Ticagrelor-Associated Conduction Disorder: A Case Report and Review of the Literature

A rare case of late-onset ticagrelor-induced sinus arrest

Ticagrelor is a potent reversible P2Y12 inhibitor with proven superiority over clopidogrel. Ticagrelor increases the tissue concentration of adenosine, thereby leading to bradyarrhythmia. This complication is reported to occur very early after initiating the drug. A randomized controlled trial reported that ticagrelor-induced pauses have an early onset without much clinical impact. However, our patient developed ticagrelor-induced hemodynamically significant sinus arrest 10 months after coronary artery stenting, which improved after stopping the drug. Ticagrelor should be considered as one of the uncommon reasons for late-onset sinus pause or bradyarrhythmia.

Ticagrelor-associated ventricular pauses: a case report and literature review

Background

Case summary

Discussion

Effects of ticagrelor on the sodium/calcium exchanger 1 (NCX1) in cardiac derived H9c2 cells

Ticagrelor is a direct acting and reversibly binding P2Y₁₂ antagonist approved for the prevention of thromboembolic events. Clinical effects of ticagrelor cannot be simply accounted for by pure platelet inhibition, and off-target mechanisms can potentially play a role. In particular, recent evidence suggests that ticagrelor may also influence heart function and improve the evolution of myocardial ischemic injury by more direct effects on myocytes. The cardiac sodium/calcium exchanger 1 (NCX1) is a critical player in the generation and control of calcium (Ca²⁺) signals, which orchestrate multiple myocyte activities in health and disease. Altered expression and/or activity of NCX1 can have profound consequences for the function and fate of myocytes. Whether ticagrelor affects cardiac NCX1 has not been investigated yet. To explore this hypothesis, we analyzed the expression, localization and activity of NCX1 in the heart derived H9c2-NCX1 cells following ticagrelor exposure. We found that ticagrelor concentration- and time-dependently reduced the activity of the cardiac NCX1 in H9c2 cells. In particular, the inhibitory effect of ticagrelor on the Ca²⁺-influx mode of NCX1 was evident within 1 h and further developed after 24 h, when NCX1 activity was suppressed by about 55% in cells treated with 1 μM ticagrelor. Ticagrelor-induced inhibition of exchanger activity was reached at clinically relevant concentrations, without affecting the expression levels and subcellular distribution of NCX1. Collectively, these findings suggest that cardiac NCX1 is a new downstream target of ticagrelor, which may contribute to the therapeutic profile of ticagrelor in clinical practice.