observed in African-American subjects (N=124). No other connexin-43 SNPs were associated with events. Conclusions: Genetic variants in connexin-43 are independently associated with risk of ventricular arrhythmia in patients referred for primary prevention ICDs. Prospective studies should address whether these novel markers improve risk stratification.

Predictors of Appropriate ICD Therapy in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy: Long Term Experience of a Tertiary Care Center

IntroductionArrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare genetically transmitted disease prone to ventricular arrhythmias. We therefore investigated the clinical, echocardiographical and electrophysiological predictors of appropriate implantable cardioverter defibrillator (ICD) therapy in patients with ARVC.MethodsA retrospective analysis was performed in 26 patients (median age of 40 years at diagnosis, 21 males and 5 females) with ARVC who underwent ICD implantation.ResultsOver a median (range) follow-up period of 10 (2.7, 37) years, appropriate ICD therapy for ventricular arrhythmias was documented in 12 (46%) out of 26 patients. In all patients with appropriate ICD therapy the ICD was originally inserted for secondary prevention. Median time from ICD implantation to ICD therapy was 9 months (range 3.6, 54 months). History of heart failure was a significant predictor of appropriate ICD therapy (p = 0.033). Left ventricular disease involvement (p = 0.059) and age at implantation (p = 0.063) were borderline significant predictors. Patients with syncope at time of diagnosis were significantly less likely to receive ICD therapy (p = 0.02). Invasive electrophysiological testing was not significantly associated with appropriate ICD therapy.ConclusionIn our cohort of patients with ARVC, history of heart failure was a significant predictor of appropriate ICD therapy, whereas left ventricular involvement and age at time of ICD implantation were of borderline significance. These predictors should be tested in larger prospective cohorts to optimize ICD therapy in this rare cardiomyopathy.

Infarct tissue characterization in implantable cardioverter-defibrillator recipients for primary versus secondary prevention following myocardial infarction: a study with contrast-enhancement cardiovascular magnetic resonance imaging

Knowledge about potential differences in infarct tissue characteristics between patients with prior life-threatening ventricular arrhythmia versus patients receiving prophylactic implantable cardioverter-defibrillator (ICD) might help to improve the current risk stratification in myocardial infarction (MI) patients who are considered for ICD implantation. In a consecutive series of (ICD) recipients for primary and secondary prevention following MI, we used contrast-enhanced (CE) cardiovascular magnetic resonance (CMR) imaging to evaluate differences in infarct tissue characteristics. Cine-CMR measurements included left ventricular end-diastolic and end-systolic volumes (EDV, ESV), left ventricular ejection fraction (LVEF), wall motion score index (WMSI), and mass. CE-CMR images were analyzed for core, peri, and total infarct size, infarct localization (according to coronary artery territory), and transmural extent. In this study, 95 ICD recipients were included. In the primary prevention group (n = 66), LVEF was lower (23 ± 9 % vs. 31 ± 14 %; P < 0.01), ESV and WMSI were higher (223 ± 75 ml vs. 184 ± 97 ml, P = 0.04, and 1.89 ± 0.52 vs. 1.47 ± 0.68; P < 0.01), and anterior infarct localization was more frequent (P = 0.02) than in the secondary prevention group (n = 29). There were no differences in infarct tissue characteristics between patients treated for primary versus secondary prevention (P > 0.6 for all). During 21 ± 9 months of follow-up, 3 (5 %) patients in the primary prevention group and 9 (31 %) in the secondary prevention group experienced appropriate ICD therapy for treatment of ventricular arrhythmia (P < 0.01). There was no difference in infarct tissue characteristics between recipients of ICD for primary versus secondary prevention, while the secondary prevention group showed a higher frequency of applied ICD therapy for ventricular arrhythmia.

