inimary:The assessment of chronic phannacological atnient of stable angina requires serial exercise stress ;rings. It is well known that exercise tolerance can be ,proved by the training effect of performing repeated ;tings. Our study investigated the values of heart rate, stolic blood pressure, rate-pressure product, and duratn of exercise at 0.1 mV ST depression during exercise d the same parameters plus the maximal ST-segment pression at peak exercise, collected from three differt tests. The first and second werc performed at one-week ervals before, and the third (75 days after the first), was rformed after a double-blind study with a drug versus tcebo. We found a significant increase of exercise duion at 0.1 mV ST depression and at peak exercise, while if 12 patients increased exercise duration from the send to the third test. Individual variability of exercise ration showed increasing values, ranging from 0 to 7 1 % rst vs. third test). In contrast, the ratio of heart rate and rtolic blood pressure did not differ between the tests. ir data criticized the use of mean values of exercise time -phamiacological studies; moreover, individual variaity could affect results independently of drug or placebo ministration. These findings should be taken into acunt in order to exclude misleading results. . dc Arcangelis is presently a medical student.
We used an upright bicycle exercise to study recovery systolic blood pressure (SBP) response in 183
subjects (166 males and 17 females, ranging in age from 17 to 73 years). We calculated the recovery SBP ratio
(recovery ratio - RR) (recovery 1 and 3 min SBP divided by the peak exercise SBP, measured immediately before
end point and evaluated their data according to clinical presentation, atypical chest pain, typical angina), hypertension
(n = 49), presence of previous myocardial infarction (n = 34), and coronary artery disease (n = 93).
A control group was formed of 26 normal young volunteers and 25 subjects with a normal coronary tree or trivial
lesions (O-V group). In the former group, RR were 0.85 ± (SD) 0.09 and 0.73 ± 0.08 respectively, while in the latter
group were 0.85 ± 0.08 and 0.71 ± 0.08, respectively. Both ratios were significantly higher than in the O-V group
only in patients with multivessel disease (with or without myocardial infarction) both in normotensive and hypertensive
groups. To assess the role of an abnormal recovery SBP response for detecting presence of coronary stenoses or residual
stenoses after myocardial infarction, we calculated upper limits of normal response (2 SD above the mean values of
both ratios in controls; 1.01 and 0.88 respectively in first and third minute of recovery). An abnormal RR response
was found in 28% of patients with coronary stenoses or residual stenoses, while we found an abnormal ratio in 2
subjects without coronary stenoses (n = 51) or residual stenoses after infarction (n = 5). Hypertension increased the
incidence of abnormal ratios, thereby affecting the use of this criterion. In conclusion, an abnormal recovery SBP ratio, not related to exercise blood pressure value or heart rate, was rarely observed in patients with coronary artery disease, but, when noted during stress testing procedures in normotensive patients, should be considered a highly specific indicator and therefore potentially useful clinical tool.
Several studies investigated the human heart rate (HR)-QT interval relationship using different formulae,
but in clinical use the necessity of a simple means of correction is apparent. We assessed the resting supine
HR-QT relation in health nonhospitalized subjects (age range 20-60 years, 494 men and 536 women) undergoing
noninvasive diagnostic examination, and patients with a history or evidence of heart disease were excluded. The
electrocardiographic data were recorded and calculated by a Marquette computer-assisted system (QT as mean of all
standard leads). A linear relationship was found between the HR and QT interval in males and females, as follows:
males (n = 494), QT - 524 ms, 2.05 HR, r = -0.85; females (n = 536), QT = 515 ms, 1.88 HR, r = -0.80. The
correlation coefficients are highly significant in both cases (p < 0.001). The use of curvilinear regression formulae
permits quite similar correlation coefficients.
The present results show that over the resting range of HR, in subjects without heart disease, a linear relationship
exists between HR and QT interval and a rate-corrected ‘index’ value can be easily calculated in clinical use.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.