Comparison and predictors of implantable cardioverter-defibrillator therapy for primary and secondary prevention.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) are effective in detecting and treating ventricular arrhythmias. Studies on ICD therapy for different indications (primary and secondary prevention) and possible predictors of ICD therapy are limited. In this study, the incidence and type of ICD therapy were related to the indication and the underlying cardiac pathology. METHODS: A single-centre, retrospective and observational study was performed of 482 patients who underwent ICD implantation for primary (53.3%) or secondary prevention (46.7%) between 2015 and 2020 at the Radboud University Medical Centre. RESULTS: During a median follow-up of 2.4 years (interquartile range 0.2-3.9), the occurrence of appropriate ICD therapy for primary versus secondary prevention was 9.7% and 27.6%, respectively (p < 0.001). Time to appropriate ICD therapy was significantly shorter in the secondary prevention group (p < 0.001). No difference in ICD therapy was seen for different underlying aetiologies. In the majority of cases (70%) ICD therapy was given for ventricular tachycardia (VT). The occurrence of adverse events (16.3% vs 17.3%, p = 0.772), hospitalisation for cardiovascular reasons (29.2% vs 35.1%, p = 0.559) and all-cause mortality (12.5% vs 11.6%, p = 0.763) were similar in both groups. Male gender (3.53, 95% confidence interval (CI) (1.003, 12.403), p = 0.049) and secondary prevention indication (4.90, 95% CI (1.495, 16.066), p = 0.009) were predictors of appropriate ICD therapy. CONCLUSION: The risk associated with appropriate ICD therapy is higher in secondary prevention patients, who have their first therapy within a shorter time frame after device implantation. Rates of complications, hospitalisation and all-cause mortality are comparable. Future treatment options should target the prevention of ICD therapy, mainly by preventing the recurrence of VT.

Primary prevention implantable cardioverter-defibrillators in hypertrophic cardiomyopathy-Are there predictors of appropriate therapy?

BACKGROUND: Identifying patients with hypertrophic cardiomyopathy (HCM) who warrant a primary prevention implantable cardioverter-defibrillator (ICD) is crucial. ICDs are effective in terminating life-threatening arrhythmias; however, ICDs carry risks of complications. OBJECTIVE: The purpose of this study was to assess the incidence and predictors of appropriate ICD therapies, inappropriate shocks, and device-related complications in patients with HCM and primary prevention ICDs. METHODS: All patients with HCM who underwent primary prevention ICD implantation at Toronto General Hospital between September 2000 and December 2017 were identified. Therapies (shocks or antitachycardia pacing) for ventricular tachycardia >180 beats/min or ventricular fibrillation were considered appropriate. RESULTS: Three hundred two patients were followed for a mean 6.1 ± 4.3 years (1801 patient-years of follow-up). Thirty-eight patients (12.6%) received at least 1 appropriate ICD therapy (2.3%/y); the 5-year cumulative probability of receiving appropriate ICD therapy was 9.6%. None of the conventional risk factors nor the European Society of Cardiology risk score was associated with appropriate ICD therapy. In multivariable analysis, age < 40 years at implantation and atrial fibrillation were independent predictors of appropriate ICD therapy. In a subgroup of patients who had undergone cardiac magnetic resonance imaging before ICD implantation, severe late gadolinium enhancement was the strongest predictor of appropriate ICD therapies. ICD-related complications or inappropriate shocks occurred in 87 patients (28.8%), with an inappropriate shock rate of 2.1%/y; the 5-year cumulative probability was 10.7%. CONCLUSION: The incidence of appropriate ICD therapies in patients with HCM and primary prevention ICDs is lower than previously reported; a high proportion of patients suffer from an ICD-related complication. Traditional risk factors have low predictive utility. Severe late gadolinium enhancement, atrial fibrillation, and young age are important predictors of ventricular tachyarrhythmias in HCM.

Long-Term Outcomes Among a Nationwide Cohort of Patients Using an Implantable Cardioverter-Defibrillator: UMBRELLA Study Final Results.