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ORAL PRESENTATION

Primary Prevention Implantable Cardioverter Defibrillator Recipients: The Need for Defibrillator Back-Up After an Event-Free First Battery Service-Life

In primary prevention implantable cardioverter defibrillator (ICD) patients, the relatively low incidence of ventricular arrhythmias (VA) combined with the limited battery service-life potentially results in a large group of patients who have had no benefit of the ICD during first service-life. Data on the occurrence of VA after device replacement remain scarce. The purpose of this study was to give clinicians better insight in the dilemma whether or not to replace an ICD after an event-free first battery service-life. All patients treated with an ICD for primary prevention who had a replacement because of battery depletion and who did not receive appropriate therapy before device replacement were included in this analysis. Of 154 primary prevention ICD patients needing replacement because of battery depletion, 114 (74%) patients (mean age 61 ± 11 years, 80% male) had not received appropriate ICD therapy for VA. Follow-up was 71 ± 24 months after the initial implantation and 25 ± 21 months after device replacement. Following replacement, 3-year cumulative incidence of appropriate therapy in response to ventricular tachycardia or ventricular fibrillation was 14% (95% CI 5-22%). The majority of primary prevention ICD patients do not experience VA during first battery service-life. However, a substantial part of these patients does experience appropriate ICD therapy after replacement.

Prediction of Appropriate Defibrillator Therapy in Heart Failure Patients Treated With Cardiac Resynchronization Therapy

The necessity of implantable cardioverter-defibrillator (ICD) implantation in patients with systolic heart failure (HF) who undergo cardiac resynchronization therapy (CRT) may be questioned. The aim of this study was to identify patients at low risk for sustained ventricular arrhythmia. One hundred sixty-nine consecutive patients with HF (mean age 60 +/- 12 years, 125 men, 73% in New York Heart Association class III) referred for CRT and prophylactic, primary prevention ICD implantation underwent baseline clinical and echocardiographic assessment and regular device follow-up. The primary study end point was appropriate ICD therapy. During a mean follow-up period of 654 +/- 394 days, 35 patients (21%) had sustained ventricular arrhythmias requiring appropriate ICD therapy. Of the 3 patients who experienced sudden cardiac death, 2 had been treated with appropriate ICD therapy before sudden cardiac death. In a multivariate model, only history of nonsustained ventricular tachycardia (p = 0.001), a severely (<20%) decreased left ventricular ejection fraction (p = 0.001), and digitalis therapy (p = 0.08) independently predicted appropriate ICD therapy. Patients with 0 (n = 46), 1 (n = 36), 2 (n = 73), and 3 (n = 14) risk factors for appropriate ICD therapy had a 7%, 14%, 27%, and 64% and 0%, 6%, 10%, and 43% incidence of appropriate ICD therapy for ventricular arrhythmias and for rapid ventricular tachycardia or ventricular fibrillation, respectively. In conclusion, apart from commonsense considerations (age and significant co-morbidities), ICD addition seems ineffective in CRT patients without nonsustained ventricular tachycardia, digoxin therapy, and severely reduced left ventricular systolic function.

Time‐Dependence of Appropriate Implantable Defibrillator Therapy in Patients with Ischemic Cardiomyopathy

Little is known about the risk of appropriate implantable cardioverter-defibrillator (ICD) therapy outside the context of controlled clinical trials where routine practice patients are followed for longer durations and questions of device replacement frequently arise. We assessed the incidence and time-dependence of appropriate ICD therapy in a routine clinical practice primary prevention population with prior myocardial infarction (MI) and reduced left ventricular ejection fraction (LVEF). Patients with prior MI and LVEF <or=35%, who received an ICD at our institution (1995-2005) for primary prevention, were identified. Incidence and time-dependence of first appropriate ICD therapy for ventricular arrhythmia (VA) and rapid VA (cycle length <or=260 ms) were determined. Of 525 ICD recipients for primary prevention, 115 (22%) had appropriate ICD therapy. Incidence of first appropriate ICD therapy was highest in the first year postimplant (20%), decreased to 12% in year 2, and remained at 6-11% yearly thereafter. A similar trend was observed with rapid VA, a higher risk in the first year (6%), and a lower but persistent risk thereafter (3.8% in year 7). In a routine clinical practice primary prevention population with prior MI and LVEF <or=35%, the incidence of first ICD therapy for VA, including potentially life-threatening VA, is highest in the first year postimplant, and persists for up to seven years thereafter. Risk of first appropriate ICD therapy persists over time, and thus replacement of ICDs appears to be indicated for all patients.