Inappropriate Inappropriate Implantable Cardioverter-defibrillator Therapies Research Articles

Improved outcomes of cardiac resynchronization therapy with a defibrillator in systolic heart failure: Analysis of the Japan cardiac device treatment registry database

AbstractBackgroundTemporal change in outcomes of heart failure patients receiving cardiac resynchronization therapy with a defibrillator (CRT‐D) is unknown.MethodsWe assess outcomes and underlying heart diseases of patients receiving CRT‐D with analyzing database of the Japan cardiac device treatment registry (JCDTR) at the implantation year 2011–2015 and New JCDTR at the implantation year 2018–2021.ResultsProportion of nonischemic heart diseases was about 70% in both the groups (JCDTR: 69%; New JCDTR: 72%). Cardiac sarcoidosis increased with the rate of 5% in the JCDTR to 9% in the New JCDTR group. During an average follow‐up of 21 months, death from any cause occurred in 167 of 906 patients in the JCDTR group (18%) and 79 of 611 patients in the New JCDTR group (13%) (adjusted hazard ratio [aHR] in the New JCDTR group, 0.72; 95% confidence interval [CI]: 0.55–0.94; p = .017). The superiority was mainly driven by reduction in the risk of noncardiac death. With regard to appropriate and inappropriate implantable cardioverter–defibrillator (ICD) therapy, there was a significant reduction in the New JCDTR group versus the JCDTR group (aHR in the New JCDTR group, 0.76; 95% CI: 0.59–0.98; p = .032 for appropriate ICD therapy; aHR in the New JCDTR group, 0.24; 95% CI: 0.12–0.50; p < .0001 for inappropriate ICD therapy).ConclusionsAll‐cause mortality was reduced in CRT‐D patients implanted during 2018–2021 compared to those during 2011–2015, with a significant reduction in noncardiac death.

Risk factors for the first and second inappropriate implantable cardioverter-defibrillator therapy.

IntroductionVarious risk factors for the first inappropriate implantable cardioverter-defibrillator (ICD) therapy event have been reported, including a history of atrial fibrillation/atrial flutter (AF/AFL), younger age, and multiple zones. Nonetheless, which factors are concordant with real-world data has not been clarified, and risk factors for the second inappropriate ICD therapy event have not been well examined. This study aimed to clarify the risk factors for the first and second inappropriate ICD therapy events.MethodsWe conducted a post-hoc secondary analysis of data from a multicenter, prospective observational study (the Nippon Storm Study) designed to clarify the risk factors for electrical storm.ResultsThe analysis included data from 1549 patients who received ICD or cardiac resynchronization therapy with defibrillator (CRT-D). Over a median follow-up of 28 months, 293 inappropriate ICD therapy events occurred in 153 (10.0%) patients. On multivariate Cox regression analysis, the risk factors for the first inappropriate ICD therapy event were younger age (hazard ratio [HR], 0.986; p = 0.028), AF/AFL (HR, 2.324; p = 0.002), ICD without CRT implantation (HR, 2.377; p = 0.004), and multiple zones (HR, 1.852; p = 0.010). “No-intervention” after the first inappropriate ICD therapy event was the sole risk factor for the second inappropriate ICD therapy event.ConclusionsRisk factors for the first inappropriate ICD therapy event were similar to those previously reported. Immediate intervention after the first inappropriate ICD therapy event could reduce the risk of the second inappropriate event.

Implantable cardiac defibrillator events in patients with arrhythmogenic right ventricular cardiomyopathy

ObjectiveArrhythmogenic right ventricular cardiomyopathy (ARVC) is associated with a risk of sudden cardiac death. Optimal risk stratification is still under debate. The main purpose of this long-term, single-centre observation was...

Temporal Incidence of Appropriate and Inappropriate Therapy and Mortality in Secondary Prevention ICD Patients by Cardiac Diagnosis.

