S-ICD: Game-Changer in Preventing Sudden Cardiac Death
S-ICD: Game-Changer in Preventing Sudden Cardiac Death
Implantable cardioverter-defibrillators (ICDs) have become standard therapy in patients at high risk for sudden death. but their disadvantages, such as failure of the transvenous leads, premature depletion, endocarditis, and inappropriate shocks, have recently become evident. With the aim of avoiding these effects, a completely subcutaneous ICD (S-ICD), with no transvenous leads, has been developed that senses, detects, and treats malignant VTs.
The S-ICD® System (Cameron Health, Inc.; San Clemente, California) operates by analyzing both the rate and morphologic characteristics of the detected rhythm. The device can be programmed as single zone or dual zone. It calculates heart rate on the basis of the average of the last 4 intervals. As soon as the heart rate crosses the lowest programmed detection zone, further analysis is performed to determine whether therapy is required. Therapy consists of an 80-J shock, with potential temporary transthoracic back-up pacing for 30 seconds. No other back-up pacing is provided.
Other potential advantages of the S-ICD are that it can be implanted without fluoroscopy, implantation time is predictable compared with a traditional ICD implant, and implantation can be performed in a sterile procedure room.
In 2 small, nonrandomized studies, the S-ICD consistently detected and converted ventricular fibrillation (VF) induced during electrophysiologic testing.The device also successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia seen in one of the trials.
The S-ICD System received the CE Mark in Europe in 2009 and is now commercially available in a number of European countries. In the United States, a premarket approval submission for the S-ICD was filed with the Food and Drug Administration (FDA) in December 2011 after completion of an Investigational Device Exemption (IDE) clinical study that reportedly met its primary safety and efficacy endpoints.
On the basis of these and other data, the FDA Circulatory System Devices Panel recommended approval of the S-ICD System in April 2012. The proposed US indications for use are to provide defibrillation therapy for the treatment of life-threatening ventricular tachyarrhythmias in patients who do not have symptomatic bradycardia; incessant VT; or spontaneous, frequently recurring VT that is reliably terminated with antitachycardia pacing (ATP).
IDE study. Dr. Burke presented the main results of the S-ICD System IDE study at the annual meeting of the Heart Rhythm Society (HRS), held May 9-12, 2012, in Boston, Massachusetts. The international, prospective, nonrandomized clinical study enrolled 330 patients aged 18 years or older who met current American Heart Association/American College of Cardiology/HRS class I and II indications for ICD implantation or replacement of an existing ICD. Key exclusion criteria included having prior ventricular tachycardia that was reliably terminated with anti-tachycardia pacing, having existing epicardial patches or subcutaneous array, having a unipolar pacemaker, or having severe renal dysfunction.
The study cohort was predominantly (74%) male and 45% nonwhite; the mean age was 52 years, and the mean ejection fraction was 36%. The mean body mass index (BMI) was 30 kg/m. Most patients had coronary heart disease (61%) and hypertension (58%); 41% had had prior myocardial infarction, and 11% had a channelopathy.
A transvenous ICD had previously been implanted in 13% of patients. The ICD indication was primary prevention in 79%.
A total of 321 patients underwent an implant procedure. No fluoroscopy was used in 95% of cases. The primary efficacy endpoint, the acute induced VF conversion rate at 180 days against a performance goal of 88%, was met, with successful conversions with 80-J or spontaneous conversions in 100% of the 304 patients who completed the testing protocol. Therapy was avoided in 63% of patients with VT/VF rhythms that met criteria to charge the device but terminated spontaneously without any reports of syncope.
The primary safety endpoint -- the complication-free rate at 180 days after implant -- was met, with 99.0% for type I complications (device-related complications that require invasive interaction) and 92.1% for device-, labeling-, and procedure-related complications; performance goals were 79%.
There were 18 suspected or confirmed infections during the study, of which 14 were superficial or incisional infections managed without the need for explant. Only 4 (1.3%) infections requiring explantation occurred, all early in study enrollment. No endocarditis was reported.
