Measurement Of Coronary Flow Velocity Reserve Research Articles

Coronary Microvascular Dysfunction Restored After Surgery in Inflammatory Bowel Disease: A Prospective Observational Study.

BackgroundWe aimed to investigate the presence and severity of coronary microvascular dysfunction (CMD) in inflammatory bowel disease (IBD) including Crohn disease and ulcerative colitis and to elucidate the influence of surgical resection of the diseased intestines on CMD by assessing coronary flow velocity reserve (CFVR) using transthoracic Doppler echocardiography.Methods and ResultsThirty‐seven patients with IBD (aged 44±15 years; 22 patients with Crohn disease and 15 patients with ulcerative colitis) and 30 controls (aged 46±12 years) were enrolled. For CFVR measurement, coronary flow velocity was recorded at rest and during hyperemia by ADP infusion using transthoracic Doppler echocardiography, and CFVR <2.5 defined CMD. CFVR measurement was repeated before and within 1 year after surgery. CFVR was similarly and significantly lower in patients with Crohn disease and those with ulcerative colitis than controls (Crohn disease: 2.92±1.03 [P<0.05 versus controls], ulcerative colitis: 2.99±0.65 [P<0.05 versus controls], and controls: 3.84±0.75). Multiple linear regression analysis showed that the presence of IBD and baseline hs‐CRP (high‐sensitivity C‐reactive protein) were independently associated with low CFVR among all study participants (β=−0.403 [P=0.001] and −0.237 [P=0.037], respectively). Hyperemic coronary flow velocity significantly improved after surgery only in patients with IBD who had CMD. CFVR significantly improved in patients with IBD who had both CMD and non‐CMD, and the extent of CFVR improvements were greater in patients with CMD than non‐CMD. Multiple linear regression analysis showed that the reduction of hs‐CRP was independently associated with improvement of hyperemic coronary flow velocity and CFVR among all patients with IBD (β=−0.481 [P=0.003] and β=−0.334 [P=0.043], respectively).ConclusionsIBD is associated with CMD, which improved after surgical resection of diseased intestines.

Prognostic Value of Preserved Coronary Flow Velocity Reserve by Noninvasive Transthoracic Doppler Echocardiography in Patients With Angiographically Intermediate Left Main Stenosis

The potential of angiography to evaluate the hemodynamic severity of a left main coronary artery (LM) stenosis is limited. Noninvasive transthoracic Doppler echocardiographic coronary flow velocity reserve (CFVR) evaluation of intermediate coronary stenosis has demonstrated remarkably high negative prognostic value. The aim of this study was to assess clinical outcomes in patients with angiographically intermediate LM stenosis and preserved CFVR (>2.0) as evaluated by transthoracic Doppler echocardiographic CFVR. The initial study population included 102 patients with intermediate coronary stenosis of the LM referred for transthoracic Doppler echocardiographic CFVR assessment. Peak diastolic CFVR measurements were performed in the distal segment of the left anterior descending coronary artery after intravenous adenosine (140μg/kg/min), and CFVR was calculated as the ratio between maximal hyperemic and baseline coronary flow velocity. Nineteen patients had impaired CFVR (≤2.0) and were excluded from further analysis, as well as two patients with poor acoustic windows. The final group consisted of 81 patients (mean age, 60±9years; 76 men) evaluated for adverse cardiac events including death, myocardial infarction, and revascularization. Mean follow-up duration was 62±26months. Mean CFVR was 2.4±0.4. Total event-free survival was 75 of 81 (92.6%), as six patients were referred for revascularization (five patients with coronary artery bypass grafting, one patient with percutaneous coronary intervention). There were no documented myocardial infarctions or cardiovascular deaths in the follow-up period. In patients with angiographically intermediate and equivocal LM stenosis and preserved CFVR values of >2.0, revascularization can be safely deferred.

