Implantable Cardioverter-defibrillator Therapy In Patients Research Articles

Long-term follow-up in patients with hypertrophic cardiomyopathy after defibrillator implantation: analysis of appropriate and inappropriate therapy

Abstract Background Treatment with implantable cardioverter-defibrillators (ICD) is effective for prevention of sudden cardiac death (SCD) in patients with hypertrophic cardiomyopathy (HCM). Assessment of SCD risk and identification of patients most likely to benefit from primary prevention ICD is challenging. Purpose To investigate the long-term incidence of appropriate and inappropriate ICD therapy in patients with HCM. Methods This was a retrospective cohort study including all patients with HCM and ICDs implanted between 1995 to 2022 in our region (population 2.6 million). Both patients treated with primary and secondary prevention ICD were included. Data was retrieved from medical records. Patients with an ICD implanted for primary prevention were stratified into risk groups according to European Society of Cardiology HCM Risk-SCD score. Results We included 187 patients (65% male) with HCM and ICDs implanted for primary (80%) or secondary (20%) prevention. The median age at ICD implantation was 50 years (IQR: 40 to 61 years). During a mean follow-up of 9 years (IQR: 4 to 12 years), 53 patients (28%) experienced appropriate ICD therapy (antitachycardia pacing and/or shock), while 17 (9%) patients received inappropriate therapy. Patients with an ICD as secondary prevention were almost twice as likely to receive appropriate ICD therapy compared to patients with a primary prevention ICD (42% vs. 25%, p=0.04). The proportion of patients receiving appropriate shocks was 7 times higher in patients with an HCM Risk-SCD score ≥6% compared to patients with a risk score <4% (29% vs. 4%, p<0.001). There was no significant difference in the proportion of appropriate shocks between patients with a HCM Risk-SCD score ≥6% and patients with a risk score of 4%-6% (29% vs. 21%, p=0.49). (Figure 1). Conclusion One in four patients with HCM treated with an ICD experienced appropriate device intervention during 9 years of follow up. Patients with an HCM Risk-SCD score ≥6% had a 7-fold higher risk of appropriate ICD therapy compared to patients with an HCM Risk-SCD score <4%. There was no significant difference in the risk of appropriate shock therapy between patients with a risk score ≥6% and patients with a risk score of 4%-6%. The findings indicate the need for improved selection of patient with HCM for implantation of ICD’s.

Effect of ICD on patients with improved EF in idiopathic dilated cardiomyopathy

Abstract Background The efficacy of implantable cardioverter defibrillator (ICD) therapy in patients who had heart failure with improved ejection fraction (HFimpEF) above guidelines indication for ICD (>35%) during generator change is still controversial. This meta-analysis assesses the impact of ICD therapy in patients with HFimpEF with EF >35% and patient with NICM. Methods Databases were searched for studies reporting the association between ICD in patients with NICM and HFimpEF and ventricular arrhythmias (VA) and sudden cardiac death (SCD); including Ovid MEDLINE, EMBASE, Web of Science, and Google Scholar. The search was not restricted to time or publication status. The minimal follow up duration was one year. Results A total of 38 studies and 13,538 patients (5,829 with improved EF vs 7,709 with EF <35% during follow up) were included; mean follow up was 43 months (ranging between 12 to 74 months). Mean age was 63.5 and 75% were males. Patients with HFimpEF with ICD, wither alone or as part of CRT therapy, was associated with lower risk of VA and SCD (OR 0.39, 95% CI 0.32-0.47; P<0.01; annual rate 4.1 vs. 8%). Sub-analysis for patients with ICD for patient with NICM was associated with lower risk of VA and SCD (OR 0.25, 95% CI 0.1-0.62; P<0.01; annual rate 2.9 vs. 10.2%). (Figure) Conclusion Improved EF is associated with reduced VA but with still elevated risk in HFimpEF especially in NICM.

Appropriate Implantable Cardioverter-Defibrillator Therapy in Patients with Ventricular Arrhythmia of Unclear Cause in Secondary Prevention of Sudden Cardiac Death.

