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      Early dipyridamole stress myocardial SPECT to detect residual stenosis of infarct related artery: comparison with coronary angiography and fractional flow reserve.

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          Abstract

          Background

          The detection of residual stenosis of infarct related artery (IRA) at early stage after acute myocardial infarction (AMI) is crucial in clinical decision making for interventional revascularization. The aim of this study was to evaluate the relevancy of early dipyridamole stress myocardial SPECT to detect functionally and luminologically significant residual stenosis of IRA after AMI.

          Methods

          Twenty five consecutive patients (M:F=19:6, age: 56±13yrs) with AMI underwent SPECT and coronary angiography within 5 days of the attack. Infarct related arteries with FFR < 0.75 and diameter stenosis (DST) >70% were regarded to have functionally and morphologically significant residual stenosis. Reversible perfusion defect was defined if there was improvement of the perfusion score more than one grade in infarct segments on rest images of SPECT compared with stress images.

          Results

          Mean FFR and DST were 0.76±0.14 and 74±15%. SPECT showed no significant correlation with both FFR and DST with Kendall’s coefficiency of 0.28 (p=0.05) and 0.13 (p=0.35). The sensitivity and specificity of SPECT to detect functionally and morphologically significant residual stenosis were 92%, 31% and 83%, 29%.

          Conclusion

          The early dipyridamole stress myocardial SPECT after AMI does not seem to be a useful non-invasive test for the detection of functionally and luminologically significant residual stenosis of IRA.

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          Most cited references 31

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          Measurement of fractional flow reserve to assess the functional severity of coronary-artery stenoses.

          The clinical significance of coronary-artery stenoses of moderate severity can be difficult to determine. Myocardial fractional flow reserve (FFR) is a new index of the functional severity of coronary stenoses that is calculated from pressure measurements made during coronary arteriography. We compared this index with the results of noninvasive tests commonly used to detect myocardial ischemia, to determine the usefulness of the index. In 45 consecutive patients with moderate coronary stenosis and chest pain of uncertain origin, we performed bicycle exercise testing, thallium scintigraphy, stress echocardiography with dobutamine, and quantitative coronary arteriography and compared the results with measurements of FFR. In all 21 patients with an FFR of less than 0.75, reversible myocardial ischemia was demonstrated unequivocally on at least one noninvasive test. After coronary angioplasty or bypass surgery was performed, all the positive test results reverted to normal. In contrast, 21 of the 24 patients with an FFR of 0.75 or higher tested negative for reversible myocardial ischemia on all the noninvasive tests. No revascularization procedures were performed in these patients, and none were required during 14 months of follow-up. The sensitivity of FFR in the identification of reversible ischemia was 88 percent, the specificity 100 percent, the positive predictive value 100 percent, the negative predictive value 88 percent, and the accuracy 93 percent. In patients with coronary stenosis of moderate severity, FFR appears to be a useful index of the functional severity of the stenoses and the need for coronary revascularization.
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            Experimental basis of determining maximum coronary, myocardial, and collateral blood flow by pressure measurements for assessing functional stenosis severity before and after percutaneous transluminal coronary angioplasty.

            Severity of coronary artery stenosis has been defined in terms of geometric dimensions, pressure gradient-flow relations, resistance to flow and coronary flow reserve, or maximum flow capacity after maximum arteriolar vasodilation. A direct relation between coronary pressure and flow, however, may only be presumed if the resistances in the coronary circulation are constant (and minimal) as theoretically is the case during maximum arteriolar vasodilation. In that case, pressure measurements theoretically can be used to predict maximum flow and assess functional stenosis severity. A theoretical model was developed for the different components of the coronary circulation, and a set of equations was derived by which the relative maximum flow or fractional flow reserve in both the stenotic epicardial artery and the myocardial vascular bed and the proportional contribution of coronary arterial and collateral flow to myocardial blood flow are calculated from measurements of arterial, distal coronary, and central venous pressures during maximum arteriolar vasodilation. To test this model, five dogs were acutely instrumented with an epicardial, coronary Doppler flow velocity transducer. Distal coronary pressures were measured by an ultrathin pressure-monitoring guide wire (0.015 in.) with minimal influence on transstenotic pressure gradient. Fractional flow reserve was calculated from the pressure measurements and compared with relative maximum coronary artery flow measured directly by the Doppler flowmeter at three different levels of arterial pressure for each of 12 different severities of stenosis at each pressure level. Relative maximum blood flow through the stenotic artery (Qs) measured directly by the Doppler flowmeter showed an excellent correlation with the pressure-derived values of Qs (r = 0.98 +/- 0.01, intercept = 0.02 +/- 0.03, slope = 0.98 +/- 0.04), of the relative maximum myocardial flow (r = 0.98 +/- 0.02, intercept = 0.26 +/- 0.07, slope = 0.73 +/- 0.08), and of the collateral blood flow (r = 0.96 +/- 0.04, intercept = 0.24 +/- 0.07, slope = -0.24 +/- 0.06). Moreover, the theoretically predicted constant relation between mean arterial pressure and coronary wedge pressure, both corrected for venous pressure, was confirmed experimentally (r = 0.97 +/- 0.03, intercept = 9.5 +/- 13.3, slope = 4.4 +/- 1.2). These results provide the experimental basis for determining relative maximum flow or fractional flow reserve of both the epicardial coronary artery and the myocardium, including collateral flow, from pressure measurements during maximum arteriolar vasodilation. With a suitable guide wire for reliably measuring distal coronary pressure clinically, this method may have potential applications during percutaneous transluminal coronary angioplasty for assessing changes in the functional severity of coronary artery stenoses and for estimating collateral flow achievable during occlusion of the coronary artery.
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              Risk stratification and survival after myocardial infarction.

               AJ Moss (1983)
              We assessed the role of physiologic measurements of heart function in predicting mortality after myocardial infarction. Most of the 866 patients enrolled in our multicenter study underwent 24-hour Holter monitoring and determination of the resting radionuclide ventricular ejection fraction before discharge. Univariate analyses showed a progressive increase in cardiac mortality during one year as the ejection fraction fell below 0.40 and as the number of ventricular ectopic depolarizations exceeded one per hour. Only four risk factors among eight prespecified variables were independent predictors of mortality: an ejection fraction below 0.40, ventricular ectopy of 10 or more depolarizations per hour, advanced New York Heart Association functional class before infarction, and rales heard in the upper two thirds of the lung fields while the patient was in the coronary-care unit. Various combinations of these four factors identified five risk subgroups with two-year mortality rates ranging from 3 per cent (no factors) to 60 per cent (all four factors).
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                Author and article information

                Affiliations
                Division of Cardiology, Departments of Internal Medicine, Inha University College of Medicine, Inchon, Korea
                [* ]Nuclear Medicine, Inha University College of Medicine, Inchon, Korea
                Author notes
                Address reprint requests to: Jeong Kee Seo, M.D., Division of Cardiology, Departments of Internal Medicine, Inha University College of Medicine, 7-206, Shinheung-Dong 3-Ga, Jung-Ku, Inchon, Korea, 400-103
                Journal
                Korean J Intern Med
                Korean J. Intern. Med
                The Korean Journal of Internal Medicine
                Korean Association of Internal Medicine
                1226-3303
                2005-6648
                March 2002
                : 17
                : 1
                : 7-13
                kjim-17-1-7-2
                10.3904/kjim.2002.17.1.7
                4531649
                12014218
                Copyright © 2002 The Korean Association of Internal Medicine

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

                Categories
                Original Article

                Internal medicine

                single-photon, emission-computed, tomography, dipyridamole, myocardial infarction

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