特发性长QT综合征QT离散度与尖端扭转性室性心动速的关系

目的探讨QT离散度与特发性长QT综合征（LQT1）发生尖端扭转性室性心动过速的关系.方法79例基因（11p15.5）携带者根据晕厥发作的频度和程度分为3组：轻度（0～4次,n=59）,中度（5～100次,n=14）和重度（有心脏骤停史,n=5）.比较：3组首次心电图QT离散度的差异;19例小于35岁的中、重度患者长期用β阻滞剂后QT离散度的变化;9例患者用β阻滞剂前后踏车试验QT离散度的变化.结果（1）3组间QT离散度有显著差异（P＜0.01）;（2）13例长期用β阻滞剂者,10例QT离散度缩小（P＜0.05）;（3）患者用β阻滞剂前,QT离散度与运动负荷呈正相关,用β阻滞剂后,呈负相关.结论QT离散度是估计病情的敏感而可靠的指标;小于35岁的中、重度LQT1（包括“无症状”者）应长期用β阻滞剂.

Relationship between torsades de pointes and QT dispersion in idiopathic long QT syndrome

OBJECTIVE: To investigate the relationship between QT dispersion and torsades de pointes (TDP) in idiopathic long QT syndrome (LQT1). METHODS: Seventy-nine carriers of the gene on the chromosome 11p15.5 were divided into 3 groups according to the severity and frequency of syncope episodes, namely the mild (0-4 episodes, n=59), moderate (5-100 episodes, n=14) and severe (with history of cardiac arrest, n=5). The differences in QT dispersion in the initial ECGs recorded were compared between the 3 groups, and the QT dispersion changes after chronic beta-blocker therapy in 19 moderate to severe cases under 35 years, along with the changes during exercise in 9 cases before and after beta-blocker therapy were evaluated and compared. RESULTS: QT dispersion was significantly different between the 3 groups (P<0.01), and after chronic beta-blocker therapy, QT dispersion decreased in 10 of the 13 cases (P<0.05). During the exercise test, the QT dispersion was positively correlated with the exercise load before beta-blocker treatment but inversely correlated after the treatment (P<0.01). CONCLUSIONS: QT dispersion is a sensitive and reliable marker to predict TDP and beta blocker should be given to moderate or severe LQT1 cases under 35 years, especially in the asymptomatic cases at risk of TDP.