In this study, we sought to investigate the occurrence of appropriate implantable cardioverter-defibrillator (ICD) therapies and inappropriate shocks in secondary prevention ICD recipients with ventricular arrhythmia of unclear cause and ventricular arrhythmia in the context of underlying heart disease. In this retrospective study, consecutive patients with an ICD implanted for secondary prevention in the University Medical Center Groningen (UMCG), the Netherlands between 1 January 2012 and 31 December 2018 were included. Patients were classified as having ventricular arrhythmia of unclear cause if no clear cause was found which could explain the index ventricular arrhythmia. The primary outcome was appropriate ICD therapy. The study population consisted of 257 patients. In 220 patients, an underlying heart disease could be identified as the cause of ventricular arrhythmia, while 37 patients had an unclear cause of ventricular arrhythmia. The median age was 64 years (interquartile range (IQR) 53-72 years). Forty-five (18%) patients were women. During a median duration of follow-up of 6.2 years (IQR 4.8-7.8 years), appropriate ICD therapy occurred in 95 (37%) patients. This number was 90 (41%) in the group with a clear etiology and 5 (14%) in the group with an unclear etiology. In multivariable analysis, index ventricular arrhythmia of unclear cause was associated with fewer appropriate ICD therapies (HR 0.37 [95% CI 0.14-0.99]; p = 0.048), as well as an increased risk of inappropriate ICD shocks (HR 3.71 [95% CI 1.17-11.80]; p = 0.026). Index ventricular arrhythmia of unclear cause was significantly associated with fewer appropriate ICD therapies.

Updated risk assessments for sudden cardiac death in hypertrophic cardiomyopathy patients with implantable cardioverter-defibrillator.

Hypertrophic cardiomyopathy (HCM) is a genetic disease associated with a risk of malignant ventricular tachyarrhythmias and sudden cardiac death (SCD). Assessment of the SCD risk is crucial for its clinical management, and there has been considerable interest in developing risk stratification strategies. An implantable cardioverter-defibrillator (ICD) is a life-saving treatment for patients with HCM who are at a high-risk of ventricular tachyarrhythmias and SCD. However, a substantial number of ICD recipients experience adverse effects arising from inappropriate device therapy and implant-related complications. This has led to numerous investigations of the risk of SCD and the indications for ICD implantation. American guidelines were recently updated to include new risk markers, including left ventricular systolic dysfunction, apical aneurysm, and extensive late gadolinium enhancement, while European guidelines recommend individualized estimated 5-year SCD risk assessment models. Studies evaluating other risk factors for SCD in patients with HCM have also been published. Drawing on recent guidelines and publications on clinical risk factors, we focus this review on updated risk assessments for SCD with ICD therapy in patients with HCM.

Effect of Novel Programming on Inappropriate Implantable Cardioverter-Defibrillator Therapy in Patients With Very Low Ejection Fraction (from A MADIT-RIT)

The Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy showed a significant reduction in the risk of inappropriate therapy in patients with a programmed high-rate cutoff ≥200 beats per minute or delayed therapy for events ≥170 beats per minute compared with conventional programming. We aimed to characterize outcomes by left ventricular ejection fraction (LVEF) ranges for patients with high-rate, delayed, or conventional implantable cardioverter-defibrillator programming. We assessed the effect of LVEF (LVEF <15%, LVEF 15% to 25%, LVEF >25%) on the risk of inappropriate conventional implantable cardioverter-defibrillator therapy and death in Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy. Inappropriate therapies and death were independently evaluated by the adjudication committee. Statistical methods involved Kaplan-Meier time-to-event graphs and Cox proportional hazards regression analyses. The study involved 140 patients (9%) with LVEF 15%, 585 with LVEF 15% to 25% (39%), and 774 with LVEF >25% (52%). High-rate or delayed programming significantly reduced the risk of inappropriate therapy compared with conventional programming in patients with all LVEFs (p <0.001 for all LVEF). Patients with LVEF <15% had an exceptional 97% lower risk of inappropriate therapy, with high-rate programming than conventional programming (hazard ratio 0.028, p=0.001), without an increase in mortality. High-rate and delayed programming is superior to conventional programming in all LVEF ranges, without adverse effects.

Outcomes after transvenous defibrillator implantation in cardiac sarcoidosis: A systematic review.

