Long-term follow-up of the two-incision implantation technique for the subcutaneous implantable cardioverter-defibrillator

Ten years of subcutaneous defibrillator therapy: Consolidated clinical evidence and future perspectives

The subcutaneous implantable cardioverter defibrillator (S-ICD) was developed as an alternative to the traditional transvenous implantable cardioverter defibrillator (TV-ICD), aiming to provide easier implantation, simplified detection algorithm of malignant ventricular arrhythmias and prevention from placing components in the cardiovascular system. The S-ICD is implanted subcutaneously or intramuscularly with the generator placed in the left midaxillary line and the lead tunneled subcutaneously in the left para-sternal region. Preimplant electrocardiogram screening is recommended to prevent implantation in patients at high risk of T wave over-sensing. Currently, the S-ICD is unsuitable for patients requiring pacing or cardiac resynchronization. Since the beginning, the S-ICD underwent extensive preclinical investigation until the first prospective multicentre trial demonstrating high efficacy and safety led to market release. While earlier studies focused on younger patients with higher ejection fraction, more recent studies showed favorable outcomes even in patients with comorbidities similar to those typically observed in patients receiving TV-ICD. The development of second and third generation devices has contributed to reduce inappropriate shocks and overcome previous limitations. The aim of this paper is to review the evidence in the literature over the past decade supporting S-ICD as a valid alternative to TV-ICD in terms of safety and efficacy, highlighting the improvements in technology, as well as outcomes.

Two-incision versus three-incision implantation technique of subcutaneous implantable cardioverter defibrillator: Systematic review and meta-analysis of 2076 patients

INTRODUCTION

The implantable cardioverter-defibrillator (ICD) was designed to detect and treat ventricular arrhythmias, which account for nearly half of all cardiovascular fatalities. Transvenous ICD (TV-ICD) complications were reduced by introducing subcutaneous ICD (S-ICD). S-ICD can be implanted using a three (3IT)- or two (2IT)-incision technique. This systematic review and meta-analysis was conducted to compare the 3IT to the 2IT.

METHODS

We searched medical electronic databases of Cochrane Central, Embase, PubMed, Scopus, and Web of Science (WOS) from the study's inception until March 8, 2023. We compared 2IT and 3IT techniques of S-ICDs in terms of procedural, safety, and efficacy outcomes. We used Review Manager software for the statistical analysis. We calculated the risk ratio (RR) with its 95% confidence interval (CI) for dichotomous variables; and the mean difference with its 95% CI for continuous variables. We measured the heterogeneity using the chi-squared and I-squared tests. If the data were heterogeneous, the random-effect (RE) model was applied; otherwise, the fixed-effect model (FE) was used.

RESULTS

We included three retrospective observational studies of 2076 patients, 1209 in the 2IT group and 867 in the 3IT. There was no statistically significant difference in erosion after S-ICD when 2IT compared with 3IT (RR = 0.27, 95% CI: [0.07, 1.02]; P = .05) (I2 = 0%, P = .90). There was no difference in risk of infection, lead dislocation, or inappropriate shock with either incision technique (RR = 0.78, 95% CI: [0.48, 1.29]; P = .34) (I2 = 0%, P = .71) and (RR = 0.37, 95% CI: [0.02, 8.14]; P = .53) (I2 = 66%, P = .05) respectively. Our meta-analysis showed that the efficacy of both techniques is comparable; Appropriate shock (RR = 0.94, 95% CI: [0.78, 1.12]; P = .48) (I2 = 0%, P = .81) and first shock efficacy (RR = 0.89, 95% CI: [0.44, 1.82]; P = .76) (I2 = 0%, P = .87).

CONCLUSION

2IT and 3IT of S-ICD have comparable efficacy and complication rates; however, the 3IT exposes patients to an additional incision without any additional benefits. These findings may provide clinicians with a simpler method for subcutaneous ICD implantation and likely result in improved cosmetic outcomes. Before the 2IT technique can be considered the standard of care, randomized controlled trials (RCTs) must be conducted to assess its long-term safety and efficacy.

