The quick answer is any amount that is found to be statistically significant, even if it is 13-14% RRR as with Victoza and Jardiance, can be viewed as a success. Whether or not BETonMACE, with its smaller trial size relative to EMPA-REG OUTCOME and LEADER, is powered to detect that smaller difference is a different question. Perhaps the 175 event sample size estimate analysis serves the purpose of increasing the sample size in the event that apabetalone seems to be reducing MACE but at a level of less than 25-30% RRR. 

Also, keep in mind that Jardiance mainly got the attention it received not because of its significant 14% RRR in 3-point MACE, but because one of the components of the 3-point MACE (cardiovascular death) was significantly reduced by 38%.