Complex sentence: Where the ST segment is horizontal it is fairly straightforward to identify where the S-wave finishes and the ST segment begins but a sloping ST segment can cause more difficulty but the J-point can usually be identified by the change in gradient.
Split into simpler sentences: Where the ST segment is horizontal it is fairly straightforward to identify where the S-wave finishes and the ST segment begins. A sloping ST segment can cause more difficulty but the J-point can usually be identified by the change in gradient.