ECG+ app: frequently asked questions

You feel something off with your heart — a flutter, a skipped beat, a racing pulse for no reason. You record an ECG on your Apple Watch, but it comes back "normal," or "inconclusive". Your cardiologist runs a 12-lead ECG, and it shows nothing — because the episode isn't happening right then. Everything checks out, yet you're still worried.

That's the gap ECG+ fills. On its own, your Apple Watch only classifies your rhythm as sinus rhythm or AFib. ECG+ reads that same recording and reveals what the built-in app leaves out: it marks individual premature beats (PACs and PVCs), measures QT/QTc and HRV, and tracks your PAC/PVC burden over time.

So every time you feel something off with your heart, you can capture it and bring your doctor a clear, specific report — turning a fleeting feeling into evidence and a focused, productive conversation.

ECG+ is for anyone who records ECGs on their Apple Watch and wants more than a sinus-rhythm-or-AFib result. It's especially helpful if you feel palpitations, skipped or extra beats, or a fluttering or racing heart and want to capture what's happening in the moment. It's just as useful if you simply like to stay on top of your heart health — whether heart conditions run in your family, or you just want the reassurance of keeping an eye on things over time.

It reads the same recording to mark individual premature beats (PACs and PVCs), measure QT/QTc and HRV, and track your premature-beat burden over time — so you can understand your recordings and bring a clear, doctor-ready report to your appointment.

ECG+ is an informational tool, not a diagnosis or a replacement for medical care — always confirm findings with your doctor.

The built-in Apple ECG app does not report a QT or QTc value — it only classifies the overall rhythm. ECG+ calculates your QTc from the same single-lead recording. Because Apple Watch records a single lead (Lead I), QTc from any watch-based app is an estimate with limits compared to a clinical 12-lead ECG, so a prolonged result should always be confirmed by a doctor.

The built-in app classifies the overall rhythm (sinus rhythm, AFib, high or low heart rate, or inconclusive) but does not label the individual premature (ectopic) beats — the skipped beats, extra beats, or fluttering palpitations you can feel. ECG+ analyzes the same recording and marks each PAC and PVC on the strip, and calculates your premature-beat burden.

Each heartbeat has a P wave (atrial activity), a QRS complex (the main ventricular spike), and a T wave (ventricular recovery), appearing in that order and evenly spaced on a normal beat. ECG+ marks the R peak of each beat and highlights abnormal beats and patterns, making the rhythm easier to follow than a raw strip. See everything ECG+ marks for examples. A single-lead Apple Watch ECG shows these waves but does not replace a full 12-lead reading.

Sinus rhythm means your heart was beating in a normal, regular pattern from its natural pacemaker during the recording. It's a reassuring result — but it only describes the overall rhythm during those 30 seconds, and doesn't rule out premature beats or problems that weren't happening at that moment. More on sinus rhythm.

A "normal" result on Apple Watch is reported as Sinus Rhythm — a regular rhythm, typically between 50 and 100 beats per minute, with no signs of AFib. Keep in mind the watch only checks sinus rhythm versus AFib, so a normal result doesn't mean every aspect of your heart has been checked.

An AFib result means the watch detected an irregular rhythm consistent with atrial fibrillation. If you haven't been diagnosed with AFib, share the recording with your doctor — don't ignore it, but don't panic either. Save the ECG (and analyze it in ECG+ for more detail) to bring to your appointment.

Two common reasons. First, the watch only classifies your rhythm as sinus or AFib, so it doesn't flag premature beats (PACs and PVCs) — a very common cause of palpitations. Second, if the episode wasn't happening during the 30-second recording, there's nothing to catch. ECG+ analyzes the same recording for the detail the watch skips, so record whenever you feel something and check it in ECG+.

No. Neither the built-in app nor ECG+ can reliably detect a heart attack — a single-lead ECG cannot show this the way a clinical 12-lead ECG can.

Inconclusive means the watch couldn't classify your recording as either sinus rhythm or AFib — often due to a heart rate outside the supported range, a short or noisy recording, or a rhythm the classifier isn't designed to label. An inconclusive result can still hold meaningful detail. Here's what "inconclusive" means and how to fix it.

A "poor recording" is most often caused by moisture — damp skin, sweat, or wet contacts. For a clean reading, make sure your wrist, the watch back and the Digital Crown are completely dry, rest your arm on a table, and stay still for the full 30 seconds. More on fixing a "poor recording".

A wavy, drifting or noisy baseline usually comes from movement, muscle tension, dry skin, or loose contact. For a clean trace, rest your forearm on a table, relax your arm, make sure your skin and the watch are dry, and hold still for the full 30 seconds. A very noisy recording may come back as "poor recording".

Yes — detecting atrial fibrillation is exactly what the built-in ECG app is designed and FDA-cleared to do, and in Apple's validation it classified AFib with high accuracy. It does not, however, detect other arrhythmias.

No. The built-in app only classifies your rhythm as sinus rhythm or AFib (plus high or low heart rate, or inconclusive). It doesn't label premature beats (PACs and PVCs), bigeminy, trigeminy, Long QT, or T-wave changes. ECG+ reads the same recording and identifies these — see everything ECG+ marks.

Quite a lot. A single-lead Apple Watch ECG can't detect a heart attack, stroke, blood clots, blocked arteries or heart failure, and it doesn't identify most arrhythmias beyond AFib — including premature beats, a common cause of symptoms. A normal result should never be used to rule out heart disease. For chest pain or heart-attack symptoms, call emergency services.