IntroductionSarcoidosis is a systemic inflammatory disorder associated with ventricular arrhythmias (VAs) and sudden death in the context of cardiac involvement. Guidelines advocate implantable cardioverter‐defibrillator (ICD) implantation in specific subcohorts, but there is a paucity of data on outcomes.Methods and ResultsA systematic review was performed to assess outcomes in patients with definite or probable cardiac sarcoidosis (CS) treated with ICD. Observational studies were identified from multiple databases from inception to 21st May 2021. Outcomes of interest included appropriate and inappropriate ICD therapies in addition to all‐cause mortality. Study quality was assessed individually using the Newcastle Ottawa Scale (NOS).Eight studies were identified comprising 530 patients, with follow‐up period of 24–66 months (weighted average 40 months). Mean age was 53.9 years with ejection fraction of 41.3%. Overall incidence of appropriate therapy was 38.1% during follow‐up. Left ventricular systolic dysfunction (LVSD) with ejection fraction <40% was a predictor of appropriate therapy in the majority of studies, as were sustained VAs during electrophysiological testing (EP) in one study. There was no interaction with device indication (i.e. primary or secondary). Where documented, inappropriate therapy was primarily driven by atrial arrhythmias. All‐cause mortality was 6.0% over a median follow‐up period of 42 months. Only three studies achieved good quality in the comparability domain of NOS.ConclusionsAppropriate ICD therapy in patients with CS is commonly associated with LVSD, which can act as a surrogate for scar burden. The utility of EP testing in this setting remains unclear.

Delayed detection programming significantly reduces inappropriate ICD therapies in patients with left-ventricular assist devices

Abstract Funding Acknowledgements Type of funding sources: None. Background Implantation of a left ventricular assist device (LVAD) is an established therapy for end-stage heart failure, either as bridge to transplantation or as destination therapy. Virtually all LVAD patients carry an implantable cardioverter-defibrillator (ICD) for primary or secondary prevention. The risk of ventricular tachyarrhythmias is significant in LVAD patients, but so is the burden of supraventricular tachycardia and the ensuing risk of inappropriate ICD therapies. The present retrospective study sought to quantify the impact of standard ICD programming vs. a ICD programming with long detection delays on the occurrence of inappropriate ICD therapies. Methods and results We retrospectively identified 337 consecutive patients (292 male, mean age 54.2 ± 12.3 years) who received a continuous-flow LVAD at our institution. Median follow-up duration was 2.3 (IQR 1.3, 3.7) years. Heart failure etiology was ischemic cardiomyopathy in 155 patients (46.0 %) and non-ischemic dilated cardiomyopathy in 150 (44.5 %). Other etiologies accounted for 32 patients (9.4 %). ICDs implanted at the time of LVAD implantation were single chamber devices in 176 patients (52.2 %), dual chamber devices in 45 patients (13.4 %), and CRT-D in 116 patients (34.4 %) A total of 2228 ICD-treated arrhythmia episodes occurred in 153 patients. 2066 (92.6 %) episodes were appropriate interventions for ventricular arrhythmias. 162 (7.3 %) treatments were inappropriate due to supraventricular tachyarrhythmias (n=115; 71.4 %), sinus tachycardia (n=15; 9.3 %) or oversensing (n=21; 12.9%). We retrospectively compared a standard programming (number of intervals for detection [NID] in the slowest therapy zone ≤ 40) and a long delay programming (NID &amp;gt; 40) and investigated the time to the first inappropriate therapy. A total of 285 patients were programmed to NID ≤ 40 at the first ICD interrogation after LVAD implant, 47 were programmed to NID &amp;gt; 40. Therapies were inactive in the remaining 5 patients. Median NID was 30 (IQR 23, 35) in the standard programming group and 60 (IQR 50, 76) in the long delay group, with similar rates for detection (median cycle lengths 340 [IQR 330, 350] ms and 330 [IQR 322, 340] ms for standard and long delay, respectively). Long delay programming was associated with significantly higher freedom from inappropriate therapies during follow-up (Hazard ratio 0.14, p [log rank] 0.027). No significant difference was observed between groups with regard to time to first appropriate therapy. Conclusion A number of intervals for detection greater than 40 in the slowest therapy zone was associated with a significantly increased freedom from inappropriate therapies in this large retrospective single-center cohort of LVAD patients with an ICD and should be considered as the default ICD programming strategy in this population.