Background Large-scale studies describing modern populations using an implantable cardioverter-defibrillator (ICD) are lacking. We aimed to analyze the incidence of arrhythmia, device interventions, and mortality in a broad spectrum of real-world ICD patients with different heart disorders. Methods and Results The UMBRELLA study is a prospective, multicenter, nationwide study of contemporary patients using an ICD followed up by remote monitoring, with a blinded review of arrhythmic episodes. From November 2005 to November 2017, 4296 patients were followed up. After 46.6±27.3 months, 16 067 episodes of sustained ventricular arrhythmia occurred in 1344 patients (31.3%). Appropriate ICD therapy occurred in 27.3% of study population. Patients with ischemic cardiomyopathy (hazard ratio [HR], 1.51; 95% CI, 1.29-1.78), dilated cardiomyopathy (HR, 1.28; 95% CI, 1.07-1.53), and valvular heart disease (HR, 1.94; 95% CI, 1.43-2.62) exhibited a higher risk of appropriate ICD therapies, whereas patients with hypertrophic cardiomyopathy (HR, 0.72; 95% CI, 0.54-0.96) and Brugada syndrome (HR, 0.25; 95% CI, 0.14-0.45) showed a lower risk. All-cause death was 13.4% at follow-up. Ischemic cardiomyopathy (HR, 3.09; 95% CI, 2.58-5.90), dilated cardiomyopathy (HR, 3.33; 95% CI, 2.18-5.10), and valvular heart disease (HR, 3.97; 95% CI, 2.25-6.99) had the worst prognoses. Delayed high-rate detection was enabled in 39.7% of patients, and single-zone programming occurred in 52.6% of primary prevention patients. Both parameters correlated with lower risk of first appropriate ICD therapy, with no excess risk of mortality. The rate of inappropriate shocks at follow-up was low (6%) and did not differ among type of ICD but was lower in SmartShock-capable devices. Conclusions Irrespective of the cause, contemporary ICD patients with heart failure-related disorders had a similar risk of ICD life-saving interventions and death. Current ICD programming recommendations still need to be implemented. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NTC01561144.

[Electrical storm : Recognition and management]. / Elektrischer Sturm : Erkennung und Beherrschung.

The electrical storm (ES) defined as ≥3 sustained episodes of ventricular tachycardia within a 24 h period comprises a wide spectrum of clinical entities. Mostly patients suffer from severe heart insufficiency and comorbidities making an immediate transfer into a heart center with multidisciplinary expertise in the treatment of ES mandatory. As these patients are often traumatized by ongoing tachycardia despite multiple cardioversions, early deep sedation and ß­blockade to break the vicious circle of sympathico-adrenergic hyperactivation is very effective. Multiple ICD discharges suggesting the diagnosis of ES are inadequate in one third of cases. Pharmacological suppression, frequency control or ablation of supraventricular tachycardias (SVT) help in most cases. In some cases "oversensing" demands optimization of ICD programming. Even so not all adequate ICD discharges, however, are necessary. Since every ICD discharge worsens the patient's prognosis, any kind of ICD discharge should be prevented as far as hemodynamically feasible. After clinical stabilization of the patient with simultaneous acquisition of ECG and testing for reversible causes of ES, ES should be terminated by external or internal cardioversion followed by urgent but elective therapy. Some cases of ES, however, may require immediate escalation of therapy with emergency ablation or revascularization sometimes with circulatory support systems. If ES still persists, a further step in escalation may be taken by cardiac sympathetic denervation. Due to the poor prognosis of patients after ES, close monitoring of the patient, preferably with telemedicine, is indicated.

Programming implantable cardioverter-defibrillator in primary prevention: Guideline concordance and outcomes.

BACKGROUND: Inappropriate therapy is a common adverse effect in patients with an implantable cardioverter-defibrillator (ICD) that may be prevented by appropriate programming. OBJECTIVE: The purpose of this study was to assess the outcomes of device programming based on a 2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement and a 2019 focused update on optimal ICD programming and testing. METHODS: Consecutive patients who underwent ICD insertion for primary prevention from 2014-2016 at 3 centers were included in the retrospective analysis. Patients were classified into 2 groups based on the tachycardia programming at the time of implant: guideline concordant group (GC) and non-guideline concordant group (NGC). Kaplan-Meier analysis and Cox proportional hazard models were used to estimate freedom from ICD therapy (antitachycardia pacing or shock), ICD shock, and death. RESULTS: A total of 772 patients were included in the study (mean age 63.3 ± 13.8 years). Of this total, 258 patients (33.4%) were in the GC group and 514 patients (66.6%) were in the NGC group. During mean follow-up of 2.02 ± 0.91 years, guideline concordant programming was associated with a 53% reduction in ICD therapy (P <.01) and 50% reduction in ICD shock (P = .02). There were no significant differences in mortality (6% in GC group vs11% in NGC group; P = .22). CONCLUSION: Only one-third of the studied population had an ICD device programmed in concordance with current guidelines. ICD programming based on the current guidelines was associated with a significantly lower rate of ICD therapy and shock without changes in mortality during intermediate-term follow-up.

