Hey tada,

I think the answer to your question may lie in the fact that these graphs reflect a CUMULATIVE event rate thus the longer the period the more total events will be observed as a percentage of a finite total at the end of the trial.  It is also noticeable that the middle potion of each graph has a flatter spot which could be related to patient enrolment whereby patients are still being added thus slowing the MACE rate as a percentage of the total at the time.  The fact that the patient population is a sick population, and assuming that the treatment is meaningful, I would expect the biggest divergence in a cumulative measure to occur towards the end of the treatment period and in post treatment follow up. Given that atherosclerosis is a slow progressive condition, meaningful treatment of the test group would either slow or regress the disease, resulting in a lower event rate and fewer total events while the placebo group would continue to have events at a greater rate and a greater proportional total.

Hopefully this type of trend will be observed with triple MACE in the larger and longer BetOnMace trial and treatment will result in more test patients having no MACE or taking a longer time to a MACE than that which is observed in the placebo group. 

Just what I think, would appreciate feedback.