Canadian Implantable Defibrillator Study - CIDS


ICDs vs. amiodarone for mortality in patients with sudden death or VT.


In patients at high risk for arrhythmic death because of ventricular tachyarrhythmia, an initial decision to use the ICD will reduce the risk of arrhythmic death compared to therapy with amiodarone.

Study Design

Study Design:

Patients Screened: Not given
Patients Enrolled: 259

Patient Populations:

In the absence of acute myocardial infarction (AMI) within 72 hours or electrolyte imbalance, patients manifest any of the following arrhythmias:
Documented ventricular fibrillation (VF).
Out-of-hospital cardiac arrest requiring defibrillation or cardioversion.
Documented sustained VT at a rate of > 150 bpm, causing presyncope or angina in a patient with a left ventricular ejection fraction < 35%.
Profound unmonitored syncope with subsequent documentation of either spontaneous ventricular tachycardia of > 10 seconds or sustained monomorphic ventricular tachycardia induced by programmed ventricular stimulation. Ventricular tachycardia is considered sustained if it lasts > 30 seconds or requires cardioversion.
If the qualifying VT was induced in the electrophysiology (EP) laboratory, there must also be a spontaneous documented sustained VT; or the arrhythmia induced in the EP laboratory must be a monomorphic sustained VT.


Therapy of the VT with a drug selected by serial EP testing is planned.
Therapy of the VT by map-guided ablation of a ventricular aneurysm is planned.
Therapy of the VT by coronary artery bypass graft (CABG) surgery is planned.
No therapy of the VT is planned, other than β-blocker therapy.
Excessive perioperative risk for implantation of the ICD (such as end-stage obstructive lung disease).
Previous intolerance to amiodarone or failure of amiodarone therapy to prevent life-threatening VT.
Previous use of ICD therapy.
Medical condition other than VT making 1 year survival unlikely.
Long QT syndrome.
Previous use of amiodarone therapy for > 6 weeks prior to randomization.

Primary Endpoints:

Arrhythmic death or any other death occurring within 30 days of randomization

Secondary Endpoints:

All-cause mortality
Nonfatal VT or VF

Drug/Procedures Used:

Implantation as soon as possible after randomization.
Other surgical procedures (such as CABG) may be done concurrently.
Either thoracotomy or nonthoracotomy lead systems may be used.
ICD may be any device that can detect VT or VF and can electrically defibrillate and cardiovert the heart. Successful defibrillation threshold is 3 consecutive successful defibrillations at >10J below the maximum ICD output

Amiodarone (oral)
> 1200 mg/day for at least 1 week in the hospital
Followed by > 400 mg/day for at least 10 weeks
Followed by > 300 mg/day
If intolerable side effects occur, dose can be lowered to minimum of 200 mg/day
Patients who cannot tolerate minimum dose of amiodarone because of side effects, may receive another form of therapy, chosen by the investigator.
If VF or rapid sustained VT occurs while on amiodarone, investigator may consider other treatments. For patients randomized to not receive an ICD , the ICD should only be chosen as a last resort.

Concomitant Medications:

Antiarrhythmic drugs can be used for patients in either treatment group under the following conditions:
To control VT or supra-ventricular tachycardias that are symptomatic or that might cause inappropriate discharge of the ICD
To reduce the frequency of episodes of sustained VT or VF to a level that will not cause undue discomfort to the patient or premature depletion of the ICD battery

The choice of antiarrhythmic drug is up to the coinvestigator caring for the patient. General study policy is that, in patients randomized to ICD, antiarrhythmic drugs other than amiodarone should be assessed primarily, and amiodarone used only as a last resort

Principal Findings:

Not yet available


Not yet available


1. Am J Cardiol 1993;72:103F-108F Design and baseline results
2. Circulation 1998;98(SupplI):I-93: EF subgroups

Keywords: Myocardial Infarction, Electric Countershock, Ventricular Fibrillation, Syncope, Thoracotomy, Electrophysiology, Out-of-Hospital Cardiac Arrest, Tachycardia, Ventricular, Stroke Volume, Defibrillators, Implantable, Death, Sudden, Cardiac

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