Study Finds Ticagrelor Not Superior to Clopidogrel in ACS Patients Undergoing PCI

Results of a new study from a team of Swedish investigators are disputing the notion ticagrelor is superior to clopidogrel in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI).

Using data from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR), investigators performed an analysis and found ticagrelor was not superior to clopidogrel—conflicting current guidelines.

“In this observational study, treatment with ticagrelor was not superior to clopidogrel in patients with ACS treated with PCI and was associated with an increased risk of bleeding. Benefits of ticagrelor, as demonstrated in the PLATO trial, may not be externally valid when applied to unselected patients with ACS undergoing PCI,” wrote study investigators.

As it stands, major guidelines in both the US and Europe recommend the use of ticagrelor over clopidogrel in patients with ACS. However, most of these are based on the PLATO study whose results have been called into question in recent years based on the results of other observational studies in patients with ACS. To create a more definitive conclusion on the generalizability of PLATO results, investigators conducted a study to investigate whether ticagrelor was superior to clopidogrel in an unselected population of patients with ACS who underwent PCI.

Led by Sebastian Völz, MD, PhD, of the Department of Cardiology at Sahlgrenska University Hospital in Gothenburg, Sweden, investigators designed their study to use data from SCAAR for PCI performed in Västra Götaland County, Sweden between 2005-2015. Investigators noted this county contains 5 hospitals and represents about 20% of all data in SCAAR.

In total, investigators identified 15,097 patients for inclusion in their study. Of these, 12,168 (80.6%) were treated with clopidogrel and 2929 (19.4%) were treated with ticagrelor. Investigators highlighted there were no differences between the groups in regard to age, sex, creatine clearance, BMI, diabetes mellitus, smoking status, treated vessel, culprit vessels occlusion, and the use of thrombus aspiration during PCI.

The primary outcome of interest for the study was a combined end point of mortality or stent thrombosis at 30 days. Secondary end points included at 30 days and 1‐year, stent thrombosis at 30 days, in‐hospital bleeding, in‐hospital neurologic complications, and long‐term mortality. Investigators pointed out instrumental variable 2-stage least squares regression was used to adjust for confounders in their analyses.

In total, 555 events occurred at 30 days, including 53 stent thromboses. Results of the analysis indicated ticagrelor was not associated with a lower risk for the combined end point of mortality or stent thrombosis at 30 days (aOR, 1.20; 95% CI, 0.87-1.61; P=.250). When examining secondary end points, investigators found no difference in the estimated risk of death at 30 days (aOR, 1.18; 95% CI, 0.88-1.64; P=.287) and 1-year (aOR, 1.28; 95% CI, 0.86-1.93; P=.222) between the ticagrelor and clopidogrel arms of the study.

Additionally, there was no difference between the groups in regard to stent thrombosis at 30 days (aOR, 1.30; 95% CI, 0.54–3.10; P=0.556), neurologic complications during hospitalization (aOR, 0.95; 95% CI, 0.44-2.02; P=.891), or long-term mortality (aHR, 1.07; 95% CI, 0.89-1.29; P=.437). Conversely, results suggested ticagrelor was found to be associated with an increased risk of bleeding (aOR, 2.88; 95% CI, 1.53-5.44; P=.001).

Investigators pointed out data related to in-hospital bleeding and in-hospital neurologic complications were missing in 1757 patients.

Investigators noted multiple limitations for clinicians to take into account when interpreting the results of this study. Limitations highlighted by investigators included needing to take into account Swedish practice and outcomes do not necessarily reflect care in other areas of the world, the observational design creates risk for potential confounding, and the events in the study were not adjudicated by an adjudication committee, among others.

This study, “Ticagrelor is Not Superior to Clopidogrel in Patients With Acute Coronary Syndromes Undergoing PCI: A Report from Swedish Coronary Angiography and Angioplasty Registry,” was published in the Journal of the American Heart Association.