Cambridge Heart, Inc. and the Role of Risk Stratification in Patients at Risk of Sudden Cardiac Death

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Citation
US Cardiology 2006;2005:2(1):1-3

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Over 400,000 people die from sudden cardiac death (SCD) also know as cardiac arrest in the US each year. This public health problem occurs when the heart beats in an uncontrollably fast rhythm so that the ventricles of the heart do not have the chance to fill with blood. The result is that the body becomes immediately starved of blood and oxygen and the patient dies within five to 10 minutes unless the heart can be shocked, or defibrillated, back into a normal rhythm.

In the present environment defibrillation of the patient to 'shockÔÇÖ their heart back into a normal rhythm is well recognized. Automated external defibrillators (AED) have become available on commercial aircraft, in airports, many office buildings and places of public assembly. They are rarely used, but their immediate availability can be lifesaving. Individuals with known risk factors such as coronary artery disease (CAD) or heart failure (HF) are at substantially higher risk of SCD than the general population, although sudden cardiac arrest is often the first symptom of the problem. Those individuals with known risk factors may be eligible for an implantable cardioverter defibrillator (ICD). This device - implanted into the chest - monitors the heart 24 hours a day and is always available to potentially defibrillate or shock a patient if necessary.To preclude the risk of suddenly dying from a cardiac arrest, everyone could be fitted with an ICD, however, ICDs are invasive, expenisve devices and carry their own inherent risks.This explains why ICD use is restricted to individuals known to be at substantially elevated risk.

Until the last couple of years, patients thought to be at risk of SCD were evaluated via an invasive electrophysiology study. During this procedure, the electrophysiologist (a cardiologist who specializes in rhythm disorders) would use small jolts of electricity transmitted by a catheter placed into the heart, to attempt to pace the patients into the same fast beat rhythm that would kill them from a cardiac arrest. If the cardiologist can 'induceÔÇÖ the patient into this deadly abnormal rhythm they would then be defibrillated and given the ICD. The invasive diagnostic test is both uncomfortable and daunting so many cardiologists have elected not to refer their patients for the test and have opted for a more conservative approach with their patients - namely treatment through appropriate medications.

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