The downsloping PR segment and the upsloping ST segment do not make a smooth, scooped-out curvature. In fact, there is a 3-mm dropoff of the ST segment (the J point, the beginning of the ST segment, ...
The downsloping PR segment and the upsloping ST segment make a smooth, scooped-out curvature, with the J point (the beginning of the ST segment) and the end of the PR segment being at the same level, ...