Coronary Flow Velocity Reserve Using Dobutamine Test for Noninvasive Functional Assessment of Myocardial Bridging

Background: It has been shown that coronary flow velocity reserve (CFVR) measurement by transthoracic Doppler echocardiography (TTDE) during dobutamine (DOB) provocation provides a more accurate functional evaluation of myocardial bridging (MB) compared to adenosine. However; the cut-off value of CFVR during DOB for identification of MB associated with myocardial ischemia has not been fully clarified. Purpose: This prospective study aimed to determine the cut-off value of TTDE-CFVR during DOB in patients with isolated-MB, as compared with stress-induced wall motion abnormalities (VMA) during exercise stress-echocardiography (SE) as reference. Methods: Eighty-one symptomatic patients (55 males [68%], mean age 56 ± 10 years; range: 27–74 years) with the existence of isolated-MB on the left anterior descending artery (LAD) and systolic MB-compression ≥50% diameter stenosis (DS) were eligible to participate in the study. Each patient underwent treadmill exercise-SE, invasive coronary angiography, and TTDE-CFVR measurements in the distal segment of LAD during DOB infusion (DOB: 10–40 μg/kg/min). Using quantitative coronary angiography, both minimal luminal diameter (MLD) and percent DS at MB-site at end-systole and end-diastole were determined. Results: Stress-induced myocardial ischemia with the occurrence of WMA was found in 23 patients (28%). CFVR during peak DOB was significantly lower in the SE-positive group compared with the SE-negative group (1.94 ± 0.16 vs. 2.78 ± 0.53; p < 0.001). ROC analyses identified the optimal CFVR cut-off value ≤ 2.1 obtained during high-dose dobutamine (>20 µg/kg/min) for the identification of MB associated with stress-induced WMA, with a sensitivity, specificity, positive and negative predictive value of 96%, 95%, 88%, and 98%, respectively (AUC 0.986; 95% CI: 0.967–1.000; p < 0.001). Multivariate logistic regression analysis revealed that MLD and percent DS, both at end-diastole, were the only independent predictors of ischemic CFVR values ≤2.1 (OR: 0.023; 95% CI: 0.001–0.534; p = 0.019; OR: 1.147; 95% CI: 1.042–1.263; p = 0.005; respectively). Conclusions: Noninvasive CFVR during dobutamine provocation appears to be an additional and important noninvasive tool to determine the functional severity of isolated-MB. A transthoracic CFVR cut-off ≤2.1 measured at a high-dobutamine dose may be adequate for detecting myocardial ischemia in patients with isolated-MB.

Characteristics of coronary flow velocity reserve on transthoracic Doppler echocardiography in patients with a history of Kawasaki disease

Whether the acute inflammation caused by Kawasaki disease will have an effect on the endothelial function of coronary arteries in the future is unknown. Methods: The coronary flow velocity reserve of the left anterior descending artery was examined by transthoracic Doppler echocardiography in 189 patients (male 125, female 64) with a history of Kawasaki disease and 10 volunteers (control). Their ages ranged from 6 to 40 years (median 22 years). The patients were divided into nine groups based on the left anterior descending artery lesions. The coronary flow velocity reserve was measured by intravenous administration of adenosine triphosphate (0.15 mg/kg/minute) while fasting. The coronary flow velocity reserve was calculated as the ratio of hyperaemic to basal mean diastolic flow velocities. The respective groups were as follows: control, no coronary artery lesions (n = 39), no coronary artery lesions in the right coronary artery (n = 29), regression (n = 11), aneurysm at the bifurcation of the left coronary artery (n = 26), aneurysm of the left anterior descending artery (n = 15), localised stenosis <75% (n = 12), localised stenosis ≥75% (n = 17), segmental stenosis (n = 5) and coronary artery bypass grafting (n = 36). One-factor ANOVA followed by Tukey’s test was used to compare the coronary flow velocity reserve among the groups. Results: The coronary flow velocity reserve was significantly lower in the localised stenosis ≥75%, segmental stenosis and coronary artery grafting groups than in the other groups (p < 0.05). Conclusions: The endothelial function in the epicoronary artery was preserved in patients with a history of Kawasaki disease and dilated coronary artery lesions.

