In-Hospital Outcomes of Dual Loading Antiplatelet Therapy in Patients 75 Years and Older With Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention: Findings From the CCC-ACS (Improving Care for Cardiovascular Disease in China-Acute Coronary Syndrome) Project

Abstract

Background: Elderly patients with acute coronary syndrome (ACS) are at high risk for ischemic and bleeding events. This study aimed to evaluate the clinical effectiveness and safety of dual loading antiplatelet therapy for patients 75 years and older undergoing percutaneous coronary intervention for ACS.

Methods and results: The Improving Care for Cardiovascular Disease in China-ACS project was a collaborative study of the American Heart Association and Chinese Society of Cardiology. A total of 5887 patients 75 years and older with ACS who had percutaneous coronary intervention and received dual antiplatelet therapy with aspirin and P2Y12 inhibitors (clopidogrel or ticagrelor) between November 2014 and June 2017 were enrolled. The primary effectiveness and safety outcomes were in-hospital major adverse cardiovascular events and major bleeding. Hazard ratios (HRs) of in-hospital outcomes with different loading statuses of antiplatelet therapy were estimated using Cox proportional hazard models with multivariate adjustment. A propensity score-matched analysis was also conducted. Compared with patients receiving a dual nonloading dose, patients taking a dual loading dose had increased risks of both major adverse cardiovascular events (HR, 1.66, 95% confidence interval, 1.13-2.44; [P=0.010]) and major bleeding (HR, 2.34, 95% confidence interval, 1.75-3.13; [P<0.001]). Among 3284 propensity score-matched patients, a dual loading dose was associated with a 1.36-fold risk of major adverse cardiovascular events (HR, 1.36; 95% confidence interval, 0.88-2.11 [P=0.168]) and a 2.08-fold risk of major bleeding (HR, 2.08; 95% confidence interval, 1.47-2.93 [P<0.001]).

Conclusions: A dual loading dose of antiplatelet therapy was associated with increased major bleeding risk but not with decreased major adverse cardiovascular events risk among patients 75 years and older undergoing percutaneous coronary intervention for ACS in China.

Clinical trial registration: URL: http://www.ClinicalTrials.gov. Unique identifier: NCT02306616.

Keywords: acute coronary syndrome; antiplatelet therapy; elderly; loading dose; percutaneous coronary intervention.

© 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Figures

Figure 1

Flow diagram of selection of the study population. ACS indicates acute coronary syndrome; DAPT, dual antiplatelet therapy; PCI, percutaneous coronary intervention.

Figure 2

In‐hospital outcomes within 15 days after hospitalization. The incidence of in‐hospital primary effectiveness outcomes (major adverse cardiovascular event [MACE]) was higher in the dual loading group compared with other groups, mainly resulting from a higher proportion of cardiac death, in both the whole study population (A) and the propensity score–matched population (B). The incidence of both major bleeding and all bleeding was much higher in the dual loading group, compared with the nonloading group in both the whole study population (C) and the propensity score–matched population (D). The proportion of component outcomes is also shown by dosage categories. MI indicates myocardial infarction.

Figure 3

Cumulative Kaplan–Meier curve estimates of effectiveness outcomes during the 15‐day in‐hospital period. A and B, Data for the primary effectiveness outcomes of a major adverse cardiovascular event (MACE) in the whole study population and the propensity score–matched population, respectively. C and D, Data for the secondary effectiveness outcomes of all‐cause death in the whole study population and the propensity score–matched population, respectively.

Figure 4

Cumulative Kaplan–Meier curve estimates of safety outcomes during the 15‐day in‐hospital period. A and B, Data for the primary safety outcomes of major bleeding in the whole study population and the propensity score–matched population, respectively. C and D, Data for the secondary safety outcomes of all‐cause death in the whole study population and the propensity score–matched population, respectively.