| Purpose: |
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The overall hypothesis of this study is that subtle interactions between structural
(substrate) and functional (trigger) abnormalities of the heart, some of which are
genetically-determined, can be used to identify patients at high risk of sudden cardiac
death (SCD). Such information may be used to better define patients most likely to benefit
from implantation of an internal defibrillator (ICD). The prospective, observational study
to enroll, categorize and follow patients who receive an ICD for primary prevention of SCD
(PROSE-ICD) was established to :
1. to gain a better understanding of the biological mechanisms that predispose to SCD
2. to develop readily determined clinical, electrocardiographic, genetic and blood protein
markers identify patients with an increased risk of dying suddenly
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| Study Summary: |
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PROSE-ICD is a multicenter prospective cohort study of patients who undergo ICD implantation
for primary prevention of SCD, designed to compare patients who sustain SCD (as measured by
an appropriate ICD firing for rapid VT or VF) to those who do not. The cohort for this
observational study consists of patients with cardiomyopathy who have an ICD implanted for
primary SCD prevention according to recent trials (MADIT II, SCD-HeFT, DEFINITE) and
practice guidelines.
Patients are followed longitudinally for clinical, ECG, genomic and proteomic markers and
for index events. The primary outcome variable is an appropriate adjudicated ICD firing for
rapid ventricular tachycardia or fibrillation.
The study standardizes initial therapeutic ICD settings, reflecting the current standard of
care rather than an intervention, because by definition the study cohort consists of
patients without a history of malignant arrhythmia, in whom the ICD functions simply as a
defibrillator rather than as a more complex device employing anti-tachycardia pacing or
tiered therapy. In order to facilitate the identification of rhythms prompting ICD therapy,
programming includes far field ventricular electrogram storage. For patients who have
firings (appropriate or not), all subsequent clinical care (including drug and device
prescriptions) will be managed independently by the clinical attending
electrophysiologist/cardiologist according to the local standard of care, unaffected by the
study protocol. For safety reasons, any clinically-significant data (such as symptomatic
complaints or documented episodes of ventricular arrhythmia) obtained during the study will
be promptly communicated to the clinical attending physician both by telephone and in
writing.
After informed consent, patients undergo an initial history and examination conducted by an
attending electrophysiologist. Thereafter, patients are generally seen by an ICD nurse every
3 months and are evaluated for the purposes of the study every six months. The physician
and/or nurse will record the variables shown in Table D1 on paper forms or directly into
LIMS web-based entry form. At each routine clinic visit (Q 3 month intervals) the ICD will
be interrogated and any episodes of ventricular tachycardia lasting >10 beats with a cycle
length < 400 ms, ventricular fibrillation, or any anti-tachycardia pacing or ICD therapies
will be recorded. If a ventricular arrhythmia is detected blood will be drawn and a digital
ECG will be performed as described for the 6 month follow up visits. Further evaluation and
treatment of the arrhythmia will be managed independently by the clinical attending
physician, who will be notified of the arrhythmia by telephone, with written confirmation
and documentation. At alternate visits (every 6 months) the patient will be evaluated by an
attending electrophysiologist, a 60cc blood sample will be obtained, a 5-minute digital ECG,
and any additional laboratory and diagnostic testing will be performed as clinically
indicated.
Data on clinical events (admission for MI/ACS, admission for CHF, diagnostic angiography,
revascularization, ICD device revision) will be collected by medical record review. Patients
will be followed for a minimum of four years or until death, cardiac transplantation or
ventricular assist device implantation. A patient who experiences an appropriate ICD firing
will have been considered to meet the primary endpoint of the study but will continue to be
followed, particularly for the development of adverse events.
A clinical events committee comprised of three experienced electrophysiologists, who are not
investigators on this study or in the Hopkins Reynolds Center, adjudicate whether ICD
firings are appropriate and whether episodes of VT/VF are related to ischemia, based on
reports of device interrogation and other clinical documentation.The events committee will
also adjudicate deaths in the study as cardiac or non-cardiac and sudden or non-sudden by
review of the medical records, records of interviews of family and friends and ICD
interrogation. Death within one hour of symptom onset and/or VT/VF on ICD interrogation that
was not corrected by the device is considered SCD. All other deaths will be adjudicated as
non-sudden including any terminal or hospice chronic care patient whose ICD is programmed
off.
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