作者: E G Nabel , J Barry , M B Rocco , S Campbell , K Mead
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摘要: Ambulatory electrocardiographic (ECG) monitoring of patients with chronic stable angina has demonstrated frequent and prolonged episodes ischemic ST segment depression, but its clinical use requires an understanding the components extent variability. Therefore, variations in frequency duration depression were evaluated ambulatory ECG recording at daily, weekly, monthly intervals 42 known coronary artery disease. Data analyzed a nested analysis variance design that yields estimates components. From components, power calculations minimum significant percent reductions ischemia derived. During 4,656 hours monitoring, 1,262 detected. The was 6.3 +/- 0.45/24 hr (mean SEM), 18.3 2.8/24 hr. Because variability over time, ability to detect changes dependent upon number subjects, length period, between periods. In trial, for example, sample size 25 monitored 48 1 week control test conditions would require 65% reduction frequency, whereas 50 under similar 46% attribute change 90% therapeutic intervention rather than spontaneous variation. When single patient or month repeat sessions, must be eliminated activity 95% confidence level.(ABSTRACT TRUNCATED AT 250 WORDS)