Kardi AI raises €5.3M Series A to scale its heart-rhythm monitoring app

Kardi AI, a Prague-headquartered medtech startup, announced on Nov. 11 that it closed a €5.3 million Series A round led by German healthtech fund Callisto Health, with participation from Seed Starter, BrightCap Ventures, Purple Ventures, DEPO Ventures and Garage Angels, according to Tech.eu. The round, which values the company at €23 million, was independently confirmed by The Recursive, which called it the largest round a Czech medtech startup has raised to date. The company's platform pairs a fitness chest strap with an ECG sensor, a mobile app, and an AI model that analyzes long-term heart-rhythm data to flag arrhythmia risk during everyday activity rather than in a short clinical snapshot.

The company says it will use the funds to push beyond its existing footprint in Czechia, Poland, Slovakia, Romania and Bulgaria into Germany, and separately into India, the UAE and Singapore, while continuing to develop predictive models that estimate a patient's arrhythmia risk over time instead of just classifying a single recording. That's a materially different expansion shape than a typical software raise: each new market brings its own mobile distribution channel, payment rules, data-residency expectations and often a different primary language, and all of that gets layered on top of a continuous-monitoring app that has to keep syncing sensor data reliably in the background on both iOS and Android.

Why the app layer is the harder scaling problem

A wearable-plus-AI product like Kardi AI's lives or dies on the companion app's ability to stay connected to a Bluetooth sensor for hours at a time, buffer readings through dropped connections, and push a risk signal to the user without causing alarm fatigue — and it has to do all of that identically whether the phone is a Samsung sold in Mumbai or an iPhone sold in Berlin. Teams that build and maintain separate native codebases per platform typically find that background-sync behavior, battery-optimization quirks and permission prompts drift apart across OS versions within a year, which is exactly the maintenance gap a mobile app development team with cross-platform healthtech experience is built to close: one shared data layer and UI that behaves the same way across markets, instead of two codebases quietly diverging the moment a new country launches.

What this means for medtech teams planning a multi-market launch

Kardi AI's raise is a reminder that in consumer-facing medtech, the regulatory and modeling work often moves faster than the distribution problem it creates. A startup that lands funding to enter three new regions in a single quarter needs a mobile engineering partner that can localize, test against regional carrier and OS variance, and ship updates on a predictable cadence, not a team that treats each new market as a one-off rebuild.