Coronary microvascular dysfunction is not associated with a history of reproductive risk factors in women with angina pectoris—An iPOWER substudy

BackgroundReproductive risk factors such as preeclampsia and recurrent miscarriages have been associated with adverse cardiovascular (CV) events. Underlying coronary microvascular dysfunction (CMD) may be a common denominator. PurposeWe investigated whether a history of reproductive risk factors was associated with CMD in women with angina pectoris and no obstructive coronary artery disease (CAD). MethodsParticipants from the iPOWER study, including women with angina pectoris and no obstructive CAD (<50% stenosis), were invited to complete an electronic survey regarding reproductive risk factors: recurrent miscarriages, gestational diabetes, preeclampsia, rhesus immunity, polycystic ovary syndrome and menopausal status as well as migraine and Raynaud phenomenon. CMD was assessed by transthoracic Doppler echocardiography with measurement of coronary flow velocity reserve (CFVR) during high-dose dipyridamole infusion, and analyzed in three categories with cut-off points at 2.0 and 2.5. Associations between CFVR and a history of reproductive risk factors were examined by age-adjusted trend test. ResultsThe questionnaire was completed by 613 women (73% of those invited), of whom 550 had a successful CFVR measurement. There was no significant difference in baseline characteristics between participants and non-participants. Median (interquartile range (IQR)) age was 62.8 (54.8; 68.7) years, median (IQR) BMI 26.2 (23.2; 29.8) kg/m2, and 81.5% were postmenopausal. We did not find any significant associations between any of the reproductive risk factors, Raynaud’s phenomenon or migraine and CFVR. ConclusionThe lack of association between coronary microvascular function and a history of reproductive risk factors, migraine and Raynaud’s phenomenon suggests that a common vascular pathophysiological mechanism underlying these conditions is unlikely.

Noninvasive assessment of coronary blood flow by transthoracic Doppler echocardiography: basic to practical use in the emergency room.

Echo Doppler is widely available in the clinical setting, and the feasibility of coronary flow detection in the left anterior descending coronary artery has been reported as >90% with the use of a high-frequency transducer. Coronary flow detection takes only a few minutes by skilled echocardiologists, and this noninvasive technique can provide useful physiological information in patients with various types of coronary artery disease. Coronary flow velocity reserve measurement by echo Doppler is a simple and easy technique. It is available in the echo laboratory as well as in the outpatient clinic, and can be used as an alternative examination to screen for significant coronary stenosis in patients with stable angina. Moreover, physiological information provided by coronary flow velocity reserve can be used in combination with other imaging modalities that can provide anatomical information of the coronary arteries such as coronary computed tomography or coronary angiography. Coronary flow velocity in patients with acute coronary syndrome (ACS) enables rapid noninvasive differentiation of TIMI-III from TIMI-II coronary reperfusion before emergency coronary intervention. Transthoracic coronary flow detection by echo Doppler contributes to the assessment of the coronary reperfusion status in the emergency room for patients with ACS, prior to invasive coronary angiography.

Effects of nitroglycerine on coronary flow velocity before and during adenosine provocation.

BackgroundTransthoracic echocardiography-assessed coronary flow velocity reserve (CFVR) evaluates coronary microvascular arterial function. Coronary flow velocity measurements at baseline and during hyperemia are used to calculate CFVR. Adenosine infusion induces hyperemia but it is not known if it causes a maximal response. We hypothesized that pre-treatment with nitroglycerine before adenosine provocation enhances hyperemia.MethodsTwenty-three healthy study subjects (mean age 27.5 ± 5.5, 35% women) underwent CFVR measurements before and after pretreatment with sublingual nitroglycerine (0.5 mg). Hyperemia was induced by adenosine infusion (140 μg/kg/min). In addition, the effect of nitroglycerin on left main coronary artery diameter was assessed.ResultsPretreatment with nitroglycerine increased median CFVR from 3.6 (range 2.8–4.3) to 5.0 (4.1–6.0), p = 0.002. The increase was caused by a marked reduction in baseline coronary flow velocity 17 (15–24) vs 27 (19–31) cm/s, p < 0.0001) while hyperemic velocity remained unchanged (90 (68–116) vs 93 (75–105) cm/s, p = 0.48). Nitroglycerin significantly dilated the left main coronary artery (from median 3.1 (2.7–3.6) mm to 3.8 (3.1–4.3) mm, p = 0.018).ConclusionPretreatment with nitroglycerine dilates coronary arteries and increases coronary flow velocity reserve indicating that adenosine alone causes a submaximal hyperemia.

