Garmin ECG Accuracy Beaten by Amazfit Reports Meta-Analysis

Garmin takes a medical-grade approach to detecting Atrial Fibrillation (AFib). Its heart rhythm checking tool, the ECG app, is approved by the FDA and other regulators to reliably detect AFib.

In official clinical tests, the Garmin ECG app demonstrated extremely high accuracy, detecting AFib 99.5% of the time and a normal rhythm 100% of the time when the signal was clear.

There’s one major catch.

The Garmin ECG test is “on-demand“—you must manually start it. The watch does not continuously monitor your heart rhythm in the background. This limits its ability to catch AFib events that are intermittent or happen while you sleep.

Active vs. Passive AFib Monitoring

AFib is often intermittent, meaning it comes and goes. For many users, a watch that constantly scans the heart rhythm in the background (Passive Monitoring) is more valuable than one that relies on manual readings (Active Monitoring) only when the wearer feels symptoms.

Several of Garmin’s competitors, notably Apple and Amazfit, employ a similar passive approach. Instead of an ECG (which measures electrical signals), they analyse the PPG waveform. PPG, or Photoplethysmography, is the method used by traditional optical heart rate monitors to check for irregular pulse rhythms indicative of AFib.

The large-scale meta-analysis by Barrera et al. (2025) confirmed that the PPG-based method achieves diagnostic accuracy comparable to that of ECG. Specifically, one high-quality study of an Amazfit PPG device included in the analysis reported excellent overall diagnostic accuracy for AFib detection.

Amazfit: Superior Performance in Meta-Analysis

The Barrera et al. (2025) meta-analysis found that the Amazfit brand showed excellent overall diagnostic accuracy for AFib detection.

Amazfit: Key Stats

The Head-to-Head Comparisons

The analysis suggested Amazfit’s superior performance, including:

• Significantly higher odds of diagnosing AFib than both the Apple Watch and Withings.
• Comparable accuracy to the leading Samsung smartwatch.

Crucially, the study also found a clear advantage over some older Garmin devices that rely only on PPG. For instance, Amazfit’s 98.87% specificity was significantly better than the 88.24% recorded for the Garmin Forerunner 945 (which uses an older Gen 4 PPG sensor, not the newer Elevate Gen 5 ECG).

Note: It’s important to remember that most of the head-to-head results cited above compare Amazfit’s PPG-based detection to other manufacturers’ PPG detection. Garmin’s approved, on-demand ECG remains a separate, highly accurate test with its own limitations. The analysis only supports the idea that the better-implemented PPG systems (like Amazfit’s) can rival ECGs for general diagnostic accuracy.

Noise, False Alarms, and Trust

A major challenge for all smartwatches is the high rate of false alerts. These often happen because the watch confuses actual AFib with harmless irregular heartbeats (like a premature contraction) or simple noise from movement and poor skin contact.

False AFib alerts can be harmful. Studies show that repeated false positives can lead to a significant decrease in a patient’s self-reported physical health, making them less confident in managing their chronic symptoms [Tran et al., 2023].

Even the highly accurate Garmin ECG app is not immune to signal issues. Garmin correctly instructs users to remain still and ensure good contact, but one clinical study still found 11.5% of recordings were inconclusive. It is challenging to get a clean reading in a real-world setting.

Mathematical Gymnastics

I’m not entirely convinced.

I’m sure the researchers understand statistics better than I do. However, I can’t see how using Garmin’s prior-generation Elevate 4 PPG sensor, along with other PPG sensors, is a good way to determine accuracy against ECG.

• What kind of accuracy or agreement between the PPG sensors is determined en masse for it to be compared to ECG?
• Presumably, Garmin’s Elevate Gen 5 offers better PPG and, as noted, accurate on-demand ECG.

Conclusion: Active ECG vs. Passive PPG — The Real-World Winner

The distinction between Active ECG and Passive PPG monitoring determines real-world diagnostic success for intermittent conditions, such as AFib.

• Garmin’s Limitation: While the Garmin ECG app offers near-perfect accuracy (99.5% AFib detection) when manually initiated with a perfect signal, its on-demand nature limits the chances of catching intermittent AFib events.
• Amazfit’s Advantage: The Barrera et al. meta-analysis supports the notion that a well-executed, continuous PPG system provides superior overall diagnostic performance in real-world settings.

The Key Takeaway: For a consumer seeking the highest probability of detecting an AFib event throughout the day and night, a continuous system, such as Amazfit, Samsung, or Apple, provides a better overall diagnostic solution than a highly accurate but manual one.