That study was on hospitals though - although yes the same applies for surgeons (1), and obstetricians [although the benefits begin to deteriorate at around 50 (2)].

But cardiologists were what the original study was on, and they don't perform surgery. Rather, they are relied on for their "expert judgement", a highly questionable concept (3).

(1) http://www.sciencedirect.com/science/article/pii/S1743919113...

(2) http://www.bmj.com/content/344/bmj.d8041.short

(3) https://www0.gsb.columbia.edu/mygsb/faculty/research/pubfile...