New Oral Antiplatelets: Will they change your practice?

Some people are already changing their practice. Some interventional cardiologists are quick to take on the new OAP probably in certain cases like stent thrombosis, while others are going more general. In the midst of all these, clopidogrel is also facing the generic battle. Many generic clopidogrel in the market, some appear to be more reliable than others – though you have to testify this yourself.
As to the new OAP, Prasugrel and Ticagrelor are the two main ones. Prasugrel reduced composite primary endpoints which mainly was reduction in MIs, in acute coronary syndrome patients undergoing PCI (TRITON TIMI 38). There was no reduction in mortality. There was also a small but significant reduction of stent thrombosis events.
While ticagrelor, as published in PLATO study, is the first OAP to have shown benefit in reducing mortality, MIs, total mortality as well as stent thrombosis events. The benefit covers a wide range of subgroups including ACS treated both medically or with PCIs, STEMI patients (subjected to primary PCI). In diabetic subgroup, there was a difference but reported to be non-significatn statistically.
With prasugrel, the main problem is increased in bleeding. Prasugrel may not be suitable for those weighing less than 60kg or elderly (or dose need to be reduced … waiting for the evidence). Ticagrelor did not significantly increase bleeding, though a small subgroup of patients had increased incidence of fatal intracranial bleed (11:1 placebo).
The only problem, apart from costs, for ticagrelor is it being dosed at BID, which may pose compliance problem. Prasugrel is given once daily, however priced at twice that of clopidogrel! and you cannot yet use it to ACS patients treated medically. Subgroups that appear to benefit are diabetics and weighing more than 60kg, aged below 70s (or simply 60s and below).
Despite both OAP showing a much higher IPA activities, there are still a lot of debate on IPA testing itself, no direct evidence to show that higher IPA translates to better outcome, and here you are faced with the risk of increased bleeding itself.
Nevertheless OAP testing may be the way to go, to convince ourselves whether or not generic clopidogrel is equivalent to the original. The problem with using generic clopidogrel, when, say a patient has an atherothrombotic event while being treated with a generic clopidogrel, you can hardly put the blame on generic. Unless, you do IPA test, stop the generic, give a washout time (risk to patients!), then start on original clopidogrel, and retest IPA – a messy procedure. Definitely, I would recommend monitoring our patients on generic clopidogrel – though you may not have to do it on all the patients, at least a periodic IPA protocol testing (random) can act as a safety assurance that patients are not exposed to an increased thrombotic risk due to suboptimal treatment.
Back to new OAP, which one? And is there an easy way to pick a group of patients whom you know will not respond to clopidogrel? Our ACS populations, have a 21% rate of non-responders – you will not know this group until you do the IPA test – or do we need to conduct the genetic test? is the next question. In the background, will there be a group of patients who are going to be ‘non-responders’ to the new OAP?