Heart failure · Sudden-death prevention
The ICD in heart failure:
who benefits, and how much.
An implantable cardioverter-defibrillator watches the heart rhythm and shocks or paces it back to normal if a dangerous arrhythmia starts. In heart failure with a persistently low ejection fraction, it is the main protection against sudden cardiac death.
Quick answer
Who needs an ICD with heart failure?
Guidelines recommend a primary-prevention ICD for heart failure patients whose ejection fraction remains 35% or less, with NYHA class II–III symptoms despite optimised medication, who are expected to live more than a year. After a heart attack, the patient must also be at least 40 days out. The evidence is strongest when heart failure is caused by coronary disease. In SCD-HeFT, an ICD reduced the risk of death by 23% compared with placebo.
14.2% vs 19.8%
Mortality, post-heart-attack
ICD vs medical therapy, EF ≤30%, 1,232 patients, 20 months
MADIT-II, NEJM 2002
HR 0.77
23% lower death risk
ICD vs placebo, EF ≤35%, NYHA II–III, 2,521 patients
SCD-HeFT, NEJM 2005
7.2 points
Absolute mortality drop
At 5 years in SCD-HeFT; amiodarone gave no survival benefit
SCD-HeFT, NEJM 2005
4.3% vs 8.2%
Sudden death, non-ischaemic
Overall mortality not significantly different (21.6% vs 23.4%)
DANISH, NEJM 2016
98.7%
EV-ICD defibrillation success
At implant, 302 tested patients
EV-ICD pivotal, NEJM 2022
92.6%
EV-ICD free of major complications
At 6 months (Kaplan-Meier)
EV-ICD pivotal, NEJM 2022
ICD types
Single, dual or extravascular.
Single-chamber ICD
One lead in the right ventricle that senses, paces and shocks. SCD-HeFT used a conservatively programmed, shock-only single-lead ICD.
1 transvenous lead
Dual-chamber ICD
Adds an atrial lead, usually chosen when the patient also needs atrial pacing (for example, a slow heart rate) or better rhythm discrimination.
2 transvenous leads
Extravascular ICD (EV-ICD)
A single lead placed under the breastbone, outside the heart and veins, which can still deliver anti-tachycardia and pause-prevention pacing. It avoids long-term transvenous-lead complications but cannot provide ongoing pacing.
Substernal lead
CRT-D
If you also qualify for cardiac resynchronization, a CRT-D combines biventricular pacing with an ICD in one device.
See CRT page
The evidence
What the major ICD trials showed
The case for the ICD rests on two large trials from the 2000s. A third, more recent trial showed the benefit is smaller in non-ischaemic heart failure treated with modern therapy, which is why the ESC rates that group lower (class IIa).
| Trial | Patients | Result |
|---|---|---|
| MADIT-II (NEJM 2002) | 1,232 · prior heart attack, EF ≤30% | Mortality 14.2% with ICD vs 19.8% without over ~20 months (HR 0.69, P=0.016) |
| SCD-HeFT (NEJM 2005) | 2,521 · NYHA II–III, EF ≤35%, ischaemic and non-ischaemic | Deaths 22% ICD vs 29% placebo; HR 0.77 (P=0.007). Amiodarone: no survival benefit |
| DANISH (NEJM 2016) | 1,116 · non-ischaemic, EF ≤35%; 58% also had CRT | All-cause death 21.6% vs 23.4% (HR 0.87, P=0.28, not significant); sudden death 4.3% vs 8.2% (HR 0.50) |
| EV-ICD pivotal (NEJM 2022) | 356 enrolled · class I/IIa ICD indication | Defibrillation success 98.7%; 92.6% free of major complications at 6 months; 29 patients had 118 inappropriate shocks |
HR = hazard ratio. Figures from the published abstracts; see references.
Timing
Why doctors wait before implanting
Ejection fraction often improves once guideline medicines are optimised or a reversible cause is treated. That is why the decision is taken after at least three months of therapy, and at least 40 days after a heart attack. An ICD fitted too early can turn out to be unnecessary.