Predictors and outcomes of atrial tachyarrhythmia among patients with implantable defibrillators.

BACKGROUND: Atrial tachyarrhythmias (ATAs) are common among heart failure (HF) patients. OBJECTIVE: The purpose of this study was to assess predictors for the development of new ATA and its components (atrial fibrillation/flutter [AF], supraventricular tachycardia [SVT]), and their association with subsequent clinical outcomes. METHODS: We assessed predictors for first and recurrent ATA, AF, and SVT among 1500 patients in MADIT-RIT (Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy). We also investigated the association of new ATA, AF, or SVT with subsequent ventricular arrhythmia (VA), adverse events (HF hospitalization, syncope, or death), or death by time-dependent analysis. RESULTS: During 17 months of follow-up, 286 patients (19%) developed new ATA, of whom 92 (6%) had AF and 194 (12%) had SVT. Younger age (≤65 years), diastolic blood pressure ≥72 mm Hg, heart rate ≥63 bpm, absence of diabetes, and prior atrial arrhythmia were independent predictors of ATA. Prior atrial arrhythmia was the only predictor of AF (hazard ratio 3.14; P <.001). New ATA was associated with significantly increased risk for subsequent VA (HR 2.12; P <.001), increased adverse events (HR 1.42; P <.001), and death (HR 1.85; P = .038). New AF and new SVT were both independently associated with >2-fold increased risk for the development of subsequent VA (HR 2.21; P = .012l and HR 2.15; P <.001, respectively) and adverse events. CONCLUSION: Among MADIT-RIT patients, younger age, absence of diabetes, higher blood pressure, higher heart rate, and prior atrial arrhythmia predicted device-detected ATA. Both AF and SVT were associated with increased risk for subsequent VA and adverse events. Aggressive management should be considered in HF patients who develop new-onset, device-detected ATA to improve clinical outcomes.

Incidence and predictors of implantable cardioverter-defibrillator therapy and its complications in idiopathic ventricular fibrillation patients.

AIMS: Idiopathic ventricular fibrillation (IVF) is a rare cause of sudden cardiac arrest. Implantable cardioverter-defibrillator (ICD) implantation is currently the only treatment option. Limited data are available on the prevalence and complications of ICD therapy in these patients. We sought to investigate ICD therapy and its complications in patients with IVF. METHODS AND RESULTS: Patients were selected from a national registry of IVF patients. Patients in whom no underlying diagnosis was found during follow-up were eligible for inclusion. Recurrence of ventricular arrhythmia (VA) was derived from medical and ICD records, electrogram records of ICD therapies were used to differentiate between appropriate or inappropriate interventions. Independent predictors for appropriate ICD shock were calculated using cox regression. In 217 IVF patients, recurrence of sustained VAs occurred in 66 patients (30%) during a median follow-up period of 6.1 years. Ten patients died (4.6%). Thirty-eight patients (17.5%) experienced inappropriate ICD therapy, and 32 patients (14.7%) had device-related complications. Symptoms before cardiac arrest [hazard ratio (HR): 2.51, 95% confidence interval (CI): 1.48-4.24], signs of conduction disease (HR: 2.27, 95% CI: 1.15-4.47), and carrier of the DPP6 risk haplotype (HR: 3.24, 1.70-6.17) were identified as independent predictors of appropriate shock occurrence. CONCLUSION: Implantable cardioverter-defibrillator therapy is an effective treatment in IVF, treating recurrences of potentially lethal VAs in approximately one-third of patients during long-term follow-up. However, device-related complications and inappropriate shocks were also frequent. We found significant predictors for appropriate ICD therapy. This may imply that these patients require additional management to prevent recurrent events.

Ablation of atrial fibrillation in patients with Brugada syndrome: A systematic review of the literature.

