Ticagrelor-aspirin DAPT reduces risk for different types of MI
Ticagrelor added to low-dose aspirin reduced the risk for spontaneous MI, MI related to stent thrombosis and STEMI compared with placebo in patients with diabetes and CAD, according to a new analysis of the THEMIS trial.
Jérémie Abtan, MD, PhD, interventional cardiologist at Assistance Publique – Hôpitaux de Paris, France, and colleagues reported results of an analysis of the incidence of MI types in patients treated with ticagrelor (Brilinta, AstraZeneca) in the THEMIS trial. Their findings were published in a research letter in Circulation: Cardiovascular Interventions.
In the main THEMIS trial, as Healio previously reported, ticagrelor added to low-dose aspirin reduced the incidence of ischemic events in patients with stable CAD and diabetes without a history of MI or stroke, but increased major bleeding compared with aspirin alone. Results of the THEMIS trial were presented at the 2019 European Society of Cardiology Congress and simultaneously published in The New England Journal of Medicine.
For the new analysis Abtan and colleagues sought to determine which of the types of MI, according to the fourth universal definition of MI, were main drivers of the reduction in ischemic events observed with ticagrelor use.
Overall, 19,220 patients were randomly assigned to twice-daily ticagrelor 90 mg or matching placebo, in addition to aspirin 75 mg to 150 mg. MI occurred in 602 patients (3.1% overall; 3.3% of placebo group vs. 2.6% of ticagrelor group at 36 months; HR = 0.84; 95% CI, 0.71-0.98; P = .03), according to the analysis.
Type 1 MI was the most common, in 509 patients (84.6% of patients with adjudicated MIs), the researchers wrote. Ticagrelor-aspirin DAPT reduced risk for type 1 MI compared with aspirin alone (2.2% vs. 2.8%; HR = 0.84; 95% CI, 0.71-1; P = .05). The reduction in risk was similar regardless of whether a patient had prior PCI, according to the results.
Type 2 MI was reported in 63 patients (10.5% of total MI). Risk for type 2 MI was similar in those assigned ticagrelor-aspirin or aspirin alone (0.3% vs. 0.3%; HR = 1.34; 95% CI, 0.81-2.21; P = .25), the researchers reported.
The third most common was type 4b MI, in 22 patients (3.7% of all MIs). The incidence of type 4b MI was lower in the ticagrelor group compared with the aspirin alone group (0.1% vs. 0.2%; HR = 0.38; 95% CI, 0.15-0.96; P = .04), according to the results.
Type 3 MI occurred in 13 patients (2.2% of total MI).
Type 4a MI occurred in 11 patients (1.8% of total MI).
No incidences of type 5 MI were reported.
In addition, ticagrelor use reduced risk for STEMI compared with placebo (HR = 0.31; 95% CI, 0.19-0.49; P < .0001), regardless of whether patients had prior PCI, according to the results.
“In the THEMIS trial, the vast majority of MIs were adjudicated as spontaneous MI (type 1). Compared with placebo, ticagrelor significantly reduced the risk of spontaneous MI (type 1), MI related to stent thrombosis (type 4b), and the risk of ST segment elevation MI,” Abtan and colleagues wrote. “No apparent heterogeneity for the treatment effect across MI subtypes was identified between the subgroups of those with and without a history of PCI.”