平板运动负荷试验中QT滞后现象对冠心病的诊断价值

Value of QT hysteresis during treadmill exercise test for diagnosing coronary heart disease

目的探讨平板运动负荷试验（TET）中QT滞后指数在冠心病无创诊断中的价值。方法连续选取100例因疑诊冠心病在我院行TET和选择性冠状动脉造影（SCA）的患者。根据SCA结果分为阳性组[55例，年龄（56．0±7．9）岁]和阴性组[45例，年龄（53．2±6．7）岁]，分析TET心电图，每例测量50个点的RR间期、QTp间期和QTe间期。以RR间期为横坐标，QTp间期、QTe间期为纵坐标，作散点图和QT／RR曲线，计算QT滞后指数。结果SCA阳性组的QTp滞后指数[（22．4±10．3）ms比（6．7±4．6）ms，P〈0．001]和QTe滞后指数[（27．1±11．1）ms比（7．6±4．6）ms，P〈0．001]明显高于阴性组。QTp或QTe滞后指数≥10ms诊断冠心病的敏感性分别为89．1％（49／55）和94．5％（52／55），特异性分别为82．2％（37／45）和80．0％（36／45）。若同时符合TET传统诊断标准和QT滞后诊断标准，诊断冠心病的敏感性QTp为94．3％（33／35）、QTe为94．6％（35／37），特异性二者均为100％。QTp滞后指数（r=-0．399，P〈0．001）和QTe滞后指数（r=-0．547，P〈0．001）与杜克平板评分显著相关。结论QT滞后指数用于冠心病无创筛查具有较高的敏感性和特异性，与传统诊断标准结合，可提高平板运动负荷试验对冠心病的诊断效力。

Objective To investigate the value of QT hysteresis index during treadmill exercise test （TET） in diagnosing coronary heart disease （CHD）. Methods One hundred consecutive patients suspected for CHD were referred for TET and selective coronary angiography （CAG）. Patients were divided into positive [n =55, age （56. 0 ±7.9）years] and negative [n =45, age （53.2 ±6. 7）years] group based on their CAG results. For each TET recording, 50 points were selected for the RR, QTp, and QTe interval measurements. QTp and QTe intervaI was plotted against corresponding RR interval. QT/RR curve was constructed by connect all point, QT hysteresis index was calculated for each patient. Results The QTp [（22.4±10.3） ms vs. （6.7±4.6） ms, P〈0.001] andQTe [（27.1 ±11.1） msvs. （7.6±4.6） ms, P 〈 0. 001 ] hysteresis index of patients in positive group were significantly higher than those in negative group. The sensitivity of QTp and QTe hysteresis index for diagnosing CHD was 89. 1% （49/55） and 94. 5% （52/55） , respectively, and the specificity was 82. 2% （37/45） and 80. 0% （36/45）, respectively. If the patient fulfilled both the classical TET and QT hysteresis criteria, the sensitivity for diagnosing CHD increased to 94. 3% （33/35, QTp） and 94. 6% （35/37, QTe）, and the specificity were both 100% （26/26, 26/26）. Moreover, QTp （r = - 0. 399, P 〈 0. 001 ） and QTe （r = - 0. 547, P 〈 0. 001 ） hysteresis index highly correlated to Duke treadmill score. Conclusion QT hysteresis index is useful parameter for CHD diagnosis and which could improve the diagnostic value of TET for CHD in combination with the classical TET criteria for diagnosis of CHD.