Coronary Flow Velocity Research Articles

The importance of vasodilator stress echocardiography in predicting all-cause mortality and acute heart failure in hypertrophic cardiomyopathy

Abstract Background Reduced coronary flow velocity reserve (CFVR) in the left anterior descending coronary artery (LAD) during vasodilator stress echocardiography (VSE) is a marker of poor outcome and is associated with higher baseline coronary flow velocity (CFV) in hypertrophic cardiomyopathy (HCM). However, whether resting CFV has additive predictive value to CFVR during VSE in HCM is unknown. Aim To assess the prognostic value of baseline CFV and CFVR during VSE in HCM. Methods 325 adult HCM patients (age=52+15 years, 147 [45%] females) with preserved left ventricular function and no known coronary artery disease who underwent VSE in 6 certified centers between 1999 and 2021 were prospectively analyzed. VSE modality was adenosine (0.14 mg/kg/min in 2', n=232) or dipyridamole (0.84 mg/kg in 6', n=93). CFVR in the LAD was assessed by transthoracic (n=306) or transoesophageal (n=19) echocardiography. Patients were followed for a median of 67 months (IQ range 31-103 months), the primary endpoint was a composite of all-cause mortality and acute heart failure (HF). Results Receiver operating characteristic analysis was used to determine the best cut-off value of CFV (>31 cm/s, elevated) and CFVR (≤2.0, reduced) to predict the primary endpoint. Patients with reduced CFVR had more frequently elevated baseline CFV (75% vs 49%, p<0.001). Elevated resting CFV was a predictor of composite endpoint at univariable (HR 2.04, 95% CI 11.05-3.97, p=0.035) but not at multivariable analysis. A reduced CFVR was an independent predictor of all-cause mortality (HR 5.50, 95% CI 1.94-15.59, p=0.001), acute HF (HR 5.80, 95% CI 1.60-21.00, p=0.007), and the composite end-point (HR 4.95, 95% CI 2.39-10.25, p<0.001). The 5-year event rate was 6-fold higher in patients with reduced CFVR compared to patients with preserved CFVR (19% vs 3%, p<0.001), with no additional impact of resting CFV (see Figure). Conclusion LAD CFVR ≤2.0 during VSE is a strong and independent predictor of all-cause mortality and acute HF in HCM. Elevated resting CFV is more frequent in patients with reduced CFVR, but has no independent prognostic value when CFVR is considered.Kaplan-Meier event-free survival curves

High resting coronary flow velocity and reduced coronary flow velocity reserve independently predict worse survival in diabetic patients without inducible ischemia and normal left ventricular function

Abstract Background High resting coronary flow velocity (CFV) in the mid-distal left anterior descending coronary artery (LAD) can be easily assessed with transthoracic echocardiography (TTE) and is a predictor of worse survival. Purpose In this study, we sought to assess the relationship between resting CFV, coronary flow velocity reserve (CFVR), and outcome in patients without inducible regional wall motion abnormality during stress echo (SE). Methods In a prospective multicenter study design, we enrolled 6,887 patients (age 65±11 years, 3,838 men, 1,963 diabetics), with left ventricular ejection fraction (LVEF) ≥50% referred for SE. Recruitment (years 2004-2022) involved 7 accredited laboratories, with inter-observer variability <10% for CFV measurement at study entry. Baseline peak diastolic CFV (abnormal value >32 cm/s) was obtained by pulsed-wave Doppler in mid-distal LAD. Coronary flow velocity reserve (CFVR, abnormal value ≤2.0) was assessed with dipyridamole. All-cause death was the only end-point. Results The mean CFV of LAD was 30±11 cm/s. The mean CFVR was 2.37±0.58. During a median follow-up of 6.0±4.2, 1,015 (15%) patients died. At Cox analysis, resting CFV >32 cm/s independently predicted mortality together with CFVR <2, age, diabetes, previous myocardial infarction, history of coronary surgery and LVEF. Resting CFV allowed effective risk stratification either in diabetics and nondiabetics although the difference in survival based on resting CFV was more marked in the former (Figure). In addition, it added significant (p<0.0001) prognostic information to CFVR result in the diabetic, but not in the non-diabetic population (Figure). Conclusion High resting CFV with TTE in mid-distal LAD predicts worse survival in patients without inducible ischemia. The value is independent and additive to CFVR in diabetic patients. The combination of high resting CFV-low CFVR is associated with worse survival.