Noninvasive assessment of myocardial bridging by coronary flow velocity reserve with transthoracic Doppler echocardiography: vasodilator vs. inotropic stimulation

BackgroundTo consider hemodynamic assessment of myocardial bridging (MB) adequate, it is believed that inotropic stimulation with dobutamine should be estimated because its dynamic nature depends on the degree of extravascular coronary compression. This study evaluated comparative assessment of hemodynamic relevance of MB using coronary flow velocity reserve (CFVR) measurements by transthoracic Doppler echocardiography (TTDE) with vasodilatative and inotropic challenges. MethodsThis prospective study included forty-four patients with angiographic evidence of isolated MB of the left anterior descending coronary artery (LAD) and systolic compression of ≥50% diameter stenosis. All patients were evaluated by exercise stress-echocardiography (ExSE) test for signs of myocardial ischemia, and CFVR of the distal segment of LAD during iv.infusion of adenosine (ADO:140μg/kg/min) and iv.infusion of dobutamine (DOB:10-40μg/kg/min), separately. ResultsExercise-SE was positive for myocardial ischemia in 8/44 (18%) of patients. CFVR during ADO was significantly higher than CFVR during peak DOB (2.85±0.68 vs. 2.44±0.48, p=0.002). CFVR during peak DOB was significantly lower in SE-positive group in comparison to SE-negative group (2.01±0.16 vs. 2.54±0.47, p<0.001), but not for ADO (2.47±0.51 vs. 2.89±0.70, p=0.168), respectively. Multivariable logistic analysis showed that CFVR peak DOB was the most significant predictor of functional significant MB (OR 0.011, 95%CI: 0.001–0.507, p=0.021). Receiver-operating characteristic curves have shown that TTDE-CFVR obtained by high-dose of dobutamine infusion is better than those by adenosine regarding to functional status of MB (AUC 0.861, p=0.004; AUC 0.674, p=0.179, respectively). ConclusionsNon-invasive CFVR measurement by TTDE during inotropic stimulation, in comparison to vasodilation, provides more reliable functional evaluation of MB.

A novel method for left anterior coronary artery flow velocity assessment by transthoracic echocardiography at the peak of a supine bicycle test.

Assessment of coronary flow is only performed during pharmacological tests. Supine bicycle tests permit the visualization of coronary flow assessments during exercise. To assess the parameters of coronary flow in the left anterior descending artery (LAD) during exercise, which could be a sign of significant LAD narrowing. A total of 253 patients were enrolled: Group 1, 186 non-selective participants before undergoing a coronary angiography; and Group 2, 67 controls without coronary artery disease (CAD). All the patients performed a supine bicycle echocardiography test. Coronary flow velocities and coronary flow velocity reserve (CFVR) were measured at the mid-segment of the LAD during exercise. Patients in Group 1 underwent a coronary angiography. In comparison with participants without significant LAD stenosis, patients with LAD lesions had a lower ΔV (16 ± 21 vs. 27 ± 20 cm/s, P < 0.04) and a lower CFVR (1.5 ± 0.8 vs. 2.0 ± 0.6, P < 0.004). In comparison with patients without significant proximal LAD stenosis, the patients with proximal LAD lesions had a lower flow velocity at the peak of exercise (49 ± 32 vs. 61 ± 19 cm/s, P < 0.02), a lower ΔV (13 ± 19 vs. 26 ± 22 cm/s, P < 0.004), and a lower CFVR (1.4 ± 0.6 vs. 1.9 ± 0.7, P < 0.0001). In comparison with the control group, the patients with LAD stenosis had a lower flow velocity at the peak of exercise, a lower ΔV, and a lower CFVR. Non-invasive CFVR measurement in the LAD could provide valuable additional information to a conventional echocardiography exercise test. In routine clinical practice, CFVR is sufficient for a diagnosis of severe stenosis.

Coronary Artery Imaging with Transthoracic Doppler Echocardiography

Coronary artery imaging with transthoracic Doppler echocardiography is a simple and useful technique to diagnose significant coronary artery stenosis. The visualization of mosaic flow in the proximal left coronary artery provides a direct indication of the presence of significant stenosis at the corresponding site during routine echocardiography. Coronary flow velocity reserve (CFVR) has a high diagnostic accuracy and feasibility in detecting the presence of functionally significant coronary stenosis in the left anterior descending coronary artery (LAD) and in the right coronary artery. The measurement of CFVR in the LAD also provides prognostic information in patients with intermediate coronary stenosis. This review summarizes the utility of transthoracic coronary artery imaging.

