P4786Dual antithrombotic therapy is similarly effective to triple therapy in preventing thrombotic events in patients with atrial fibrillation and acute coronary syndrome
Authors: Motovska Z , Melicharova H , Knot J , Dusek J , Simek S S , Varvarovsky I , Hlinomaz O , Blaha M , Klika P , Jarkovsky J 
Published: October 2019

Abstract

Background
Antithrombotic therapy is effective in preventing ischemic and thromboembolic events, however it simultaneously increases the risk of bleeding. The efforts thus focus on balancing the intensity of combined antiplatelet and anticoagulant therapy.

Purpose
The study aimed to compare efficacy and safety of single (aspirin/clopidogrel) or dual (aspirin plus clopidogrel) antiplatelet therapy in combination with an oral anticoagulant in non-selected patient population with atrial fibrillation (AFib) and an acute coronary syndrome (ACS).

Methods
The analysis used data from National Registry of Reimbursed Health Services (NRRHS), which contains data of the entirety of health care paid from the public health insurance (almost 100% of healthcare in the Czech Republic) combined with the database of death records. Occurrence of an ACS, stroke, and bleeding requiring hospitalization within one year was compared in patients discharged on dual and triple antithrombotic therapy. Dual antithrombotic therapy consists of aspirin/clopidogrel plus an oral anticoagulant. Triple antithrombotic therapy was defined as combination of aspirin, clopidogrel and an oral anticoagulant.

Results
Over a four-year period (2012–2016) 104 000 patients with an ACS were hospitalized in the Czech Republic. AFib (any types) was reported in 12.4% (N=12 891) of them (21.2% in patients 75+ years old). +AFib (vs. −AFib) patients were a higher risk population with respect to the comorbidity (diabetes, hypertension, renal disease, stroke, heart failure) (p<0.05 for all comorbidities). Oral anticoagulant therapy was indicated in 25.3% of them. PCI was performed in 57.7% (−AFib) and 43.4% (+AFib) patients, respectively. Hospital mortality was significantly higher in +AFib patients (8.6% and 5.6%, OR (95% CI): 1.585 (1.481; 1.696), p<0.001).
We identified 1017 patients discharged on dual and 967 patients on triple antithrombotic therapy. Risk of recurrent ACS within one year with dual therapy was comparable to that with triple therapy (OR (95% CI): 1.219 (0.766; 1.940), p=0.403). The same was also observed for the risk of stroke (1.273 (0.648; 2.501), p=0.483).
After six months, persistence on dual antithrombotic therapy (33.4% patients) was higher than on triple therapy (10.3%, p<0.001). Within the first three months, de-escalation from triple antithrombotic therapy to dual antithrombotic therapy (in 212 patients) was accompanied by a significant increase of bleeding requiring hospitalization (0% on dual vs. 3.3% on triple therapy, p=0.048).

Conclusion
Protective effect of dual antithrombotic therapy on the occurence of recurrent major adverse cardiovascular event is comparable to that of the triple antithrombotic therapy in non-selected patients with an acute coronary syndrome and atrial fibrillation. Moreover, long-term persistence on triple therapy is significantly lower due to bleeding risk.