Ticagrelor in Post-STEMI Adverse Ventricular Remodeling: There Is More Than Meets the Platelet

A Comprehensive Review of the Pleiotropic Effects of Ticagrelor

AIMS

This review summarizes the findings of preclinical studies evaluating the pleiotropic effects of ticagrelor. These include attenuation of ischemia-reperfusion injury (IRI), inflammation, adverse cardiac remodeling, and atherosclerosis. In doing so, it aims to provide novel insights into ticagrelor's mechanisms and benefits over other P2Y12 inhibitors. It also generates viable hypotheses for the results of seminal clinical trials assessing ticagrelor use in acute and chronic coronary syndromes.

METHODS AND RESULTS

A comprehensive review of the preclinical literature demonstrates that ticagrelor protects against IRI in the setting of both an acute myocardial infarction (MI), and when MI occurs while on chronic treatment. Maintenance therapy with ticagrelor also likely mitigates adverse inflammation, cardiac remodeling, and atherosclerosis, while improving stem cell recruitment. These effects are probably mediated by ticagrelor's ability to increase local interstitial adenosine levels which activate downstream cardio-protective molecules. Attenuation and augmentation of these pleiotropic effects by high-dose aspirin and caffeine, and statins respectively may help explain variable outcomes in PLATO and subsequent randomized controlled trials (RCTs).

CONCLUSION

Most RCTs and meta-analyses have not evaluated the pleiotropic effects of ticagrelor. We need further studies comparing cardiovascular outcomes in patients treated with ticagrelor versus other P2Y12 inhibitors that are mindful of the unique pleiotropic advantages afforded by ticagrelor, as well as possible interactions with other therapies (e.g., aspirin, statins, caffeine).

Translation of experimental cardioprotective capability of P2Y12 inhibitors into clinical outcome in patients with ST-elevation myocardial infarction

We studied the translational cardioprotective potential of P2Y₁₂ inhibitors against acute myocardial ischemia/reperfusion injury (IRI) in an animal model of acute myocardial infarction and in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). P2Y₁₂ inhibitors may have pleiotropic effects to induce cardioprotection against acute myocardial IRI beyond their inhibitory effects on platelet aggregation. We compared the cardioprotective effects of clopidogrel, prasugrel, and ticagrelor on infarct size in an in vivo rat model of acute myocardial IRI, and investigated the effects of the P2Y₁₂ inhibitors on enzymatic infarct size (48-h area-under-the-curve (AUC) troponin T release) and clinical outcomes in a retrospective study of STEMI patients from the CONDI-2/ERIC-PPCI trial using propensity score analyses. Loading with ticagrelor in rats reduced infarct size after acute myocardial IRI compared to controls (37 ± 11% vs 52 ± 8%, p < 0.01), whereas clopidogrel and prasugrel did not (50 ± 11%, p > 0.99 and 49 ± 9%, p > 0.99, respectively). Correspondingly, troponin release was reduced in STEMI patients treated with ticagrelor compared to clopidogrel (adjusted 48-h AUC ratio: 0.67, 95% CI 0.47-0.94). Compared to clopidogrel, the composite endpoint of cardiac death or hospitalization for heart failure within 12 months was reduced in STEMI patients loaded with ticagrelor (HR 0.63; 95% CI 0.42-0.94) but not prasugrel (HR 0.84, 95% CI 0.43-1.63), prior to PPCI. Major adverse cardiovascular events did not differ between clopidogrel, ticagrelor, or prasugrel. The cardioprotective effects of ticagrelor in reducing infarct size may contribute to the clinical benefit observed in STEMI patients undergoing PPCI.