Conference Coverage

Genotyping for thrombosis control in PCI equal to standard therapy


 

AT THE ESC CONGRESS 2019

Genotype-guided selection of oral P2Y 12 inhibitors for patients having percutaneous coronary intervention with stent implantation derives no clinical benefits overall when compared to standard treatment, according to results of the large, randomized POPular Genetics trial, although genotype guidance did result in lower rates of primary minor bleeding.

The study was presented at the annual congress of the European Society of Cardiology Study in Paris and published simultaneously in the New England Journal of Medicine.

CDC/Janice Carr

This scanning electron micrograph (SEM) depicted a closer view of a number of red blood cells found enmeshed in a fibrinous matrix on the luminal surface of an indwelling vascular catheter; Magnified 7766x.

POPular Genetics (CYP2C19 Genotype-Guided Antiplatelet Therapy in ST-Segment Elevation Myocardial Infarction Patients – Patient Outcome After Primary PCI) randomized 2,488 patients who had PCI to either P2Y12 inhibitor on the basis of early genetic testing for the CYP2C19 gene (1,242 patients) or standard treatment with either ticagrelor or prasugrel (1,246 patients) for 12 months. In the genotype-guided group, patients were assigned to one of two arms depending on results; carriers of CYP2C19*2 or CYP2C19*3 loss-of-function alleles received ticagrelor or prasugrel, and non-carriers receive clopidogrel. The study was conducted from Jun. 2011 to Apr. 2018.

Net adverse clinical events, which included any-cause death, myocardial infarction, stent thrombosis, stroke or major bleeding based on the Platelet Inhibition and Patient Outcomes (PLATO) criteria at 12 months were similar between both groups: 5.1% in the genotype-guided patients and 5.9% in the standard-treatment group (P less than .001), but rates of PLATO major or minor bleeding were 9.8% and 12.5%, respectively (P = .04).

When secondary outcomes were evaluated, no significant differences emerged between the two groups. Secondary outcomes included combined thrombotic outcomes (death from vascular causes, myocardial infarction, stent thrombosis or stroke; 2.7% for the genotype-guided group vs. 3.3% in the standard-treatment group), and PLATO major bleeding (2.3% in both groups). The difference in the primary bleeding outcomes between the groups was driven by a lower incidence of PLATO minor bleeding in the genotype-guided group, 7.6% vs. 10.5%.

The two takeaways from POPular Genetics, said Daniel M.F. Claassens, MD, and coauthors, are that giving clopidogrel to patients without a CYP2C19 loss-of-function allele did not elevate their risk of combined any-cause death and other adverse cardiac outcomes, including major bleeding, 12 months after PCI; and that giving clopidogrel to the genotype-guided group lowered the risk of minor bleeding.

Dr. Claassens and coauthors noted that since the Netherlands trial was designed in 2011, the development of newer-generation stents has considerably lowered rates of thrombotic events after acute coronary syndromes. “With the lower-than-anticipated incidence of the primary combined outcome in our trial, the prespecified noninferiority margin was wider relative to the incidence than originally expected,” they said. While the primary combined outcome was 21% higher than the incidence in the standard-treatment group at the upper end of the 95% confidence interval, the incidence was 11% higher in the standard-treatment group at the observed upper end of the 95% CI. This “gives stronger support to the conclusion that genotype-guided P2Y12 treatment is noninferior to standard treatment for the occurrence of thrombotic events,” Dr. Claassens and coauthors said.

The study report noted a number of limitations, including that more polymorphisms of the CyP2C19 gene may be linked to increased thrombotic or bleeding risk. “Therefore, our strategy based solely on the CYP2C19 genotype may not be the most useful strategy for some patients,” Dr. Claassens and coauthors said.

POPular Genetics received funding from the Netherlands Organization for Health Research and Development (ZonMw). Dr. Claassens receives grants from ZonMw and non-financial support from Spartan Biosciences.

SOURCE: Claassens DMF, et al. N Engl J. Med. Published online September 3, doi.org/10.1016/S0140-6736(19)31996-8.

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