The need for a rapid-acting anticoagulant is real –
but is cangrelor the answer?
Not necessarily, according to Dr. Richard A. Lange and Dr. L. David Hills. At face value, the CHAMPION PHOENIX trial data look
good – certainly better than the past two CHAMPION studies, in which the drug
failed to achieve its primary endpoints. PHOENIX
investigators concluded that this study succeeded where its predecessors failed.
But PHOENIX
is riddled with methodological flaws that taint the findings, they wrote.
Unlike patients who took clopidogrel, those who took
the study drug did experience a maximal antiplatelet effect before and during percutaneous
coronary intervention (PCI). But 25% of the clopidogrel group received a 300 mg
loading dose – an amount inferior to the 600 mg dose the rest of the patients
received.
"Furthermore, 37% of the patients in the clopidogrel
group received the drug during or after PCI; as a result, the antiplatelet
effects of clopidogrel were suboptimal at the time of PCI. In the case of the
63% of the patients who received clopidogrel before PCI, information on the
time from the administration of clopidogrel to PCI is not provided, thereby making
it difficult to ascertain whether the antiplatelet effects of the drug were
maximal at the time of PCI," they wrote.
And, Dr. Lange and Dr. Hills noted, "in many centers, patients with
an acute coronary syndrome (which was the diagnosis at presentation in 44% of
the patients in this study) receive ticagrelor or prasugrel, since these drugs
are superior to clopidogrel at reducing PCI-related complications."
There are no studies comparing cangrelor to those drugs.
They also pointed out that a composite primary
endpoint of reduction in periprocedural myocardial infarction and stent
thrombosis drove the positive findings in CHAPMION PHOENIX. But the investigators
didn’t provide enough detail to really break the findings down.
"It is often difficult to distinguish a myocardial
infarction that occurs before randomization from one that occurs after
randomization, especially when the time from hospitalization to PCI is brief,"
Dr. Lange and Dr. Hills noted.
The PHOENIX
study findings didn’t describe how stent thromboses were identified, nor did the findings mention whether all
coronary angiograms were interpreted by a core lab.
"On the basis of these concerns, it would seem that
although some patients undergoing PCI may benefit from intravenous ADP-receptor
antagonist, such as cangrelor, the routine use of this therapy for all patients
undergoing PCI is not yet justified," they wrote.
Dr. Lange and Dr. Hills are from the University of Texas Health Sciences Center, San Antonio. They made these comments in an editorial accompanying the study (N. Engl. J. Med. 2013; DOI:10.1056/NEJMe1302504). They did not disclose having any conflicts of interest.