Cut-off value of coronary flow velocity reserve obtained by transthoracic Doppler echocardiography during intravenous infusion of dobutamine for diagnosis of functional significant myocardial bridging

Background Recent studies showed that coronary flow velocity reserve (CFVR) measurement by transthoracic Doppler echocardiography (TTDE) during inotropic stimulation with dobutamine (DOB), in comparison to vasodilation with adenosine, provides more reliable functional evaluation of myocardial bridging (MB). However, the adequate cut-off value of CFVR during DOB for diagnosing functional significant MB has not been fully established. Purpose The purpose of the study was to evaluate the adequate cut-off value of TTDE- CFVR during DOB for diagnosis of functional significant MB. Methods This prospective study included 79 patients (54 males, mean age 55±10 years) with angiographic evidence of isolated MB on the left anterior descending artery (LAD) and systolic compression ≥50% diameter stenosis. Exercise stress-echocardiography test (ExSE) and TTDE-CFVR in the distal segment of LAD during DOB infusion (DOB: 10–40μg/kg/min) were performed in all patients. Percent diameter stenosis (DS) of MB at end-systole and end-diastole were analyzed using quantitative coronary angiography. Results Exercise-SE was positive for myocardial ischemia in 22/79 (28%). CFVR during peak DOB was significantly lower in SE-positive group in comparison to SE-negative group (1.94±0.16 vs. 2.78±0.53, p&lt;0.001). ROC analysis identifies the optimal CFVR during peak DOB cut-off value &lt;2.1 (AUC 0.985, 95% CI: 0.965–1.000, p&lt;0.001), with a sensitivity of 96% and specificity of 95%, positive predictive value of 88%, and negative predictive value of 98%, for identifying functionally significant MB associated with stress-induced myocardial ischemia. The categorical agreement between TTDE-CFVR at peak DOB and ExSE was high (kappa value = 0.877, p&lt;0.001). Multivariate logistic regression analysis showed that percent DS at end-diastole was the only independent predictor of ischemic CFVR value &lt;2.1 (OR: 1.136, 95% CI: 1.045–1.235, p=0.003). Conclusion A cut-off value &lt;2.1 of CFVR during DOB infusion obtained by TTDE may adequate discriminate functional significant MB that induce myocardial ischemia which is caused by an incomplete diastolic MB-decompression. FUNDunding Acknowledgement Type of funding sources: None.

Early effect of percutaneous coronary intervention of non-left anterior descending artery on coronary flow velocity reserve of left anterior descending artery assessed by transthoracic Doppler echocardiography

Background Limited data are available regarding the influence of percutaneous coronary intervention (PCI) of non-totally occluded lesions (non-CTO) on the coronary flow of non-target vessels. We sought to investigate the short-term impact of the non-left anterior descending artery (non-LAD) PCI on the coronary flow physiology of LAD using transthoracic Doppler echocardiography (TDE). Methods and results We consecutively studied 50 patients who underwent successful PCI of non-LAD and non-CTO lesions and a coronary flow velocity assessment of LAD at rest and maximal hyperemia before and at 2 days after the procedure by TDE. Coronary flow velocity reserve (CFVR) was calculated as the ratio of hyperemic to resting diastolic peak velocity (hDPV/bDPV). We evaluated the changes in LAD coronary flow characteristics after PCI of non-LAD and explored the determinants of the change in LAD-CFVR. The median fractional flow reserve (FFR) of the culprit lesion and the LAD quantitative flow ratio (QFR) were 0.67 and 0.88, respectively. After non-LAD PCI, LAD-CFVR was decreased in 33 patients (66.0%). LAD-CFVR significantly decreased (pre-PCI: 2.41, post-PCI: 2.03, p = 0.001) due to a significant decrease in LAD-hDPV (P = 0.007). The prevalence of impaired LAD-CFVR (≤2.0) significantly increased (pre: 30%, post: 48%, P = 0.027). Multivariable linear regression analysis showed that pre-PCI LAD-CFVR was independent predictor of the change in LAD-CFVR after PCI. Conclusions LAD-CFVR significantly decreased after successful non-LAD PCI due to the postprocedural reduction of coronary flow assessed by LAD-hDPV.