Ticagrelor Therapy in Patient with Advanced Conduction Disease: Is it Really Safe?

Background: Dual antiplatelet therapy (DAPT) is a cornerstone of treatment in acute coronary syndrome (ACS). Ticagrelor as a part of DAPT is widely used in this setting. In the landmark PLATO trial ticagrelor was linked to increased incidence of mainly asymptomatic ventricular pauses. We report two cases of life-threatening complete atrioventricular block (CAVB) complicating ticagrelor therapy.
Case 1: A 52-year-old patient on chronic bisoprolol treatment and pre-existing CLBBB was admitted with ACS. He was initially treated with clopidogrel, but after revascularization, on the second hospitalization day, he was switched to ticagrelor. Four hours after receiving the recommended loading dose of ticagrelor, he developed severe symptomatic bradycardia with CAVB. The patient was unresponsive to medical therapy and required temporary invasive temporary pacing. The CAVB resolved completely after discontinuation of ticagrelor.
Case 2: A 71-year-old patient was hospitalized with myocardial infarction and CLBBB. The DAPT with ticagrelor was started, the primary stenting of LAD was performed. Two days later, the treatment with 1.25 mg of bisoprolol was initiated. 3 hours later, the patient experienced syncope with CAVB and extreme bradycardia. After short CPR, the invasive temporary pacing was started. The therapy with ticagrelor and bisoprolol was stopped and clopidogrel reinstituted. In two days, the patient returned to stable sinus rhythm and pacemaker was removed. There were no recurrences during follow up.
Conclusions: Ticagrelor therapy in patients with pre-existing significant conduction disease and concomitant beta-blocker therapy may be associated with severe bradyarrhythmic complications. This may be due to increase in plasma adenosine concentration. We recommend caution in prescribing ticagrelor in patients with significant impairment of atrioventricular conduction.