Supraventricular arrhythmias are common in Brugada syndrome (BS), and notoriously difficult to manage with medical therapy secondary to associated risks. Pulmonary vein isolation (PVI) is often utilized instead, but its outcomes in this population are not well-known. We aim to provide a holistic evaluation of interventional treatment for Atrial fibrillation (AF) in the BS population. Electronic databases Medline, Embase, Cinahl, Cochrane, and Scopus were systematically searched for publications between 01/01/1995 and 12/31/2017. Studies were screened based on predefined inclusion and exclusion criteria. A total of 49 patients with BS and AF were included. Age range from 28.8 to 64 years, and 77.5% were male. 38 patients were implanted with implantable cardioverter-defibrillators (ICD) at baseline, and of them, 39% suffered inappropriate shocks for rapid AF. 34/49 (69%) of patients achieved remission following a single PVI procedure. Of the remaining, 13 patients underwent one or more repeat ablation procedures. Overall, 45/49 (91.8%) of patients remained in remission during long-term follow-up after one or more PVI procedures in the absence of antiarrhythmic drug (AAD) therapy. Postablation, no patients suffered inappropriate ICD shock. Furthermore, no major complications secondary to PVI occurred in any patient. AF ablation achieves acute and long-term success in the vast majority of patients. It is effective in preventing inappropriate ICD therapy secondary to rapid AF. Complication rates of PVI in BS are low. Thus, in light of the risks of AADs and risk of inappropriate ICD shocks in the BS population, catheter ablation could represent an appropriate first-line therapy for paroxysmal atrial fibrillation in BS patients.

Role of medical reaction in management of inappropriate ventricular arrhythmia diagnosis: the inappropriate Therapy and HOme monitoRiNg (THORN) registry.

AIMS: Implantable cardioverter-defibrillators (ICDs) reduce sudden cardiac death in selected patients but inappropriate ICD shocks have been associated with increased mortality. The THORN registry aims to describe the rate of inappropriate ventricular arrhythmia diagnoses and therapies in patients followed by remote monitoring, as well as the following delay to next patient contact (DNPC). METHODS AND RESULTS: One thousand eight hundred and eighty-two patients issued from a large remote monitoring database first implanted with an ICD for primary or secondary prevention in 110 French hospitals from 2007 to 2014 constitute the THORN population. Among them, 504 patients were additionally followed prospectively for evaluation of the DNPC. Eight hundred and ninety-five out of 1551 (58%) patients had ischaemic heart disease and 358/771 (46%) were implanted for secondary prevention. During 13.7 ± 3.4 months of follow-up, the prevalence of first inappropriate diagnosis in a ventricular arrhythmia zone with enabled therapy was 162/1882 (9%). Among those patients, 122/162 (75%) suffered at least one inappropriate therapy and 58/162 (36%) at least one inappropriate shock. Eighty-three out of 162 (51%) of first inappropriate diagnosis occurred during the first 4 months following implantation. The median DNPC was 8 days (interquartile range 1-26). At least one other day with recording of an inappropriate diagnosis of the same cause occurred in 13/43 (30%) of available DNPC periods, with an inappropriate therapy in 7/13 (54%). CONCLUSION: Inappropriate diagnoses occurred in 9% of patients implanted with an ICD during the first 14 months. The DNPC after inadequate ventricular arrhythmia diagnoses remains long in daily practice and should be optimized. CLINICALTRIALS.GOV IDENTIFIER: NCT01594112.

Clinical outcome in patients with implantable cardioverter-defibrillator and cancer: a nationwide study.

AIMS: Patients with cancer are insufficiently represented in randomized clinical trials investigating efficacy of implantable cardioverter-defibrillators (ICDs). We aimed to describe outcomes in patients with a pre-existing diagnosis of cancer at time of ICD implantation. METHODS AND RESULTS: We utilized Danish nationwide registries to identify primary and secondary prevention ICD implantations from 2007 to 2012. Multivariable Cox models were used to assess the risk of appropriate ICD therapy and mortality in patients with and without cancer at time of implantation. During a median follow-up of 2.1 years, 2935 primary prevention ICD and 2730 secondary prevention ICD implantations were identified. Out of these [289 (5.1%)] had pre-existing cancer [primary 140 (4.8%), secondary 149 (5.5%)]. No differential risk for appropriate ICD therapy was found between patients with or without cancer, [primary cancer: 19/140, no cancer: 380/2795, hazard ratio (HR) = 1.07 (0.67-1.69)] and [secondary cancer: 42/149, no cancer: 699/2581, HR = 1.28 (0.93-1.75)]. In primary patients, cancer was not associated with higher risk of 1-year [cancer: 10/140, no cancer: 133/2795, HR = 1.20 (0.84-2.28)] or all-time mortality [cancer: 22/140, no cancer: 339/2795, HR = 1.13 (0.74-1.75)]. In secondary patients, cancer was associated with a higher 1-year [cancer: 19/149, no cancer: 108/2581, HR = 2.62 (1.60-4.29)] and all-time mortality [cancer: 44/149, no cancer: 315/2581, HR = 2.36 (1.71-3.24)]. CONCLUSION: Implantable cardioverter-defibrillators were implanted in a minority of cancer patients. No difference in risk of appropriate therapy was observed between cancer and non-cancer patients, regardless of implant indication. Cancer was associated with increased mortality in secondary prevention ICD patients, but not in primary prevention ICD patients. In secondary prevention ICD patients, the majority of deaths were attributable to cancer.