Coronary Flow Velocity Reserve Assessed by Transthoracic Doppler: The iPOWER Study: Factors Influencing Feasibility and Quality

Coronary flow velocity reserve (CFVR) measured by transthoracic Doppler echocardiography is a noninvasive measure of microvascular function, but it has not achieved widespread use, mainly because of concerns of validity and feasibility. The aim of this study was to describe the feasibility and factorsassociated with the quality of CFVR obtained in a large prospective study of women suspected of having microvascular disease. Women with angina-like chest pain and no obstructive coronary artery disease on coronary angiography (<50% stenosis) were consecutively examined by transthoracic Doppler echocardiography of the left anterior descending coronary artery to measure CFVR (n=947). Quality was evaluated on the basis of(1)identification of the left anterior descending coronary artery, (2) maintained probe position throughout the examination, (3) visibility and configuration of the left anterior descending coronary artery in two-dimensional color Doppler mode, and (4) gradual, consistent increases of characteristic, well-defined flow velocity curves in pulsed-wave mode. The mean age (SD) was 62.1±9.7 years. On the basis of the evaluations, patients were divided into four groups according to quality score: nonfeasible (n=28 [3%]), low quality (n=80 [8%]), medium quality (n=451 [48%]), and high quality (n=388 [41%]). Quality score was associated with diabetes (P<.01), body mass index (P=.02), waist circumference (P=.05), nonsignificant atherosclerosis on coronary angiography (P=.03), and operator experience (P<.01). Low examination quality was associated with lower CFVR (P=.03), also after multivariate adjustment. Transthoracic Doppler echocardiographic measurement of CFVR is highly feasible and of good quality in experienced hands. However, CFVR is possibly underestimated when examination quality is low. Awareness of pitfalls and potential bias may improve the validity and interpretation of the measures obtained.

Coronary Flow Velocity Reserve Assessment with Transthoracic Doppler Echocardiography.

Coronary flow velocity reserve (CFVR) reflects global coronary atherosclerotic burden, endothelial function and state of the microvasculature. It could be measured using transthoracic Doppler echocardiography in a non-invasive, feasible, reliable and reproducible fashion, following a standardised protocol with different vasodilatory stimuli. CFVR measurement is a recommended complement to vasodilator stress echocardiography. It could serve as a diagnostic tool for coronary microvascular dysfunction and in the setting of epicardial coronary artery stenoses could help in identification and assessment of functional significance of coronary lesions and follow-up of patients after coronary interventions. CFVR has also a prognostic significance in different clinical situations.

Incremental Value of Coronary Flow Velocity Reserve, Measured by Transthoracic Echocardiography, Compared with Computed Tomography Angiography Alone, for Detecting Flow-Limiting Coronary Stenoses

Computed tomographic (CT) angiography provides high sensitivity for the detection of coronary stenosis, while its specificity is relatively low. The aim of this study was to determine the incremental value of coronary flow velocity reserve (CFVR) by transthoracic echocardiography when used with CT angiography for detecting stenosis of the major coronary arteries compared with invasive quantitative coronary angiography. Sixty patients who underwent CFVR measurement before coronary angiography were retrospectively selected, and the cutoff value of CFVR to predict diameter stenosis > 70% was determined using receiver operating characteristic curve analysis. Second, CFVR measurement and CT angiography were prospectively performed in 50 patients who were scheduled to undergo coronary angiography. CT angiography using a 64-detector row scanner and CFVR measurement in the proximal to middle portions of the three major coronary arteries by transthoracic echocardiography were performed on the same day, <48hours before invasive angiography. The cutoff values of CFVR were determined to be 2.0 for the left anterior descending coronary artery and 2.1 for the circumflex and right coronary arteries. Using these determined cutoff values, the sensitivity, specificity, and positive and negative predictive value of CFVR to identify diameter stenosis ≥ 70% stenosis on invasive quantitative coronary angiography were determined to be 84%, 87%, 66%, and 95%, respectively, and those of CT angiography were 91%, 80%, 58%, and 97%, respectively, in the prospective study with 50 patients. The combination of ≥70% stenosis on CT angiography and impaired CFVR was 94% specific for ≥70% stenosis, while the presence of <70% stenosis on CT angiography and preserved CFVR was 100% specific for the exclusion of ≥70% stenosis on invasive quantitative coronary angiography. When the results of CT angiography and CFVR are concordant, the combination is highly accurate in the detection and exclusion of coronary stenosis. CFVR measurement in addition to CT angiography could behelpful in identifying false-positive CT angiographic results.

