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How are you managing regulatory issues? The Apple watch is not a legal medical device, so my understanding is that it cannot make any diagnoses recommendations to the user.
I would assume any alerts they give would be something like "we have detected an anomaly in X metric we monitor, please consult with your doctor/health professional".
This is really exciting! Quick question for you.

Have you experimented at all with using the Apple Watch to measure blood pressure?

I have done some reading that suggests the optical sensor could measure blood pressure with some accuracy, but that Apple is hesitant to release it as a feature due to regulatory and accuracy concerns. It's my #1 wished for feature.

Is it possible you're talking about blood oxygen saturation? http://www.cultofmac.com/320322/apple-watch-sensors-are-capa...
Measuring blood pressure (non-invasively) requires applying pressure to the artery and determining at what point that pressure obstructs blood flow. That would be a) challenging to do with a watch, and b) really annoying to the user.
Not entirely true, there is a clever method that works without (pulse transit time measurement). You measure the electrical signal of the heartbeat, and the acoustic signal, and take advantage of the fact that the acoustic signal propagates slower in blood than the electrical signal propagates through nerves. This difference is directly related to blood pressure! I don't know if you can get away with one measurement on the wrist + some clever calibration, or if you need two points (e.g. one close to the heart). If you take two measurements, you can apparently also calculate the aortal pressure, which is different from the pressure in your arm, and hard to obtain non-invasively. (I'm not an expert so I'm sorry if I got something slightly wrong :-) .)

There was a startup that worked on using this, but they failed (due to financial but also regulatory reasons), and then remotely bricked all their sold devices...

I really wish someone would develop this further. Even if it is not as accurate as a normal measurement, the implications would be huge. There are so many people running around with hypertension who have no idea. I also don't see a risk in false positives in this case, since in principle everybody is recommended to have their blood pressure checked - false positives who go to the doctor are then just like people who read an article and go to the doctor, and are weeded out there. False negatives might be a problem - but if you don't advertise it as a blood pressure measurement tool, but just implement it as an additional warning in a smart watch, you'd reduce the false sense of security people would get if it didn't work properly.

Newer Chinese "Fitbits" promise that. But they only use an optical system and it doesn't work for me even after entering a baseline.
Here's some reading on the alternatives I was thinking about.

https://www.medgadget.com/2012/01/company-claims-optical-blo...

https://www.ncbi.nlm.nih.gov/pubmed/24110216

When will we see this make it to production for all Cardiogram users?