Ticagrelor is a direct and rapid-acting antagonist of the P2Y12-adenosine
diphosphate receptor found on platelets. The drug is recommended as a first-line
antiplatelet agent in patients with
acute coronary syndromes, as evidenced in its superiority compared to
clopidogrel according to the Platelet Inhibition and Patient Outcomes study. Specifically, the mechanism of action has been proven to show higher inhibition and less variability in its action on P2Y12 receptors compared to
clopidogrel. Additionally,
ticagrelor inhibits the
equilibrative nucleoside transporter 1 adenosine transporter protein leading to an increased concentration of
adenosine in the blood, particularly at sites of
ischemia. This effect increases the biological efficacy of
ticagrelor in terms of cardioprotection, anticoagulation effects, and anti-inflammatory effects. However, the effects are also thought to be responsible for some of the adverse pharmacological effects reported with
ticagrelor, such as
bradycardia and ventricular pauses > 3 seconds. Herein, we report a case of recurrent sinus arrest and ventricular
asystole in a patient pre-treated with
ticagrelor and subsequent physiological assessment of a coronary lesion with fractional flow reserve using intravenous
adenosine infusion.