This study sought to estimate the temporal development in rates and incidences of appropriate and inappropriate implantable cardioverter-defibrillator (ICD) therapy and shocks by cardiac diagnosis in a real-world population of patients with secondary prevention ICDs. Data on cardiac diagnoses and temporal development of ICD therapies in patients with secondary prevention ICDs are limited. Patients (N=4,587) with a secondary prevention ICD were identified from the Danish Pacemaker and ICD Register (January 1, 2007, to December 31, 2016) and linked to nationwide administrative registers. The outcome of appropriate and inappropriate ICD therapy and all-cause mortality were analyzed by annual event rates, cumulative incidence plots, and Cox regression models. During a mean follow-up of 3.6 ± 2.4 years, 1,362 patients (30%) experienced appropriate ICD therapy (16.8% shocks), and 350 patients (7.6%) experienced inappropriate ICD therapy (4.6% shocks). From 2007 to 2016, there was a significant temporal reduction in both appropriate and inappropriate ICD therapy from 28.2 (95% confidence interval [CI]: 21.6 to 37.0) to 7.9 (95% CI: 6.8 to 9.1) and 10.0 (95% CI: 6.4 to 15.5) to 1.0 (95% CI: 0.7 to 1.5) per 100 person-years (p for trends<0.001). Multivariate Cox regression analyses showed that arrhythmogenic right ventricular cardiomyopathy was associated with the highest probability of appropriate ICD therapy (hazard ratio: 2.45; 95% CI: 1.77 to 3.39; p<0.0001), whereas patients with hypertrophic cardiomyopathy had the lowest probability (hazard ratio: 0.62; 95% CI: 0.42 to 0.93; p=0.0196) when compared to patients with ischemic heart disease. In this nationwide real-life cohort of patients with secondary prevention ICDs, we observed a significant temporal decline in delivered appropriate and inappropriate shocks and ICD therapies in the last decade. A large proportion of patients still experienced ICD therapy but with significant differences by cardiac diagnosis.

Systolic Blood Pressure and Risk for Ventricular Arrhythmia in Patients With an Implantable Cardioverter Defibrillator

Low systolic blood pressure (SBP) was previously suggested to be a marker for heart failure and mortality in patients with low left ventricular ejection fraction. We aimed to explore the association of SBP on risk of ventricular tachyarrhythmias (VTA) and atrial arrhythmias as well as appropriate and inappropriate Implantable Cardioverter Defibrillator (ICD) therapy. The study population comprised 1,481 of 1,500 (99%) patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy trial. Multivariate Cox proportional hazards regression modeling was used to identify the association of baseline SBP (recorded prior to ICD implantation) with the risk of VTA > 170 beats/min during follow-up (primary end point) and atrial arrhythmia, appropriate and inappropriate ICD therapy, hospitalization and death (secondary end points). SBP was dichotomized at 120 mm Hg (approximate mean and median) and was also assessed as a continuous measure. Multivariate analysis showed that each 10 mm Hg decrement in SBP was associated with corresponding 11% increased risk for VTA (p = 0.008). Low SBP (≤120 mm Hg) was associated with a significant 58% (p = 0.002) increased risk for VTA ≥170 beats/min; 53% (p = 0.019) increased risk for VTA ≥200 beats/min; and 65% (p = 0.001) increased risk for appropriate ICD therapy, as compared with SBP >120 mm Hg. Low SBP was not associated with increased risk of atrial arrhythmias, and inappropriate ICD therapy. In conclusion, in MADIT-RIT, SBP (≤120 mm Hg) predicted higher rates of VTA. These findings suggest that SBP may be utilized for VTA risk stratification in candidates for primary ICD therapy.

Reduction of inappropriate implantable cardioverter-defibrillator therapies using enhanced supraventricular tachycardia discriminators: the ReduceIT study.