A real‐world experience of subcutaneous and transvenous implantable cardiac defibrillators—comparison with the PRAETORIAN study

Background

Methods

Results

Conclusion

The Subcutaneous ICD: A Review of the UNTOUCHED and PRAETORIAN Trials

The ICD is an important part of the treatment and prevention of sudden cardiac death in many high-risk populations. Traditional transvenous ICDs (TV-ICDs) are associated with certain short- and long- term risks. The subcutaneous ICD (S-ICD) was developed in order to avoid these risks and complications. However, this system is associated with its own set of limitations and complications. First, patient selection is important, as S-ICDs do not provide pacing therapy currently. Second, pre-procedural screening is important to minimise T wave and myopotential oversensing. Finally, until recently, the S-ICD was primarily used in younger patients with fewer co-morbidities and less structural heart disease, limiting the general applicability of the device. S-ICDs achieve excellent rates of arrhythmia conversion and have demonstrated noninferiority to TV-ICDs in terms of complication rates in real-world studies. The objective of this review is to discuss the latest literature, including the UNTOUCHED and PRAETORIAN trials, and to address the risk of inappropriate shocks.

Acute shock efficacy of the subcutaneous implantable cardioverter-defibrillator according to the implantation technique

BACKGROUND

The traditional technique for subcutaneous implantable cardioverter defibrillator (S-ICD) implantation involves three incisions and a subcutaneous (SC) pocket. An intermuscular (IM) 2-incision technique has been recently adopted.

AIMS

We assessed acute defibrillation efficacy (DE) of S-ICD (DE ≤65 J) according to the implantation technique.

METHODS

We analyzed consecutive patients who underwent S-ICD implantation and DE testing at 53 Italian centers. Regression analysis was used to determine the association between DFT and implantation technique.

RESULTS

A total of 805 patients were enrolled. Four groups were assessed: IM + 2 incisions (n = 546), SC + 2 incisions (n = 133), SC + 3 incisions (n = 111), and IM + 3 incisions (n = 15). DE was ≤65 J in 782 (97.1%) patients. Patients with DE ≤65 J showed a trend towards lower body mass index (25.1 vs. 26.5; p = .12), were less frequently on antiarrhythmic drugs (13% vs. 26%; p = .06) and more commonly underwent implantation with the 2-incision technique (85% vs. 70%; p = .04). The IM + 2-incision technique showed the lowest defibrillation failure rate (2.2%) and shock impedance (66 Ohm, interquartile range: 57-77). On multivariate analysis, the 2-incision technique was associated with a lower incidence of shock failure (hazard ratio: 0.305; 95% confidence interval: 0.102-0.907; p = .033). Shock impedance was lower with the IM than with the SC approach (66 vs. 70 Ohm p = .002) and with the 2-incision than the 3-incision technique (67 vs. 72 Ohm; p = .006).

CONCLUSIONS

In a large population of S-ICD patients, we observed a high defibrillation success rate. The IM + 2-incision technique provides lower shock impedance and a higher likelihood of successful defibrillation.

Long-term follow-up of the two-incision implantation technique for the subcutaneous implantable cardioverter-defibrillator

Introduction

The two‐incision implantation technique of the subcutaneous implantable cardioverter‐defibrillator (S‐ICD) was introduced as an alternative to the standard three‐incision approach by omitting the superior parasternal incision. Thereby, complications may be prevented. Short‐term follow‐up demonstrated the safety and efficacy of the two‐incision technique. However, long‐term results are lacking.

Methods

This retrospective study included patients implanted between February 2009 and June 2020. Patients were divided into a group of patients who were implanted with the standard three‐incision technique and a group who were implanted with the two‐incision technique. Outcomes were defibrillation impedance and efficacy and complications requiring intervention.

Results

A total of 268 patients were included (age 42.4 ± 16.6 years, 35.4% female, BMI 25.1 ± 4.5 kg/m²). Thirty‐one patients underwent S‐ICD implantation with the three‐incision technique and 237 patients with the two‐incision technique. First shock efficacy during defibrillation testing was 93% in the three‐incision group versus 94% in the two‐incision group (P = .69), and shock impedance was 85 versus 68 ohms (P = .04). First shock success was 75% versus 76% for spontaneous episodes (P = 1.00). Complication‐free survival at 5‐year follow‐up in the three‐incision group was estimated at 0.96 (95% CI 0.90‐1.00) versus 0.98 (95% CI 0.96‐1.00) in the two‐incision group (P = .20) and for inappropriate shocks at 5‐year 0.77 (95% CI 0.63‐0.94) versus 0.83 (95% CI 0.77‐0.89, P = .30), respectively.

Conclusion

Five‐year follow‐up in this S‐ICD cohort showed similar complication rates and effectiveness of two‐incision technique compared to the three‐incision technique. This technique offers physicians a less invasive and more simplified implantation procedure for the S‐ICD, with a better cosmetic result.