Specific indications and clinical outcome in patients with subcutaneous implantable cardioverter-defibrillator (ICD) - A nationwide multicentre registry

BACKGROUND

Subcutaneous implantable cardioverter-defibrillators (S-ICD) are an innovative and less invasive alternative to transvenous ICD (TV-ICD) in selected patients. We aimed to investigate the underlying diseases and the specific indications for implanting S-ICD in clinical practice, as well as the prevalence of shock delivery and complications.

METHODS AND RESULTS

From December 2012, data of 236 patients (30,5% female; age 48,6±16,8years) were gathered from 12 centres in Austria. Follow-up data over a period of 1,7±1,1years were available for 231 patients (in total 359,2 patient-years). Predominant underlying diseases were ischemic cardiomyopathy (iCMP; 32,0%), idiopathic ventricular fibrillation (22,6%) and dilated cardiomyopathy (dCMP; 17,3%). The most frequent indications for implantation were sudden cardiac death survival (27,4%), primary prevention for iCMP (23,9%) and for dCMP (12,8%), and previous explantation of TV-ICD (12,4%). Appropriate shocks were documented in 16 patients (6,9%), iCMP being the predominant underlying disease. Arrhythmia conversion was successful in all patients, efficacy of the first shock was 96%. Inappropriate shock rate was 5,2%, predominantly caused by oversensing of T wave or artefacts. A device upgrade to an ICD system with pacing function was necessary in <1%. Clinical complications needing surgical revision occurred in 8 patients (3,5%).

CONCLUSIONS

S-ICD were mostly implanted for primary prevention, one fourth of our cases were sudden death survivors. Clinical and functional complication rate was relatively low. In conclusion, S-ICD is a safe and efficient alternative in a larger population of ICD candidates, when no cardiac pacing is needed. EC-number: C-136-17.

Long-Term Evaluation of Biotronik Linox and Linox(smart) Implantable Cardioverter Defibrillator Leads

INTRODUCTION

Expert consensus holds that post-market, systematic surveillance of ICD leads is essential to ensure confirmation of adequate lead performance. GALAXY (NCT00836589) and CELESTIAL (NCT00810264) are ongoing multicenter, prospective, non-randomized registries conducted to confirm the long-term safety and reliability of Biotronik leads.

METHODS AND RESULTS

ICD and CRT-D patients are followed for Linox and Linox(smart) ICD lead performance and safety for 5 years post-implant. All procedural and system-related adverse events (AEs) were assessed at each follow-up, along with lead electrical parameters. An independent CEC of EPs adjudicated AEs to determine AE category and lead relatedness. The analysis used categories of lead observations per ISO 5841-2 (Third edition). A total of 3,933 leads were implanted in 3,840 patients (73.0% male, mean age 67.0 ± 12.2 years) at 146 US centers. The estimated cumulative survival probability was 96.3% at 5 years after implant for Linox leads and 96.6% at 4 years after implant for Linox(smart) leads. A comparison of the Linox and Linox(smart) survival functions did not find evidence of a difference (P = 0.2155). The most common AEs were oversensing (23, 0.58%), conductor fracture (14, 0.36%), failure to capture (13, 0.33%), lead dislodgement (12, 0.31%), insulation breach (10, 0.25%), and abnormal pacing impedance (8, 0.20%).

CONCLUSIONS

Linox and Linox(smart) ICD leads are safe, reliable and infrequently associated with lead-related AEs. Additionally, estimated cumulative survival probability is clinically acceptable and well within industry standards. Ongoing data collection will confirm the longer-term safety and performance of the Linox family of ICD leads.

Video-assisted thoracoscopic implantation of cardioverter-defibrillator systems

Implantation of cardioverter-defibrillators in patients with limited venous access due to recurrent infections, thrombosis, or congenital anomalies can be challenging. For this subset of patients, we performed a video-assisted thoracoscopic intrapericardial implantation using standard shock electrodes and epicardial leads. The pulse generator was placed in pectoral or subcostal position. All pacing and sensing parameters and defibrillation thresholds were satisfactory and stable in time. No major complications were reported. Our limited experience suggests that this technique is a potential alternative in patients where endocardial implantation should be avoided.

Generator and lead-related complications of implantable cardioverter defibrillators

BACKGROUND

Increase in the number of patients treated with Implantable Cardioverter Defibrillator (ICD) requests more attention regarding its complications.

OBJECTIVES

This study aimed to assess the generator- and lead-related complications at implantation and during follow-up in the patients who were treated with ICD for primary and secondary prevention reasons.