Device-detected sleep-disordered breathing predicts implantable defibrillator therapy in patients with heart failure

Abstract Funding Acknowledgements Type of funding sources: None. Background Sleep-disordered breathing is highly prevalent in heart failure (HF) and it has been suggested as a risk factor for malignant ventricular arrhythmias. The Respiratory Disturbance Index (RDI) algorithm computed by select implantable cardioverter defibrillators (ICDs) can identify severe sleep apnea (SA). Purpose In the present analysis we evaluated the association between ICD-detected SA and the incidence of appropriate ICD therapy in patients with HF. Methods We enrolled 411 HF patients (age 69±10years, 77% male, ejection fraction 32±8%), implanted with an ICD endowed with an algorithm (ApneaScan, Boston Scientific) that calculates the RDI each night. In this analysis the weekly mean RDI value was considered. The endpoint was the first appropriate ICD shock. The median follow-up was 26 months [25th–75th percentile: 16-35]. Results During follow-up, one or more ICD shocks were documented in 58 (14%) patients. Patients with shocks were younger (66±13years versus 70±10years, p=0.038), and more frequently implanted for secondary prevention (21% versus 10%, p=0.026). The maximum RDI value calculated during the entire follow-up period did not differ between patients with and without shocks (55±15episodes/h versus 54±14episodes/h, p=0.539). However, the ICD-detected RDI showed a considerable variability during follow-up. The overall median of the weekly RDI was 33episodes/h [25th–75th percentile: 24-45]. Using a time-dependent Cox regression model, the continuously measured weekly mean RDI≥45episodes/h was independently associated with shock occurrence (HR:4.63, 95%CI:2.54-8.43, p&amp;lt;0.001), after correction for baseline confounders (age, secondary prevention). Conclusions In HF patients, patients were more likely to receive appropriate ICD shocks during periods of time when they exhibited more sleep-disordered breathing.

Subcutaneous versus transvenous implantable defibrillator in patients with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiomyopathy. The implantable cardioverter-defibrillator (ICD) is important for prevention of sudden cardiac death (SCD) in patients at high risk. In recent years, the subcutaneous implantable cardioverter-defibrillator (S-ICD) has emerged as a viable alternative to the transvenous implantable cardioverter-defibrillator (TV-ICD). The S-ICD does not require intravascular access; however, it cannot provide antitachycardia pacing (ATP) therapy. The purpose of this study was to assess the real-world incidence of ICD therapy in patients with HCM implanted with TV-ICD vs S-ICD. We compared the incidence of ATP and shock therapies among all HCM patients with S-ICD and TV-ICD enrolled in the Boston Scientific ALTITUDE database. Cumulative Kaplan-Meier incidence was used to compare therapy-free survival, and Cox proportional hazard ratios were calculated. We performed unmatched as well as propensity match analyses. We included 2047 patients with TV-ICD and 626 patients with S-ICD, followed for an average of 1650.5 ± 1038.5 days and 933.4 ± 550.6 days, respectively. Patients with HCM and TV-ICD had a significantly higher rate of device therapy compared to those with S-ICD (32.7 vs 14.5 therapies per 100 patient-years, respectively; P <.001), driven by a high incidence of ATP therapy in the TV-ICD group, which accounted for >67% of therapies delivered. Shock incidence was similar between groups, both in the general and the matched cohorts. Patients with HCM and S-ICD had a significantly lower therapy rate than patients with TV-ICD without difference in shock therapy, suggesting potentially unnecessary ATP therapy. Empirical ATP programming in patients with HCM may be unbeneficial.

