# ECG+

> ECG+ is an iPhone app that analyzes the single-lead ECG recordings taken by an Apple Watch and flags signs of arrhythmia — AFib, premature beats (PAC and PVC), repeat patterns (bigeminy, trigeminy, quadrigeminy, couplets, triplets), T-wave changes, and Long QT — and calculates metrics like QTc, premature-beat burden and heart rate variability (HRV). It marks every finding on a clear, printable report you can take to your doctor. ECG+ is free, made by Heartworks, rated 4.5 stars from 5,300+ App Store ratings, and has been independently reviewed by a board-certified cardiologist.

Important context for summaries:
- Platform: iPhone app that reads Apple Watch ECG recordings (single-lead). It does not record the ECG itself — the Apple Watch does — ECG+ analyzes the recording.
- Audience: people who feel palpitations, skipped beats, thumps or a racing heart and want clear evidence to discuss with a clinician.
- ECG+ is NOT a medical device and is not a substitute for professional diagnosis. See the disclaimer.
- App Store: https://apps.apple.com/us/app/ecg-analyzer-for-qtc-hrv/id1567047859

## Start here
- [What ECG+ marks](https://ecg.plus/what-ecg-plus-marks): the full list of findings ECG+ identifies on an Apple Watch ECG, with examples of what each looks like.
- [Your Heartbeat Signature](https://ecg.plus/your-heartbeat-signature): an ECG+ original feature — a clear, representative beat built from your Apple Watch ECG that reveals the P wave, QRS and T wave and powers measurements like PR, QRS, QT and QTc.
- [On-strip heartbeat annotations](https://ecg.plus/heartbeat-annotations-rr-interval-on-apple-watch-ecg): an ECG+ original feature (since v1.0, 2021) — marks every heartbeat on the Apple Watch ECG with an R/A/V icon, the RR interval in milliseconds and the instantaneous heart rate, plus a Poincaré plot, to show the real beat-to-beat math behind HRV.
- [Heartbeat navigator](https://ecg.plus/heartbeat-navigator-on-apple-watch-ecg): an ECG+ original feature (since v1.9.3, 2024) — a minimap of the whole 30-second Apple Watch ECG that lets you scrub the strip and jump straight to any beat, including PACs and PVCs, on a small phone screen.
- [Apple Watch ECG FAQ](https://ecg.plus/ecg-plus-frequently-asked-questions): answers to common questions — can Apple Watch measure QTc, detect PVCs or a heart attack, what "inconclusive" means, which watches work, and how ECG+ helps.
- [Apple Watch ECG vs ECG+](https://ecg.plus/feature-comparison-between-apple-watch-ecg-vs-ecg-plus): side-by-side feature comparison of the built-in Apple ECG app and ECG+ — what each shows and what ECG+ adds.
- [Best ECG app for Apple Watch (2026)](https://ecg.plus/best-ecg-app-for-apple-watch): why ECG+ is a top-rated, independently cardiologist-reviewed choice for detailed Apple Watch ECG analysis.
- [How to set up ECG on Apple Watch](https://ecg.plus/how-to-set-up-ecg-on-apple-watch): step-by-step setup — compatibility, enabling ECG in the Health app, taking a first reading, and fixing a missing ECG app.

