Sudden Cardiac Death and ICD's: Primary and Secondary Prevention

Did you know that ICD*s (Internal Cardioverter Defibrillators) have been implanted for more than 25 years? Research began in 1969, with the first implant in 1980. Upon initial approval in 1991, defibrillators were indicated for individuals who had survived an event of sudden cardiac death (SCD), which is described as death occurring from ventricular tachycardiac (VT) or ventricular fibrillation (VF). An ICD can treat these rhythms with either painless overdrive pacing (for stable VT) or with a defibrillation shock (for rapid VT or VF).
Indications were expanded in 1999 to include:

    °Documented sustained VT not associated with AMI and without a reversible cause, and
    °Familial or inherited conditions, including long QT syndrome and hypertrophic cardiomyopathy (CM), predisposing to a high risk of VF.
Guidelines were extended in 2002 to include:
    °Bridge to cardiac transplantation with symptoms (e.g., syncope) attributable to VT, and
    °Syncope of unexplained etiology or family history of unexplained SCD in association with Brugada syndrome (a rare inherited cause of sudden cardiac death, with characteristic ECG findings of right bundle branch block and persistent ST elevation in leads V1 to V3).
In 2003, the results of the MADIT II trial led to an expansion in the indications for ICD*s, to include
    °CAD and prior MI, and EF = 35%, with inducible sustained VT or VF noted on an EP study, and
    °Prior MI and EF =30%, with QRS > 120 ms.
In 2005, the SCD-HeFT trial recognized the efficacy of the ICD in patients with nonischemic CM to further broaden the indications to include:
    °Ischemic dilated CM with documented prior MI, NYHA Class II or III, and EF = 35% (MI at least days prior, and any revascularization at least 90
days prior), and
    °Non-ischemic dilated CM, NYHA Class II or III, and an EF = 35% which had persisted 9 months after diagnosis, and
    °Individuals who meet the CMS criteria (NYHA Class III*IV heart failure and a QRS>120ms) for cardiac resynchronization through a biventricular pacing device (CRT) are able to receive the benefits of a combined CRT and ICD.

ICD implantation and management can be quite involved, and optimal ICD care is accomplished by qualified Electrophysiologists or high volume implanting General Cardiologists. The Heart Rhythm Society has developed credentialing criteria for implanting physicians, with stringent guidelines for the level of training and volume of procedures required, which the CMS registry will use for tracking and for reimbursement. Recent studies have confirmed that device complications are much more common among physicians who implant fewer than 12 devices a year, and other studies have shown that physicians who implant more than 30 devices a year are more likely to use advanced device features. Dr Roger K. Muse is board Certified in Cardiology and Electrophysiology, and has implanted and managed thousands of devices.  He is involved in teaching and clinical research in Electrophysiology.

For questions or consults, please call 210-226-4800.

References:
ACC/AHA 2005 Guideline Update for the Diagnosis and Management of Chronic Heart Failure in the Adult: http://www.acc.org/clinical/topic/topic.htm#guidelines <http://www.acc.org/clinical/topic/topic.htm>
ICD Indications: ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices: <http://www.acc.org/clinical/guidelines/pacemaker/summary_article.pdf>