What started as a personal system is now available as an app.

This is a personal account of one person's experience tracking health data through a health event. It is not medical advice, and it does not describe what any app or device can do for you. Individual experiences vary.

More than a month after the ablation, signals remain stable. No complications. No arrhythmic patterns detected. Load is increasing gradually and the body's response remains proportional.

The system that produced this picture started as notes in Apple Notes and grew into a structured episode timeline, then a daily analysis framework, then a codebase of over 1,000 lines, and eventually a native iOS app drawing directly from Apple Health.

That app is Trendwell.

It does what the personal system did: ingests Apple Health data, runs a deterministic classification framework against it, and produces a structured daily and weekly state description. The same logic, applied consistently, every day — without adjustment, without selective interpretation.

The output is not a score. It is a structured characterisation of state: stable, variable, or shifted. How the current pattern compares to recent windows. Whether anything is beginning to change. The descriptions use language like "stable under moderate load" or "resting state elevated relative to prior window" — not "you should" or "this means."

Trendwell is not a medical device. It does not diagnose, recommend, or predict. What it does is apply consistent structure to continuous health data and make the current state legible — the same thing the personal system was designed to do, now packaged to run automatically for anyone with an iPhone and Apple Watch.

The underlying problem it addresses isn't unique to cardiac recovery. It applies to anyone training, managing fatigue, returning from illness, or simply trying to understand whether their health signals are within a familiar range or beginning to shift.

The data is already there, in Apple Health, accumulating daily. Most of it goes unexamined. Trendwell is the interpretation layer.