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

Abstract

Objective: Microvascular obstruction (MO) is a factor of adverse outcome in patients with ST-elevated myocardial infarction (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 myocardial infarction (NSTEMI). Methods: Twenty-five patients with first acute NSTEMI underwent a cine and first-pass perfusion cardiac magnetic resonance (CMR) study, with late gadolinium 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 ± 1.2%). Patients with MO had a significantly larger infarct size than patients without (14.1 ± 5.9 vs. 5.3 ± 4.1% LV mass; p < 0.001). There was no significant difference between both groups for the LV functional parameters and LV ejection fraction (58.5 ± 6.8 vs. 62.6 ± 9.6%; p = 0.29). Patients with MO showed a higher troponin I release (570 ± 364 vs. 148 ± 103 IU; p = 0.003) and a higher creatine kinase release (29,887 ± 18,263 vs. 10,287 ± 5,283 IU; p = 0.007). Conclusions: In patients with acute NSTEMI, MO has a frequency similar to that observed in patients with STEMI and also correlates with the infarct extent. The prognostic significance on clinical outcome remains to be shown in this specific population.

Prognostic Value of Microvascular Damage Determined by Cardiac Magnetic Resonance in Non ST-Segment Elevation Myocardial Infarction

“…30 Thus, our results emphasize the potential interest of interventional strategies such as thrombus aspiration for the management of microvascular perfusion. 31 As previously described in several studies, 29,32 we found an heterogeneous repartition of IS in this population of NSTEMI patients, with 18 patients showing no visible hyperenhancement on LGE images, and a mean IS of 9.1% Ϯ 8.5% of myocardial volume for the overall population. However, IS in this population is lower than IS described in STEMI patients.…”

“…This proportion is in keeping with a previous study in 25 patients who reported a frequency of PMO of 32%. 29 Thus, the prevalence of PMO in NSTEMI patients seems slightly lower than that observed in STEMI patients. 10,24 Among the many factors that contribute to the development of PMO, distal embolization could occur in various proportions and may partly explain the great prevalence of PMO in the setting of NSTEMI after PCI, as reflected by the high incidence of periprocedural myocardial infarction in these patients.…”

Microvascular obstruction assessed by 3-tesla magnetic resonance imaging in acute myocardial infarction is correlated with plasma troponin I levels

“…Thus, it would appear that the results observed in the context of STEMI are also applicable in NSTEMI [32]. …”

Anatomical and functional evaluation of the myocardium in patients with acute coronary syndrome (NSTEMI) using MR imaging

“…Exclusion criteria were acute myocardial infarction with ST-segment elevation (STEMI), severe cardiac failure, claustrophobia and any absolute contraindication to MR imaging. Images were acquired with a 1.5-area infartuale; così da poter individuare la cosiddetta zona di penombra ischemica, che potrebbe essere salvata dal progredire del fronte d'onda ischemico da un immediato e repentino trattamento di rivascolarizzazione [7][8][9]. Secondo questo punto di vista la RM consente di identificare con elevati valori di sensibilità e specificità l'area di mismatch tra l'evento ischemico cronico ed acuto in modo non invasivo ed altamente affidabile [10][11][12][13][14].…”

“…In delineating the recovery of ventricular function in a patient who has suffered an acute coronary syndrome (ACS), magnetic resonance (MR) imaging allows both the identification of nonviable myocardium or myocardial scar from previous, more-or-less recent, episodes of ischaemia-infarction and depiction of any reactive oedema that has formed in the infarcted area. This allows identification of the so-called ischaemic penumbra that could be salvaged by immediate revascularisation [7][8][9]. MR imaging has been shown to identify with a high level of sensitivity and specificity the area of mismatch ischemiche acute dalle croniche, quantificando il mismatch ischemia/necro.…”