Grady T A, Chiu A C, Snader C E, Marwick T H, Thomas J D, Pashkow F J, Lauer M S
Department of Cardiology, George M. and Linda H. Kaufman Center for Heart Failure, Cleveland Clinic Foundation, Ohio 44195-5245, USA.
JAMA. 1998 Jan 14;279(2):153-6. doi: 10.1001/jama.279.2.153.
Approximately 0.5% of all patients who undergo exercise testing develop a transient left bundle-branch block (LBBB) during exercise, but its prognostic significance is unclear.
To determine whether exercise-induced LBBB is an independent predictor of mortality and cardiac morbidity.
Matched control cohort study. Between September 1990 and February 10, 1994, 17277 exercise stress tests were performed on patients.
Tertiary care, academic medical center.
From the cohort, 70 cases of exercise-induced LBBB were identified. The controls comprised 70 individuals without LBBB at rest or during exercise that matched the 70 cases based on age, test date, sex, prior history of coronary artery disease, hypertension, diabetes, smoking, and beta-blocker use.
All-cause mortality, percutaneous coronary intervention, open heart surgery, nonfatal myocardial infarction, documented symptomatic or sustained ventricular tachydysrhythmia, or implantation of a permanent pacemaker or an implantable cardiac defibrillator.
A total of 37 events (28 events from the exercise-induced LBBB cases and 9 from the control cohort) occurred in 25 patients (17 exercise-induced LBBB patients and 8 control patients) during a mean follow-up period of 3.7 (0.9 years) (median, 3.8 years [range, 0.9-5.2 years]). There were 7 deaths, of which 5 occurred among patients with exercise-induced LBBB. Four-year Kaplan-Meier event rates were 19% among exercise-induced LBBB patients and 10% among controls (log-rank chi2, 5.2; P=.02). After further adjusting for small differences in age, exercise-induced LBBB remained associated with a higher risk of primary events (adjusted relative risk, 2.78; 95% confidence interval, 1.16-6.65; P=.02).
Exercise-induced LBBB independently predicts a higher risk of death and major cardiac events.
在所有接受运动试验的患者中，约0.5%在运动期间会出现短暂性左束支传导阻滞（LBBB），但其预后意义尚不清楚。
确定运动诱发的LBBB是否是死亡率和心脏发病率的独立预测因素。
匹配对照队列研究。1990年9月至1994年2月10日期间，对患者进行了17277次运动应激试验。
三级医疗学术医学中心。
在该队列中，识别出70例运动诱发LBBB的病例。对照组包括70名在静息或运动期间无LBBB的个体，这些个体根据年龄、测试日期、性别、冠状动脉疾病既往史、高血压、糖尿病、吸烟和β受体阻滞剂使用情况与70例病例相匹配。
全因死亡率、经皮冠状动脉介入治疗、心脏直视手术、非致命性心肌梗死、记录在案的有症状或持续性室性快速心律失常，或植入永久性起搏器或植入式心脏除颤器。
在平均随访期3.7（0.9年）（中位数，3.8年[范围，0.9 - 5.2年]）内，25例患者（17例运动诱发LBBB患者和8例对照患者）共发生37起事件（28起事件来自运动诱发LBBB病例，9起来自对照队列）。有7例死亡，其中5例发生在运动诱发LBBB的患者中。运动诱发LBBB患者的四年Kaplan - Meier事件发生率为19%，对照组为10%（对数秩检验χ² = 5.2；P = 0.02）。在进一步调整年龄的微小差异后，运动诱发LBBB仍与较高的主要事件风险相关（调整后相对风险，2.78；95%置信区间，1.16 - 6.65；P = 0.02）。
运动诱发的LBBB独立预测更高的死亡风险和主要心脏事件风险。
