DETECTION AND PROGNOSIS OF SILENT MYOCARDIAL ISCHEMIA

在726名看似健康的巴尔的摩老龄纵向研究(BLSA)中 自那以来接受过连续最大运动测试的男性和女性 1969年，研究人员比较了那些最初发生心脏事件的人 试验呈阳性(I组)，由阴性转为阳性者 (II组和那些在6.4年以上保持负值的人的平均随访 (III组)。通过比例风险分析，I组和II组的 相同的心脏事件风险增加(RR分别为2.78和2.72 分别)与第三组受试者比较。因此，在无症状的情况下 志愿者，从阴性到阳性的连续运动心电转换 对未来冠状动脉事件的预测价值与最初的 心电图呈阳性反应。 为了区分年龄和无症状性心肌缺血(SI)的影响， 左心室(LV)对最大立位周期测功术的反应 比较3组：8名临床健康老年人 男性(平均年龄76岁)，既往有异常的心电图和铊扫描(TS) 对最大跑步机运动(OSI)的反应；16名年龄匹配的男性 正常的心电图和TS反应(OC)；21名年轻人(平均年龄=33岁) (YC)。静息时左室射血分数(EF)、舒张末容量指数(EDVI) 收缩末期容量指数(ESVI)在3组间差异无统计学意义。使用 周期运动LVEF在青年组显著增加，在OC组较少，在最小 在现场视察中。相比之下，运动性左心室扩大(增加(ESVI)) 在OSI中最明显，OC增加较少；EDVI 实际上在YC尽了最大努力降到了基准值以下。因此， 与年龄相关的心脏扩张和直立循环对EF的钝化反应 在运动性SI的老年受试者中被夸大。

Among 726 apparently healthy Baltimore Longitudinal Study of Aging (BLSA) men and women who have undergone serial maximal exercise testing since 1969, the risk of future cardiac events was compared in those whose initial test was positive (Group I), those who converted from negative to positive (Group II and those who remained negative over a 6.4 year mean followup (Group III). By proportional hazards analysis, Groups I and II had a nearly identical enhanced risk of a cardiac event (RR of 2.78 and 2.72 respectively) compared to Group III subjects. Thus, in asymptomatic volunteers, serial conversion from a negative to a positive exercise ECG has a similar predictive value for a future coronary event as an initially positive ECG response. To separate the effects of age and silent myocardial ischemia (SI), on the left ventricular (LV) response to maximal upright cycle ergometry, we compared 3 groups: 8 clinically healthy older men (mean age - 76) with prior abnormal ECG and thallium scan (TS) responses to maximal treadmill exercise (OSI); 16 age-matched men with normal ECG and TS responses (OC); and 21 young (mean age = 33) controls (YC). At rest LV ejection fraction (EF), end-diastolic volume index (EDVI) and end-systolic volume index (ESVI) were similar in the 3 groups. With cycle exercise LVEF increased markedly in the YC, less in the OC and least in the OSI. In contrast, exercise-induced LV dilatation (increased (ESVI) was most pronounced in the OSI with a lesser increase in the OC; EDVI actually declined below baseline values by maximal effort in the YC. Thus, age-related cardiac dilatation and blunted EF response to upright cycling are exaggerated in older subjects with exercise-induced SI.