CI-524-02 ASSOCIATION BETWEEN DEVICE-DETECTED SLEEP APNEA AND IMPLANTABLE DEFIBRILLATOR THERAPY IN PATIENTS WITH HEART FAILURE

Sleep-disordered breathing is highly prevalent in heart failure (HF) and it has been suggested as a risk factor for malignant ventricular arrhythmias. The Respiratory Disturbance Index (RDI) algorithm computed by select implantable cardioverter defibrillators (ICDs) can identify severe sleep apnea (SA). In the present analysis we evaluated the association between ICD-detected SA and the incidence of appropriate ICD therapy in patients with HF. We enrolled 411 HF patients (age 69±10years, 77% male, ejection fraction 32±8%), implanted with an ICD endowed with an algorithm (ApneaScan, Boston Scientific) that calculates the RDI each night. In this analysis the weekly mean RDI value was considered. The endpoint was the first appropriate ICD shock. The median follow-up was 26 months [25th-75th percentile: 16-35]. During follow-up, one or more ICD shocks were documented in 58 (14%) patients. Patients with shocks were younger (66±13years versus 70±10years, p=0.038), and more frequently implanted for secondary prevention (21% versus 10%, p=0.026). The maximum RDI value calculated during the entire follow-up period did not differ between patients with and without shocks (55±15episodes/h versus 54±14episodes/h, p=0.539). However, the ICD-detected RDI showed a considerable variability during follow-up. The overall median of the weekly RDI was 33episodes/h [25th-75th percentile: 24-45]. Using a time-dependent Cox regression model, the continuously measured weekly mean RDI≥45episodes/h was independently associated with shock occurrence (HR:4.63, 95%CI:2.54-8.43, p<0.001), after correction for baseline confounders (age, secondary prevention). In HF patients, patients were more likely to receive appropriate ICD shocks during periods of time when they exhibited more sleep-disordered breathing.

Predictors of cardiovascular mortality after an electrical storm in patients with structural heart disease

BackgroundElectrical storms (ESs) in patients with structural heart disease (SHD) have been reported to be associated with a poor prognosis. However, the detailed cause of death and influence of implantable cardioverter defibrillator (ICD) therapy in ES patients have not been fully investigated. Therefore, we sought to explore the detailed clinical course after an ES and the impact of the ICD therapy in patients with SHDs. MethodsWe retrospectively analyzed 31 consecutive patients with ESs who had undergone an ICD implantation. ESs were defined as three or more ventricular arrhythmias within 24 h. ResultsDuring a mean follow up of 4.5 years, 13 patients died. Among them, cardiovascular death (CVD) was observed in 11/13 (85%), and the leading cause of the CVD was end-stage heart failure. A New York Heart Association class ≥III at the time of the ES occurrence (HR 6.51 95% CI 1.94–25.1, p = 0.003) and any shock therapy (HR 5.94 95% CI 1.06–112.2, p = 0.04) were associated with CVD. ConclusionIn the current single center study, the major cause of death in ES patients with SHDs was end-stage heart failure. Any shock therapy was associated with CVD. Arrhythmia management to avoid ICD shocks might reduce the mortality in ES patients.

Selvester Score May Be a Predictor of ICD Therapies in Patients with Non-Ischemic Dilated Cardiomyopathy.

The benefit of implantable cardioverter-defibrillator (ICD) in patients with non-ischemic dilated cardiomyopathy (DCM) is still an issue under discussion. Studies examining the relationship between ventricular scar tissue and ICD shock with cardiac magnetic resonance (CMR) are promising. CMR studies have shown that ventricular scar tissue size and Selvester score show a correlation. In the light of this information, this study aimed to investigate the potential relationship between Selvester score and ICD therapies. The study included 48 patients who had undergone ICD implantation with a diagnosis of DCM and who had undergone routine 6-month ICD control in outpatient clinic controls between December 2018 and October 2019. Selvester score and other data were compared between patients who received ICD therapy (n=10) and those who did not (n=38). Selvester score (P<0.001) was higher in ICD therapy group. Positive correlation was found between ICD shock therapy and Selvester score (P=0.002, r=0.843). Selvester score was detected as an independent predictor for ICD therapy after multiple linear regression analysis (P=0.004). Receiver operating characteristic curve analysis showed that Selvester score (P<0.001) was a significant predictor of ICD therapy. Selvester score cutoff points of 5 for were calculated to estimate ICD therapy, with a sensitivity of 100% and specifity of 81%. In our study, it was found that a high Selvester score may be a predictor for ICD therapies in patients with DCM. As an inexpensive and non-invasive method, Selvester score can help in the decision-making in these patients.

Arrhythmic and Mortality Outcomes Among Ischemic Versus Nonischemic Cardiomyopathy Patients Receiving Primary ICD Therapy.

