Pilot Study of Hypertrophic Cardiomyopathy & Implantable Cardioverter Defibrillator Assessment: (Subcutaneous vs Transvenous) (HICD)

Pilot randomised trial to assess recruitment for a larger trial to compare the efficacy and adverse effects of the subcutaneous and transvenous ICD in patients with hypertrophic cardiomyopathy (HCM) and indication for ICD therapy, with no requirement for pacing

Study Overview

• Status: Completed
• Conditions: Implantable Defibrillator User; Hypertrophic Cardiomyopathy; Ventricular Arrythmia; Implantable Cardioverter Ventricular Lead Dysfunction or Complication
• Intervention / Treatment: Device: Implantable Cardioverter Defibrillator implant

Detailed Description

This study aims to test the feasibility of conducting a trial to investigate the use of subcutaneous implantable defibrillator (SICD) in patients with hypertrophic cardiomyopathy (HCM) and to determine whether SICD produces more complications than conventional, transvenous implantable defibrillator (TV ICD).

The primary analysis for the main trial is designed to test whether the S-ICD is non-inferior to the TV-ICD with respect to the primary endpoint of inappropriate shock treatment and complications. For the incidence of the primary endpoint statistical significance and 99% confidence intervals are calculated using Cox' proportional hazards model. Non-inferiority is considered to be established if the upper boundary of the one-sided 99% confidence interval did not exceed 1.92 (absolute difference < 12%).

Participant duration is expected to be 14 months. (12 months follow up post device implant) Recruitment duration expected to be 6-10 months.

• Study Type: Interventional
• Enrollment (Actual): 5
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom, EC1A 7BE
    • St Bartholomew'S Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Hypertrophic Cardiomyopathy and a referred for ICD therapy with no pacing requirement.

Exclusion Criteria:

• Patients with sustained ventricular tachycardia less than 170 bpm
• Patients having an indication for pacing therapy. E.g. sick sinus syndrome.
• Patients failing appropriate QRS/T-wave sensing with the automated S-ICD ECG automated patient screening provided by Boston Scientific
• A minimum of 1 sensing vector passing in supine, standing.
• Patients with incessant ventricular tachycardia
• Patients who have had a previous ICD implant
• Patient who receives cardiac contractility modulation therapy or are likely to receive cardiac contractility modulation therapy
• Patients with a serious known concomitant disease with a life expectancy of less than one year
• Patients with circumstances that prevent follow-up (no permanent home or address, transient, etc.)
• Patients who are unable to give informed consent
• Patients who are not suitable for TV-ICD implantation, according to the discretion of the physician, are not screened for enrolment (SVC occlusion).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Transvenous Implantable Defibrillator; Routine TV ICD implant	Device: Implantable Cardioverter Defibrillator implant; ICD implant to protect patients from life threatening ventricular tachycardia or ventricular fibrillation
Active Comparator: Subcutaneous Implantable Defibrillator; SICD ICD implant as per study protocol	Device: Implantable Cardioverter Defibrillator implant; ICD implant to protect patients from life threatening ventricular tachycardia or ventricular fibrillation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Rate of recruitment	Assessment of rate of recruitment per month	through study completion, expected at 10 months to 1 year
Composite of inappropriate shock and ICD related complications	Rate of inappropriate shocks and ICD related complications across the patients over a 12 month period.	12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
All- cause mortality	% of patients who die	12 months
MACE events	Major Adverse Cardiac Event (MACE), defined as cardiac death, myocardial infarction, percutaneous coronary intervention, coronary artery bypass grafting and/or any valve surgery.	12 months
Appropriate shocks and patients with appropriate shocks	Rate over 12 months determined by IBHRE accredited Cardiac Scientist	12 months
Inappropriate shocks and patients with inappropriate shocks	Rate over 12 months determined by IBHRE accredited Cardiac Scientist	12 months
Complications	individually, defined as infections, bleedings, thrombotic events, pneumothorax, perforation/tamponade, lead reposition and lead- or device failures	12 months
Cardiac decompensation	Measured by admissions for Heart failure or unplanned outpatient appointments.	12 months
Crossovers to the other arm	Amount of patients moving from SICD to TV group and visa versa over 12 month period.	12 months
Appropriate shock treatment in ATP or monitor zone	Rate over 12 months determined by IBHRE accredited Cardiac Scientist	12 months
Quality of life assessed by SF-36 survey	Scores for the different domains are converted and pooled using a scoring key, for a total score indicating a range of low to high QOL.	12 months
Quality of life assessed by EQ5D survey	Scores for the different domains are converted and pooled using a scoring key, for a total score indicating a range of low to high QOL.	12 months
Cardiac (pre-) syncope events	rate of patients with these events over a 12 month period	12 months
Time to successful therapy	Time in months or days from implant to date of succesful therapy	12 months
First shock conversion efficacy	% of first shocks that cardiovert ventricular arrhythmia	12 months
Implant procedure time	Duration of implant from needle to skin to skin closure.	Procedure duration- average of 2 hours expected
Hospitalization rate	Rate of patient hospitalisation for cardiac and non-cardiac causes over a 12 month period.	12 months
Fluoroscopy time	Amount of fluoroscopy required to complete implant procedure, expected fluoroscopy time of approximately 1 minute per patient.	Procedure duration- average of 2 hours expected

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Drop out rate	% of patients that do not complete the sudy	12 months
Data Quality	% of data completed	12 months
Eligibility of SICD	% Of patients referred for recruitment was SICD screening making patients illegible. Either Yes or no.	12 months

Collaborators and Investigators

• Sponsor: Barts & The London NHS Trust
• Collaborators: Queen Mary University of London; Boston Scientific Corporation

Study record dates

Study Major Dates

• Study Start (Actual): January 10, 2024
• Primary Completion (Actual): January 7, 2026
• Study Completion (Actual): January 7, 2026

Study Registration Dates

• First Submitted: June 13, 2023
• First Submitted That Met QC Criteria: July 3, 2023
• First Posted (Actual): July 10, 2023

Study Record Updates

• Last Update Posted (Actual): February 19, 2026
• Last Update Submitted That Met QC Criteria: February 17, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: Transvenous Implantable Defibrillator; Subcutaneous Implantable Defibrillator
• Additional Relevant MeSH Terms: Aortic Valve Disease; Cardiovascular Diseases; Heart Diseases; Heart Valve Diseases; Cardiomyopathies; Aortic Stenosis, Subvalvular; Aortic Valve Stenosis; Cardiomyopathy, Hypertrophic; Equipment and Supplies; Defibrillators; Electrodes; Electrical Equipment and Supplies; Electrodes, Implanted; Prostheses and Implants; Defibrillators, Implantable
• Other Study ID Numbers: 158953

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No