To get a clean ECG waveform from MAXREFDES101 do the following:
Ensure there is a good electrical contact between the electrodes and the skin. You may clean the skin with alcohol wipes to remove any oil or dirt.
Filter out the mains frequency as otherwise it distorts the ECG measurement
You may need to invert the waveform depending on the location of the watch (Left hand or Right hand) as you could be measuring the inverted cardiac vector.