Proximal culprit lesion and coronary artery occlusion independently predict the risk of microvascular obstruction in acute myocardial infarction.

Microvascular obstruction (MO) and coronary flow have been independently described to have a high prognostic impact after acute myocardial infarction (AMI). Their interdependence has not been precisely elucidated, so far. Aim of this study was to investigate the impact of coronary flow on the occurrence of MO in patients with AMI. 336 patients with revascularized AMI were examined by cardiac magnetic resonance imaging. Patients were categorised into two groups based on the presence of MO. Procedural characteristics and marker of infarct size were analyzed. MO was present in 110 (33 %) and absent in 226 (67 %) patients. Both groups differed significantly regarding pre- and post-interventional thrombolysis in myocardial infarction (TIMI) flow. After multivariable regression analysis pre-interventional TIMI-flow 0, proximal culprit lesion, post-interventional TIMI-flow <III and creatine-kinase-myocardial band (CK-MB) remained strong independent predictors for MO. Odds ratios for pre-interventional TIMI-flow 0 were 2.31 (95 % CI 1.04-5.11, P = 0.034); for proximal culprit lesion 11.94 (95 % CI 5.70-25.01, P < 0.001); for post-interventional TIMI-flow III 0.28 (95 % CI 0.10-0.74, P = 0.010) and for CK-MB 1.50 (95 % CI 1.24-1.82, P < 0.001). Pre-interventional proximal coronary artery occlusion (TIMI 0) and insufficient post-interventional coronary reperfusion (TIMI-flow  <III) have a high impact on the occurrence of MO in AMI.