Subcutaneous Implantable Cardioverter-defibrillator Eligibility Research Articles

Electrocardiographic changes during haemodialysis and the potential impact on subcutaneous implantable cardioverter defibrillator eligibility

IntroductionHaemodialysis patients who require defibrillator therapy are expected to benefit from the entirely avascular subcutaneous defibrillator (S-ICD), but haemodialysis is associated with dynamic changes in R and T wave amplitude which can impact S-ICD eligibility. A continuous assessment of S-ICD eligibility during haemodialysis has not previously been performed. Material and methodsContinuous surface ECG recordings were obtained from a cohort of patients undergoing maintenance haemodialysis, but without an indication for an ICD. Automated vector screening was retrospectively performed at one-minute intervals throughout the dialysis session. Variations in S-ICD eligibility were calculated and in vectors with high degrees of variation, the underlying mechanism was identified. Results72 vector recordings (mean duration 254.1 ± 6.0 min) were obtained from 24 patients (mean age 64.3 ± 5.5 years, 68% male). At the start of haemodialysis 47 vectors were S-ICD eligible (65.2%). At the end of session, all of these vectors had remained eligible, and an additional 6 vectors had also become eligible (73.6%). High vector score variability was observed in 7 patients and the commonest cause was a progressive change in R:T ratio (71.5%). ConclusionIn a haemodialysis population, a single haemodialysis session can be associated with a potential change in S-ICD eligibility in 8.4% of vectors, with up to 12.5% of vectors showing high degrees of variability, most commonly due to variations in R:T ratio. In an S-ICD population with similar characteristics S-ICD screening prior to haemodialysis would be expected to more accurately identify vectors that retain eligibility.

Abstract 9203: Role of Artificial Intelligence and Utilisation of Deep Learning Methods in Screening for Subcutaneous Implantable Cardioverter Defibrillator Eligibility

Introduction: There is a Class I recommendation for S-ICD in patients with no pacing indication at a high risk of infection. S-ICD eligibility is assessed at pre-implant screening where ECG traces taken in multiple postures are used as a surrogate for S-ICD vectors. In HF patients undergoing diuresis, changes in electrolytes, and fluid shifts can cause changes in R and T waves amplitudes. Subsequently, T:R ratio - a major predictor of S-ICD eligibility - is dynamic. Hypothesis: We hypothesize that prolonged screening for S-ICD eligibility identifies HF patients with high probability of T wave oversensing (TWO) and inappropriate shocks that can otherwise be missed using current screening practices. Methods: We ran a prospective study where participants with structurally normal hearts and HF patients undergoing diuresis on clinical grounds were fitted with Holters®. The leads were placed to correspond to the 3 vectors of an S-ICD. We used a convolutional neural network-based model utilising phase space reconstruction matrix as a state-of-the-art tool to assess T:R ratios over 24 hours against eligibility cut-off of 1:3 based on the manufacturer screening tool. Results: A total of 21 patients (mean age 58.43 ± 18.92, 62% male) were enrolled (14 HF, 7 normal hearts). We found a significant difference in the mean and SD of the T/R ratios between both groups. Mean T/R ratio was 0.181 ± 0.084 and 0.104 ± 0.054, and SD was 0.093 ± 0.048 and 0.067 ± 0.036 in HF and normal heart groups, respectively. T/R ratio was above the eligibility threshold with medians of 4.68% (0- 64.6%) and 0.03 % (0 - 30.4%) in HF and normal heart groups, respectively. There was no difference in the mean, SD or median between leads within the same group. Conclusions: T:R ratio, a main determinant for S-ICD eligibility is higher and with more tendency to fluctuate in HF patients. We report an accurate method that utilises prolonged screening to select HF patients eligible for S-ICD with low probability of TWO and inappropriate shocks.

Eligibility for subcutaneous implantable cardioverter-defibrillator in adults with congenital heart disease.