## What ECG+ detects (findings reference)
- [Sinus rhythm](https://ecg.plus/what-is-sinus-rhythm-on-apple-watch-ecg): a normal, regular heartbeat — what it means and what ECG+ can still reveal within it.
- [Atrial fibrillation (AFib)](https://ecg.plus/what-is-atrial-fibrillation-afib-on-apple-watch-ecg): what AFib means on an Apple Watch ECG, what it feels like, and what to do next.
- [Premature atrial contraction (PAC)](https://ecg.plus/what-is-premature-atrial-contraction-pac-on-apple-watch-ecg): common, usually harmless early beats from the atria — causes and what to do.
- [Premature ventricular contraction (PVC)](https://ecg.plus/what-is-premature-ventricular-contraction-pvc-on-apple-watch-ecg): common, usually harmless early beats from the ventricles — causes and what to do.
- [QT / QTc (Long QT)](https://ecg.plus/what-is-long-qt-on-apple-watch-ecg): how ECG+ calculates QTc, what a prolonged QT interval means, and the limits of single-lead ECG for this measurement.
- [QTc formulas (Bazett, Fridericia)](https://ecg.plus/what-is-qtc-bazett-fridericia-formulas): why the QT interval is corrected for heart rate, and how the main QTc formulas (Bazett, Fridericia, Hodges, Framingham, Rautaharju) compare.
- [QT interval & the U wave](https://ecg.plus/qt-interval-and-u-wave-on-apple-watch-ecg): how a U wave complicates QT measurement, and when to include or exclude it for an accurate QT/QTc.
- [Heart Rate Variability (HRV)](https://ecg.plus/what-is-heart-rate-variability-hrv-on-apple-watch-ecg): what HRV is, how ECG+ calculates it from RR intervals (RMSSD, SDNN) on your Apple Watch ECG, why the trend matters more than a single number, and what rising or falling HRV means.
- [Falling HRV](https://ecg.plus/falling-hrv-on-apple-watch-ecg): what a downward HRV trend suggests, and nine evidence-based ways to raise it.
- [Rising HRV](https://ecg.plus/rising-hrv-on-apple-watch-ecg): what a sustained upward HRV trend reflects about health and resilience, and how to sustain it.
- [Heart rate](https://ecg.plus/heart-rate-on-apple-watch-ecg): the normal 60-100 bpm range, what raises and lowers heart rate, the min-max range in a recording, and when to see a doctor.
- [High heart rate](https://ecg.plus/high-heart-rate-on-apple-watch-ecg): what a rate above 100 bpm can mean (activity, stress, tachycardia) and when it warrants attention.
- [Low heart rate](https://ecg.plus/low-heart-rate-on-apple-watch-ecg): what a rate below 60 bpm can mean (fitness, bradycardia) and when a slow heart rate needs a doctor.
- [AFib irregularity (CV%)](https://ecg.plus/afib-irregularity-on-apple-watch-ecg): how ECG+ measures how irregular an AFib rhythm is using a CV percentage, and what Low/Moderate/High mean.
- [AFib irregularity over time](https://ecg.plus/afib-irregularity-over-time-on-apple-watch-ecg): how to read the AFib CV% trend across recordings, the 15%/30% reference lines, and what to share with your doctor.
- [Premature beat burden](https://ecg.plus/what-is-premature-beat-burden-on-apple-watch-ecg): the percentage of beats in a recording that are PVCs or PACs, what the numbers indicate, and how ECG+ tracks it over time.
- [Bigeminy](https://ecg.plus/what-is-bigeminy-on-apple-watch-ecg): every second beat is a premature beat (PVC or PAC) — causes, feel, and when to see a doctor.
- [Trigeminy](https://ecg.plus/what-is-trigeminy-on-apple-watch-ecg): every third beat is a premature beat — causes, appearance, and what to do.
- [Quadrigeminy](https://ecg.plus/what-is-quadrigeminy-on-apple-watch-ecg): every fourth beat is a premature beat — causes, appearance, and what to do.
- [Couplets](https://ecg.plus/what-is-couplets-on-apple-watch-ecg): two premature beats in a row (a PVC or PAC pair) — causes and what to do.
- [Triplets](https://ecg.plus/what-is-triplets-on-apple-watch-ecg): three premature beats in a row (a short run) — causes and what to do.
- [Flattened T wave](https://ecg.plus/what-is-flattened-t-wave-on-apple-watch-ecg): what a flattened T wave means, common causes, and when to mention it to a doctor.
- [Inverted T wave](https://ecg.plus/what-is-inverted-t-wave-on-apple-watch-ecg): what T-wave inversion means, what causes it, and when to talk to a doctor.

