Gryglewska B, Grodzicki T, Czarnecka D, Kawecka-Jaszcz K, Kocemba J
Department of Gerontology and Family Medicine, Collegium Medicum of Jagiellonian University, Cracow, Poland.
J Hypertens. 2000 Apr;18(4):461-4. doi: 10.1097/00004872-200018040-00016.
To determine the predictors and risk of increased QT dispersion in the elderly hypertensive patients.
A 12-lead electrocardiogram (ECG), M-mode echocardiography and ambulatory blood pressure as well as Holter monitoring were performed for 67 patients over 60 years of age with essential hypertension (I and II(o) WHO). The presence of ischaemic changes on ECG was evaluated based on the Minnesota Code. QT intervals were corrected with Bazett's formulae and QT dispersion was determined as the difference between maximal and minimal QTc intervals. Interventricular septal thickness (IVSTd), left ventricular internal diameter (LVDd) and posterior wall thickness (PWTd) were measured and left ventricular mass index (LVMI) was calculated. Subjects were divided according to the median of QTc dispersion (0.10 s). The differences between groups were assessed using chi-squared and Student's t-test.
Subjects with increased QTc dispersion did not differ from those with low QTc dispersion when age, gender and body mass index were analysed. Similarly, the average systolic blood pressure, diastolic blood pressure and blood pressure variability were comparable in both groups. The mean QTc interval was similar in both groups. In patients with increased QT dispersion, left ventricular hypertrophy (LVH) and ischaemic changes on ECG were more frequently recognized (respectively 41.2 versus 18.2%, P < 0.001; 47.1 versus 21.2%, P < 0.05). Moreover, these subjects presented a significantly greater number of premature ventricular beats (317.1 +/- 665.6 versus 64.88 +/- 188.6, P < 0.05) and higher classes of Lown's arrhythmia scale (classes III-IV, 23.35% versus 9.1%). LVMI was insignificantly higher in the group with greater QTc dispersion (165.82 +/- 54.5 versus 145.07 +/- 36.47 g/ m2). Other echocardiographic indices of LVH were similar in both groups. On the other hand, the analysis of regression indicated positive correlation between the dispersion of QTc interval and thickness of left ventricle walls (for IVSd - r = 0.37; for PWd - r = 0.31), relative wall thickness (r = 0.28) and LVMI (r = 0.28).
QTc dispersion is increased in the elderly hypertensive individuals, with the presence of LVH and myocardial ischaemia on ECG. These patients are more likely to demonstrate severe ventricular dysrhythmias.
确定老年高血压患者QT离散度增加的预测因素及风险。
对67例60岁以上的原发性高血压（WHO I级和II（o）级）患者进行12导联心电图（ECG）、M型超声心动图、动态血压及动态心电图监测。根据明尼苏达编码评估心电图上缺血性改变的存在情况。采用Bazett公式校正QT间期，并将QT离散度确定为最大和最小QTc间期之间的差值。测量室间隔厚度（IVSTd）、左心室内径（LVDd）和后壁厚度（PWTd），并计算左心室质量指数（LVMI）。根据QTc离散度的中位数（0.10秒）将受试者分组。采用卡方检验和Student t检验评估组间差异。
分析年龄、性别和体重指数时，QTc离散度增加的受试者与QTc离散度低的受试者无差异。同样，两组的平均收缩压、舒张压和血压变异性相当。两组的平均QTc间期相似。QT离散度增加的患者中，心电图上左心室肥厚（LVH）和缺血性改变更常见（分别为41.2%对18.2%，P<0.001；47.1%对21.2%，P<0.05）。此外，这些受试者出现的室性早搏明显更多（317.1±665.6对64.88±188.6，P<0.05），且Lown心律失常分级更高（III-IV级，23.35%对9.1%）。QTc离散度较大的组中LVMI略高（165.82±54.5对145.07±36.47 g/m2）。两组LVH的其他超声心动图指标相似。另一方面，回归分析表明QTc间期离散度与左心室壁厚度（IVSd - r = 0.37；PWd - r = 0.31）、相对壁厚度（r = 0.28）和LVMI（r = 0.28）之间呈正相关。
老年高血压患者QTc离散度增加，心电图上存在LVH和心肌缺血。这些患者更有可能出现严重的室性心律失常。