AimsPatients with adult congenital heart disease (ACHD) carry an increased risk for sudden cardiac death. Implantable cardioverter‐defibrillator (ICD) therapy may be challenging in these patients due to anatomical barriers, repeated cardiac surgery, or complicated transvenous access. Thus, the subcutaneous ICD (S‐ICD) can be a promising alternative in this patient population. Patients with ACHD show significant electrocardiogram (ECG) abnormalities, which could affect S‐ICD sensing because it depends on surface ECG.Methods and resultsOne hundred patients with ACHD were screened for S‐ICD eligibility. Standard ECG‐based screening test and automated S‐ICD screening test were performed in all patients. Sixty‐six patients (66%) were male. Underlying congenital heart disease (CHD) was mainly CHD of great complexity (71%) and moderate complexity (29%), including repaired tetralogy of Fallot (20%), which was the most common entity. Thirty‐seven patients (37%) already had a pacemaker (23%) or ICD (14%) implanted. Automated screening test identified 83 patients (83%) eligible for S‐ICD implantation in either left parasternal position (78%) or right parasternal position (75%). Absence of sinus rhythm, QRS duration, and a paced QRS complex were associated with S‐ICD screening failure in univariate analysis. Receiver operating characteristic curve and multivariate analysis revealed a QRS duration ≥148 ms as the only independent predictor for S‐ICD screening failure.ConclusionsPatients with ACHD show satisfactory eligibility rates (83%) for S‐ICD implantation utilizing the automated screening test, including patients with CHD of high complexity. S‐ICD therapy should be considered with caution in ACHD patients with a QRS duration ≥148 ms and/or need for ventricular pacing.

A novel screening tool to unmask potential interference between S-ICD and left ventricular assist device.

In patients with a left ventricular assist device (LVAD), the subcutaneous implantable cardioverter-defibrillator (S-ICD) can be an alternative to transvenous ICD systems due to reduced risk of systemic infection, which could lead to extraction of the ICD as well as the LVAD. S-ICD eligibility is lower in patients with LVAD than in patients with end-stage heart failure without LVAD. Several reports have shown inappropriate S-ICD therapy in the coexistence of LVAD and S-ICD. The aim of the present study was to evaluate S-ICD eligibility in patients with LVAD using the established electrocardiogram (ECG)-based screening test as well as a novel device-based screening test to identify potentially inappropriate S-ICD sensing in this specific patient cohort. The present study included 115 patients implanted with an LVAD. The standard ECG-based screening test and a novel device-based screening test were performed in all patients. Eighty patients (70%) were eligible for S-ICD therapy with the standard ECG-based screening test. Performance of the novel device-based screening test identified device-device interference in 14 of these 80 patients (12%). Using a novel extended device-based S-ICD screening method, a small number of patients with LVAD deemed eligible for S-ICD with the standard ECG-based screening test exhibit device-device interference. Careful S-ICD screening should be performed in patients with LVAD, who are candidates for S-ICD therapy, to prevent inappropriate sensing or ICD therapy.

Eligibility for subcutaneous implantable cardioverter-defibrillator in patients with left ventricular assist device

PurposeThe subcutaneous implantable cardioverter-defibrillator (S-ICD) could be a promising alternative to the conventional transvenous ICD in patients with LVAD due to its reduced risk of infection. However, surface ECG is altered following LVAD implantation and, since S-ICD detection is based on surface ECG, S-ICD could be potentially affected. The aim of the present study was to analyze S-ICD eligibility in patients with LVAD.MethodsSeventy-five patients implanted with an LVAD were included in this prospective single-center study. The ECG-based screening test and the automated screening test were performed in all patients.ResultsFifty-five (73.3%) patients had either a positive ECG-based or automated screening test. Out of these, 28 (37.3%) patients were found eligible for S-ICD implantation with both screening tests performed. ECG-based screening test was positive in 50 (66.6%) patients; automated screening test was positive in 33 (44.0%) patients. Three ECG-based screening tests could not be evaluated due to artifacts. With the automated screening test, in 9 (12.0%) patients, the test yielded no result.ConclusionsPatients implanted with an LVAD showed lower S-ICD eligibility rates compared with patients without LVAD. With an S-ICD eligibility rate of maximal 73.3%, S-ICD therapy may be a feasible option in these patients. Nevertheless, S-ICD implantation should be carefully weighed against potential device-device interference. Prospective studies regarding S-ICD eligibility before and after LVAD implantation are required to further elucidate the role of S-ICD therapy in this population.

