Who should receive an ICD?
ICD implantation should be considered to prevent SCD in women with heart failure at high risk for sudden dangerous heart rhythms, whether or not they have experienced symptoms. ICDs do not improve the heart's functioning or delay the progression of heart failure. Although ICDs can prevent sudden cardiac death, experiencing shocks can negatively affect quality of life and the implantation procedure involves some risk. These negatives need to be carefully weighed against the potential benefits by a woman and her doctor.4
Women with mild to moderate heart failure symptoms who have no history of heart rhythm problems, but who have blood pumping problems (ejection fraction 35% or less) are at increased risk for sudden cardiac death and may benefit from an ICD.4 In patients at risk, an ICD can reduce the chances of dying by as much as 30%.5,6 In one study of more than 1200 patients (only 16% were women) with blood pumping problems and a history of heart attack, an ICD reduced the chances of dying by 31% overall over 20 months. There were too few women in the study to determine if women benefited as much as men.7 Another trial of more than 2500 patients (23% were women) with mild or moderate heart failure had lower death rates when treated with an ICD instead of medical therapy alone (22% versus 29%), whether or not the heart failure had been caused by a heart attack.6 There were not enough women in the study to determine if they benefited as much as men.
Women who have already survived a cardiac arrest or have had serious heart rhythm problems in the past ( ventricular tachycardia or fibrillation) are at increased risk for SCD and other heart events, and should receive an ICD to prevent dying in case the rhythm problems recur.4 For example, in one study that combined data from 3 trials in nearly 1900 patients (only 19% were women), an ICD cut the chances of SCD in half. Overall, women or men who received an ICD lived an average of 4.4 months longer during the 6 year study compared with patients who did not receive an ICD. Those with worse blood pumping problems benefited most; results of this study were not broken down by gender.8
Should I be tested to see if I need an ICD?
Women who experience severe heart rhythm problems (including sustained ventricular tachycardia or ventricular fibrillation) are at increased risk for SCD. You should undergo testing to see if you have these heart rhythm problems and would benefit from an ICD if you have heart failure and:9
- You have had repeated episodes of palpitations (an irregular awareness of the heartbeat, or a feeling that the heart is beating rapidly, strongly, or pounding against the chest)
- You have had repeated episodes of fainting or near-fainting (called syncope) and there is no known cause. People who experience syncope are at increased risk for sudden cardiac death.10
- Your ECG showed signs of abnormal electrical conduction in the pumping chambers of the heart
Who should NOT receive an ICD?
Patients who with severe heart failure (Stage D) or other serious illnesses (such as lung or kidney disease) who are unlikely to survive for more than a year should not receive an ICD.4 While an ICD could prevent sudden cardiac death, the procedure itself is risky in very sick patients and is unlikely to increase the person's lifespan.
Some reversible causes (such as overdose of digitalis drugs, getting too little oxygen, abnormal balance of chemicals in the blood, and severe infections) can result in ventricular tachycardias. Instead of an ICD implantation, addressing the underlying cause will prevent the heart rhythm problem from happening again.
Do ICDs work as well in women as in men?
It is difficult to know for sure because women only make up between 8% and 23% of subjects in the major trials. This is not usually enough to draw conclusions about women in particular, or to compare the results in women with those in men.
However, a few studies have attempted to determine the relative benefit of ICDs in women and men. Most find that, after correction for other factors, women who are eligible appear to benefit from ICD implantation.11-13
Are women missing out on the benefits of ICDs?
Maybe. Fewer women than men receive ICDs (34,000 women compared with 80,000 men annually).1 This is partly because certain clinical characteristics make more men suited for ICD implantation: women are more likely than men to have diastolic heart failure (heart failure with normal ejection fraction), and ICDs do not benefit these patients. Because SCD is 3 to 4 times more common in men than in women, doctors may be more likely to take aggressive prevention measures in men.1 In addition, women tend to develop heart disease at an older age and may therefore be less likely to have extended survival with an ICD and more likely to suffer complications after the implantation procedure.
However, some studies show that even when other factors are taken into account women are less likely to receive an ICD when they need one than men are. One analysis of 26,000 patients who received a pacemaker or ICD found that women were 40% less likely than men to receive an ICD, independent of other factors.14 Another study of more than 13,000 patients found that white women were 38% less likely and black women 44% less likely to receive an ICD when they were eligible compared to white men.15
Are there any alternatives to ICD implantation?
ICD implantation is the most effective way to prevent death from serious heart rhythm problems in patients with heart failure. Many heart rhythm drugs can actually make heart failure worse (see Medications to Avoid).
Amiodarone is one of the few heart rhythm drugs that does not increase the risk of dying in patients with heart failure, but it cannot prevent death from serious heart rhythm problems. In a study of more than 2500 patients (23% were women), those treated with amiodarone had lower survival rates than patients who received an ICD, and similar survival rates as that seen with standard medical treatment.6 This drug may be used in patients who are not eligible for ICD implantation. If you are eligible for an ICD the device is the best way to prevent the complications of serious heart rhythm problems.