Coronary artery disease
Relation of Myocardial Perfusion Defects and Nonsignificant Coronary Lesions by Angiography With Insights from Intravascular Ultrasound and Coronary Pressure Measurements

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Several studies have demonstrated a correlation between myocardial ischemia and severity of coronary lesions as determined by intravascular ultrasound (IVUS) and fractional flow reserve (FFR) measurements. However, their value for the assessment of mild coronary stenoses that are associated with myocardial perfusion abnormalities has not been well studied. The objective of this study was to prospectively compare the results of myocardial perfusion as determined by exercise/dipyridamole myocardial single-photon emission computed tomography with IVUS and FFR measurements in patients who had angiographically mild coronary stenosis (<50% diameter stenosis by quantitative coronary angiography). Forty-eight patients who had stable coronary disease (61 ± 11 years of age; 6 women) were included. All had mild coronary stenosis in the proximal/middle segment of ≥1 coronary artery and had undergone maximal exercise myocardial technetium-99m tetrofosmin single-photon emission computed tomography within 48 hours before coronary angiography. IVUS measurements included lesion lumen area, external elastic membrane area, lesion plaque burden (calculated as external elastic membrane minus lumen area, divided by external elastic membrane, and multiplied by 100), and lumen area stenosis (calculated as reference lumen area minus lesion lumen area, divided by reference lumen area, multiplied by 100). Fifty-three coronary lesions were studied, with a mean percent diameter stenosis of 34.9 ± 7.9% on angiography. Myocardial perfusion defects were demonstrated by single-photon emission computed tomography in 11 patients (12 myocardial regions) with no differences in lesion percent diameter stenosis compared with those without perfusion defects. The presence of reversible perfusion defects was associated with a higher lesion plaque burden as evaluated by IVUS (67.4 ± 8.1% vs 60.2 ± 9.3%, p = 0.01). FFR values did not differ in the presence or absence of perfusion defects (0.90 ± 0.06 vs 0.92 ± 0.07, respectively; p = NS). In conclusion, plaque burden as determined by IVUS may partly explain the presence of myocardial perfusion defects in cases of angiographically nonsignificant coronary lesions. However, the high FFR values associated with these lesions suggest that other mechanisms, such as endothelial/microvascular dysfunction, might also account for perfusion abnormalities in these patients.

Section snippets

Study population

The study population consisted of 48 patients who had mild coronary stenosis (<50% diameter stenosis) in the proximal/middle segment of ≥1 coronary artery and had been included in a study of coronary atherosclerosis progression and regression. Patients who had another lesion in the evaluated coronary artery and/or had lesions with >50% diameter stenosis were excluded. The decision about patients’ treatment was left to the discretion of the cardiologist who was responsible for the patient, and

Results

Clinical characteristics of the study population are presented in Table 1. All patients underwent myocardial perfusion single-photon emission computed tomography, coronary angiography, IVUS, and FFR measurements, and no complications were observed with any of these explorations.

Discussion

The results of this study showed that, in a population of patients who had stable coronary disease, up to 23% of angiographically mild coronary lesions were associated with myocardial perfusion defects as determined by single-photon emission computed tomography. Angiographic severity of these lesions was similar to that of lesions that were not associated with myocardial perfusion defects, but a greater lesion plaque burden as determined by IVUS was demonstrated in the presence of perfusion

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    This study was supported by grants from the Sociedad Española de Cardiologia and the Redes Temáticas de Investigación Cooperativa, Instituto Carlos III (Red C03/01, RECAVA), Madrid, Spain.

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