Eligibility for subcutaneous implantable cardioverter-defibrillator in congenital heart disease

Adult congenital heart disease (ACHD) patients can benefit from a subcutaneous implantable cardioverter-defibrillator (S-ICD). The purpose of this study was to assess left- and right-sided S-ICD eligibility in ACHD patients, use machine learning to predict S-ICD eligibility in ACHD patients, and transform 12-lead electrocardiogram (ECG) to S-ICD 3-lead ECG, and vice versa. ACHD outpatients (n = 101; age 42 ± 14 years; 52% female; 85% white; left ventricular ejection fraction [LVEF] 56% ± 9%) were enrolled in a prospective study. Supine and standing 12-lead ECG were recorded simultaneously with a right- and left-sided S-ICD 3-lead ECG. Peak-to-peak QRS and T amplitudes; RR, PR, QT, QTc, and QRS intervals; Tmax, and R/Tmax (31 predictor variables) were tested. Model selection, training, and testing were performed using supine ECG datasets. Validation was performed using standing ECG datasets and an out-of-sample non-ACHD population (n = 68; age 54 ± 16 years; 54% female; 94% white; LVEF 61% ± 8%). Forty percent of participants were ineligible for S-ICD. Tetralogy of Fallot patients passed right-sided screening (57%) more often than left-sided screening (21%; McNemar χ2P = .025). Female participants had greater odds of eligibility (adjusted odds ratio [OR] 5.9; 95% confidence interval [CI] 1.6-21.7; P = .008). Validation of the ridge models was satisfactory for standing left-sided (receiver operating characteristic area under the curve [ROC AUC] 0.687; 95% CI 0.582-0.791) and right-sided (ROC AUC 0.655; 95% CI 0.549-0.762) S-ICD eligibility prediction. Validation of transformation matrices showed satisfactory agreement (<0.1 mV difference). Nearly half of the contemporary ACHD population is ineligible for S-ICD. The odds of S-ICD eligibility are greater for female than for male ACHD patients. Machine learning prediction of S-ICD eligibility can be used for screening of S-ICD candidates.

Conventional and alternative preimplantation ECG screening for subcutaneous ICD in high risk hypertrophic cardiomyopathy patients

IntroductionPatients with hypertrophic cardiomyopathy (HCM) relatively often fail preimplantation ECG screening for subcutaneous implantable cardioverter-defibrillator (S-ICD). We aimed to evaluate impact of conventional and alternative ECG electrodes placement on eligibility for S-ICD implantation in HCM patients at high risk of sudden cardiac death (SCD). We hypothesized that modified electrodes placement will influence QRS-T morphology and thus it will increase S-ICD eligibility in the screening process. Material and methodsThis study enrolled 17 HCM patients at high risk of SCD (5-year SCD risk above 5%) referred for an ICD implantation. ECG screening for S-ICD eligibility in horizontal and vertical position was performed in each patient, in two different screening electrodes configuration: conventional (recommended by manufacturer) and alternative (precordial electrodes shifted rightwards and lateral electrodes dorsally). We evaluated QRS and T waves amplitude as well as T wave index. Primary, secondary and alternate sensing vectors were assessed. ResultsPreimplantation ECG screening with alternative electrodes placement resulted in more sensing vectors that were screened successfully (77 vs. 88, p = 0.05). Modified screening combined with a standard one allowed more patients to qualify for S-ICD implantation (17/17 vs. 12/17, p = 0.04). Electrocardiographically, the alternative positioning of ECG electrodes resulted in significant decrease in absolute values of QRS complex and T waves amplitudes in almost all sensing vectors, which was responsible for successful screening. ConclusionsThe use of alternative placement of screening electrodes may be a valuable method to increase eligibility for S-ICD implantation in HCM patients at high risk of SCD.

Prevalence of subcutaneous implantable cardioverter-defibrillator based on template ECG screening and ineligible surface ECG predicting factors in patients with hypertrophic cardiomyopathy in China.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) may provide comparable protection while avoiding the disadvantage of transvenous lead, but the abnormal features of the hypertrophic cardiomyopathy (HCM) electrocardiogram (ECG) make it a challenge for S-ICD template screening. We aimed to investigate S-ICD eligibility according to the S-ICD manufacturer's surface ECG screening template in China, and further analyze its corresponding ineligible predicting factors in 12-lead suface ECG. A total of 179 HCM patients (114 males; mean age: 45 ± 14years) underwent S-ICD screening at rest and on exercise, among which 91 patients (50.8%) were eligible for S-ICD. Among the patients who passed screening, 43 (47.3%) had 3 vectors eligibility; 64 (70.3%) screening qualified on both sides; 10 patients (11.0%) passed the screening while the electrodes located only on the left parasternal line versus 17 patients (18.7%) moved to the right line. The secondary sensing vector (Lead III) was mostly appropriate (53.6%), followed by the primary sensing vector (lead II, 53.1%) and the alternate sensing vector (Lead I, 46.9%). Higher R wave was the major cause, accounted for 70.5%, for screening failure. There existed significant difference in T wave in lead II, aVF, V5 and V6, adds R/T ratio in lead V5 and V6, between the screening success group (group A) and screening failure group (group B) at rest and on exercise. A multivariable logistic regression analysis was performed to identify that R/T ≤ 3.5 in lead V5 was the independent factor to predict the screening ineligibility, with odds ratio 3.648. S-ICD screening success is 50.8% in HCM patients, which is much lower than that in other studies. R/T ≤ 3.5 in lead V5 in 12-lead surface ECG was an independent predicting factor for screening failure.

