Pre-PCI angiographic TIMI flow in the culprit coronary artery influences infarct size and microvascular obstruction in STEMI patients.

Objective: The influence of initial-thrombolysis in myocardial infarction (i-TIMI) coronary flow in the culprit coronary artery on myocardial infarct and microvascular obstruction (MVO) size is unclear. We assessed the impact on infarct size of i-TIMI flow in the culprit coronary artery, as well as on MVO incidence and size, by contrast-enhanced cardiac magnetic resonance (ce-CMR).

Methods: In a prospective, multicenter study, pre-percutaneous coronary intervention (PCI) coronary occlusion was defined by an i-TIMI flow ≤1, and patency was defined by an i-TIMI flow ≥2. Infarct size, as well as MVO presence and size, were measured on ce-CMR 72h after admission.

Results: A total of 140 patients presenting with ST-elevated myocardial infarction referred for primary PCI were included. There was no significant difference in final post-PCI TIMI flow between the groups (2.95±0.02 vs. 2.97±0.02, respectively; p=0.44). In the i-TIMI flow ≤1 group, infarct size was significantly larger (32±17g vs. 21±17g, respectively; p=0.002), MVO was significantly more frequent (74% vs. 53%, respectively; p=0.012), and MVO size was significantly larger [1.3 IQR (0; 7.1) vs. 0 IQR (0; 1.6)], compared to in the i-TIMI ≥2 patient group.

Conclusion: Initial angiographic TIMI flow in the culprit coronary artery prior to any PCI predicted final infarct size and MVO size: the better was the i-TIMI flow, the smaller were the infarct and MVO size.