The Association between Aortic Distensibility and Coronary Flow Reserve in Newly Diagnosed Diabetic Patients

Aortic distensibility (AD) is an important parameter affecting coronary hemodynamics. Coronary flow velocity reserve (CFVR) is a reliable marker of coronary endothelial function in diabetic patients. The aim of this study was to investigate the association between AD and CFVR in newly diagnosed diabetic patients. We studied 77 patients with newly diagnosed diabetes mellitus (DM) and 30 age- and sex-matched healthy control subjects. CFVR was calculated as the hyperemic to resting coronary diastolic velocities ratio by using transthoracic echocardiography. Pulse pressure (PP) and AD were calculated. Fasting blood glucose, HbA1c and PP were significantly higher in patients with diabetes (P < 0.001, P < 0.001 and P = 0.009, respectively). Other clinical and demographical characteristics, laboratory findings and echocardiographic findings were similar in both groups (P > 0.05, for all). The measurement of CFVR and AD in patients with diabetes were significantly lower compared with the controls (P < 0.001 and P = 0.001, respectively). CFVR was significantly negatively correlated with age, body mass index, HbA1c, systolic blood pressure, and PP, while significantly positively correlated with AD (P < 0.05, for all). Multivariate regression analysis showed that only AD (β = 0.485, P < 0.0001) and HbA1c (β = -0.362, P < 0.0001) were independently associated with CFVR. The cutoff value of AD obtained by the receiver operator characteristic (ROC) curve analysis was 2.44 for the prediction of impaired CFVR. Aortic distensibility and HbA1c were independently associated with CFVR. The decrease in AD may be used as a marker of impaired coronary microcirculation in asymptomatic diabetic patients.

Detection of Coronary Artery Disease Using Coronary Flow Velocity Reserve by Transthoracic Doppler Echocardiography versus Multidetector Computed Tomography Coronary Angiography: Influence of Calcium Score

There have been no clinical data specifying the degree of calcium deposition at which coronary flow velocity reserve (CFVR) measurement using transthoracic Doppler echocardiography surpasses 320-row multidetector computed tomographic coronary angiography (CTCA) in detecting obstructive coronary artery disease. One hundred seventy patients who underwent invasive coronary angiography, transthoracic Doppler echocardiography, and CTCA were prospectively enrolled. Coronary artery stenosis was defined as percentage diameter stenosis ≥ 50% on invasive coronary angiography. CFVR < 2.0 and narrowing ≥ 50% measured with CTCA were the thresholds indicating the presence of coronary artery stenosis. The degree of coronary artery calcification was also assessed using the Agatston calcium score method by computed tomography. The majority of patients (89%) were classified as having either high or intermediate pretest probability of coronary artery disease. Significant coronary artery stenoses by invasive coronary angiography were found in 71 patients and 104 vessels. Although the overall diagnostic performance of CTCA was comparable with that of CFVR measurement for detecting coronary artery stenosis, only the diagnostic performance of CTCA was negatively affected by the extent of a patient's coronary artery calcification. Receiver operating characteristic curve analysis indicated that only CFVR measurement is diagnostically accurate when calcium scores are >319 in the patient-based assessment, 189 for the left anterior descending coronary artery, 98 for the left circumflex coronary artery and 282 for the right coronary artery. Transthoracic Doppler echocardiography and 320-row multidetector CTCA successfully diagnosed significant coronary artery stenosis with high feasibility and accuracy. However, only the diagnostic performance of CTCA was negatively affected by the extent of a patient's coronary artery calcification, and therefore the diagnostic performance of CFVR measurement for detecting coronary artery stenosis surpassed that of CTCA when the calcium score exceeded specified cutoff values.