Candidacy for a Subcutaneous Implantable Cardioverter Defibrillator in Patients with Cardiac Resynchronization Therapy.

In patients requiring an implantable cardioverter defibrillator (ICD), the combined use of a prior pacemaker and a subcutaneous ICD (S-ICD) could be an alternative treatment option to implantation of new leads or upgrading of pacemakers to an ICD if vascular access is limited. Here, we assessed the prevalence of S-ICD's eligibility according to surface electrogram screening in those receiving cardiac resynchronization therapy (CRT). S-ICD's eligibility was assessed in patients with a CRT pacemaker or a CRT defibrillator using the S-ICD template screening tool. Eligibility was defined as fulfillment of the template in both supine and upright positions in one or more leads during biventricular pacing. Among 44 patients (34 men, age: 67 ± 12), 36 (82%) were found to be eligible. The T/QRS amplitude ratio in lead II was significantly lower in those who were eligible (0.31 ± 0.16 versus 0.44 ± 0.18 in the ineligible group, P = 0.04). The lead position, underlying disease, and other electrocardiographic findings were not different between those who were eligible and those who were not. The majority of patients with biventricular pacing were eligible for S-ICD based on current screening tests and may benefit from this treatment. Further study is required.

The utility of routine clinical 12-lead ECG in assessing eligibility for subcutaneous implantable cardioverter defibrillator

IntroductionThe subcutaneous implantable cardioverter-defibrillator (S-ICD) is a life-saving device. Recording of a specialized 3-lead electrocardiogram (ECG) is required for S-ICD eligibility assessment. The goals of this study were: (1) evaluate the effect of ECG filtering on S-ICD eligibility, and (2) simplify S-ICD eligibility assessment by development of an S-ICD ineligibility prediction tool, which utilizes the widely available routine 12-lead ECG. Methods and resultsProspective cross-sectional study participants [n = 68; 54% male; 94% white, with wide ranges of age (18–81 y), body mass index (19–53), QRS duration (66–150 ms), and left ventricular ejection fraction (37–77%)] underwent 12-lead supine, 3-lead supine and standing ECG recording. All 3-lead ECG recordings were assessed using the standard S-ICD pre-implantation ECG morphology screening. Backward, stepwise, logistic regression was used to build a model for 12-lead prediction of S-ICD eligibility. Select electrocardiogram waves and complexes: QRS, R-, S, and T-amplitudes on all 12 leads, averaged QT interval, QRS duration, and R/T ratio in the lead with the largest T wave (R/Tmax) were included as predictors. The effect of ECG filtering on ECG morphology was evaluated. A total of 9 participants (13%) failed S-ICD screening prior to filtering. Filtering at 3–40 Hz, similar to the S-ICD default, reduced S-ICD ineligibility to 4%. A regression model that included RII, SII-aVL, TI, II, aVL, aVF, V3-V6, and R/Tmax perfectly predicted S-ICD eligibility, with an Area Under the Receiver Operating Characteristic Curve of 1.0. ConclusionRoutine clinical 12-lead ECG can be used to predict S-ICD eligibility. ECG filtering may improve S-ICD eligibility.

Exercise stress test reveals ineligibility for subcutaneous implantable cardioverter defibrillator in patients with Brugada syndrome.

