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GPI use appears to reduce mortality, increase bleeding in patients with ACS undergoing PCI
In a registry population of patients with ACS undergoing PCI, treatment with glycoprotein IIb/IIIa inhibitors was associated with reduced mortality but increased bleeding.
Researchers analyzed 970,865 patients from the National Cardiovascular Data Registry CathPCI Registry who underwent PCI for ACS between July 2009 and September 2011. They assessed the impact of glycoprotein IIb/IIIa inhibitor (GPI) use on the primary outcome of all-cause in-hospital mortality and the secondary outcome of major bleeding.
In the study population, 33.6% of patients received a GPI. Results from unadjusted analysis indicated that those receiving a GPI had higher rates of mortality (2.4% vs. 1.4%; P < .001) and major bleeding (3.7% vs. 1.5%; P < .001).
Adjustments show mortality benefit
To account for potential bias, the researchers also conducted adjusted analyses, including multivariable logistic regression, propensity matching and instrumental variable analysis. In these analyses, GPI use was linked to lower mortality risk. RRs for the various analyses were as follows:
- multivariable analysis: RR = 0.83; 95% CI, 0.79-0.88;
- propensity matched analysis: RR = 0.9; 95% CI, 0.86-0.95; and
- instrumental variable analysis: RR = 0.72; 95% CI, 0.5-0.97.
The elevated risk for major bleeding persisted (multivariable: RR = 1.93; 95% CI, 1.83-2.04; propensity matched: RR = 1.83; 95% CI, 1.74-1.92; instrumental variable: RR = 1.53; 95% CI, 1.27-2.13) in all adjusted analyses, according to the researchers.
Results from subgroup analyses indicated that the mortality benefit associated with GPI use was present in those with STEMI but not among those with non-STEMI or unstable angina (P < .0001), in those not given bivalirudin (Angiomax, The Medicines Company) but not those given bivalirudin (P < .0001), and in those with high mortality risk but not those with low or moderate mortality risk (P = .005). The increased bleeding risk was consistent across all subgroups.
“These findings suggest that in the modern era of angioplasty, there may still be a role for the judicious use of GPI in high-risk patients, particularly if heparin, instead of bivalirudin, is used for anticoagulation, as it was in over one-half of patients included in this study,” researcher David M. Safley, MD, associate professor of medicine at the University of Missouri–Kansas City, said in a press release.
Randomized trials hold sway
In a related editorial, A. Michael Lincoff, MD, wrote that although observational evidence is not as strong as that from randomized clinical trials, the study results “would seem to suggest a remarkable benefit of GPI in patients undergoing PCI for ACS, with 10% to 28% reductions in mortality that would far outweigh in importance the 50% to 90% increases in major bleeding.”
A. Michael Lincoff
Although the results regarding concurrent use of GPI and bivalirudin are consistent with those of randomized controlled trials, the finding that GPI use had a more pronounced benefit on mortality in those with STEMI “lacks biological plausibility and raises concerns regarding unadjusted confounding of these observational data,” Lincoff, from the department of cardiovascular medicine at Cleveland Clinic, wrote.
He concluded that “selection of pharmacotherapy must continue to be guided by the findings of the randomized trials.” – by Erik Swain
Disclosures: The analysis was supported by an investigator-initiated research grant from Merck. One researcher reports financial ties with Abbott Vascular, AstraZeneca, Boston Scientific, Eli Lilly, Medtronic and Merck. Lincoff reports receiving research funding from AstraZeneca, CSL, Eli Lilly, Pfizer and Takeda and consulting for Amgen.