Smartwatch choice for heart problem

Sova

Hi all
Please help me choose smartwatch/fitness tracker/HR monitor. Few months ago I had heart attack(ouch!!), so now when I exercise I have to keep below 150 beats per minute. My exercises are tennis and skiing and my main requirements are
wrist heart rate monitor as accurate as possiblevibration alert when I go over the HR limit. will work below zero and on high altitudeGood to have:
2 types of vibration alerts: one at 140 beats to tell me in the middle of the tennis point to go for the win-or-lose shot (because few more shots will get me over 150) and a different type of vibration alert at 150 to tell me to stop immediately as going over 150 is dangerous. As I recover further I hope to push those limits up.waterproof - in case I fall while skiing or play tennis in light rainI don't need GPS and zillion other smartwatch features, hoping not to pay for functionality I will not use. I have iphone and android tablet - not sure if that's important factor.
Spent lot of time googling and I think only several Garmin products (Vivoactive, Vivosmart, Vivomove) and Apple Watch deliver that.
Any other products I should consider? I would like to hear from experts and first hand experience using them.
I am in the UK, looked at ibeat ( FAQ - iBeat - The Heart Monitor Smartwatch That Can Save Your Life ) but that wont be around here for a while and I think it does not tick all the boxes.
Right now I use Polar FT7 but at times heart rate is lost, there is no vibration, so I have to look at the rate every so often.
Many thanks for taking time to read and respond.

peterson

The xiaomi mi band 2 will achieve most of what you want.
I can’t vouche for it’s accuracy (as I have no accurate means to check) .
It can be paired via Bluetooth to a mi fit app and the latest version can be set to constantly monitor HR with a single vibrating alarm at a set level.

With normal use, battery life is excellent, at least a month.
You can get it via Gearbest (who I used), delivery from China was quite speedy considering or Geekbuying who I found a liitle slower.

There seem to be many ‘versions’ at different prices but avg is about £20...
Well recommended.

Mi Band 2 FAQ: Specs, Price, Look, Package, Usage, App & More  (Updating) - Mi Band 2 - Xiaomi MIUI Official Forum

Sova

peterson, thanks for this tip. I will checkout Xiaomi. Slightly concerned about the brand and the accuracy. Meanwhile I had hints that polar A370 can do the trick, Emailed polar support 5 days ago to confirm, no answer yet. Any other suggestions, anyone?