Microcontroller for ECG (Holter monitor)

Since I have very little previous experience with microcontrollers, I'm looking for an advice on which microcontroller to get that will be appropriate for Holter monitoring (ECG signals from external circuit with 3 channels)? It should be as small as possible with low battery usage (because of for 24 h+ monitoring) and good enough performance for ECG application. As far as connectivity goes, I will use Bluetooth and maybe Wi-Fi, but Bluetooth is crucial for sure. Are there any suitable microcontrollers with Bluetooth integrated or would I have to pair it with external BT module? If that is the case, which combination would you then recommend to me?

Any advise would be greatly appreciated! Thanks :)

Do you intend to spend more than 24 hours continuously sending data via Bluetooth? I believe it would consume much of the battery in your circuit, which would increase the weight and volume of your device.

I'm developing something similar, but I opted for a datalogging system using a microSD shield. The storage capacity is sufficient and the programming it's quite simple. If the real-time monitoring is not a priority in your project, I believe the datalogging system would be helpful