Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Original Research Cardiology 2009;113:50–58 DOI: 10.1159/000167042 Presence and Extent of Cardiac Magnetic Resonance Microvascular Obstruction in Reperfused Non-ST-Elevated Myocardial Infarction and Correlation with Infarct Size and Myocardial Enzyme Release N. Mewton E. Bonnefoy D. Revel M. Ovize G. Kirkorian P. Croisille Hôpital Cardiovasculaire Louis Pradel, Université de Lyon, Hospices Civils de Lyon, Lyon, France observed in patients with STEMI and also correlates with the infarct extent. The prognostic significance on clinical out- come remains to be shown in this specific population. Copyright © 2008 S. Karger AG, Basel Introduction In the course of acute ST-elevated myocardial infarc- tion (STEMI) treated by early reperfusion therapy, mi- crovascular obstruction (MO), also known as the ‘no-re- flow’ phenomenon, has been reported in more than 30% of patients [1–4]. Myocardial MO is associated with ad- vanced myocardial damage followed by adverse left ven- tricular (LV) remodeling and a lack of recovery of region- al wall function [5]. Recent studies, where MO was de- fined either with cardiac magnetic resonance imaging (CMR), myocardial contrast echography or coronary an- giography, reported MO as a strong predictor of poor prognosis in STEMI patients [1–4, 6, 7]. The prevalence and prognosis value of MO in the course of non-ST-elevated myocardial infarctions (NSTEMIs), which represent one third of all acute coro- nary syndromes, remains unknown [8] . Underlying ath- erothrombotic processes resulting in NSTEMIs are simi- lar to those observed in STEMIs, but mostly result in an Key Words Acute coronary syndromes  Acute myocardial infarction  Cardiac magnetic resonance  Microvascular obstruction Abstract Objective: Microvascular obstruction (MO) is a factor of ad- verse outcome in patients with ST-elevated myocardial in- farction (STEMI). We assessed the presence and extent of MO and its relationship with infarct size and left ventricular (LV) functional parameters after acute non-ST-elevated myocar- dial infarction (NSTEMI). Methods: Twenty-five patients with first acute NSTEMI underwent a cine and first-pass perfusion cardiac magnetic resonance (CMR) study, with late gadolini- um enhancement imaging 72 h after myocardial infarction. Results: MO was detected in 32% of patients, and its extent comprised 0.5–3.1% of the total LV mass (mean 1.9 8 1.2%). Patients with MO had a significantly larger infarct size than patients without (14.1 8 5.9 vs. 5.3 8 4.1% LV mass; p ! 0.001). There was no significant difference between both groups for the LV functional parameters and LV ejection frac- tion (58.5 8 6.8 vs. 62.6 8 9.6%; p = 0.29). Patients with MO showed a higher troponin I release (570 8 364 vs. 148 8 103 IU; p = 0.003) and a higher creatine kinase release (29,887 8 18,263 vs. 10,287 8 5,283 IU; p = 0.007). Conclusions: In pa- tients with acute NSTEMI, MO has a frequency similar to that Received: March 25, 2008 Accepted after revision: July 7, 2008 Published online: November 4, 2008 Dr. Nathan Mewton 28, avenue Doyen Lépine FR–69677 Lyon (France) Tel. +33 47 235 7541, Fax +33 47 235 7341 E-Mail nathan.mewton@chu-lyon.fr © 2008 S. Karger AG, Basel 0008–6312/09/1131–0050$26.00/0 Accessible online at: www.karger.com/crd