Implantable defibrillators (ICDs) are highly effective at preventing sudden cardiac death from heart arrhythmias. Unfortunately, most of the more than 400,000 Americans who die suddenly each year never learn that their risk is high - and therefore, they never have the opportunity to consider an ICD.
Anyone who has significant heart disease, or has close family members who have had sudden death, should talk to their doctor about their own risk of sudden death.
If your risk is high, you should have a discussion about an ICD.
Do You Have an Increased Risk of Sudden Death?
People who are at an increased risk for sudden death generally fall into four categories:
1) People who have significant coronary artery disease (CAD).
The plaques associated with CAD can suddenly rupture, producing a spectrum of conditions that are called Acute Coronary Syndrome (ACS).
One of the dire outcomes of ACS is cardiac arrest. This occurs because plaque rupture can acutely disrupt the cardiac electrical system, producing sudden ventricular tachycardia (VT ) or ventricular fibrillation (VF). It is estimated that in about 30% of people who have significant CAD, sudden death is the very first sign that the disease is present.
Generally speaking, however, people who have CAD but who have not yet had a myocardial infarction (heart attack) do not need ICDs. Rather, these individuals need to undertake aggressive measures at controlling the risk factors that are known to accelerate CAD and that make plaque rupture more likely.
Good medical care and effective lifestyle modification can greatly reduce the risk of sudden death, heart attacks, and angina.
2) People who have already had episodes of VT or VF,
especially if the arrhythmia has caused cardiac arrest or loss of consciousness. These people have a very high risk of having another cardiac arrest - probably a 1 in 5 chance each year - and virtually all of them should be offered an ICD.
3) People who have heart failure with a significantly reduced left ventricular ejection fraction.
It is estimated that almost 50% of patients with severe heart failure eventually experience a cardiac arrest. Current guidelines recommend that ICDs ought to be considered for people whose ejection fractions are reduced to 35% or lower.
This is one reason why, if you have heart disease of almost any type, it is important to know your ejection fraction.
4) People who have inherited heart defects that make VT or VF more likely to occur.
Such conditions include long QT syndrome, hypertrophic cardiomyopathy, and Brugada syndrome. ICDs can prevent sudden death in these inherited conditions and should be strongly considered in many affected individuals. Anyone with a strong family history of sudden death should discuss their family history with their doctor and ask whether any special testing ought to be done. In most cases, a simple ECG and perhaps an echocardiogram would be sufficient to rule out the most common inherited cardiac disorders that increase the risk of sudden death.
If you believe any of these four categories may apply to you, you need to have a serious conversation with your doctor about evaluating your risk for sudden cardiac death.