Inappropriate implantable cardioverter-defibrillator (ICD) shocks are associated with greater healthcare resource utilization, poorer quality-of-life, and higher mortality. We aimed to investigate the performance of enhanced supraventricular tachycardia (SVT) discrimination algorithms (morphology discrimination, rate stability, and sudden or chamber onset) for reducing inappropriate ICD therapies in patients with ICD/cardiac resynchronization therapy devices. This prospective, non-randomized, multicenter study (ReduceIT) study took place at 56 sites across Germany and Estonia. Adults at risk of sudden cardiac death undergoing St. Jude Medical™ ICD or CRT-D implantation were included. The primary endpoint was freedom from inappropriate ICD shock at 12months and was analyzed in the intention to treat (ITT) and per-protocol population. Overall, 733 patients (65.9 ± 11.4years) were included, of which 40.9% and 59.1% received a single- and dual-chamber detection device, respectively. During follow-up (median 11.9 [0-21.6] months), 96.3% of patients experienced no inappropriate therapy (ITT). The sensitivity, specificity, and accuracy for VT/VF were 91.9%, 95.5%, and 94.7%, respectively. In the per-protocol population (n = 620), the proportion of patients free from inappropriate shock at 12months was 98.4% (n = 610; 95% CI 97.1-99.2%) and exceeded the expected value of 93% (p < 0.0001) which was derived from the rates in the SPICE, ATPonFastVT, and DECREASE studies. A total of 44 patients (6.0%) died during follow-up, 19 deaths were cardiac-related which is consistent with a meta-analysis of EMPIRIC, MADIT-RIT, ADVANCE III, and PROVIDE. Serious device and procedure-related adverse effects occurred in 9.8% of patients. In ICD/CRT-D devices with advanced SVT discriminators, device programming according to clinical setting and detection chamber significantly reduces the rate of inappropriate ICD shocks without compromising patient safety. The algorithms and settings described herein have particular clinical importance and their employment may be of benefit to ICD recipients.

P2277Utility of cardiovascular implantable electronic device (CIED)-derived patient activity, a novel digital biomarker, to predict inappropriate therapy

Abstract Background The role of cardiovascular implantable electronic device (CIED)-derived activity to predict inappropriate implantable cardioverter-defibrillator (ICD) therapy is not known. The Multicenter Automatic Defibrillator Implantation Trial – Reduce Inappropriate Therapy (MADIT-RIT) enrolled 1500 patients with contemporary indication for an ICD or a CRT-D. We aimed to identify whether activity, as a digital biomarker, predicted inappropriate therapy. Methods In 1500 patients enrolled in MADIT-RIT, CIED-derived patient activity was acquired daily. CIED-derived activity was averaged for the first 30 days following randomization and utilized in this study to predict inappropriate therapy post- 30-day. Kaplan-Meier survival analysis and multivariate Cox proportional hazards regression models were used to evaluate first inappropriate therapy by 30-day CIED-derived patient activity quintiles, and by 30-day device derived patient activity as a continuous measurement. Results There were a total of 1463 patients with activity data available (90%), 135 patients received at least one inappropriate therapy during the post-30 day follow-up period. Patients in the highest quintile (Q5) of CIED-derived activity (more active) were younger, more often males and more likely to have had a prior ablation of an atrial arrhythmia. Patients in the highest quintile of 30-day CIED-derived median activity had the highest risk of receiving inappropriate therapy, 21% at 2 years as compared 7–11% in the other four quintiles (Figure, p&lt;0.001 for the overall duration). Patients with the highest level of 30-day median patient activity (Q5) had 1.75 times higher risk of any inappropriate therapy as compared with lower levels of activity, Q1-Q4 (HR=1.75, 95% CI: 1.23–2.50, p&lt;0.002). Each 10% increase in CIED-derived 30-day median patient activity was associated with a significant, 73% increase in risk of receiving inappropriate therapy (HR=1.73, 95% CI: 1.17–2.54, p=0.005). Patients in the highest quintile for activity had a 68% increase in the risk of SVT excluding atrial fibrillation, atrial flutter or atrial tachycardia (HR=1.69, 95% CI: 1.26–2.25, p=0.004), despite 96% receiving beta-blocker medications. Inappropriate ICD Therapies by Activity Conclusions CIED-derived 30-day median patient activity predicted subsequent inappropriate therapy in ICD and CRT-D patients enrolled in MADIT-RIT. Patients with high levels of 30-day CIED-derived median patient activity were at a significantly higher risk of receiving inappropriate therapy. Activity, as a digital biomarker, may have utility in predicting and managing the risk of inappropriate therapy in this population. Acknowledgement/Funding Boston Scientific

Heart failure severity, inappropriate ICD therapy, and novel ICD programming: a MADIT-RIT substudy.

