Department of Cardiology, Golden Jubilee National Hospital, Glasgow, Scotland.
JACC Cardiovasc Interv. 2010 Jul;3(7):715-22. doi: 10.1016/j.jcin.2010.04.009.
This study investigated the relationship between the index of microcirculatory resistance (IMR) with myocardial injury and microvascular obstruction (MVO) assessed by contrast-enhanced cardiac magnetic resonance (ceCMR) imaging in a broad range of ST-segment elevation myocardial infarction (STEMI) patients undergoing emergency percutaneous coronary intervention (PCI).
Contrast-enhanced cardiac magnetic resonance imaging is the gold standard for assessment of microvascular obstruction (MVO), left ventricular (LV) ejection fraction, and infarct volumes in ST-segment elevation myocardial infarction (STEMI). However, ceCMR is not available acutely. The index of microcirculatory resistance is a simple invasive measure of microvascular function available at the time of emergency PCI. We investigated the relationship between IMR with myocardial injury and MVO assessed by ceCMR in STEMI patients undergoing emergency PCI.
Fifty-seven patients with STEMI were included and 53 (93%) and 47 (82%) patients had complete ceCMR scans 2 days and 3 months following MI, respectively. Microvascular obstruction was defined as a dark core of hypoenhancement within the area of hyperenhanced infarct tissue 10 to 15 min following intravenous gadolinium (0.1 mmol/kg).
The median IMR (interquartile range [IQR]) was 35 (24 to 63) U. Twenty-seven patients (46%) had MVO. We found that IMR (median [IQR]) was higher in patients with MVO (38 [29 to 55] U) than in patients without MVO (27 [18 to 36] U); p = 0.003). The index of microcirculatory resistance was a negative multivariable predictor of LV ejection fraction, (p < or = 0.001) and infarct volume (p = 0.01) on the ceCMR scan 2 days after MI, and IMR was a multivariable predictor of LV ejection fraction (p = 0.028) and infarct volume (p = 0.048) at 3 months.
The index of microcirculatory resistance measured acutely was higher in patients with MVO on ceCMR, and IMR independently predicted LV function and infarct volume. This easily measured physiological parameter provides important prognostic information at the time of emergency PCI.
本研究旨在探讨在广泛的 ST 段抬高型心肌梗死（STEMI）患者中，经急诊经皮冠状动脉介入治疗（PCI）时，微血管阻力指数（IMR）与心肌损伤和对比增强心脏磁共振（ceCMR）成像评估的微血 管阻塞（MVO）之间的关系。
对比增强心脏磁共振成像是评估微血 管阻塞（MVO）、左心室（LV）射血分数和 ST 段抬高型心肌梗死（STEMI）梗死体积的金标准。然而，ceCMR 不能在急性期使用。IMR 是一种简单的微血管功能的有创测量方法，可在急诊 PCI 时获得。我们研究了在 STEMI 患者中，急诊 PCI 时 IMR 与 ceCMR 评估的心肌损伤和 MVO 之间的关系。
纳入 57 例 STEMI 患者，其中 53 例（93%）和 47 例（82%）患者分别在 MI 后 2 天和 3 个月时完成了完整的 ceCMR 扫描。微血管阻塞定义为静脉注射钆（0.1mmol/kg）后 10-15 分钟，在高增强梗死组织内出现的暗核心低增强区域。
中位 IMR（四分位距 [IQR]）为 35（24-63）U。27 例（46%）患者存在 MVO。我们发现，有 MVO 的患者的 IMR（中位数 [IQR]）更高（38 [29-55] U），无 MVO 的患者的 IMR 更低（27 [18-36] U）；p = 0.003）。IMR 是 ceCMR 扫描 2 天后 LV 射血分数的负多变量预测因子（p < or = 0.001）和梗死体积（p = 0.01），IMR 也是 LV 射血分数的多变量预测因子（p = 0.028）和梗死体积的多变量预测因子（p = 0.048）。
ceCMR 上的 MVO 患者的 IMR 测量值在急性期更高，IMR 独立预测 LV 功能和梗死体积。这个容易测量的生理参数在急诊 PCI 时提供了重要的预后信息。
