Scirica BM, et al. - In acute coronary syndrome (ACS), patients receiving either ticagrelor or clopidogrel were compared for rates of clinically relevant arrhythmias in relation to any mild baseline conduction abnormality. Even in ACS patients who presented with mild conduction abnormalities on their baseline electrocardiographic (ECG), no increased arrhythmic events were reported as a result of treatment with ticagrelor vs clopidogrel.

Methods

• Researchers examined all subjects in the electrocardiographic (ECG) substudy of Platelet Inhibition and Patient Outcomes (PLATO) trial, other than those with missing baseline ECG or with a pacemaker at baseline (N = 15,460).
• Conduction abnormality was defined as sinus bradycardia, first-degree AV block, hemiblock, or bundle branch block.
• The composite of any symptomatic brady- or tachyarrhythmia, permanent pacemaker placement or cardiac arrest through 12 months was the primary arrhythmic outcome.

Results

• Data showed that patients with baseline conduction abnormalities (N = 4256, 27.5%) were older and more likely to experience the primary arrhythmic outcome.
• The composite arrhythmic endpoint did not differ by ticagrelor vs clopidogrel in those with baseline conduction disease (1-year cumulative incidence rate: 17% for both study arms; hazard ratio [HR]: 0.99 (0.86–1.15]) or without baseline conduction disease (1-year cumulative incidence rate: clopidogrel 12.8% vs. ticagrelor 12.4%; HR: 0.98 [0.88–1.09]).
• Ticagrelor and clopidogrel did not show statistically significant differences in the rates of bradycardic or any individual arrhythmic events in patients with baseline conduction abnormalities.