Magrì Damiano, Sciomer Susanna, Fedele Francesco, Gualdi Gianfranco, Casciani Emanuele, Pugliese Pellegrina, Losardo Anna, Ferrazza Giancarlo, Pasquazzi Eleonora, Schifano Erika, Magnanti Marzia, Matera Sabrina, Marigliano Vincenzo, Piccirillo Gianfranco
Dipartimento di Scienze Cardiovascolari, Respiratorie e Morfologiche, Policlinico Umberto I, Università La Sapienza, Rome, Italy.
Eur J Haematol. 2007 Oct;79(4):322-9. doi: 10.1111/j.1600-0609.2007.00921.x. Epub 2007 Jul 26.
Despite recent progress in iron chelation therapy, sudden cardiac death due to malignant ventricular arrhythmias remains a vexing, clinical problem in patients with beta-thalassemia major (TM). In this study we assessed whether the major indices of QT variability, emerging tools for risk stratification of sudden cardiac death, differ in young asymptomatic patients with TM and healthy persons.
Thirty patients with TM and 30 healthy control subjects underwent a 5-min electrocardiography recording to calculate the following variables: QT variance (QT(v)), QT(v) normalized for mean QT (QTVN) and QT variability index (QTVI). All subjects also underwent a two-dimensional and Doppler echocardiography study and magnetic resonance imaging (MRI) to determine cardiac and hepatic T2* values.
No differences were observed in clinical and conventional echo-Doppler findings in healthy control subjects and patients with TM whereas QT(v), QTVN and QTVI values were significantly higher in patients than those in controls (QT(v), P < 0.001; QTVN, P < 0.05 and QTVI, P < 0.001) and cardiac T2* and hepatic MRI T2* values were significantly lower in patients with TM (P < 0.001). The indices of temporal QT variability correlated significantly with MRI data.
Young asymptomatic patients with TM have increased cardiac repolarization variability as assessed by QT variability indices, probably due to cardiac iron deposition. These easily assessed, non-invasive markers could be used to identify increased myocardial repolarization lability early in asymptomatic patients with TM.
尽管铁螯合疗法最近取得了进展，但重型β地中海贫血（TM）患者因恶性室性心律失常导致的心源性猝死仍然是一个棘手的临床问题。在本研究中，我们评估了QT变异性的主要指标（用于心源性猝死风险分层的新兴工具）在年轻无症状TM患者和健康人中是否存在差异。
30例TM患者和30名健康对照者进行了5分钟的心电图记录，以计算以下变量：QT方差（QT(v)）、根据平均QT标准化的QT(v)（QTVN）和QT变异性指数（QTVI）。所有受试者还进行了二维和多普勒超声心动图研究以及磁共振成像（MRI），以确定心脏和肝脏的T2*值。
健康对照者和TM患者的临床及传统超声多普勒检查结果未观察到差异，然而患者的QT(v)、QTVN和QTVI值显著高于对照组（QT(v)，P<0.001；QTVN，P<0.05；QTVI，P<0.001），TM患者的心脏T2和肝脏MRI T2值显著更低（P<0.001）。QT时间变异性指标与MRI数据显著相关。
通过QT变异性指标评估，年轻无症状TM患者的心脏复极变异性增加，可能是由于心脏铁沉积。这些易于评估的非侵入性标志物可用于在无症状TM患者早期识别心肌复极不稳定性增加。