The effects of heart failure (HF) severity on risk of inappropriate implantable cardioverter-defibrillator (ICD) therapy have not been thoroughly investigated. We aimed to study the association between HF severity and inappropriate ICD therapy in MADIT-RIT. MADIT-RIT randomized 1,500 patients to three ICD programming arms: conventional (Arm A), high-rate cut-off (Arm B: ≥200beats/min), and delayed therapy (Arm C: 60-second delay for ≥170beats/min). We evaluated the association between New York Heart Association (NYHA) class III (n=256) versus class I-II (n=251) and inappropriate ICD therapy in Arm A patients with ICD-only and cardiac resynchronization therapy with defibrillator (CRT-D). We additionally assessed benefit of novel ICD programming in Arms B and C versus Arm A by NYHA classification. In Arm A, the risk of inappropriate therapy was significantly higher in those with NYHA III versus NYHA I-II for both ICD (hazard ratio [HR]=2.55, confidence interval [CI]: 1.51-4.30, P<0.001) and CRT-D patients (HR=3.73, CI: 1.14-12.23, P=0.030). This was consistent for inappropriate ATP and inappropriate ICD therapy<200beats/min, but not for inappropriate shocks. Novel ICD programming significantly reduced inappropriate therapy in patients with both NYHA III (Arm B vs Arm A: HR=0.08, P<0.001; Arm C vs Arm A: HR=0.17, P<0.001) and NYHA I-II (Arm B vs Arm A: HR=0.25, P<0.001; Arm C vs Arm A: HR=0.28, P<0.001). Patients with more severe HF are at increased risk for inappropriate ICD therapy, particularly ATP due to arrhythmias<200beats/min. Novel programming with high-rate cut-off or delayed detection reduces inappropriate ICD therapies in both mild and moderate HF.

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

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. 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). 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). 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.

Postpacing Interval During Right Ventricular Overdrive Pacing to Discriminate Supraventricular from Ventricular tachycardia.

Failure to differentiate supraventricular from ventricular arrhythmias is the most frequent cause of inappropriate implantable cardioverter-defibrillator (ICD) therapies. We hypothesized that the postpacing interval (PPI) after overdrive right ventricular pacing may differentiate ventricular (VT) from supraventricular tachycardia (SVT) such as sinus tachycardia, atrial flutter and atrial tachycardia. This hypothesis is based on the entrainment maneuver. Reentrant tachycardia circuit for VTs would haveshorter distance to RV apex than SVTs have, and the conduction time between a ventricular pacing site and the tachycardia origin is expected to be shorter in VTs than in SVTs. 220episodes from 38 patients with single chamber ICDs that RV overdrive pacing could not terminate or change the tachycardia cycle length (TCL) were retrospectively reviewed. Episodes were classified as VTs (n=115) and SVTs (n=105). TCLs, PPIs and PPI-TCL were compared between groups. The cycle length of VTs was shorter than SVTs (320.6±30.3 vs 366.5±40 ms, p=0.001). PPI and PPI-TCL of VTs were shorter than SVTs (504.7±128.3 vs 689.2±121.8 ms, p=0.001, 184±103 vs 322.6±106.6 ms, p=0.001; respectively). ROC curve analysis demonstrated a 525 ms cut-off value for PPI has 89% sensitivity and 57.4% specificity to predict inappropriate ICD therapies due to SVTs (AUC:0.852). Similarly, A PPI-TCL <195 ms favored VT as a diagnosis rather than SVT with a 90% sensitivity, and 51% specificity (AUC:0.838). Analyzing of PPI during overdrive pacing from RV apex may discriminate supraventricular from ventricular tachycardia. This criterion may have a potential role in implantable devices that use a single ventricular lead.

Characteristics and outcomes of diabetic patients with an implantable cardioverter defibrillator in a real world setting: results from the Israeli ICD registry.