For atrial fibrillation it's accurate — in Apple's validation study the ECG app showed roughly 98% sensitivity for AFib and 99% specificity for sinus rhythm among classifiable recordings. But that accuracy applies only to the AFib-versus-sinus question; the watch isn't designed to judge other conditions, and a normal result doesn't mean your heart is fully checked.

Yes. The Apple Watch ECG app received FDA clearance (De Novo) in 2018 as a single-lead ECG and an AFib-detection feature, for Apple Watch Series 4 and later. It's cleared as an over-the-counter, non-diagnostic device — not a replacement for clinical testing.

If your heart rate is below 50 or above roughly 120–150 BPM (the upper limit depends on your watch and software version), the ECG app can't reliably check for AFib and will usually return "inconclusive". Resting and re-recording when your heart rate is back in range often gives a clear result.

No — and it isn't meant to be. Your Apple Watch records a single lead (Lead I); a clinical ECG records 12 leads from multiple angles, which is why it can detect heart attacks and complex problems a watch can't. The watch's strength is convenience: you can capture a symptom the moment it happens, then bring it to your doctor. See Apple Watch ECG vs ECG+.

You take the ECG on your Apple Watch, not in ECG+: open the ECG app on your watch, rest your arm on a table, and hold a finger from your opposite hand on the Digital Crown for the full 30 seconds. The recording saves to Apple Health, and ECG+ then reads and analyzes it automatically. If the ECG app isn't on your watch yet, see how to set up ECG on Apple Watch.

You start each one yourself. Apple Watch does not take ECGs automatically or continuously — when you feel a skipped beat, thump or racing heart, open the ECG app on your watch and record a 30-second reading. ECG+ then analyzes whatever recordings are in Apple Health.

The most common cause is moisture or poor contact — if the watch can't find a clear heartbeat, the countdown resets — the ECG starts, stops after a few seconds, and keeps starting over without ever finishing. Make sure your wrist, the watch back and the Digital Crown are completely dry, the band is snug, and you stay still for the full 30 seconds. See fixing a "poor recording". If it still never completes, the watch's ECG sensor may be faulty — Apple can check or replace it.

This usually happens after switching to a new iPhone or watch. To restore it, open the Health app on your iPhone, search for ECG, tap it, and follow the set-up prompts. Note that Apple Watch SE models don't support ECG at all, as they lack the required sensor. Full steps: how to set up ECG on Apple Watch.

Open the recording you want, then tap the share (or PDF) icon in the top-right corner. From there you can email, message, print, or save the PDF report to give to your doctor. The report includes the ECG strip plus ECG+'s measurements and findings.

That's intentional. During atrial fibrillation the rhythm is irregular by nature, which artificially inflates HRV and makes it misleading. So for AFib recordings ECG+ hides HRV and instead shows an irregularity (coefficient of variation, CV%) value that better reflects how irregular the rhythm is. HRV and heart-rate range still appear on non-AFib recordings.

ECG recordings must be deleted from Apple Health, not from ECG+ — Apple doesn't allow third-party apps to delete Health data. Open the Health app, go to Search → Heart → Electrocardiograms (ECG), select the recording and delete it. Within ECG+ you can also hide recordings using the filter, and unhide them again later.

Not currently. ECG+ analyzes single-lead ECGs recorded by Apple Watch and synced through Apple Health. Devices like KardiaMobile and Withings don't share their ECG data with Apple Health or ECG+, and chest straps such as the Polar H10 use a sampling rate too low for ECG+'s analysis.

ECG+ works with recordings from any Apple Watch that supports the ECG app — Apple Watch Series 4 and later, plus Apple Watch Ultra. ECG+ reads the ECGs you've already recorded through Apple Health, so any watch that can produce an ECG will work. New to it? See how to set up ECG on Apple Watch.

No. ECG+ analyzes the ECG recordings already stored in Apple Health, so there's nothing to re-record. Take an ECG with your Apple Watch as usual, then open ECG+ to see the detailed analysis.

No. ECG+ is an analysis and information tool that helps you understand your Apple Watch ECG and share it with your doctor. It is not a medical device and is not a substitute for professional diagnosis or care. Any finding should be confirmed with a clinician. See the full disclaimer.

ECG+ holds a 4.5-star rating from over 5,000 App Store ratings and was independently reviewed by cardiologist Dr. Anthony Pearson, who found it accurately identified PVCs in every recording he checked. Users including ICU nurses and paramedics report its readings match clinical interpretations. As with any tool, findings should be confirmed by a doctor.

ECG+ is free to download on the App Store, and its advanced analysis is available through ECG+ Premium, offered as a monthly or yearly subscription. You can manage or cancel anytime in your iPhone Settings.

Subscriptions are billed by Apple, so they're managed on your device: open Settings → tap your name → Subscriptions → ECG+ → Cancel. For a refund, visit Apple's billing support. Cancelling stops future charges; you keep Premium until the end of the current period.

ECG+ Premium works with Apple Family Sharing, so up to six family members can use one subscription at no extra cost. To set it up: 1) on the purchaser's iPhone, open Settings and tap your name; 2) tap Family Sharing and create your family group (or use an existing one); 3) turn on Purchase Sharing so your subscriptions are shared. Each family member then opens ECG+ on their own iPhone, signed in with their own Apple ID, and Premium unlocks automatically.