Thirty-eight patients experienced shocks due to non-VT/VF events. No patients experienced a shock due to discrimination error in conditional shock (dual) zone. Dual-zone programming was estimated to have reduced inappropriate shocks by 54% (oversensing) and 74% (supraventricular tachycardia) compared with single-zone programming.
EFFORTLESS. Elsewhere at the HRS meeting, preliminary results from 1 of the ongoing postmarketing studies of the S-ICD, the EFFORTLESS Registry, were presented by Pier D. Lambiase, MD, PhD, of The Heart Hospital, London, United Kingdom. The ongoing registry aims to document and measure early, midterm, and long-term clinical and cost-effectiveness outcomes associated with the implantation of the S-ICD System in approximately 1000 patients for up to 5 years from the date of their device implant.
Patients are currently enrolled in Europe and New Zealand. To date, 223 patients have been implanted. After an average follow-up of 389 days, data from 204 implanted patients implanted showed that 98.5% underwent successful conversion within 1 procedure. Conversion of spontaneous VT/VF was 100%. Fifteen patients (7%) received inappropriate shocks. Rates of complications and clinical events were low. Of 18 suspected or confirmed infections, only 4 (1.3%) required system explant.
The results of a study done to determine the proportion of ICD recipients who might be eligible for a S-ICD (ie, those who were ultimately considered pacing-independent) using patients who received single or dual-chamber ICD at a single center were presented by Joep Thijssen, MD, of Leiden University Medical Center, The Netherlands). Among 1971 patients who received an ICD between 1996 and 2011, those considered eligible did not develop an atrial or right ventricular pacing indication, did not have successful antitachycardia pacing without a subsequent shock, or did not upgrade to a cardiac resynchronization therapy defibrillator (CRT-D). Over 5 years of follow-up, 52% of patients were considered to be eligible for S-ICD implantation.
Important predictors of noneligibility for an S-ICD were older age, secondary prevention, congenital heart disease, severe heart failure, atrial fibrillation, and a wide QRS complex.Young persons in sinus rhythm with mild LV dysfunction and no evidence of electrical dyssynchrony who received an ICD for primary prevention were considered most likely to benefit from the suggested advantages of an S-ICD.
Background to the Interview
The Device
Implantable cardioverter-defibrillators (ICDs) have become standard therapy in patients at high risk for sudden death. but their disadvantages, such as failure of the transvenous leads, premature depletion, endocarditis, and inappropriate shocks, have recently become evident. With the aim of avoiding these effects, a completely subcutaneous ICD (S-ICD), with no transvenous leads, has been developed that senses, detects, and treats malignant VTs.
The S-ICD® System (Cameron Health, Inc.; San Clemente, California) operates by analyzing both the rate and morphologic characteristics of the detected rhythm. The device can be programmed as single zone or dual zone. It calculates heart rate on the basis of the average of the last 4 intervals. As soon as the heart rate crosses the lowest programmed detection zone, further analysis is performed to determine whether therapy is required. Therapy consists of an 80-J shock, with potential temporary transthoracic back-up pacing for 30 seconds. No other back-up pacing is provided.
Other potential advantages of the S-ICD are that it can be implanted without fluoroscopy, implantation time is predictable compared with a traditional ICD implant, and implantation can be performed in a sterile procedure room.
In 2 small, nonrandomized studies, the S-ICD consistently detected and converted ventricular fibrillation (VF) induced during electrophysiologic testing.The device also successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia seen in one of the trials.
The S-ICD System received the CE Mark in Europe in 2009 and is now commercially available in a number of European countries. In the United States, a premarket approval submission for the S-ICD was filed with the Food and Drug Administration (FDA) in December 2011 after completion of an Investigational Device Exemption (IDE) clinical study that reportedly met its primary safety and efficacy endpoints.
On the basis of these and other data, the FDA Circulatory System Devices Panel recommended approval of the S-ICD System in April 2012. The proposed US indications for use are to provide defibrillation therapy for the treatment of life-threatening ventricular tachyarrhythmias in patients who do not have symptomatic bradycardia; incessant VT; or spontaneous, frequently recurring VT that is reliably terminated with antitachycardia pacing (ATP).