AimsThere are limited data regarding the effect of diabetes mellitus (DM) on the risks of both appropriate and inappropriate implantable cardioverter defibrillator (ICD) therapy. The present study was designed to compare the outcome of appropriate and inappropriate ICD therapy in patients with or without DM.Methods and resultsThe risk of a first appropriate ICD therapy for ventricular tachyarrhythmias (including anti tachycardia pacing and shock) was compared between 764 DM and 1346 non-DM patients enrolled in the national Israeli ICD registry. We also compared the risks of inappropriate ICD therapy, and death or cardiac hospitalization between diabetic and non-diabetic patients. Diabetic patients were older, were more likely to have ischemic cardiomyopathy, lower ejection fraction, atrial fibrillation, and other co-morbidities. The 3-year cumulative incidence of appropriate ICD therapy was similar in the DM and non-DM groups (12 and 13%, respectively, p = 0.983). Multivariate analysis showed that DM did not affect the risk of appropriate ICD therapy (HR = 1.07, 95% CI 0.78–1.47, p = 0.694) or inappropriate therapy (HR = 0.72, 95% CI 0.42–1.23, p = 0.232). However, DM was associated with a 31% increased risk for death or cardiac hospitalization (p = 0.005). Results were similar in subgroup analyses including ICD and defibrillators with cardiac resynchronization therapy function recipients, primary or secondary prevention indication for an ICD.ConclusionsDespite a significant excess of cardiac hospitalizations and mortality in the diabetic population, there was no difference in the rate of ICD treatments, suggesting that the outcome difference is not related to arrhythmias.

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.

176-54: Characteristics and Outcomes of Diabetic Patients with an Implantable Cardioverter Defibrillator in a Real World Setting: Results From the Israeli ICD Registry

Aims: There are limited data regarding the effect of diabetes mellitus (DM) on the risks of appropriate and inappropriate implantable cardioverter defibrillator (ICD) therapy. The present study was designed to compare the risk of appropriate and inappropriate ICD therapy in patients with or without DM. Methods and Results: The risk of a first appropriate ICD therapy for ventricular tachyarrhythmias (including anti tachycardia pacing [ATP] and shock) was compared between 764 DM and 1346 non-DM patients enrolled in the national Israeli ICD registry. We also compared the risks of inappropriate ICD therapy, and death or cardiac hospitalization between diabetic and non-diabetic patients. Diabetic patients were older, were more likely to have ischemic cardiomyopathy, lower ejection fraction, atrial fibrillation, and other co-morbidities. The 3-year cumulative incidence of appropriate ICD therapy was similar in the DM and non-DM groups (Figure). Multivariate analysis showed that DMdid not affect the risk of appropriate ICD therapy (HR = 1.07, 95% CI 0.78–1.47, p = 0.694) or inappropriate therapy (HR = 0.72, 95% CI 0.42–1.23, p = 0.232). However, DM was associated with a 31% increased risk for death or cardiac hospitalization (p= 0.005). Results were similarin subgroup analyses including ICD and CRT-D recipients, primary or secondary prevention indication for an ICD. Conclusions: Despite a significant excess of cardiac hospitalizations and mortality in the diabetic population, there was no difference in the rate of ICD treatments, suggesting that the outcome difference is non-arrhythmic.

Novel ICD Programming and Inappropriate ICD Therapy in CRT-D Versus ICD Patients

The Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate therapy (MADIT-RIT) trial showed a significant reduction in inappropriate implantable cardioverter defibrillator (ICD) therapy in patients programmed to high-rate cut-off (Arm B) or delayed ventricular tachycardia therapy (Arm C), compared with conventional programming (Arm A). There is limited data on the effect of cardiac resynchronization therapy with a cardioverter defibrillator (CRT-D) on the effect of ICD programming. We aimed to elucidate the effect of CRT-D on ICD programming to reduce inappropriate ICD therapy in patients implanted with CRT-D or an ICD, enrolled in MADIT-RIT. The primary end point of this study was the first inappropriate ICD therapy. Secondary end points were inappropriate anti-tachycardia pacing and inappropriate ICD shock. The study enrolled 742 (49%) patients with an ICD and 757 (51%) patients with a CRT-D. Patients implanted with a CRT-D had 62% lower risk of inappropriate ICD therapy than those with an ICD only (hazard ratio [HR] =0.38, 95% confidence interval: 0.25-0.57; P<0.001). High-rate cut-off or delayed ventricular tachycardia therapy programming significantly reduced the risk of inappropriate ICD therapy compared with conventional ICD programming in ICD (HR=0.14 [B versus A]; HR=0.21 [C versus A]) and CRT-D patients (HR=0.15 [B versus A]; HR=0.23 [C versus A]; P<0.001 for all). There was a significant reduction in inappropriate anti-tachycardia pacings in both group and a significant reduction in inappropriate ICD shock in CRT-D patients. Patients implanted with a CRT-D have lower risk of inappropriate ICD therapy than those with an ICD. Innovative ICD programming significantly reduces the risk of inappropriate ICD therapy in both ICD and CRT-D patients. http://clinicaltrials.gov; Unique identifier: NCT00947310.