For international patients, that means bringing a recent echocardiogram taken on your current medicines. If your last echo predates medication changes, the cardiologist may ask for a new one before deciding.
Arrhythmia centres
Where ICDs are
implanted in China.
Fuwai Hospital 阜外医院
National Center for Cardiovascular Diseases; large arrhythmia and heart failure programme
Beijing Anzhen Hospital 北京安贞医院
Major cardiology centre with an advanced heart failure programme
Zhongshan Hospital, Fudan University 复旦大学附属中山医院
Shanghai's leading cardiology department
FAQ
ICD questions — answered.
- Does an ICD improve heart failure symptoms?
- No. An ICD only treats dangerous rhythms; it does not make the heart pump better. If you also need symptom relief and have a wide QRS, a CRT-D combines resynchronization with defibrillation.
- Is an ICD worth it in non-ischaemic heart failure?
- It is less clear-cut. In DANISH, an ICD halved sudden death (4.3% vs 8.2%) but did not significantly reduce overall mortality (21.6% vs 23.4%). The ESC gives a class IIa recommendation in this group. The decision weighs age, other illnesses and patient preference.
- What is an extravascular ICD?
- It places the lead under the breastbone instead of inside the heart. In the pivotal study of 356 patients, it defibrillated 98.7% of induced arrhythmias at implant, and 92.6% of patients were free of major complications at 6 months. Inappropriate shocks did occur (118 shocks in 29 patients). It suits patients who do not need ongoing pacing.
- How long is the hospital stay for an ICD?
- A transvenous ICD is usually implanted under local anaesthetic with sedation, and the hospital stay is short. We suggest planning about a week in China for a wound check and device programming before flying.
- Can I fly home after an ICD implant?
- Usually yes, after your doctor confirms the wound and leads are stable. Carry your device ID card, because the device can trigger airport security scanners. Arrange follow-up with a clinic at home that can interrogate your device brand.
Related guides
Heart failure treatment (hub)
The step-by-step pathway from medication to devices, LVAD and transplant.
Read the guideCRT-P / CRT-D (biventricular pacing)
For wide QRS with left bundle branch block: trial data and criteria.
Read the guideCardiac contractility modulation (CCM)
A device option for narrow QRS, EF 25–45% — approved in China.
Read the guideLVAD (artificial heart pump)
HeartMate 3 and Chinese-made pumps: outcomes and approvals.
Read the guideHeart transplant in China
Outcomes, volumes — and the rules for foreign patients.
Read the guideCardiac surgery in China
Bypass, valve surgery, TAVR and other procedures that treat reversible causes.
Read the guideSources
References
- Moss AJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction (MADIT-II). N Engl J Med. 2002;346(12):877–883.
- Bardy GH, et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure (SCD-HeFT). N Engl J Med. 2005;352(3):225–237.
- Køber L, et al. Defibrillator implantation in patients with nonischemic systolic heart failure (DANISH). N Engl J Med. 2016;375(13):1221–1230.
- Friedman P, et al. Efficacy and safety of an extravascular implantable cardioverter-defibrillator. N Engl J Med. 2022;387(14):1292–1302.
- Heidenreich PA, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: Executive Summary. J Am Coll Cardiol. 2022;79(17):1757–1780.
- McDonagh TA, et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J. 2021;42(36):3599–3726.
Not sure you need an ICD?
Get a written second opinion.
Send your echo, ECG and medication list. A partner cardiologist will say whether you meet ICD criteria now, or whether medication should be optimised and the echo repeated first.
This page is for general education only and is not medical advice. Device and surgical treatment for heart failure depends on your ejection fraction, ECG, symptoms, other conditions and how you respond to medication, and only your cardiologist can decide what fits. Trial results describe groups of patients, not what will happen to you. We are an independent patient-coordination service and are not affiliated with any device manufacturer.