This study sought to determine the association of cardiomyopathy etiology with the likelihood of ventricular arrhythmias, appropriate implantable cardioverter-defibrillator (ICD) therapy, and mortality. There are conflicting data on the benefit of primary prevention ICD therapy in patients with ischemic versus nonischemic cardiomyopathy (ICM/NICM). The study population comprised 4803 patients with ICM (n=3,106) or NICM (n=1,697) with a primary prevention ICD enrolled in 5 randomized trials conducted between 1997 and 2017. The primary end point was sustained ventricular tachycardia (VT)≥200 beats/min or ventricular fibrillation (VF). Secondary end points included appropriate ICD therapy and all-cause mortality. Differences in cause-specific mortality, including noncardiac, sudden cardiac, and non-sudden cardiac death, were also examined. Patients with ICM were significantly older and had more comorbid conditions, whereas those with NICM had a more advanced heart failure class at enrollment and were more often prescribed medical or cardiac resynchronization therapy for heart failure. Multivariate analysis showed that ICM versus NICM had a similar risk of VT/VF events (HR: 0.98 [95%CI: 0.79-1.20]) and appropriate ICD therapy (HR: 1.03 [95%CI: 0.87-1.22]), whereas the risk of all-cause mortality was 1.8-fold higher among ICM versus NICM patients (HR: 1.84 [95%CI: 1.42-2.38]), dominated by non-sudden cardiac mortality. Combined data from 5 landmark ICD clinical trials show that ICM patients experience a similar risk of life-threatening ventricular arrhythmic events but have an increased risk of all-cause mortality, dominated by non-sudden cardiac death, compared with NICM patients.

Implantable cardioverter-defibrillators with end stage renal disease: Nationwide inpatient sample database results.

When compared to patients with normal renal function, patients with chronic kidney disease develop higher in-hospital complications post implantable cardioverter-defibrillator (ICD) therapy. However, real world data on in-hospital complications post ICD therapy in patients with end stage renal disease (ESRD) is limited. In this study, we aim to explore the procedure-related complications of ICD therapy in patients with ESRD. Using the nationwide inpatient sample (NIS) database, we conducted a retrospective analysis on ESRD patients who underwent inpatient ICD placement from 2010 to 2016. Using 1:2 propensity score matching, we compared ESRD patients to those with normal renal function. Outcomes of interest were postoperative hemorrhage and hematoma formation, blood transfusion, pericardial complications, mechanical complications requiring lead revision, vascular injury, in-hospital mortality, and length of stay. Our sample included 40,075 cases with subsequent propensity score matching between ESRD and normal renal function. Comparatively, patients with ESRD had higher odds of postoperative hemorrhage (Odds ratio [OR]=1.67, 95% confidence interval [CI] 1.4-1.99, p=<.0001), blood transfusion (OR, 3.88; CI 3.29-4.56; p=<.0001), mechanical complications requiring lead revision (OR, 1.24; CI 1.01-1.51; p=.035), vascular injury (OR, 2.02; CI 1.27-3.24; p=.0027), in-hospital mortality (OR, 4.56; CI 3.08-6.76; p=<.0001), and longer hospitalization (11 vs. 7 days, p=<.0001), but without significant difference in pericardial complications (OR, 1.9; CI 0.92-1.54; p=<.18). In this large contemporary cohort, patients with ESRD undergoing inpatient ICD therapy are at higher risk of developing postprocedural complications including hemorrhage and hematoma, blood transfusion, mechanical complications requiring lead revision, and in hospital mortality, without increased risk of pericardial complications.

Prediction of cardiac events with non-contrast magnetic resonance feature tracking in patients with ischaemic cardiomyopathy.