Non-hyperaemic coronary flow velocity acceleration indices correlate with hyperaemic microvascular resistance in patients with INOCA

Abstract Background Coronary microvascular dysfunction (CMD) is associated with an overall worse prognosis. While the diagnosis and endo-typing of CMD currently rely on hyperaemic physiological indices, the search for accurate non-hyperaemic techniques continues. Flow velocity acceleration pattern is mechanistically associated with changes in shear stress, endothelial function, arterial stiffness and pressure in pulsatile flow systems (1-3). Purpose We aim to interrogate whether resting flow velocity acceleration indices correlate with hyperaemic microvascular resistance (HMR) in patients with Ischemia and no obstructive coronary artery disease (INOCA). Methods In 21 Patients with INOCA (all of whom had presented with typical angina pectoris, had no significant epicardial stenoses but positive myocardial perfusion scan test for ischemia) invasive physiological assessment was performed by means of intracoronary Doppler. Hyperaemia was induced with intracoronary adenosine administration. Coronary flow reserve (CFR) and HMR were calculated per their definitions. Flow velocity acceleration indices were derived from the first derivative of the averaged resting flow velocity waveforms with respect to time. We have defined 6 wave peaks of interest in all patients (peak diastolic acceleration (initial prominent peak with ventricular relaxation, referred as A), early diastolic deceleration (B), early re-acceleration wave (C), peak presystolic deceleration (seen just before initial systolic acceleration peak, J), initial systolic acceleration peak (X) and pre-diastolic deceleration nadir (Z)) and calculated the ratios between them as well as adjusted them with respect to resting mean flow velocity (Figure 1). Results The mean age was 59 ± 8 years and the majority of the study group was female (%81). Cardiovascular risk factors were common amongst the study group.All patients had CFR < 2.5. Mean CFR and HMR were 2.05 ± 0.32 and 2.20 ± 0.60 mmHg.cm.sec-1 respectively. Raw C peak magnitude was significantly correlated with APVh (rho:-0.457 p:0.037) and HMR (rho:0.612 p:0.004). Adjusting the C magnitudes with APVb at patient level yielded better correlations (APVh rho:-0.496 p:0.022 ; HMR:0.642 p:0.002). The ratio between diastolic reacceleration peak (C) and presystolic peak deceleration (J), C/J , adjusted with the APVb ((C/J)/APVb) showed the most pronounced correlation with HMR (rho: 0.758 p < 0.001) (unadjusted C/J – HMR rho: 0.718 p<0.001)(Figure 2). Conclusion(s) Acceleration characteristics of resting coronary flow velocity correlate with hyperaemic microvascular resistance indicating structurally impaired coronary microcirculation, hence their utilisation may aid developing non-hyperaemic physiological markers for coronary microvascular dysfunction in patients with INOCA.Derived Acceleration WaveformsCorrelations between HMR and C/J Ratio

Mechanical LV support lowers diastolic LV pressure and prolongs diastolic coronary flow in the infarcted artery

Abstract Background Percutaneous left ventricular (LV) assist device provides not only circulatory support but also LV unloading. However, impact of LV unloading on coronary flow and mechanisms by which it is regulated remain unclear. We aimed to elucidate potential effects of LV unloading on coronary physiology in a pig model of myocardial infarction (MI). Methods First, six Yorkshire pigs underwent mechanical LV unloading using Impella two weeks after percutaneous MI induction. Regional blood flow (RBF) in infarct, border and remote myocardium were measured by fluorescent microsphere injections before and 120 min after LV unloading (Study 1). Next, we investigated coronary flow patterns with detailed temporal information. Six Yorkshire pigs were subjected to 90-minute balloon occlusion of the middle left anterior descending artery followed by reperfusion. At 60 minutes after reperfusion, LV unloading was initiated and maintained at maximal support. LV pressure, coronary flow and pressure in the infarcted artery were simultaneously recorded. Measurements were repeated with and without LV mechanical support. Coronary wave intensity was calculated from the flow/pressure data (Study 2). Results In Study 1, RBF calculated using microsphere was significantly increased only in the infarct area, but not in the border or remote areas. In Study 2, LV unloading resulted in lower LV pressure during the whole diastolic phase and higher coronary pressure during the late diastolic phase in all animals. Coronary flow velocity was higher throughout the diastole under LV unloading. In addition, the proportion of diastole to the whole cardiac cycle was significantly prolonged with LV unloading. Accordingly, area under the curve of coronary flow was increased during diastole and also for the whole cardiac cycle. In the wave intensity analysis, the magnitude of forward wave intensity was reduced by LV unloading, suggesting that the impact of forces from the aortic side was less significant under continuous device support. The duration between backward suction and pushing waves was extended, implicating earlier relaxation and delayed contraction, further supporting prolonged diastole from the myocardial force perspective. Conclusions Mechanical LV unloading increases coronary flow by prolonging diastolic phase in the infarcted artery.