Coronary flow velocity reserve in three major coronary arteries by transthoracic echocardiography for the functional assessment of coronary artery disease: a comparison with fractional flow reserve

Coronary flow velocity reserve (CFVR) measurement in three major coronary arteries by transthoracic echocardiography is a promising and non-invasive method for detecting myocardial ischaemia. Its value when compared with fractional flow reserve (FFR) is unknown. Our aim was to determine the diagnostic accuracy of CFVR in three major coronary arteries for detecting ischaemia compared with FFR. This is a prospective study in 172 vessels of 140 patients with at least one ≥50% stenosis in a major epicardial artery as determined by visual assessment on computed tomography coronary angiography. We performed CFVR measurement by transthoracic echocardiography within 48 h before coronary angiography and FFR measurement. The cut-off value of CFVR was estimated by the receiver operating characteristic (ROC) curve based on that of FFR ≤0.75. The CFVR was 1.86 ± 0.36 in coronary arteries with FFR ≤0.75 (n = 79) and 2.54 ± 0.48 in those with FFR >0.75 (n = 93, P < 0.0001). CFVR with cut-off of 2.2, determined by the ROC curve, was 85% sensitive and 79% specific in predicting the stenotic condition of the coronary artery with FFR ≤0.75 in three major vessels. In each vessel, the sensitivity and specificity were 85 and 78% (left anterior descending coronary artery), 94 and 83% (right coronary artery), and 88 and 88% (left circumflex coronary artery). CFVR was indirect proportional to FFR (r = 0.56, P < 0.0001) and to per cent diameter stenosis (r = 0.26, P = 0.0008). The non-invasive CFVR measurement could be a reliable stenosis-specific method for determining the haemodynamic significance of three major coronary arteries.

Coronary Microvasculature

Hemodynamic measurements in vivo during heart catheterization are increasingly used to drive clinical decision making in the cardiac catheterization laboratory.1 Coronary flow velocity reserve (CFVR), also referred to as coronary flow reserve, was introduced in the 1970s and was one of the first hemodynamic measurements which could be applied clinically to help evaluate these lesions.2 Moreover, the development of Doppler-tipped guide wires allowed CFVR measurements to be readily obtained. CFVR is defined as the ratio of steady-state hyperemic average peak velocity to resting average peak velocity for the artery of interest (target vessel). The concept is based on observations that increased oxygen demand is met under physiological conditions through a 4 to 5 fold increase in myocardial blood flow caused by autoregulation, and that the degree of epicardial or microvascular resistance can be determined by the ratio of hyperemic to resting blood flow. Although invasively measured CFVR is considered the gold standard, CFVR can also be measured by noninvasive imaging modalities, such as positron emission tomography, single-photon emission computerized tomography, transthoracic Doppler or myocardial contrast echocardiography, or cardiac MRI.3 Article see p 329 It is important to emphasize that CFVR reflects the combined epicardial and microvascular resistance to coronary blood flow. Although overlap between normal and abnormal measurements does exist, a CFVR<2.0 has reasonable predictive accuracy to identify hemodynamically significant stenoses in the absence of microvascular dysfunction.4,5 CFVR is, however, susceptible to fluctuating hemodynamic parameters, as well as changes in ventricular loading conditions, and varies in situations of increased basal blood flow such as fever, tachycardia, hypoxia, anemia, and ventricular hypertrophy.6 In addition, reliably obtaining reproducible Doppler envelopes can be highly variable, limiting the accuracy of CFVR measurements. Other epicardial-specific indices have emerged that include hyperemic stenosis resistance (HSR) index, which requires pressure …

Comparison of Coronary Flow Velocity Reserve Measurement by Transthoracic Doppler Echocardiography With 320-Row Multidetector Computed Tomographic Coronary Angiography in the Detection of In-Stent Restenosis in the Three Major Coronary Arteries

We sought to compare the diagnostic accuracy and feasibility of coronary flow velocity reserve (CFVR) measurement using transthoracic Doppler echocardiography (TTDE) and 320-row multidetector computed tomographic coronary angiography (CTCA) for predicting in-stent restenosis (ISR). We enrolled 126 consecutive patients with 309 implanted coronary stents in the 3 major coronary arteries. TTDE and CTCA were performed within the 2-week period before follow-up invasive coronary angiography. Binary ISR was defined as percent diameter stenosis ≥50% on invasive coronary angiogram. A CFVR <2.0 using TTDE and a narrowing of ≥50% measured with CTCA were the thresholds indicating the presence of binary ISR. Presence of ISR using invasive coronary angiography was observed in 26 (8%) stents and 26 (14%) vessels. Feasibilities of CFVR measurement and CTCA for predicting ISR in the 3 major vessels were 94% and 91%, respectively. A CFVR <2.0 revealed a 95% diagnostic accuracy with sensitivity of 87%, specificity of 96%, positive predictive value of 77%, and negative predictive value of 98%. Diagnostic accuracy of CTCA was comparable to that of CFVR measurement; however, CTC angiographic results were confounded by metal artifacts in the assessment of small-diameter stents. In conclusion, noninvasive CFVR measurement has high feasibility and accuracy for predicting ISR and is comparable to 320-row CTCA.

