[Spontaneous variability in ischemic episodes during everyday conditions. Role of ST-Holter monitoring in assessment of therapy].
To analyze the daily spontaneous variability of ischemic ST-segment changes and to derive criteria for statistical documentation of a therapeutic antiischemic effect, in 30 patients with coronary artery disease, with the aid of Holter monitoring the frequency of episodes E1 and E2 during everyday activities without medication was registered for two consecutive 24-hour periods. The spontaneous variability of the ischemic episodes of an individual patient was defined as the frequency distribution of the respective percent changes [(E2-E1)/E1].100 = (E2/E1-1).100 from day to day. To fit the curve to a normal distribution, logarithmic transformation was performed: [formula: see text] where i designates the number of patients. The constant 0.01 serves to correct for the event of episode frequency = 0. From the standard deviation sd of this logarithmic quotient, by retransformation, the one- and two-sided confidence limits K for the percent spontaneous variability are derived from the equation K = -(10-z alpha.sd-1).100; z alpha = 1.65 or 1.96. A statistically significant therapeutic effect can be assumed if, on paired comparison of 24-hour registrations with and without treatment, the limits are exceeded. Possible aggravation by the drug must be ruled out with the one-sided confidence interval. From the standard deviation sd, the standard deviation sd/square root of n for the collective of n = 5 ... to n = 30 patients was calculated and, analogously to the individual patient, the corresponding one- and two-sided 95% confidence limits for a significant therapeutic effect are defined.(ABSTRACT TRUNCATED AT 250 WORDS)
Klinik für Herz- und Kreislauferkrankungen, Deutsches Herzzentrum München.
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Redl
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Rudolph
D000203:Activities of Daily Living; D016001:Confidence Intervals; D003327:Coronary Disease / Q000188:drug therapy / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D015716:Electrocardiography, Ambulatory; D006801:Humans
Spontane Variabilität ischämischer Episoden unter alltäglichen Bedingungen. Bedeutung für die Therapiekontrolle durch ST-Holter-Monitoring.