AimsThe aim of this study was to evaluate the prognostic value of feature tracking (FT) derived cardiac magnetic resonance (CMR) strain parameters of the left ventricle (LV)/right ventricle (RV) in ischaemic cardiomyopathy (ICM) patients treated with an implantable cardioverter‐defibrillator (ICD). Current guidelines suggest a LV‐ejection fraction ≤35% as major criterion for ICD implantation in ICM, but this is a poor predictor for arrhythmic events. Supplementary parameters are missing.Methods and resultsIschaemic cardiomyopathy patients (n = 242), who underwent CMR imaging prior to primary and secondary implantation of ICD, were classified depending on EF ≤ 35% (n = 188) or >35% (n = 54). FT parameters were derived from steady‐state free precession cine views using dedicated software. The primary endpoint was a composite of cardiovascular mortality (CVM) and/or appropriate ICD therapy. There were no significant differences in FT‐function or LV‐/RV‐function parameters in patients with an EF ≤ 35% correlating to the primary endpoint. In patients with EF > 35%, standard CMR functional parameters, such as LV‐EF, did not reveal significant differences. However, significant differences in most FT parameters correlating to the primary endpoint were observed in this subgroup. LV‐GLS (left ventricular‐global longitudinal strain) and RV‐GRS (right ventricular‐global radial strain) revealed the best diagnostic performance in ROC curve analysis. The combination of LV‐GLS and RV‐GRS showed a sensitivity of 85% and a specificity of 76% for the prediction of future events.ConclusionsThe impact of FT derived measurements in the risk stratification of patients with ICM depends on LV function. The combination of LV‐GLS/RV‐GRS seems to be a predictor of cardiovascular mortality and/or appropriate ICD therapy in patients with EF > 35%.

B-PO03-169 MYOCARDIAL SCAR BURDEN QUANTIFIED BY CARDIAC MAGNETIC RESONANCE IMAGING IS PREDICTIVE OF VENTRICULAR TACHYCARDIA IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY

Patients with hypertrophic cardiomyopathy (HCM) are at a higher risk of developing ventricular tachycardia (VT) and sudden cardiac death (SCD). Previous studies have demonstrated a correlation between late gadolinium enhancement (LGE) measured by cardiac magnetic resonance imaging (MRI) quantified as % of myocardial mass and VT; however, the predictive value of a more practical and routinely performed semi-quantitative assessment of LGE remains unknown. To determine whether a semi-quantitative assessment of myocardial fibrosis by cardiac MRI (number of myocardial segments with LGE) is predictive of VT in patients with HCM. We identified 65 patients (mean age 47±17, 34% female) with a clinical diagnosis of HCM who had a cardiac MRI prior to an implantable cardioverter defibrillator (ICD) implantation for primary prevention of SCD. VT was defined as appropriate anti-tachycardia pacing or shocks for sustained ventricular arrhythmias. The MRI was analyzed by an experienced radiologist blinded to the clinical data. LGE was assessed by both quantitative (% of total myocardial mass) and semi-quantitative (number of myocardial segments involved) methods. During the follow-up period (median 33 months), seven patients experienced VT. Patients with > 6 myocardial segments with LGE were at higher risk to develop VT (OR: 5.7, p=0.03) which remained significant after adjusting for age, maximum left ventricular wall thickness, left atrial size, maximum left ventricular outflow gradient, history of nonsustained VT, unexplained syncope, and family history of SCD (p=0.03). Similarly, patients with a higher fibrosis burden (LGE >10% myocardial mass) were more likely to develop VT (OR: 8.6, p=0.01) even after adjusting for the abovementioned traditional risk factors (p=0.04). The extent of LGE, assessed by both quantitative and semi-quantitative measures, is strongly associated with ventricular arrhythmias requiring ICD therapy in patients with HCM even after accounting for traditional risk factors. Fibrosis burden as detected by cardiac MRI may serve as an imaging biomarker to improve risk stratification and patient selection for primary prevention ICD implantation in patients with HCM.