Residual Microvasuclar Dysfunction (RMVD) after percutaneous coronary intervention (PCI) assessed by stress- transthoracic Doppler echocardiography (S-TDE)

Abstract Background Microvascular dysfunction (MVD) has been increasingly acknowledged as a relevant cause of myocardial ischemia and worse prognosis. Coronary flow velocity reserve (CFVR), an integrated marker of coronary circulation, can be obtained noninvasively by stress-TDE. However, limited data is available regarding residual MVD (RMVD) of the target territory after percutaneous coronary intervention (PCI) assessed by stress- transthoracic Doppler echocardiography (S-TDE). Purpose This study aimed to investigate the echocardiographic predictors for RMVD after PCI assessed by S-TDE. Methods This study prospectively included 175 patients with chronic coronary syndrome who were scheduled for elective PCI at a single tertiary-care center between April 2019 and November 2022. All patients had anginal symptoms with de novo, functionally significant, proximal left anterior descending (LAD) lesions and underwent fractional flow reserve (FFR)-guided elective single vessel PCI for LAD. Exclusion criteria were patients with reduced left ventricular (LV) systolic function (ejection fraction < 50%), periprocedural myocardial infarction as defined by the fourth universal definition of myocardial infarction. Eligible patients underwent pre- (1 day before) and post-procedural (3 days after) LAD coronary flow assessments by S-TDE. Coronary flow velocity reserve (CFVR) was calculated as the ratio of the hyperemic peak diastolic flow velocity to the basal peak diastolic flow velocity. We also excluded the patients with suboptimal S-TDE imaging. We defined an RMVD after PCI as a post-PCI CFVR impairment (CFVR<2.0). Association between RMVD and echocardiographic parameters were evaluated. Results A total of 150 patients were included in the final analysis. RMVD was observed in forty-five (30.0%) patients after successful LAD PCI. Patients with RMVD had older age (74 [67-79] versus 72 [59-76], P=0.042) and lower estimated glomerular filtration rate (eGFR) (58.4 [37.6-75.1] mL/min/1.73m2 versus 65.9 [54.3-75.5] mL/min/1.73m2, P=0.045) than those without RMVD. Univariate logistic regression analyses revealed that higher age, lower eGFR, pre-PCI higher ratio of mitral peak velocity of early filling to early diastolic mitral annular velocity (E/e’), shorter deceleration time of diastolic coronary flow (DDT) and lower pre-PCI CFVR were associated with post-PCI RMVD. Multivariate logistic regression analyses including age and eGFR as covariates showed higher E/e’ (adjusted odds ratio [OR] 1.13, 95% confidence interval [CI] 1.02-1.25, P=0.022), shorter DDT (OR 0.999, 95% CI 0.998-1.000, P=0.045) and lower pre-PCI CFVR (OR 0.336, 95% CI 0.165-0.683, P=0.003) were independently predictive of RMVD. Conclusions In patients with preserved LV ejection fraction who underwent successful elective FFR-guided PCI for LAD, pre-PCI LV diastolic dysfunction was associated with post-PCI residual microvascular dysfunction of LAD territory.

TDE-derived impaired post-PCI Coronary flow velocity reserve predicts MACE in patients who underwent LAD PCI

Abstract Background Coronary flow velocity reserve (CFVR) can be obtained noninvasively by stress transthoracic Doppler echocardiography (S-TDE). However, prognostic significance of S-TDE-derived CFVR after percutaneous coronary intervention (PCI) remains unknown. Purpose This study aimed to investigate the relationship between post-PCI CFVR and major adverse cardiac event (MACE). Methods This study prospectively included 200 patients with stable coronary artery disease who were scheduled for elective PCI of de novo, single, functionally significant left anterior descending (LAD) lesions at a single tertiary-care center between April 2019 and November 2022. All patients underwent fractional flow reserve (FFR)-guided elective PCI. Exclusion criteria were patients with previous coronary artery bypass graft surgery, left main coronary artery disease and periprocedural myocardial infarction as defined by the fourth universal definition of myocardial infarction. Eligible patients underwent pre- (1 day before) and post-procedural (3 days after) LAD coronary flow assessments by stress-TDE. CFVR was calculated as the ratio of the hyperemic peak diastolic flow velocity to the basal peak diastolic flow velocity. We also excluded the patients with suboptimal S-TDE imaging. Association between post-PCI physiological parameters and MACE (composite of cardiac death, myocardial infarction, heart failure and target vessel revascularization) were evaluated. Results A total of 174 patients were included in the final analysis after successful LAD PCI. MACE occurred in twenty-one (12.0%) patients during the follow-up (1.9 [0.9-2.5] years). Clinical demographics were similar in patients with versus without MACE. Post-PCI S-TDE-derived CFVR was lower in patients with versus without MACE (P = 0.023), while post-PCI FFR values tended to be lower in patients with versus without MACE, albeit not significant (P = 0.077). Receiver-operating characteristic curve analysis revealed that the optimal cut-off values of post-PCI FFR and post-PCI CFVR values to predict MACE were 0.83 and 1.70, respectively. Significant differences in the MACE were detected according to post-PCI FFR (≤ 0.83 versus > 0,83: 17.9 % versus 6.7 %, P = 0.035) and post-PCI CFVR (< 1.70 versus ≥ 1.70: 33.3% versus 8.2%, P = 0.001). On a multivariable Cox-proportional hazard analysis, patients with post-PCI CFVR < 1.70 had an increased risk for MACE (adjusted hazard ratio [HR] 4.75, 95% confidence interval [CI] 1.98-11.38, P < 0.001), along with post-PCI FFR ≤ 0.83 (adjusted HR 2.78, 95% CI 1.07-7.20, P=0.035). Conclusions In patients who underwent successful elective PCI for LAD, S-TDE-derived impaired post-PCI CFVR and post-PCI FFR were independently associated with MACE.