Time-dependent variation in coronary flow velocity reserve induced by adenosine triphosphate: comparison to low-dose dipyridamole

Measuring the coronary flow velocity reserve (CFVR) by transthoracic Doppler echocardiography (TTDE) has been widely performed using adenosine. Although adenosine infusion is known to induce transient variation of hyperemia, the timing to measure the CFVR has not been well addressed. Therefore, we aimed to clarify the difference between the peak CFVR and at 2min following adenosine triphosphate (ATP) infusion compared to the CFVR after low-dose dipyridamole infusion. A total of 26 patients with coronary artery diseases underwent TTDE. The coronary flow velocity (CFV) of the left anterior descending artery (LAD) was monitored during ATP infusion at 0.14mg/kg/min. The CFVR was measured both at the first peak and at 2min following ATP infusion, and after dipyridamole infusion at 0.56mg/kg/min for 4min. The first peak of hyperemia occurred 63.7±8s after starting ATP infusion. The value of the peak CFVR was significantly higher than the CFVR at 2min following ATP stress, which was equivalent to the CFVR after dipyridamole infusion (2.30±0.92, 1.83±0.77, and 1.70±0.68, respectively, P<0.001). Applying a cut-off value of 2.0 to predict angiographic LAD stenosis, the CFVR at 2min following ATP stress was significantly correlated to the angiographic findings. However, the peak CFVR after ATP infusion did not correlate with the angiographic findings. During ATP infusion, the peak CFVR was significantly higher than the CFVR at 2min, which was equivalent to the CFVR after low-dose dipyridamole. This finding should be considered for the standardization of CFVR measurements.

Coronary flow reserve in patients with aortic stenosis and nonobstructed coronary arteries

Objective Patients with moderate and severe aortic stenosis (AS) and without obstructive epicardial coronary disease have been shown to have an impairment of coronary fl ow velocity reserve (CFVR). Recently, it has been shown that CFVR is an independent predictor for future cardiovascular events in AS patients. We investigated parameters representing left ventricular (LV) mass and wall thickness, diastolic dysfunction, LV workload and haemodynamic indexes of AS severity to determine which contributes the most to impaired CFVR in patients with AS and a nonobstructed coronary angiogram.Method and results A total of 77 patients with moderate or severe AS, mean age 65.66 ± 11.02 y (57.14% males), were enrolled in this prospective study. All patients had standard Doppler-echo study, coronary angiography and adenosine-stress transthoracic Doppler-echo for CFVR measurement. We took 2.5 as a cut-off value for impaired CFVR. Univariate analysis showed that aortic valve area (AVA), maximal velocity (Vmax), mean pressure gradient (Pmean), energy loss index (ELI), aortic valve resistance (AVR) and stroke work loss (SWL) were associated (P = 0.05) with impaired CFVR. Multivariate analysis showed that AVR was the best predictor of impaired CFVR (RR 0.900, CI: 0.983-0.997, P = 0.007). Using ROC analysis, the AVR value of 211.22 dynes∙s∙cm− 5 had the highest accuracy in predicting the impaired CFVR (AUC-0.681, P = 0.007, sensitivity 72%, specifi city 52%, CI: 0.561-0.800).Conclusion Haemodynamic indices of AS severity, together with LV workload parameters, are the main determinants of CFVR. Among all parameters, AVR is the strongest predictor of CFVR in patients with moderate or severe AS and a nonobstructed coronary angiogram.

Abstract 8796: Comparison of Coronary Flow Velocity Reserve Measurement by Transthoracic Doppler Echocardiography with 320-Row Multidetector Computed Tomography Coronary Angiography for Predicting Coronary Artery Stenosis in Calcified Lesions in the Three Major Coronary Arteries