Subcutaneous Versus Transvenous Implantable Defibrillator in Patients with Hypertrophic Cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) is the most prevalent inherited cardiomyopathy. Implantable Cardioverter Defibrillator (ICD) is important for prevention of sudden cardiac death (SCD) in patients at high risk. In recent years the subcutaneous ICD (S-ICD) has emerged as a viable alternative to the transvenous ICD (TV-ICD). The S-ICD does not require intravascular access, but cannot provide antitachycardia pacing therapy (ATP). Objective: To assess the real world incidence of ICD therapy in patients with HCM implanted with TV-ICD versus S-ICD.Methods: We compared the incidence of ATP and shock therapies between all HCM patients with S-ICD and TV-ICD enrolled in the Boston Scientific ALTITUDE database. Cumulative Kaplan Meier incidence was used to compare therapy free survival and Cox proportional hazard ratios were calculated. We performed an unmatched as well as propensity match analysis. Results: We included 2462 patients with TV-ICD and 716 patients with S-ICD followed for an average of 1348 {plus minus} 989 days. Patients with HCM and TV-ICD had significantly higher rate of device therapy as compared to those with S-ICD (31.1 vs. 14.7 therapies /100 patient year; p<0.001), driven by a high incidence of ATP therapy in the TV-ICD group which accounted for more than 67% of therapies delivered. Shock incidence was similar between groups, both in the general and in the matched cohorts. Conclusions: Patients with HCM and S-ICD had significantly lower therapy rate than patients with TV-ICD without difference in shock therapy, suggesting potentially unnecessary ATP therapy. Empiric ATP programing in patients with HCM may be unbeneficial.

Comparison of 2-year outcomes between primary and secondary prophylactic use of defibrillators in patients with coronary artery disease: A prospective propensity score-matched analysis from the Nippon Storm Study.

BackgroundThe Nippon Storm Study was a prospective observational study designed to gather clinical data on implantable cardioverter-defibrillator (ICD) therapy in Japanese patients.ObjectiveThe purpose of this subanalysis was to compare the incidence of ICD therapy in patients with left ventricular dysfunction owing to coronary artery disease (CAD) for primary and secondary prophylaxis of sudden cardiac death.MethodsWe analyzed data of 493 patients with CAD and ICDs (men, 87%; age, 68 ± 10 years; left ventricular ejection fraction, 36% ± 13%; primary prophylaxis, 36%). All patients were followed up for at least 2 years. Propensity score matching was used to select patient subgroups for comparison: 133 patients with ICD for primary prophylaxis and 133 with ICD for secondary indications.ResultsThere were no significant differences between primary and secondary prophylaxis groups with respect to the incidence of appropriate ICD therapy within 2 years (0.153 vs 0.239; hazard ratio, 1.565 [95% confidence interval (CI), 0.898–2.727]; P = .114). Two-year electrical storm risks were 3.3% and 9.6% with HR = 3.236 (95% CI, 1.058–9.896; P = .039) in patients with primary and secondary prophylaxis, respectively.ConclusionThe incidence of ICD therapy received by patients with CAD for primary and secondary prophylaxis was not significantly different based on our propensity score–matched analysis. However, secondary-prophylaxis ICD therapy seems to be associated with a significantly higher risk for electrical storm than primary-prophylaxis ICD therapy.

Usefulness of subcutaneous implantable cardioverter-defibrillator therapy in patients with Brugada syndrome.

Implantable cardioverter-defibrillators (ICDs) are the main therapy to prevent sudden cardiac death in patients with Brugada syndrome (BrS). The subcutaneous ICD (S-ICD) can eliminate lead-associated complications compared with transvenous ICD (TV-ICD). However, S-ICD is susceptible to T-wave oversensing (TWOS) and may result in more frequent inappropriate shocks in patients with BrS. This study aimed to compare inappropriate shocks between TV-ICD and S-ICD in patients with BrS. We enrolled 32 patients with BrS (including one woman; mean age 52 ± 18years) who were implanted with ICD (23 TV-ICDs and 9 S-ICDs) between January 2002 and November 2018 in Oita University Hospital. We carried out a standard surface electrocardiogram (ECG) screening tests in both supine and standing positions prior to S-ICD implantation. The patients received routine clinical review every month and device monitoring every 4months. The period of follow-up was 129 ± 51months. Six patients with BrS and TV-ICDs experienced inappropriate shocks (26%) with their ICD therapy. In contrast, two patients with BrS and S-ICDs experienced inappropriate shocks (22%). There was no significant difference between the two groups (P = 0.82). Although one case in the S-ICD group experienced TWOS-induced inappropriate shock, SMART Pass (new high-pass filter) prevented the subsequent recurrence of inappropriate shocks during ICD therapy. Our results suggest that S-ICD is not inferior to TV-ICD in the incidence of inappropriate shocks. SMART Pass may be a useful tool to prevent inappropriate ICD shocks by TWOS in patients with BrS.

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

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. 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. 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. 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%. 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.