METHODS

We retrospectively reviewed 255 consecutive patients who underwent transvenous ICD implantation for the first time in a 7-year period and were followed-up for 3 years at Tehran Heart Center. The personal and clinical data of the patients as well as specific data on the ICD implantation were retrieved. The frequency of each of the complications was reported and the study variables were compared between the patients with and without complications using Student's t-test and chi-square test where appropriate. P values less than 0.05 were considered as statistically significant.

RESULTS

Out of a total of 525 implanted leads and 255 implanted devices in 255 patients (mean age = 62.57 ± 13.50 years; male = 196 [76.9%]), complications leading to generator or lead replacement occurred in 32 patients (12.5%). The results revealed no significant difference between the patients with and without complications regarding gender and age (P = 0.206 and P = 0.824, respectively). Also, no significant difference was found between the two groups concerning the ejection fraction (P = 0.271). Lead fracture was the most frequent lead-related complication and was observed in 17 patients (6.6%). Besides, it was mainly observed in the RV leads. Generator-related complications leading to generator replacement were observed in 2 patients (0.7%).

CONCLUSIONS

Despite considerable improvements in the ICD technology, the rate of the ICD complications leading to device replacement and surgical revision, especially those related to the leads, is still clinically important.

Longitudinal follow-up of implantable cardioverter defibrillator leads

Although implantable cardioverter defibrillator (ICD) leads are prone to failure and Food and Drug Administration recall, comprehensive longitudinal studies investigating contemporary ICD lead survival rate in the United States are lacking. All patients receiving Medtronic, Boston Scientific, or St. Jude Medical transvenous ICD leads at the hospitals of the University of Pittsburgh Medical Center from 2000 to 2012 were included. Leads were classified as (1) functional lead, patient deceased; (2) functional lead, replaced; (3) failed lead, replaced; or (4) functional lead, active. Kaplan-Meier survival curves were constructed for all lead models separately and in aggregate. We followed 5,288 patients (1,020 Quattro, 623 Fidelis, 627 Riata, 828 Durata, and 2,190 Reliance) over 3.7 ± 3.3 years. Functional leads that were replaced included 30 Quattro (3%), 99 Fidelis (16%), 24 Riata (4%), 24 Durata (3%), and 62 Reliance (3%). Leads replaced because of failure included 11 Quattro (1%), 47 Fidelis (8%), 38 Riata (6%), 18 Durata (2%), and 26 Reliance (1%; p <0.001 for Food and Drug Administration recalled vs nonrecalled leads). Overall survival rate of all leads was 89.3% at 5 years. Survival curves of Riata and Fidelis diverged from nonrecalled leads at approximately 2 years. In conclusion, the overall survival rate of ICD leads is nearly 90% at 5 years. Survival curves of recalled leads diverge from nonrecalled leads after 2 years of implantation. These data have important implications on postmarket release monitoring of ICD leads and physicians' choice of leads.

Sudden cardiac death--historical perspectives

Sudden cardiac death (SCD) is an unexpected death due to cardiac causes that occurs in a short time period (generally within 1 h of symptom onset) in a person with known or unknown cardiac disease. It is believed to be involved in nearly a quarter of human deaths, with ventricular fibrillation being the most common mechanism. It is estimated that more than 7 million lives per year are lost to SCD worldwide. Historical perspectives of SCD are analyzed with a brief description on how the developments in the management of sudden cardiac arrest evolved over time.

[Current status and problems of the entirely subcutaneous ICD (S-ICD®)]

Prevention of sudden cardiac death is one of the most important tasks of cardiology. Transvenous ICD-systems have impressively proven their effectiveness in numerous randomized trials. Transvenous systems have their limitations due to frequent long-term lead complications. Having been available for a few years, the entirely subcutaneous ICD-system (S-ICD®, Boston Scientific, USA, former Cameron Health, USA) seems to be a promising alternative despite the lack of prospective data. The implantation of the SICD® can be performed easily; lead complications are rare because of the totally subcutaneous implantation. The detection and therapy of life-threatening tachyarrhythmias seems to be safe, although inappropriate therapies are a common problem in cases of insufficient ECG screening. S-ICD® is no alternative to the transvenous system due to limited programming options and the lack of stimulation, but it is an interesting supplement of ICD therapy.

United Kingdom national experience of entirely subcutaneous implantable cardioverter-defibrillator technology: important lessons to learn

AIMS

The aim of this study was to describe the early phase United Kingdom (UK) clinical experience with a novel entirely subcutaneous implantable cardioverter-defibrillator (S-ICD).

