Jmr. Detry

Selection of the optimal nonexercise stress for the evaluation of ischemic regional myocardial dysfunction and malperfusion. Comparison of dobutamine and adenosine using echocardiography and 99mTc-MIBI single photon emission computed tomography.

BackgroundThe mechanisms of action of exercise-simulating and vasodilator stressors support their combination with imaging techniques that evaluate left ventricular function and perfusion, respectively. However, reported accuracies of either pharmacological stress together with two-dimensional echocardiography (2DE) or single photon emission computed tomography (SPECT) of myocardial perfusion are similar. The purpose of this study was to establish the optimal stress for each imaging technique by comparing the results of digitized 2DE and 99mTc-methoxyisobutyl isonitrile (MIBI) SPECT using both dobutamine and adenosine stresses in the same patients and conditions. Methods and ResultsNinety-seven consecutive patients without evidence of previous infarction undergoing coronary angiography for clinical indications were studied prospectively. Dobutamine was infused during clinical, ECG, and echocardiographic monitoring in dose increments from 5 to 40 μg kg-1 min-1. Adenosine was infused under the same conditions in doses of 0.10, 0.14, and 0.18 mg

Impaired early left ventricular relaxation in coronary artery disease: effects of intracornary nifedipine.

kg-1min-1. For each protocol, the end points were achievement of peak dose, development of severe ischemia, or intolerable side effects. At peak stress, 20 mCi of MIBI was injected, and SPECT imaging was performed 2 hours later, abnormal poststress images were compared with resting SPECT. Digitized 2DE images were compared qualitatively before, during, and after stress in a cine-loop display. Significant coronary disease (n=59 patients) was defined by the quantification of >50% stenosis in a major epicardial vessel. The sensitivity of adenosine 2DE was 58%, less than those of adenosine MIBI (86%, p=0.001), dobutamine 2DE (85%, p=0.001), and dobutamine MIBI (80%, p=0.01). Their respective specificities were 87%, 71%, 82%, and 74% (p=NS). The accuracy of adenosine 2DE was 69%Y, compared with 80%Yo for adenosine MIBI (p<0.001), 84% for dobutamine 2DE (p=0.001), and 77% for dobutamine MIBI (p=0.005); the latter three did not differ significantly in either sensitivity or accuracy. ConclusionThis prospective, direct comparison of alternative pharmacological stresses in patients without myocardial infarction shows vasodilator stress scintigraphy and dobutamine stress echocardiography and scintigraphy to share equivalent levels of sensitivity. All three are significantly more sensitive than adenosine stress echocardiography. Dobutamine stress may be used for wall motion or perfusion imaging, but adenosine stress is best combined with perfusion scintigraphy.

Alternative diagnostic strategies for coronary artery disease in women: demonstration of the usefulness and efficiency of probability analysis.

It has been shown that the maximal rate of left ventricular (LV) relaxation is impaired in patients with coronary artery disease (CAD) under basal conditions. To test the hypothesis that this impaired LV relaxation could be related to viable but metabolically abnormal myocardium, we studied the time course of isovolumic LV pressure fall in 21 patients with CAD and in 13 control subjects under basal conditions. This study was repeated after intracoronary injection of the calcium antagonist nifedipine (N) in 11 patients with CAD and in eight controls. Our data showed that isovolumic pressure fall was biexponential in 20 of 21 CAD patients and in six of 13 controls. Moreover, the time constant of isovolumic pressure fall during the first 40 msec after peak (negative) dP/dt (TJ) was significantly greater in CAD patients than in controls (62 ± 3 vs 44 ± 1 msec, p < 0.002); the time constant of pressure fall during the 40-80 msec after peak (negative) dP/dt (T2) was similar in both groups (42 ± 2 vs 39 ± 2 msec, NS). Thirty seconds after injection of nifedipine, T1 and T2 were significantly prolonged in patients with CAD (14 msec and 16 msec, respectively, p < 0.005) and in controls 12 msec and 14 msec, respectively, p < 0.05), and a negative inotropic effect was observed in both groups (peak (positive) dP/dt −16% in controls and −23% in CAD patients, p < 0.01). At rest, impairment of isovolumic relaxation in CAD patients is mainly limited to the first 40 msec after peak (negative) dP/dt, suggesting a dyssynchronous wall motion. This impairment of LV relaxation is better identified by T1 than by peak (negative) dP/dt in individual patients, and cannot be improved by administration of a calcium antagonist.