Two cases of inappropriate implantable cardioverter-defibrillator therapies due to T wave oversensing induced by body twisting.

T wave oversensing (TWOS) is a common cause of inappropriate implantable cardioverter-defibrillator (ICD) therapies. Various algorithms to avoid inappropriate ICD therapy are available; however, they are not helpful to avoid TWOS. Although the reproduction of TWOS is useful to resolve the problem of TWOS, it is sometimes difficult to reproduce TWOS. We report two cases of inappropriate ICD therapy due to TWOS, which were induced only by body twisting. We can successfully manage the device based on the evidence of reproduced TWOS.

Effect of Significant Weight Change on Inappropriate Implantable Cardioverter-Defibrillator Therapy.

BACKGROUND: Weight loss has been associated with adverse outcomes among heart failure (HF) patients, including those receiving cardiac resynchronization therapy with defibrillator (CRT-D). The effect of significant weight change on inappropriate implantable cardioverter-defibrillator (ICD) therapy among CRT-D patients is not well understood. METHODS: We evaluated the impact of significant weight change at 1 year on subsequent inappropriate ICD therapy during follow-up among 993 CRT-D patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy. Patients were divided into three subgroups based on weight change at 1 year after enrollment: weight loss (weight loss ≥ 5%), weight gain (weight gain ≥ 5%), and stable weight (weight loss and weight gain < 5%). The primary end point was inappropriate ICD therapy. Secondary end point included inappropriate ICD therapy related to supraventricular arrhythmias (SVAs). RESULTS: There were 102 (10.3%) patients who experienced weight loss, 689 (69.4%) whose weight was stable, and 202 (20.3%) who gained weight at 1 year. Patients with weight loss had increased risk of subsequent inappropriate ICD therapy relative to patients with stable weight (hazard ratio [HR] = 2.35, 95% confidence interval [CI]: 1.39-3.98, P = 0.001) or weight gain (HR = 2.27, 95% CI: 1.18-4.38, P = 0.014). Furthermore, patients losing weight were at greater risk of subsequent inappropriate ICD therapy related to SVAs when compared to patients with stable weight (HR = 2.16, 95% CI: 1.18-3.95, P = 0.013) or weight gain (HR = 2.02, 95% CI: 0.95-4.29, P = 0.068). CONCLUSION: In mild HF patients receiving CRT-D, significant weight loss at 1 year is associated with increased risk of subsequent inappropriate ICD therapy, including risk related to SVAs.

Cardiac resynchronization therapy is associated with reductions in left atrial volume and inappropriate implantable cardioverter-defibrillator therapy in MADIT-CRT.

BACKGROUND: There are no prior studies assessing the relationship between left atrial volume (LAV) and inappropriate implantable cardioverter-defibrillator (ICD) therapy following treatment with cardiac resynchronization therapy. OBJECTIVE: The purpose of this study was to investigate the hypothesis that patients randomized to cardiac resynchronization therapy with defibrillator (CRT-D) in the Multicenter Automatic Defibrillator Trial-Cardiac Resynchronization Therapy (MADIT-CRT) who had significant LAV reductions would have reduced risks of inappropriate ICD therapy. METHODS: Cardiac resynchronization remodeling was assessed by measuring LAV change between baseline and 12-month echocardiograms in 751 CRT-D treated patients. Patients were stratified into quartiles based on percent reduction of LAV change. High LAV responders were those in the highest 3 quartiles of LAV reduction (LAV reduction ≥21%). Low LAV responders were those in the lowest quartile of LAV reduction (LAV reduction <21%). Clinical factors associated with ≥21% reduction in LAV were evaluated by linear regression analysis. RESULTS: In Cox proportional hazards regression analyses, high LAV responders had a 39% reduction in the risk of inappropriate therapy (hazard ratio 0.61, P = .04) and left bundle branch block patients exhibited an even greater risk reduction in inappropriate therapy (hazard ratio 0.51, P = .02) compared to low LAV responders during follow-up extending up to 3 years after the 12-month echocardiogram. High LAV responders also had a significantly lower risk of heart failure or death during follow-up than did low LAV responders. CONCLUSION: A ≥21% reduction in LAV with cardiac resynchronization therapy is associated with significant reductions in inappropriate ICD therapy and in heart failure or death during a 3-year follow-up.