METHODS AND RESULTS

A questionnaire was sent to all UK hospitals implanting S-ICDs. Nineteen of 25 (76%) hospitals responded with the details of 111 implanted patients [median 5/hospital (range 1-18)]. Mean duration of follow-up was 12.7 ± 7.1 months. Median patient age was 33 years (range 10-87 years). Underlying pathology was primary electrical disease in 43%, congenital heart disease 12%, hypertrophic cardiomyopathy 20%, ischaemic cardiomyopathy 14%, idiopathic dilated cardiomyopathy 5%, and other cardiomyopathies 7% patients. Nineteen (17%) patients required 20 re-operations, including permanent device explantation in 10 (9%). Twenty-four appropriate shocks were delivered in 13 (12%) patients, including 10 for ventricular fibrillation. One patient suffered arrhythmic death, but there were no failures to detect or terminate ventricular arrhythmias above the programmed detection rate. Fifty-one inappropriate shocks were delivered in 17 (15%) patients. Forty-one (80%) were for T-wave over-sensing and 1 (2%) for atrial flutter-wave over-sensing. The 11 patients who received inappropriate shocks due to T-wave over-sensing were significantly younger than patients who did not (24 ± 10 vs. 37 ± 19 years; P = 0.02).

CONCLUSION

The S-ICD is an important innovation in ICD technology. However, these data indicate that adverse event rates are significant during early clinical adoption. Important lessons in patient selection, implant technique, and device programming can be learnt from this experience.

Clinical experience of entirely subcutaneous implantable cardioverter-defibrillators in children and adults: cause for caution

AIMS

This paper describes our clinical experience of using an entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) in children and adults. Maintaining lead integrity and long-term vascular access are critical challenges of ICD therapy, especially in younger patients. The S-ICD has considerable theoretical advantages in selected patients without pacing indications, particularly children and young adults. Although sensing in an S-ICD may be influenced by age, pathology, and posture, there are currently few published data on clinical sensing performance outside the setting of intra-operative testing or in younger patients.

METHODS AND RESULTS

Patients were selected by a multi-disciplinary team on clinical grounds for S-ICD implantation from a broad population at risk of sudden arrhythmic death. Sixteen patients underwent implantation [median age 20 years (range 10-48 years)]. Twelve had primary electrical disease and four had congenital structural heart disease. There were no operative complications, and ventricular fibrillation (VF) induction testing was successful in all cases. During median follow-up of 9 months (range 3-15 months), three children required re-operation. Eighteen clinical shocks were delivered in six patients. Ten shocks in four patients were inappropriate due to T-wave over-sensing. Within the eight shocks for ventricular arrhythmia, three were delivered for VF, among which two had delays in detection with time to therapy of 24 and 27 s.

CONCLUSION

The S-ICD is an important new option for some patients. However, these data give cause for caution in light of the limited published data regarding clinical sensing capabilities, particularly among younger patients.

[Psychological comorbidity and quality of life in patients with an implantable cardioverter/defribrillator (ICD)]

Currently, the method of choice for protection against sudden cardiac death for high-risk patients is ICD treatment. The CIDS study could prove a significant advantage of ICD treatment compared to amiodarone therapy. However, the survival advantages can be affected by the negative side effects of ICD therapy. The therapeutic survival function of the device is, in general, associated with a consciously experienced, at the same time completely unexpected and unprepared intracardial shock experience. Within the first year after implantation, 30-50% of patients with an ICD for secondary preventative indications experience such a shock. The average shock application frequency per year (under normal conditions) is about 2.5 shocks. The experience of one or more ICD shocks is significantly associated with a decrease in quality of life. Particularly the experiencing of five or more intracardial shocks approaches the patient's psychological resilience threshold. Partners and relatives of ICD patients are, on the other hand, often helpless with respect to the demands of and stress associated with the ICD technology. In current clinical practice, the involvement of the partners in the treatment of ICD patients is generally a coincidence and is generally not systematic or target-oriented. Improved involvement of relatives can contribute to an improved prognosis. Cardiologists caring for ICD patients should be aware of the specific psychological aspects of ICD technology, integrate these aspects into the guidance and care of patients, and be able to identify and address pathologically negative affects and crises in ICD patients.

Product-experience reporting on endocardial defibrillation leads: a 4-year national perspective

The medical device industry must implement accurate programs to monitor product performance once the product is released into the market. Product-experience reports provide a means for physicians who use medical devices to provide continuous feedback to manufacturers in order to monitor device performance. We examined product-experience reports sent from Italy over 4 years (2004-2007) related to a single manufacturer's family of permanent endocardial leads (Endotak Reliance, Boston Scientific, MA, USA) used with implantable cardioverter-defibrillators. Out of 15,772 implanted leads, physicians sent in 454 (2.87%) product-experience reports. Only 126 out of 454 (28%) leads were returned to the company; most of these (101 out of 126; 80%) were related to implant procedure. Laboratory analyses of returned leads rarely showed loss of integrity (0.01%). The practice of reporting product performance and returning the device to companies should be strongly encouraged in order to better identify potential issues affecting implantable devices.