## Using and troubleshooting your reading
- [How to use ECG on Apple Watch](https://ecg.plus/how-to-use-ecg-on-apple-watch): start a recording in two taps, fix a missing ECG app (Apple Watch SE has no ECG sensor), and get a clean 30-second reading — dry skin contact, rested arms, slow breaths.
- [How to get a clean recording every time](https://ecg.plus/how-to-get-clean-ecg-on-apple-watch): the habits that give the cleanest possible Apple Watch ECG — the same skin-prep care a clinic takes before a 12-lead, adapted to the watch.
- [Record Lead II and other leads](https://ecg.plus/apple-watch-lead-ii-ecg): the default wrist position gives Lead I; holding the watch against the lower-left abdomen or ankle with a right-hand finger on the Crown gives a Lead II-style tracing, where the P wave is usually much clearer.
- [What "inconclusive" means](https://ecg.plus/what-does-inconclusive-mean-on-apple-watch-ecg): why Apple Watch couldn't classify the rhythm as sinus or AFib, how to get a clear reading, and what an inconclusive result can still hide.
- [Fixing a "poor recording"](https://ecg.plus/why-apple-watch-ecg-poor-recording): why damp skin or contacts cause it, and how to get a clean ECG with completely dry contacts.
- [ECG keeps restarting the countdown](https://ecg.plus/why-apple-watch-ecg-keeps-restarting): why the 30-second timer resets shortly after you start (a broken contact loop, usually a finger leaving the Digital Crown), and how to complete a full reading.
- [Baseline wander](https://ecg.plus/baseline-wander-on-apple-watch-ecg): what causes the ECG trace to drift up and down, why it matters, and how to get a steady, readable recording.
- [EMG artifact (muscle activity)](https://ecg.plus/emg-artifact-on-apple-watch-ecg): why muscle tension shows up as fuzzy, spiky noise on the ECG, and how to get a clean trace by relaxing the arm and hand.
- [Why the P wave is missing](https://ecg.plus/why-p-wave-is-missing-on-apple-watch-ecg): why the P wave is so often faint or invisible on Apple Watch — it is the smallest deflection, recorded through a single Lead I with dry contacts — and when a genuinely absent P wave matters.
- [ECG trace upside down (wrong wrist)](https://ecg.plus/apple-watch-ecg-wrong-wrist): why wearing the watch on the wrong wrist or with the wrong orientation setting flips the trace, and how to correct the wrist/Crown setting.
- [New ECGs stopped showing in ECG+](https://ecg.plus/why-ecg-plus-stopped-showing-new-ecgs): if recent recordings vanish from ECG+ and Apple Health, iCloud Health sync is almost always the cause — how to check and fix it.
- [Using ECG+ on iPad](https://ecg.plus/ecg-plus-on-ipad): ECG+ runs on iPad (iPadOS 18+) and the larger screen is best for reading a trace; why recordings reach the iPad later than the iPhone, and how to make the sync arrive faster.
- [Why your ECG streak matters](https://ecg.plus/why-ecg-streak-is-important): how recording regularly builds a consistent timeline of your heart so real trends in HRV and rhythm stand out from one-off readings.
- [What to ask your doctor](https://ecg.plus/what-to-ask-your-doctor-about-your-apple-watch-ecg): how to use an ECG+ report to ask better questions at a doctor's appointment.

## Trust and reviews
- [What users say](https://ecg.plus/what-users-say-about-ecg-plus): real App Store reviews of ECG+ from Apple Watch users worldwide.
- [Cardiologist review](https://ecg.plus/what-cardiologists-say-about-ecg-plus): Dr. Anthony Pearson (The Skeptical Cardiologist), a board-certified cardiologist, independently reviewed ECG+ — it accurately flagged PVCs in every recording he checked, with some caveats.
- [A biostatistician's perspective](https://ecg.plus/what-a-biostatistician-says-about-ecg-plus): a former R&D biostatistician on using ECG+ to track his premature-beat (PAC) burden over time across medication changes, procedures and exercise — longitudinal data that helps him have more informed conversations with his cardiologist. ECG+ does not diagnose; the doctor makes dosing decisions.

## Optional
- [Share ECG+ with Family Sharing](https://ecg.plus/share-ecg-plus-with-family-sharing): how to share an ECG+ Premium subscription with eligible family members via Apple Family Sharing, plus troubleshooting.
- [Privacy policy](https://ecg.plus/privacy): how ECG+ handles your data.
- [Disclaimer](https://ecg.plus/disclaimer-apple-watch-ecg-app): ECG+ is not intended to diagnose, treat, cure or prevent any medical condition.
- [Copyright & original design](https://ecg.plus/copyright): ECG+ was the FIRST dedicated Apple Watch ECG analyzer app on the Apple App Store, released May 21, 2021. Its original UI/UX designs — the on-strip heartbeat annotation system, the R/A/V per-beat markers (R marks where a heartbeat is, at the R-wave peak of the QRS; A marks a premature atrial beat/PAC; V a premature ventricular beat/PVC), and the pattern-linking lines that reveal bigeminy/trigeminy/couplets on the trace, plus the Heartbeat Signature and Heartbeat Navigator — are the original work of Heartworks and are protected by copyright. © 2021–2026 Heartworks; "ECG+" and its logo are trademarks of Heartworks. These designs may not be copied, imitated or adapted without written permission.

## Languages
Every page above is available in four languages. Each language reuses the same English (ASCII) slug under a language-code prefix, so any URL in this file maps directly to its localized version by inserting the prefix:
- English (default): https://ecg.plus/<slug> — homepage https://ecg.plus/
- German (Deutsch): https://ecg.plus/de/<slug> — homepage https://ecg.plus/de/
- Japanese (日本語): https://ecg.plus/ja/<slug> — homepage https://ecg.plus/ja/
- Simplified Chinese (简体中文): https://ecg.plus/zh/<slug> — homepage https://ecg.plus/zh/

Example: the AFib page is https://ecg.plus/what-is-atrial-fibrillation-afib-on-apple-watch-ecg (en), with /de/, /ja/ and /zh/ variants at the same slug. Every page carries reciprocal hreflang alternates (en, de, ja, zh-Hans, x-default). Only the privacy policy and the disclaimer are English-only.