Use with a Pacemaker

The heart rate monitor is optical (it uses light to watch blood moving in your arm) and should not have any problems living with a pacemaker. The ECG app is a different animal and monitors the tiny electrical signals generated as your heart beats. A pacemaker generates much larger signals and will completely confuse the ECG app. The electrical signals from the pacemaker will simply shout louder than your heart’s natural signals and any ECG recorded will be useless. The ECG function is unlikely to interfere with the pacemaker, or harm you except the stress of seeing the ECG function not working.

My advice, you can have an Apple Watch but don’t expect the ECG function to be useful if you have a pacemaker. Even if the pacemaker is one of the smart devices which only goes active than needed the watch will only tell you what you what you already know, you have a cardiac condition. If you want the cellular version you should consult your cardiologist to check the radios will not interfere with your pacemaker (unlikely to be a problem if you are allowed to use a full power cellular phone).

Yes. The watch uses optical sensors to monitor the heart beat. There are no electrical signals that could affect a pacemaker.