Characterization and predictors of first and subsequent inappropriate ICD therapy by heart rate ranges: Result of the MADIT-RIT efficacy analysis.

Data on inappropriate implantable cardioverter-defibrillator (ICD) therapy and effects of programming by heart rate are lacking. We aimed to characterize inappropriate ICD therapy and assess the effects of novel programming by heart rate. Incidence and causes of inappropriate therapy by heart rate range (below or above 200 bpm) were assessed. Predictors of inappropriate therapy and effects of programming by heart rate were evaluated with multivariate Cox regression models. Crossovers were excluded. Inappropriate therapy occurred in 9.2% of the total patient population, with 19% of patients randomized to study arm A, 3.6% in arm B, and 4.7% in arm C. Inappropriate therapies <200 bpm were attributable to supraventricular tachycardia (SVT)/sinus tachycardia (78%) or atrial fibrillation/flutter (20%). Inappropriate therapy ≥200 bpm occurred because of SVT (47%), atrial fibrillation/flutter (41%), or electromagnetic interference (13%). Conventional ICD programming was associated with more inappropriate therapy <200 bpm than high-rate or delayed therapy, as were younger age, history of atrial arrhythmia, advanced New York Heart Association functional class, ICD versus cardiac resynchronization therapy with defibrillator, and absence of diabetes. High-rate and long-delay therapy significantly reduced the risk of inappropriate therapy in the <200 bpm range. Long delay was associated with further reduction of fast (≥200 bpm) inappropriate therapy (P = .032) and a reduction in subsequent inappropriate episodes (P = .006). In MADIT-RIT, inappropriate ICD therapy is most frequent at rates below 200 bpm and can be predicted, and effectively prevented, with high-rate cutoff programming. Long-delay therapy effectively reduces fast inappropriate therapy ≥200 bpm and subsequent events. [ http://clinicaltrials.gov/ct2/show/NCT00947310].

Impact of single atrial fibrillation catheter ablation on implantable cardioverter defibrillator therapies in patients with ischaemic and non-ischaemic cardiomyopathies

Atrial fibrillation (AF) is associated with frequent appropriate and inappropriate implantable cardioverter defibrillator (ICD) therapies. Catheter ablation of AF has been shown to reduce AF burden and improve left ventricular function in heart failure patients but the impact on ICD therapies has not yet been studied. The aim of this study was to test the hypothesis that AF ablation reduces ICD therapies in patients with cardiomyopathies. In 73 consecutive patients (mean age 59 ± 10 years, 85% male) with previously implanted ICD due to ischaemic (n = 30) or dilated cardiomyopathy (n = 43) undergoing AF ablation, the prevalence and frequency of ICD therapies before and after AF ablation were compared. During the total follow-up of 3.3 ± 3 years prior to AF ablation, 5.1 ± 14.7 therapies per patient-year were delivered as opposed to 1.8 ± 10.9 in a period of 1.1 ± 0.9 years after ablation (P = 0.002). Prior to AF ablation, 39 patients (53%) received at least one ICD therapy when compared with 15 patients (21%) after ablation. Atrial fibrillation ablation was associated with freedom from any therapy regardless of appropriateness (odds ratio, OR, 0.366, CI 0.164-0.816, P = 0.014, adjusted for follow-up). Appropriate shocks significantly decreased from 0.3 ± 1.3 to 0.1 ± 0.5 per patient-year (P = 0.030). While heart failure medication and use of antiarrhythmic drugs were comparable during the entire follow-up, a statistically significant improvement of left ventricular ejection fraction (LVEF) from 36.9 ± 12.3% to 40.7 ± 6.7% (P = 0.008) was observed after AF ablation. In patients with ischaemic or dilated cardiomyopathy, catheter ablation of AF is associated with the reduction of inappropriate and appropriate ICD therapies and improvement of LVEF.