The Studies
IDE study. Dr. Burke presented the main results of the S-ICD System IDE study at the annual meeting of the Heart Rhythm Society (HRS), held May 9-12, 2012, in Boston, Massachusetts. The international, prospective, nonrandomized clinical study enrolled 330 patients aged 18 years or older who met current American Heart Association/American College of Cardiology/HRS class I and II indications for ICD implantation or replacement of an existing ICD. Key exclusion criteria included having prior ventricular tachycardia that was reliably terminated with anti-tachycardia pacing, having existing epicardial patches or subcutaneous array, having a unipolar pacemaker, or having severe renal dysfunction.
The study cohort was predominantly (74%) male and 45% nonwhite; the mean age was 52 years, and the mean ejection fraction was 36%. The mean body mass index (BMI) was 30 kg/m. Most patients had coronary heart disease (61%) and hypertension (58%); 41% had had prior myocardial infarction, and 11% had a channelopathy.
A transvenous ICD had previously been implanted in 13% of patients. The ICD indication was primary prevention in 79%.
A total of 321 patients underwent an implant procedure. No fluoroscopy was used in 95% of cases. The primary efficacy endpoint, the acute induced VF conversion rate at 180 days against a performance goal of 88%, was met, with successful conversions with 80-J or spontaneous conversions in 100% of the 304 patients who completed the testing protocol. Therapy was avoided in 63% of patients with VT/VF rhythms that met criteria to charge the device but terminated spontaneously without any reports of syncope.
The primary safety endpoint -- the complication-free rate at 180 days after implant -- was met, with 99.0% for type I complications (device-related complications that require invasive interaction) and 92.1% for device-, labeling-, and procedure-related complications; performance goals were 79%.
There were 18 suspected or confirmed infections during the study, of which 14 were superficial or incisional infections managed without the need for explant. Only 4 (1.3%) infections requiring explantation occurred, all early in study enrollment. No endocarditis was reported.
Thirty-eight patients experienced shocks due to non-VT/VF events. No patients experienced a shock due to discrimination error in conditional shock (dual) zone. Dual-zone programming was estimated to have reduced inappropriate shocks by 54% (oversensing) and 74% (supraventricular tachycardia) compared with single-zone programming.
EFFORTLESS. Elsewhere at the HRS meeting, preliminary results from 1 of the ongoing postmarketing studies of the S-ICD, the EFFORTLESS Registry, were presented by Pier D. Lambiase, MD, PhD, of The Heart Hospital, London, United Kingdom. The ongoing registry aims to document and measure early, midterm, and long-term clinical and cost-effectiveness outcomes associated with the implantation of the S-ICD System in approximately 1000 patients for up to 5 years from the date of their device implant.
Patients are currently enrolled in Europe and New Zealand. To date, 223 patients have been implanted. After an average follow-up of 389 days, data from 204 implanted patients implanted showed that 98.5% underwent successful conversion within 1 procedure. Conversion of spontaneous VT/VF was 100%. Fifteen patients (7%) received inappropriate shocks. Rates of complications and clinical events were low. Of 18 suspected or confirmed infections, only 4 (1.3%) required system explant.
The results of a study done to determine the proportion of ICD recipients who might be eligible for a S-ICD (ie, those who were ultimately considered pacing-independent) using patients who received single or dual-chamber ICD at a single center were presented by Joep Thijssen, MD, of Leiden University Medical Center, The Netherlands). Among 1971 patients who received an ICD between 1996 and 2011, those considered eligible did not develop an atrial or right ventricular pacing indication, did not have successful antitachycardia pacing without a subsequent shock, or did not upgrade to a cardiac resynchronization therapy defibrillator (CRT-D). Over 5 years of follow-up, 52% of patients were considered to be eligible for S-ICD implantation.
Important predictors of noneligibility for an S-ICD were older age, secondary prevention, congenital heart disease, severe heart failure, atrial fibrillation, and a wide QRS complex.Young persons in sinus rhythm with mild LV dysfunction and no evidence of electrical dyssynchrony who received an ICD for primary prevention were considered most likely to benefit from the suggested advantages of an S-ICD.
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