Detection of microvascular injury by evaluating epicardial blood flow in early reperfusion following primary angioplasty

BACKGROUND: In a significant proportion of patients with acute myocardial infarction (AMI), successful opening of the infarct related artery (IRA) does not translate into adequate perfusion at the tissue level. We hypothesised that deterioration of epicardial blood flow in early reperfusion may identify early signs of coronary microvascular injury. METHODS: In 272 consecutive patients (age 56.9+/-10.4 years) with AMI treated by primary angioplasty (PCI), coronary blood flow (Trombolysis in Myocardial Infarction (TIMI) scale and corrected TIMI frame count (cTFC)) was evaluated before B], immediately after O] and 15 min after O15] opening of the IRA. The sum of ST-segment elevation in standard ECG leads (sigmaST) was measured at B], at O15] and 24 h after C24]. Microvascular injury was assessed by indexes STi(O15)=sigmaST(O15)/sigmaST(B), STi(C24)=sigmaST(C24)/sigmaST(B), and by peak CK-MB release. Coronary flow deterioration (cTFC(DET)) was defined as the difference between cTFC(O15) and cTFC(O). RESULTS: TIMI-3 flow was achieved in 236 (90.8%) patients at O]. In the early phase of reperfusion (between O] and O15]), TIMI flow deteriorated by >/=1 point in 19 (7.3%) patients despite angiographic optimisation of the PCI result. At O15] 224 (86.2%) patients had TIMI-3 flow (reflow), 36 (13.8%) patients had TIMI