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

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. 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. 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. 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. 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.

Prognostic impact of inappropriate defibrillator shocks in a population cohort

BackgroundThere is a relative paucity of data linking inappropriate implantable cardioverter-defibrillator (ICD) shocks to adverse clinical outcomes.ObjectiveTo examine the association between inappropriate ICD shocks and mortality or heart transplantation in...

Usefulness of Radiofrequency Ablation of Supraventricular Tachycardia to Decrease Inappropriate Shocks from Implantable Cardioverter–Defibrillators

Inappropriate implantable cardioverter-defibrillator (ICD) therapies can lead to significant adverse events and increased mortality. These therapies are often the result of supraventricular tachycardias (SVTs). The objective of this study was to evaluate the incidence of SVT leading to inappropriate shocks in a large cohort of patients with ICDs and assess the efficacy of radiofrequency ablation (RFA) in decreasing these therapies. Patients with ICDs and recurrent SVTs were identified. A cohort of patients with ICD therapies subsequently underwent electrophysiologic study and RFA. Eighty-four patients (13%) were found to have SVT leading to 122 inappropriate ICD shocks and 130 episodes of antitachycardia pacing therapies. Median time to SVT onset after ICD implantation was 269 days. Electrophysiologic studies were performed in 30 patients. Successful RFA was performed for atrial tachycardia, atrial flutter, or atrioventricular nodal reentrant tachycardia in 22 patients. Ninety-five percent of patients who underwent successful SVT ablation had no further inappropriate ICD therapies compared to 63% of patients in whom ablation was not performed during a mean follow-up of 20.7 ± 11.9 months. In conclusion, SVT is responsible for a significant number of inappropriate ICD therapies. RFA is an effective strategy to substantially decrease subsequent inappropriate ICD therapies.

Relation of Advanced Heart Failure Symptoms to Risk of Inappropriate Defibrillator Shocks

Inappropriate implantable cardioverter-defibrillator (ICD) shocks continue to be a major source of distress to patients and a drain on the health care system. Expanding indications for ICD implantation include a large portion of patients with heart failure. This study investigated the relation between inappropriate ICD shocks and the severity of heart failure symptoms. Predictors of the time to first inappropriate ICD therapy were investigated in 230 consecutive patients implanted in 2001 and 2002. Thirty-two patients received 42 inappropriate shocks during a median follow-up of 501 days. Inappropriate shocks were due to atrial fibrillation (AF) or tachycardia (n = 31), other supraventricular tachycardias (n= 6), sinus tachycardia (n = 3), and noise or double counting (n = 2). The time to first inappropriate ICD shock was earliest in patients with advanced classes of heart failure (1- and 2-year shock-free survival of 79% and 70% for patients in New York Heart Association [NYHA] class III or IV vs 92% and 88% for patients in NYHA class I or II, respectively, p = 0.02). After correcting for age, gender, the presence of coronary artery disease, the presence of AF, the use of beta blockers, and indication for ICD implantation in a Cox regression model, advanced heart failure (NYHA class III or IV) remained an independent predictor of first inappropriate ICD shocks (hazard ratio 2.7, p = 0.01). Other predictors of the time to first inappropriate ICD shock included the presence of AF as the baseline rhythm at the time of the ICD implantation and the absence of coronary disease. In conclusion, inappropriate ICD shocks are predominantly due to AF. Advanced heart failure is an independent predictor of the time to first inappropriate ICD shocks. The effect of ICD programming and antiarrhythmic drug therapy on the incidence of inappropriate shocks deserves further investigation.