Fei L, Goldman J H, Prasad K, Keeling P J, Reardon K, Camm A J, McKenna W J
Department of Cardiological Sciences, St George's Hospital Medical School, London, U.K.
Eur Heart J. 1996 Feb;17(2):258-63. doi: 10.1093/oxfordjournals.eurheartj.a014843.
Increased QT dispersion, which has been proposed as a marker of ventricular repolarization inhomogeneity, may predispose to ventricular arrhythmias. Data on QT dispersion in patients with congestive heart failure are scarce. In this study, conventional 12-lead ECGs were recorded in 135 consecutive patients with congestive heart failure secondary to idiopathic dilated cardiomyopathy. Seventy-five patients were excluded from QT interval assessments due to one or more of the following reasons: (1) low amplitude of the T wave (n = 3), (2) atrial fibrillation (n = 26) and (3) bundle branch block (n = 46). QT dispersion was calculated as (1) QT-range: the difference between the maximum and minimum QT intervals on any of the 12 leads and (2) QT-SD: the standard deviation of the QT interval in all the 12 leads. RR intervals were measured in leads II, aVL, V2 and V5. QT-SD (20.85 +/- 5.00 ms) was significantly (r = 0.8997, P < 0.001) related to QT-range (65.65 +/- 15.77 ms), but not to the QT interval. Neither QT-range nor QT-SD was significantly related to age, left ventricular dimensions, left ventricular end diastolic pressure, left ventricular ejection fraction or left ventricular wall thickness. There was no significant difference in QT dispersion between survivors and those who died (n = 8) or were transplanted (n = 9) during 34 +/- 23 month follow-up. No significant difference in QT dispersion was observed between patients with and without ventricular tachycardia (> or = three consecutive beats) detected on 24-h Holter ECGs. RR interval variation was significantly lower in patients who died compared with survivors (standard deviation: 10.37 +/- 3.61 vs 36.02 +/- 35.03 ms, P < 0.001; coefficient of variance: 1.87 +/- 0.7% vs 4.50 +/- 4.9%, P = 0.001). This was also true in patients with bundle branch block. These observations suggest that QT dispersion in idiopathic dilated cardiomyopathy is not significantly related to either QT interval or cardiac size and function and does not predict death. The application of QT dispersion assessment is limited by the commonly encountered atrial fibrillation and bundle branch block in this patient population. However, reduced RR variation on standard 12-lead ECGs has important prognostic implications in these patients.
QT离散度增加被认为是心室复极不均一性的一个标志，可能易导致室性心律失常。关于充血性心力衰竭患者QT离散度的数据较少。在本研究中，对135例连续的特发性扩张型心肌病所致充血性心力衰竭患者记录了常规12导联心电图。75例患者因以下一种或多种原因被排除在QT间期评估之外：（1）T波振幅低（n = 3），（2）心房颤动（n = 26）和（3）束支传导阻滞（n = 46）。QT离散度计算如下：（1）QT范围：12导联中任一导联上最大和最小QT间期的差值；（2）QT标准差：12导联QT间期的标准差。在II、aVL、V2和V5导联测量RR间期。QT标准差（20.85±5.00毫秒）与QT范围（65.65±15.77毫秒）显著相关（r = 0.8997，P < 0.００１），但与QT间期无关。QT范围和QT标准差均与年龄、左心室大小、左心室舒张末期压力、左心室射血分数或左心室壁厚度无显著相关性。在34±23个月的随访期间，存活者与死亡者（n = 8）或接受移植者（n = 9）之间的QT离散度无显著差异。在24小时动态心电图检测中，有或无室性心动过速（≥3个连续搏动）的患者之间QT离散度无显著差异。与存活者相比，死亡患者的RR间期变异性显著降低（标准差：10.37±3.61对36.02±35.03毫秒，P < 0.００１；变异系数：1.87±0.7%对4.50±4.9%，P = 0.001）。束支传导阻滞患者也是如此。这些观察结果表明，特发性扩张型心肌病中的QT离散度与QT间期或心脏大小及功能均无显著相关性，也不能预测死亡。QT离散度评估的应用受到该患者群体中常见的心房颤动和束支传导阻滞的限制。然而，标准12导联心电图上RR变异性降低对这些患者具有重要的预后意义。
