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Abstract
BACKGROUND: A measurement of the coronary flow velocity reserve (CFVR) with transthoracic Doppler echocardiography (TDE) is a good noninvasive method for detecting a coronary stenosis. However, microcirculatory impairment is a major limitation in assessing the coronary stenosis by CFVR. The effect of microcirculatory impairment on the CFVR can be minimized, and the diagnostic accuracy for detecting a coronary restenosis can be improved using serial evaluations of the CFVR.
METHODS: This study prospectively measured the CFVR in 36 consecutive patients (age; 57±11 years, 23 men), in whom a successful PCI of the left anterior descending artery (LAD) was performed. The coronary flow velocity in the distal LAD was measured by TDE, and the CFVR was calculated. The initial CFVR measurement (CFVR0) was performed the next day after the PCI, and a follow-up CFVR measurement (CFVR1) was obtained on the day before the 6-month follow-up CAG. A significant decrease in the CFVR1 was defined as (CFVR0-CFVR1)/CFVR0>0.1, and a restenosis was defined as >50% of the stenosis diameter on a quantitative CAG.
RESULTS: Adequate TDE studies for the CFVR were performed in all patients, and the follow-up CAG showed a restenosis in 9 (25%) patients. The sensitivity and specificity of the CFVR1 <2.0 was 5/9 (56%), 27/27 (100%), and those of the CFVR1 <2.5 were 8/9 (89%), 22/27 (81%) for predicting a LAD restenosis, respectively. The significant decrease in the CFVR had a sensitivity of 9/9 (100%) and a specificity of 25/27 (93%). In addition, in the 15 patients with either diabetes or LVH, the significant decrease in the CFVR was more accurate (15/15, 100%) than the CFVR1 <2.5 (11/15, 73%).
CONCLUSIONS: Regardless of the associated microvascular impairment, a serial noninvasive assessment of the CFVR by TDE can improve the diagnostic accuracy of CFVR for detecting a LAD restenosis.
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