Imaging substudy links cangrelor to less microvascular obstruction in AMI shock

The prespecified multimodality imaging substudy of the randomized DAPT-SHOCK-AMI trial assessed intravenous cangrelor versus crushed oral ticagrelor in patients with acute myocardial infarction complicated by cardiogenic shock. Serial echocardiography was available for 175 patients in the acute phase, 120 at one month and 99 at one year; cardiac magnetic resonance (CMR) was available for 73, 68 and 63 patients, respectively. The primary imaging endpoint, acute CMR-detected microvascular obstruction (MVO), was evaluable in 60 patients. Blinded core laboratories analyzed the scans; the substudy was not separately powered.

Adjusted odds of acute MVO were lower with cangrelor (odds ratio 0.27, 95% CI 0.08–0.98; P=0.023), while infarct size did not differ. At one year, remote-myocardial native T1 was lower with cangrelor. Left ventricular ejection fraction increased more from the acute assessment with cangrelor on echocardiography (37.9% versus 21.7%) and CMR (15.8% versus 2.1%). Other measures, including global longitudinal strain, E/e′ and left atrial volume, also showed greater improvement; no parameter differed between groups at one month.

These imaging findings suggest possible differences in microvascular and non-infarcted myocardial injury, but do not establish a treatment mechanism or justify changing practice. The small evaluable imaging samples, multiple secondary measures and lack of separate power limit interpretation; the authors characterize the results as hypothesis-generating.