Logistic discriminant analysis improves diagnostic accuracy of exercise testing for coronary artery disease in women.

Alternative strategies using conditional probability analysis for the diagnosis of coronary artery disease (CAD) were examined in 93 infarct-free women presenting with chest pain. Another group of 42 consecutive female patients was prospectively analyzed. For this latter group, the physician had access to the pretest and posttest probability of CAD before coronary angiography. These 135 women all underwent stress electrocardiographic, thallium scintigraphic, and coronary angiographic examination. The pretest and posttest probabilities of coronary disease were derived from a computerized Bayesian algorithm. Probability estimates were calculated by the four following hypothetical strategies: SO, in which history, including risk factors, was considered; S1, in which history and stress electrocardiographic results were considered; S2, in which history and stress electrocardiographic and stress thallium scintigraphic results were considered; and S3, in which history and stress electrocardiographic results were used, but in which stress scintigraphic results were considered only if the poststress probability of CAD was between 10% and 90%, i.e., if a sufficient level of diagnostic certainty could not be obtained with the electrocardiographic results alone. The strategies were compared with respect to accuracy with the coronary angiogram as the standard. For both groups of women, S2 and S3 were found to be the most accurate in predicting the presence or absence of coronary disease (p less than .05). However, it was found with use of S3 that more than one-third of the thallium scintigrams could have been avoided without loss of accuracy. It was also found that diagnostic catheterization performed to exclude CAD as a diagnosis could have been avoided in half of the patients without loss of accuracy.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between changes in left ventricular inotropic state and relaxation in normal subjects and in patients with coronary artery disease.

BackgroundDiagnostic accuracy of the exercise electrocardiogram in women has been shown to be limited for the detection of coronary artery disease. New diagnostic methods based on computer analysis of the exercise electrocardiogram and multivariate analysis have improved the diagnostic value of exercise testing in male subjects. The aim of the present study was to assesswhether the diagnostic value of exercise testing can be enhancedin women by using multivariate analysis of exercise data. Methods and ResultsBetween 1978 and 1984, 135 infarct-free women underwent exercise testing and coronary angiography. Significant coronary artery disease was present in 41% of the patients. In this first group, maximal exercise variables were submitted to a stepwise logistic analysis. Work load, heart rate, and ST60X were selected to build a diagnostic model. The model was tested in a second group of 115 catheterized women (significant coronary artery disease in 47%) and of 76 volunteers. We compared the present model with conventional analysis of the exercise electrocardiogram, with ST changes adjusted for heart rate, and with a previously described analysis. In both groups, sensitivity was better with the present model (66% and 70%) than by conventional (68% and 59%) and by the previously describedanalysis (57% and 44%) without a loss of specificity (85% and 93%). Receiver-operator characteristic curves showed also a better diagnostic accuracy with the present model. ConclusionsIn women, logistic analysis of exercise variables improves the diagnostic value of exercise testing. It yields a significantly better sensitivity without a loss of specificity.

Effect of dexfenfluramine treatment on body weight, blood pressure and noradrenergic activity in obese hypertensive patients

The aim of the study was to examine the changes in left ventricular (LV) relaxation rate induced by variations in inotropic state. Eight normal subjects and 29 patients with coronary artery disease (CAD) were studied. First, we used interventions that increase myocardial calcium influx (atrial pacing or postpacing beat) or decrease it (intracoronary injection of nifedipine). Relaxation rate was estimated from the time constant (T1) of isovolumic LV pressure fall during the first 40 msec after peak negative dP/dt. Under basal conditions, T1 was impaired in CAD patients (58 vs 43 msec; p < 0.01), despite similar heart rate, LV pressures and peak positive dP/dt (1620 vs 1787 mm Hg/sec; NS). During atrial pacing at 135 ± 7 beats/mm, peak positive dP/dt increased to 2220 mm Hg/sec in 11 CAD patients and to 2256 mm Hg/sec in eight normal subjects. T1 decreased more in CAD patients than in normal subjects (17 vs 7 msec; p < 0.01). T1 changes also differed in the postpacing beat between CAD patients and normal subjects (−6 vs 5 msec; p < 0.01) or when nifedipine was injected during the pacing (4 vs 20 msec; p < 0.01). Intravenous calcium injection during atrial pacing in another group of 18 CAD patients further improved peak positive dP/dt and T1 (−3 msec; p < 0.05) and normalized the changes in relaxation during the postpacing beat. Our data indicate that a variable coupling between LV inotropic state and relaxation rate exists in man during changes in calcium influx and that this coupling is abnormal in CAD patients.

