Toronto General Hospital, 585 University Avenue, Toronto, Ontario, Canada.
Heart. 2011 Mar;97(5):388-93. doi: 10.1136/hrt.2010.192641.
Cardiac disease related to transfusional iron overload is the leading cause of death in patients with β-thalassaemia major. Early myocardial iron deposition predates decreased left ventricular dysfunction and currently is best assessed by cardiac magnetic resonance.
Echocardiographic speckle tracking-derived myocardial mechanics were compared with cardiac MRI T2 star (T2*) calculations in 45 chronically transfused patients with β-thalassaemia major or Diamond-Blackfan anaemia (26 retrospectively and an additional 19 for validation). Two groups were studied: patients with presumed cardiac iron overload and interventricular T2* value ≤20 ms (low T2*) and patients with >20 ms (normal T2*). They were compared with a normal control group of 18 age- and gender-matched patients.
Patients with low T2* had a uniform decrease in longitudinal and circumferential strain compared with normal controls (-16±3% vs -20±3% and -20±4% vs -23±5%, respectively; p<0.0005). Peak twist and peak apical rotation were lower in patients with low T2* than in those with normal T2* or normal control patients. Conversely, no significant difference was observed between patients with normal T2* and controls. There was a strong and direct logarithmic correlation between average global longitudinal strain and T2* values (r=-0.68, p=0.0007). Using a cut-off of ≤-17%, global longitudinal strain predicted a T2* value of <20 ms with a sensitivity of 76% and a specificity of 88%.
Myocardial mechanics offers a simple alternative to cardiac MRI for assessing significant myocardial iron deposition.
输血引起的铁过载相关的心脏疾病是重型β地中海贫血患者的主要致死原因。早期心肌铁沉积早于左心室功能下降，目前最好通过心脏磁共振评估。
在 45 例慢性输血的β地中海贫血或 Diamond-Blackfan 贫血患者（26 例回顾性和另外 19 例验证）中，比较超声心动图斑点追踪衍生心肌力学与心脏 MRI T2star（T2）计算。研究了两组患者：心室间 T2值≤20ms（低 T2）的疑似心脏铁过载患者和 T2*>20ms（正常 T2*）的患者。他们与 18 名年龄和性别匹配的正常对照组进行比较。
低 T2组患者的纵向和环向应变均较正常对照组明显下降（分别为-16±3%对-20±3%和-20±4%对-23±5%；p<0.0005）。低 T2组患者的峰值扭转和峰值心尖旋转较正常 T2组和正常对照组均明显降低。相反，正常 T2组与对照组之间无显著差异。平均整体纵向应变与 T2值之间存在强烈的直接对数相关性（r=-0.68，p=0.0007）。使用≤-17%的截断值，整体纵向应变预测 T2值<20ms 的灵敏度为 76%，特异性为 88%。
心肌力学为评估明显的心肌铁沉积提供了一种简单的心脏 MRI 替代方法。
