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Sudden Cardiac Death

Natural death due to cardiac causes, heralded by abrupt loss of consciousness within one hour of onset of acute symptoms, in a person with or without known preexisting heart disease, but in whom the time and mode of heart attack death are unexpected, arrhythmia.

Sudden Cardiac Death (SCD)

- 300,000 - 400,000 per year

- 1000 per day

- 1 every 90 seconds

- First presentation of cardiac

disease in 25-50% of patients

- SCD is 3 times more common in men

- Most Common Cause of Death in Adults in the

Mechanism of Sudden Cardiac Death

Ventricular tachyarrhythmias in 80-85%

Common misconceptions:

SCD During Holter Monitoring

- Increase in VPCs and HR in hours prior tó terminal event.

- ST changes suggestive of ischemia present in only 10-15%.

- Heart rate variability is "normal".

- Monomorphic or polymorphic VT initial arrhythmia in 75%.

Structural Abnormalities Associated with SCD

Myocardial infarction/CAD Ventricular hypertrophy Cardiomyopathy Primary Electrical Heart Disease

SCD- Role of Coronary Artery Disease

CAD is present in 75-80% of patients with SCD. Of those with CAD:

produce >75% occlusion.

- Acute myocardial infarction present in 20%.

Approaches For Prevention of SCD


1. Absolute low incidence in population (.1-.2%) means application of costly therapy, with potential side effects, and without benefit to the vast majority.

2. Application of successful therapy to the high risk patients would only prevent a minority of SCD.

Possible Solutions

1. We need to identify high risk patients among those who appear to be low risk.

2. Safe, simple, cost effective therapies must be developed if they are to be widely applied.


SCD is a national EPIDEMIC that has been neglected because of misconceptions and lack of funding for integrated, clinically relevant research. However, it is an EPIDEMIC that can be successfully treated. More research funding will be necessary to achieve the development of successful, cost . effective therapy that can be applied to a broader population than at present.

Implantable Cardioverter

Defibrillator (ICD)

Generation 1-2: Ventak Series

a) Minimal programmability

b) Shock only

c) No backup pacing

Generation 3: PCD*, Cadence*, PRX**, Siecure, Guardian, Res-Q

a) Tiered therapy

- 1-3 tachycardia zones

- multiple therapies for each zone

b) Highly programmable

- outputs

- detection criteria - onset, variability

- therapies (ATP, LECV, DF)

- Brady pacing

c) Event log

Generation 4:

a) Advanced