Detection of restenosis after successful coronary angioplasty: improved clinical decision making with use of a logistic model combining procedural and follow-up variables.

SummaryThe effect of dexfenfluramine (dF) on body weight, blood pressure and noradrenergic activity were studied in 30 obese hypertensive patients randomly divided into two groups and treated for 3 months either with dF (30 mg daily; 16 subjects) or placebo (Pl; 14 subjects). 11 patients from the dF group and 9 patients given Pl completed the entire experimental protocol, including monthly visits for metabolic and hormonal measurements, as well as a bicycle exercise test with arterial catheterisation for haemodynamic and catecholamine measurements performed before and after 3 months of treatment.A progressive significant decrease in body weight, averaging 6.0 kg after 3 months was observed in the dF-treated group, whereas loss of weight in the placebo group (1.4 kg) was not significant. While blood pressure and noradrenergic activity, assessed as changes in the plasma levels and urinary excretion of norepinephrine, remained unaffected in the Pl group, a significant drop in the supine systolic and diastolic blood pressures, as well as in the resting venous norepinephrine level and in urinary norepinephrine excretion was found after the first month of dF administration. In addition, the exercise-induced rise in systolic and diastolic blood pressure, as well as in arterial plasma norepinephrine and epinephrine concentrations, was significantly reduced after 3 months of dF administration; there were no such changes in the Pl-treated group.The results of the present study indicate that, in addition to the weight-reducing effect of dexfenfluramine, its hypotensive effect may be mediated by a decrease in noradrenergic activity.

Medical Decision-Making Applied to the Diagnosis of Coronary Artery Disease

A prospective study of 111 patients who underwent repeat coronary angiography and exercise thallium-201 scintigraphy 6 +/- 2 months after complete revascularization by percutaneous transluminal coronary angioplasty was performed to assess whether clinical, procedure-related and postangioplasty exercise variables yield independent information for the prediction of angiographic restenosis after angioplasty. Complete revascularization was defined as successful angioplasty of one or more vessels that resulted in no residual coronary lesion with greater than 50% diameter stenosis. Restenosis was defined as a residual stenosis at the time of repeat angiography of greater than 50% of luminal diameter. Restenosis occurred in 40% of the patients. The 111 patients were randomly subdivided into a learning group (n = 84) and a testing group (n = 27). A logistic discriminant analysis was performed in the learning group and the logistic model was used to estimate a logistic probability of restenosis. This probability of restenosis was validated in the testing group. In the learning group of 84 patients univariate analysis of 39 factors revealed 8 factors related to restenosis: recurrence of angina (p less than 0.0001), postangioplasty abnormal finding on exercise thallium-201 scintigram (p less than 0.0001), exercise thallium-201 scintigram score (p less than 0.0001), difference between exercise and rest ST segment depression (p less than 0.001), postangioplasty exercise ST segment depression (p less than 0.001), absolute postangioplasty stenosis diameter (p less than 0.003), postangioplasty exercise work load (p less than 0.03) and postangioplasty exercise heart rate (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnostic value of exercise electrocardiography and thallium myocardial scintigraphy in patients without previous myocardial infarction: a Bayesian approach.

The management of coronary artery disease (CAD) represents an excellent field for the application of methods of medical decision-making. The diagnosis of CAD is generally based on 3 sources of information, i.e. 1) pre-test or prior probability of disease derived from patients’s characteristics such as age, sex, nature of complaints and presence of risk factors, 2) results of non-invasive tests such as exercise electrocardiography and myocardial perfusion imaging, and 3) coronary arteriography which is the usually accepted reference method. The choice of a diagnostic strategy is determined by the information content of the non-invasive tests which depends on the pre-test likelihood of CAD and on the test characteristics (sensitivity and specificity). Other factors, however, play a role in the decision-making process. Firstly, beyond the mere presence or absence of CAD, the estimation of its severity (0, 1, 2 or 3 vessel-disease) can influence the choice of diagnostic tests and of therapeutic modalities. Secondly, among physicians, the opinions regarding the medical cost/benefit effectiveness of various diagnostic and therapeutic procedures may vary. Thirdly, the economic cost and the available financial resources to obtain a reduction of diagnostic uncertainty could be taken into account.