Objectives: This study examined the diagnostic accuracy of coronary flow velocity reserve (CFR) measurement using transthoracic Doppler echocardiography (TTDE) by comparing 320-row multidetector computed tomography coronary angiography (CTCA) for predicting coronary artery stenosis in calcified lesions in the 3 major coronary arteries. Methods and Results: Invasive coronary angiography (ICA), CTCA, and CFR measurement were performed in 101 patients. The presence of stenosis ≥50% was considered significant stenosis by ICA. By CTCA, the degree of coronary artery calcification was assessed using the Agatston calcium score (CS) method. Prospectively electrocardiographically-gated CTCA was performed with the use of test-injection method for the assessment of coronary artery stenosis. Coronary flow velocity was recorded in each target coronary artery by TTDE at rest and during hyperemia induced by intravenous infusion of adenosine triphosphate. CFR &lt;2, calculated as the ratio of hyperemic to basal peak and mean diastolic velocity, was considered ≥50% stenosis. Results: A significant coronary stenosis by ICA was found in 60 vessels. Coronary artery legions were successfully assessed in 91% and 95% of all vessels by CTCA and TTDE, respectively. CTCA had a sensitivity of 92%, a specificity of 93%, a positive predictive value (PPV) of 73%, and a negative predictive value (NPV) of 98% in patients with 0-299 CS, and had a sensitivity of 89%, a specificity of 67%, a PPV of 47%, and an NPV of 95% in patients with 300-599 CS for predicting coronary artery stenosis. In patients with ≥ 600 CS, 73% of vessels were unassessable. CFR&lt;2.0 had a sensitivity of 90%, a specificity of 90%, a PPV of 71%, and an NPV of 97% in patients with 0-299 CS, had a sensitivity of 92%, a specificity of 89%, a PPV of 79%, and an NPV of 96% in patients with 300-599 CS, and had a sensitivity of 100%, a specificity of 85%, a PPV of 77%, and an NPV of 100 % in patients with ≥ 600 CS for predicting coronary artery stenosis. Conclusions: CFR measurement accurately predicts significant coronary artery stenosis irrespectively of the degree of coronary artery calcification whereas progression of coronary calcification negatively influences diagnostic accuracy of CTCA-based assessment of coronary artery stenosis.

Coronary Flow Velocity Reserve in the Three Main Coronary Arteries Assessed with Transthoracic Doppler: A Comparative Study with Quantitative Coronary Angiography

The purpose of this study was to evaluate the potential of combined use of transthoracic Doppler echocardiographic coronary flow velocity reserve (CFVR) measurements and findings of retrograde coronary flow in the three main coronary arteries for the assessment of borderline (angiographic diameter stenosis, 50%-75%) and high-grade (angiographic diameter stenosis, 76%-100%) coronary artery stenoses. A total of 108 patients scheduled for coronary angiography because of chest pain or acute coronary syndromes were studied. CFVR was measured during adenosine-induced hyperemia in the mid to distal segments of the left anterior descending coronary artery, the marginal branches of the left circumflex coronary artery, and the posterior descending coronary artery, with peak CFVR (pCFVR) <2.0 implying hemodynamic significant stenosis. CFVR results were compared with results from quantitative coronary angiography, with stenosis severity in the left main and three major coronary arteries divided into three groups: (1) diameter stenosis 0% to 49%, (2) diameter stenosis 50% to 75%, and (3) diameter stenosis 76% to 100%. In patients with antegrade flow in the relevant coronary artery segment, CFVR was successfully measured in the mid to distal left anterior descending artery, the marginal branches of the left circumflex artery, and the posterior descending artery in 97%, 63%, and 75% of patients, respectively. CFVR was significantly different among the stenosis groups, with pCFVR of 2.79 ± 0.77 in group 1, 2.01 ± 0.72 in group 2, and 1.50 ± 0.69 in group 3 (P < .001 among groups). Angiography confirmed retrograde flow in seven of the nine arteries found by transthoracic echocardiography. Findings of pCFVR <2.0 or retrograde coronary artery flow correctly identified 42 of 49 patients with stenoses in group 3, with sensitivity, specificity, and positive and negative predictive values of 86%, 70%, 70%, and 85%, respectively. In group 2, pCFVR values were widely distributed above or below the defined pCFVR cutoff value. CFVR measurement in the mid to distal left anterior descending artery was feasible in almost all patients, and in the marginal branches of the left circumflex artery and the posterior descending artery in two thirds and three quarters of patients, respectively. Use of the combined echocardiographic criteria had high precision for diagnosing severe coronary stenoses (diameter stenosis, 76%-100%). The functional significance of angiographically borderline stenoses (diameter stenosis, 50%-75%) may be further differentiated by the use of CFVR measurements.