The eligibility of patients with Brugada syndrome (BrS) for implantation of a subcutaneous implantable cardioverter defibrillator (S-ICD) is not well known. This study aimed to clarify the eligibility of BrS patients for S-ICD using electrocardiography (ECG) at rest and during exercise testing. We also analyzed factors associated with ineligibility for S-ICD from standard 12-lead ECG at rest. We enrolled 110 consecutive BrS patients who visited Okayama university hospital from December 2015 to December 2016. All patients were assessed for S-ICD eligibility, which required one lead to satisfy the S-ICD screening template. We assessed standard 12-lead ECG parameters in all participants. Of those who passed S-ICD screening, 45 patients were assessed for S-ICD eligibility during treadmill stress test. Mean age of study patients was 54 ± 13 years and 108 (98%) were men. In total, 89 patients (81%) satisfied S-ICD indications at rest. Existence of complete right bundle branch block (CRBBB) on standard 12-lead ECG was a significant predictor of ineligibility for S-ICD (odds ratio, 5.00; P=0.03; 95%CI, 1.14-21.98). Of the 45 patients who underwent treadmill stress testing, 11 patients (24%) showed ineligibility for S-ICD during the test. CRBBB was a predictor of ineligibility for S-ICD in patients with BrS. Sinus tachycardia changes ECG morphology in some patients and stress testing should be considered before S-ICD implantation.

The Role of Conventional and Right-Sided ECG Screening for Subcutaneous ICD in a Tetralogy of Fallot Population.

Information regarding suitability for subcutaneous implantable cardioverter-defibrillator (S-ICD) implant in tetralogy of Fallot (ToF) population is scarce and needs to be further explored. (1) to determine the proportion of patients with ToF eligible for S-ICD, (2) to identify the optimal sensing vector in ToF patients, (3) to test specifically the eligibility for S-ICD with right-sided screening, and (4) to compare with the proportion of eligible patients in a nonselected ICD population. We recruited 60 consecutive patients with ToF and 40 consecutive nonselected patients. Conventional electrocardiographic screening was performed as usual. Right-sided alternative screening was studied by positioning the left arm and right arm electrodes 1 cm right lateral to the xiphoid midline. The Boston Scientific electrocardiogram (ECG) screening tool was utilized. We found a higher proportion of patients with right-sided positive screening in comparison with standard screening (77 ± 0.4% vs. 67 ± 0.4%; P < 0.0001) and a trend to higher number of appropriate leads in right-sided screening (1.3 ± 1 vs. 1.1 ± 1 ms; P = 0.07). Patients who failed the screening had a longer QRS duration and longer QT interval. Standard and right-sided screening showed a higher percent of positive patients in the control group compared to ToF patients (P < 0.001). Right-sided screening was associated with a significant 10% increase in S-ICD eligibility in ToF patients. When comparing with an acquired cardiomyopathies group, ToF showed a lower eligibility for S-ICD. The most appropriate ECG vector was the alternate vector in contrast to what is observed in the general population.

Right Parasternal Lead Placement Increases Eligibility for Subcutaneous Implantable Cardioverter Defibrillator Therapy in Adults With Congenital Heart Disease.

The subcutaneous implantable cardioverter defibrillator (S-ICD) provides an attractive option for patients with congenital heart disease (CHD) in whom a transvenous defibrillator is contraindicated. Given the unusual cardiac anatomy and repolarization strain, the surface electrocardiogram (ECG) is frequently abnormal, potentially increasing the screen failure rate. We prospectively screened 100 adult CHD patients regardless of the presence of clinical indication for ICD utilizing a standard left sternal lead placement, as well as a right parasternal position. Baseline patient and 12-lead ECG characteristics were examined to assess for predictors of screen failure. Average patient age was 48±14 years, average QRS duration was 134±37 ms, and 13 patients were pacemaker dependent. Using the standard left parasternal electrode position, 21 patients failed screening. Of these 21 patients with screen failure, 9 passed screening with the use of right parasternal electrode positioning, reducing screening failure rate from 21% to 12%. QT interval and inverted T wave anywhere in V2-V6 leads were found to be independent predictors of left parasternal screening failure (P=0.01 and P=0.04, respectively). Utilization of both left and right parasternal screening should be used in evaluation of CHD patients for S-ICD eligibility. ECG repolarization characteristics were also identified as novel predictors of screening failure in this group. (Circ J 2016; 80: 1328-1335).

