A defibrillator's been recommended for your heart? Let's get you ready to decide.

For anyone who's been offered an implantable defibrillator (ICD) to prevent a future cardiac arrest — or helping someone they love think it through.

An implantable defibrillator (ICD) is a small device put under the skin near your collarbone. It watches your heart and, if a dangerous rhythm starts, delivers a shock to try to stop a sudden cardiac arrest. When it's offered before you've ever had one — because your heart's pumping is weak and you're judged to be at risk — that's called primary prevention. This page is for that decision.

Here's the thing most people are never told: the proof a defibrillator helps is genuinely different depending on why your heart is weak. This tool sorts you into the right group, hands you the honest trial numbers for it, and gives you the questions to bring to your cardiologist — so you can walk in to decide, not just nod along.

It isn't a calculator that says "yes, have it" or "no, don't" — that's a decision only you and your cardiologist can make together. It never works out your personal risk, and it never tells you what to do.

What's been recommended, and what do you know so far?

Even one line is enough. Tell me what you've been told, in your own words. Nothing you type leaves your browser.

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Or tap an example

This tool helps you prepare questions — it can't tell if something is urgent. If you're worried right now, call 000 or your cardiologist.

Dr HB Lo

Integrative GP · Defibrillator (ICD) — decision question card

Your situation

The thing to find out first

The questions to bring — then decide together

The one question to lead with

"What's my absolute benefit — the real number out of 100 people like me — and is it survival, or only fewer sudden arrests?"

Most cardiologists will be glad you asked; a good one welcomes it.

Your four questions

Benefits
Risks
Alternatives
If I don't have the device

The honest part

This cuts both ways. A defibrillator can stop a sudden fatal rhythm — that is real and it saves some lives. It can also fire when you don't need it (a painful shock from a false alarm), and devices carry a small risk of infection (around 4–5 in 100 in the trial, similar to the no-device group) and lead problems (DANISH, NEJM 2016). None of this means decline it. It means the honest answer depends on your age, cause, and other conditions — which is exactly why this is a conversation, not an automatic yes.

These questions don't mean you distrust your cardiologist. They're the questions cardiologists ask for their own family. Asking them out loud just gets you the real numbers faster.

Take it with you

Email me the one-page question sheet to bring to my cardiologist.

A clean printable with your own words, the questions for your group, and space to write the answers in — ready to put on the desk.

Your email

There's a fuller version of this

This is the general version. The full defibrillator decision kit walks through your exact ejection fraction and cause, the wearable-vest bridge option, what living with a device is really like, and a deactivation conversation for later — with the real numbers filled in.

Pair it with the statin / risk-numbers visualiser to see what "absolute benefit" looks like as 100 people →
The four-question framework for any medical decision (BRAN) →
Prepare the rest of your cardiology appointment →
Just been to the appointment? Turn it into a plan →
The cardiovascular-decisions cluster: why the cause of a weak heart changes the treatment →