Project description:The difference between subcutaneous implantable cardioverter defibrillators (S-ICDs) and transvenous ICDs (TV-ICDs) concerns a whole extra thoracic implantation, including a defibrillator coil and pulse generator, without endovascular components. The improved safety profile has allowed the S-ICD to be rapidly taken up, especially among younger patients. Reports of its role in different cardiac diseases at high risk of SCD such as hypertrophic and arrhythmic cardiomyopathies, as well as channelopathies, is increasing. S-ICDs show comparable efficacy, reliability, and safety outcomes compared to TV-ICD. However, some technical issues (i.e., the inability to perform anti-bradycardia pacing) strongly limit the employment of S-ICDs. Therefore, it still remains only an alternative to the traditional ICD thus far. This review aims to provide a contemporary overview of the role of S-ICDs compared to TV-ICDs in clinical practice, including technical aspects regarding device manufacture and implantation techniques. Newer outlooks and future perspectives of S-ICDs are also brought up to date.
Project description:The subcutaneous implantable cardioverter-defibrillator (S-ICD) has recently been approved for commercial use in Europe, New Zealand and the United States. It is comprised of a pulse generator, placed subcutaneously in a left lateral position, and a parasternal subcutaneous lead-electrode with two sensing electrodes separated by a shocking coil. Being an entirely subcutaneous system it avoids important periprocedural and long-term complications associated with transvenous implantable cardioverter-defibrillator (TV-ICD) systems as well as the need for fluoroscopy during implant surgery. Suitable candidates include pediatric patients with congenital heart disease that limits intracavitary lead placements, those with obstructed venous access, chronic indwelling catheters or high infection risk, as well as young patients with electrical heart disease (e.g., Brugada Syndrome, long QT syndrome, and hypertrophic cardiomyopathy). Nevertheless, given the absence of intracavitary leads, the S-ICD is unable to offer pacing (apart from short-term post-shock pacing). It is therefore not suitable in patients with an indication for antibradycardia pacing or cardiac resynchronization therapy, or with a history of repetitive monomorphic ventricular tachycardia that would benefit from antitachycardia pacing. Current data from initial clinical studies and post-commercialization "real-life" case series, including over 700 patients, have so far been promising and shown that the S-ICD successfully converts induced and spontaneous ventricular tachycardia/ventricular fibrillation episodes with associated complication and inappropriate shock rates similar to that of TV-ICDs. Furthermore, by using far-field electrograms better tachyarrhythmia discrimination when compared to TV-ICDs has been reported. Future results from ongoing clinical studies will determine the S-ICD system's long-term performance, and better define suitable patient profiles.
Project description:BackgroundSubcutaneous implantable cardioverter-defibrillators (S-ICDs) are increasingly used in patients without a pacing indication, and may reduce venous complications, endocarditis and extraction morbidity. Subcutaneous implantable cardioverter-defibrillator displacements may be less obvious than their transvenous counterparts.Case summaryA 59-year-old man was found to have dilated cardiomyopathy associated with heavy alcohol intake following investigation for a stroke. Despite 2 years of alcohol cessation and optimal drug therapy, his ejection fraction remained severely impaired, and he received an S-ICD using the manufacturer recommended screening and implant method, and by an experienced operator. Ten months later, inappropriate shocks were delivered despite optimal programming. Device displacement was demonstrated by lateral chest radiography on the second instance of inappropriate therapy. On the first admission, a lateral film was not performed, and simple device programming was undertaken which failed to prevent the second occurrence. The patient requested an explant; as ventricular function had improved following initiation of sacubutril/valsartan, the clinical team opted to remove the device.DiscussionCareful inspection of lateral chest films and review of device indication are needed to reduce the risk of inappropriate shocks. This is the first description of inappropriate device activity following lone generator displacement-lead displacement is well described.
Project description:Background and objectivesPreimplantation QRS-T morphology screening (TMS) is a composite tool for selecting subcutaneous implantable cardioverter defibrillator (S-ICD) candidates. However, its role in predicting the patient's response to cardiac resynchronization therapy (CRT) is uncertain.MethodsA total of 55 consecutive de novo CRT candidates were enrolled between January 2016 and March 2017. Electrocardiogram (ECG) and TMS were performed before and soon after implantation. The ECG parameters were recorded, including QRS duration and morphology (such as ΔQRS_Index, QTc during biventricular pacing mode [BiV pacing QTc], and QRS/T ratio during biventricular pacing mode [BiV pacing QRS/T ratio]). TMS monitored three sensory vectors of the S-ICD. Six months after implantation, the responses to CRT were evaluated.ResultsThirty-nine patients (70.9%) passed the TMS during biventricular pacing mode. At the six-month follow-up, the number of responders and super-responders was significantly higher in the passing group than in the non-passing group (responders: 31/39 [79.5%] vs. 5/16 [31.3%], p<0.001; super-responders: 9/39 [23.1%] vs. 1/16 [6.3%], p=0.020). The super-response rate was higher among patients who passed all three vectors than among those who passed 1 or 2 vectors (3 vs. 2 vectors, p=0.018; 3 vs. 1 vector, p=0.003). A smaller left atrial diameter, vectors that passed TMS during biventricular pacing mode, and larger ΔQRS_Index values were independently associated with good CRT response.ConclusionsOur study demonstrated that patients on CRT who pass the TMS during biventricular pacing mode are more likely to respond and super-respond to CRT.
Project description:BackgroundAdult congenital heart disease (ACHD) patients can benefit from a subcutaneous implantable cardioverter-defibrillator (S-ICD).ObjectiveThe 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.MethodsACHD 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%).ResultsForty 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).ConclusionNearly 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.
Project description:BackgroundInfection remains a major complication of cardiac implantable electronic devices and can lead to significant morbidity and mortality. Implantable devices that avoid transvenous leads, such as the subcutaneous implantable cardioverter-defibrillator (S-ICD), can reduce the risk of serious infection-related complications, such as bloodstream infection and infective endocarditis. While the 2017 AHA/ACC/HRS guidelines include recommendations for S-ICD use for patients at high risk of infection, currently, there are no clinical trial data that address best practices for the prevention of S-ICD infections. Therefore, an expert panel was convened to develop a consensus on these topics.MethodsAn expert process mapping methodology was used to achieve consensus on the appropriate steps to minimize or prevent S-ICD infections. Two face-to-face meetings of high-volume S-ICD implanters and an infectious diseases specialist, with expertise in cardiovascular implantable electronic device infections, were conducted to develop consensus on useful strategies pre-, peri-, and postimplant to reduce S-ICD infection risk.ResultsExpert panel consensus on recommended steps for patient preparation, S-ICD implantation, and postoperative management was developed to provide guidance in individual patient management.ConclusionAchieving expert panel consensus by process mapping methodology for S-ICD infection prevention was attainable, and the results should be helpful to clinicians in adopting interventions to minimize risks of S-ICD infection.