Electrocardiographic Eligibility for Subcutaneous Implantable Cardioverter Defibrillator: Evaluation during Bicycle Exercise

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is used in patients at risk of sudden death. Our aim was to assess clinical predictors of electrocardiographic ineligibility for S-ICD, and the impact of exercise on S-ICD eligibility in an unselected series of patients requiring ICD therapy. 102 patients at risk of sudden death were evaluated at rest and during exercise. Electrocardiograph screening using limb lead electrodes (to simulate the S-ICD sensing vectors) was performed at rest and during bicycle ergometer exercise. R wave amplitude in lead D3 during exercise >16mV, baseline QTc and the sum of amplitudes of the R waves at supine >30mV were predictors of ineligibility for S-ICD. Eligibility increased from 90% to 100% of patients when evaluated with an "any of the three leads" criterion compared to current recommendations. A more restrictive criterion based on two of three ECG leads caused an eligibility drop at 66%, that further decreased to 56% during exercise; these figures improved to 79% and 81%, respectively, when an "any 2 of 3 leads" criterion was used. Huge ECG amplitude and QTc duration are associated with ineligibility in the current S-ICD release. By performing exercise testing, lead suitability changes in one patient out of 14 (7% of tested patients) and eligibility is decreased by use of a more stringent criterion for eligibility (ECG criteria satisfied in two of three leads). A dynamic selection of sensing vectors aiming at situation-specific suitability (any of three leads) would increase S-ICD eligibility to 100% of patients.

Abstract 14709: Right Sternal Lead Placement Increases Eligibility for Subcutaneous Defibrillator Implantation in Adults With Congenital Heart Disease

Introduction: The subcutaneous implantable cardioverter defibrillator (S-ICD) is an attractive option for patients with congenital heart disease (CHD) in whom a transvenous system is contraindicated. However, more than 10% of adult patients with CHD fail S-ICD screening due to a large T- to R-wave ratio. We hypothesized right-sternal electrodes may permit S-ICD placement in patients who fail left-sternal screen. Methods: We prospectively screened 40 patients with CHD for S-ICD using the standard proprietary approach. We also screened with right sternal electrodes (with left can electrode position). Results: The mean age of the cohort was 46+/-15 years; 24 males were enrolled. CHD anomalies consisted of tetralogy of Fallot (n=11), Ebstein’s anomaly (n=7), atrial septal defect (n=6), dextro-looped transposition of the great artery (n=5) and other (n=11). Left side screening ECG failed in 9 patients (23%), five of whom passed with right sternal electrodes, increasing the pass rate from 77% to 90%. Figure shows the screening ECG and chest x-ray of a patient who failed in all three vectors on the left side but passed in the alternative vector on the right side and underwent right sided implantation. Conclusions: The addition of right sternal electrodes during screening increases S-ICD eligibility and may avoid thoracotomy for high risk patients with CHD.

Eligibility for the Subcutaneous Implantable Cardioverter-Defibrillator in Patients With Hypertrophic Cardiomyopathy.

High-risk hypertrophic cardiomyopathy (HCM) patients benefit from the implantable cardioverter defibrillator (ICD). The subcutaneous ICD (S-ICD) may provide comparable protection while avoiding the shortcomings of transvenous (TV) leads. We assessed S-ICD eligibility according to surface ECG screening test in a cohort of high-risk HCM patients. 47 HCM patients (3 S-ICD candidates; 41 TV-ICD patients without pacing indication; and 3 pacemaker-dependent TV-ICD patients) underwent 4 screening protocols: standard (n = 44); exercise (n = 33); continuous pacing (n = 44); alternating paced/spontaneous QRS (n = 41). Of the 44 patients in the standard screening group, 41 (93%) were eligible. Max LV thickness was inversely related to the number of qualifying leads (3 leads: 21 ± 4 mm; 2 leads: 22 ± 6 mm; 1 lead: 25 ± 6 mm; no leads: 28 ± 11 mm; P = 0.07). Of the 33 patients in the exercise group, 5 were ineligible (3 after exercise). Of these, 2 became eligible after moving sternal electrodes from the left to the right parasternal line (eligibility rate: 30/33; 91%). Of the 44 patients in the continuous pacing group, 28 (64%) were eligible, 8 of which with right parasternal electrodes. In the paced/spontaneous QRS group (n = 41), 21 patients (51%) had at least 1 eligible lead during pacing and retained compatibility on the same lead during spontaneous rhythm, 5 of which with right parasternal electrodes. S-ICD screening failure is low in HCM, provided that patients with severe hypertrophy are carefully evaluated. Exercise test should be performed and right parasternal leads tested. Pacemaker patients display lower eligibility rate.