Shimizu Wataru, Noda Takashi, Takaki Hiroshi, Kurita Takashi, Nagaya Noritoshi, Satomi Kazuhiro, Suyama Kazuhiro, Aihara Naohiko, Kamakura Shiro, Sunagawa Kenji, Echigo Shigeyuki, Nakamura Kazufumi, Ohe Tohru, Towbin Jeffrey A, Napolitano Carlo, Priori Silvia G
Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565-8565, Japan.
J Am Coll Cardiol. 2003 Feb 19;41(4):633-42. doi: 10.1016/s0735-1097(02)02850-4.
This study was designed to test the hypothesis that epinephrine infusion may be a provocative test able to unmask nonpenetrant KCNQ1 mutation carriers.
The LQT1 form of congenital long QT syndrome is associated with high vulnerability to sympathetic stimulation and appears with incomplete penetrance.
The 12-lead electrocardiographic parameters before and after epinephrine infusion were compared among 19 mutation carriers with a baseline corrected QT interval (QTc) of > or =460 ms (Group I), 15 mutation carriers with a QTc of <460 ms (Group II), 12 nonmutation carriers (Group III), and 15 controls (Group IV).
The mean corrected Q-Tend (QTce), Q-Tpeak (QTcp), and Tpeak-end (Tcp-e) intervals among 12-leads before epinephrine were significantly larger in Group I than in the other three groups. Epinephrine (0.1 microg/kg/min) increased significantly the mean QTce, QTcp, Tcp-e, and the dispersion of QTcp in Groups I and II, but not in Groups III and IV. The sensitivity and specificity of QTce measurements to identify mutation carriers were 59% (20/34) and 100% (27/27), respectively, before epinephrine, and the sensitivity was substantially improved to 91% (31/34) without the expense of specificity (100%, 27/27) after epinephrine. The mean QTce, QTcp, and Tcp-e before and after epinephrine were significantly larger in 15 symptomatic than in 19 asymptomatic mutation carriers in Groups I and II, and the prolongation of the mean QTce with epinephrine was significantly larger in symptomatic patients.
Epinephrine challenge is a powerful test to establish electrocardiographic diagnosis in silent LQT1 mutation carriers, thus allowing implementation of prophylactic measures aimed at reducing sudden cardiac death.
本研究旨在验证肾上腺素输注可能是一种激发试验，能够揭示非穿透性KCNQ1突变携带者这一假说。
先天性长QT综合征的LQT1型与对交感神经刺激的高易感性相关，且表现为不完全外显率。
比较了19名基线校正QT间期（QTc）≥460毫秒的突变携带者（I组）、15名QTc<460毫秒的突变携带者（II组）、12名非突变携带者（III组）和15名对照组（IV组）在肾上腺素输注前后的12导联心电图参数。
肾上腺素输注前，I组12导联的平均校正Q-Tend（QTce）、Q-Tpeak（QTcp）和Tpeak-end（Tcp-e）间期显著大于其他三组。肾上腺素（0.1微克/千克/分钟）使I组和II组的平均QTce、QTcp、Tcp-e以及QTcp离散度显著增加，但III组和IV组未增加。肾上腺素输注前，QTce测量识别突变携带者的敏感性和特异性分别为59%（20/34）和100%（27/27），肾上腺素输注后敏感性显著提高至91%（31/34），而特异性未受影响（100%，27/27）。I组和II组中，15名有症状的突变携带者肾上腺素输注前后的平均QTce、QTcp和Tcp-e显著大于19名无症状突变携带者，有症状患者肾上腺素导致的平均QTce延长更显著。
肾上腺素激发试验是在无症状LQT1突变携带者中确立心电图诊断的有力方法，从而能够实施旨在降低心源性猝死的预防措施。