Stress echocardiography: application of the ABCDE protocol in patients with permanent atrial fibrillation

Abstract Objectives A new standard of practice in stress echocardiography (SE) was founded with the development of the ABCDE protocol, which added functional information to conventional ischemia diagnosis. Each step showed to provide incremental prognostic information: step A, regional wall motion abnormalities; step B, B lines; step C, left ventricular contractile reserve; step D, Doppler-based coronary flow velocity reserve in the left anterior descending coronary artery; and step E, electrocardiogram-based heart rate reserve. However, the utility of SE and ABCDE protocol in patients with atrial fibrillation (AF) has never been tested. Background A growing body of evidence suggests that AF patients have a significant residual risk of myocardial infarction despite anticoagulant treatment; furthermore, they have an increased risk of heart failure and all-cause death. However, ABCDE-SE has never been applied in this population. Methods Of the 3965 patients who completed clinically indicated ABCDE-SE and with available information on rhythm stored in the shared data bank and enrolled from 13 certified centers, 3891 were in sinus rhythm (SR, Group 1) and 50 in permanent AF (Group 2) at the time of the test. ABCDE-SE response ranged from score 0 (all steps normal) to score 5 (all steps abnormal). The employed stress was an exercise in 1626 (41%), vasodilator in 1864 (47%), and dobutamine in 475 (12%). Results Group 2 pts were older than Group 1 patients, more frequently hypertensives and diabetics, with lower ejection fraction, and with more signs of pulmonary congestion at rest. During stress, differences were magnified, and Group 2 patients showed more peak stress B-lines and higher values of peak WMSI compared with Group 1 (see Table). In addition, patients with AF had higher ABCDE scores (Group 1= 1.5 ±1.4 vs. Group 2= 2.6±1.6, p<0.0001). The distribution of the score in patients in SR and AF is shown in Figure. Conclusions Patients with AF are scarcely represented among patients undergoing SE. Patients with AF showed a higher prevalence of positivity in each step and a higher ABCDE score. More specifically, AF patients are more vulnerable than patients in SR to coronary microvascular dysfunction and chronotropic incompetence during stress.TableFigure

Abstract 13363: Echocardiographic Coronary Flow Velocity Parameters in Assessing Sub-Clinical Atherosclerosis in Inflammatory Bowel Disease Patients: A Meta-Analysis

Introduction: Chronic inflammatory diseases are linked to atherosclerosis and cardiovascular events. However, there are conflicting results in the literature regarding differences in echocardiographic Coronary Flow velocity parameters, which serve as markers of subclinical atherosclerosis, between inflammatory bowel disease (IBD) patients and healthy controls. Hypothesis: We aim to assess the Coronary Flow Velocity Reserve (CFVR), baseline Diastolic Peak Flow Velocity (DPFV), and hyperemic DPFV in IBD patients. Methods: We conducted a systematic search of databases, from January 1, 2014, to June 1, 2023, to gather relevant studies. The pooled mean differences in various parameters between IBD patients and controls were calculated using the standard mean difference with 95% confidence interval (CI), and random effect model was used when heterogeneity (I 2 ) crossed 50%. Results: 4 studies with 342 participants were included. The mean age of the IBD group was 39.25 years and of the control group was 41.25 years. Male comprised 51.46% of the study participants. IBD patients had a significantly lower CFVR (SMD; -1.12 95%CI; [-1.62, -0.61], p-value<0.01) and hyperemic DPFV (SMD; -0.68, 95%CI [-1.09, -0.27], p-value<0.01) than healthy controls. Whereas, Healthy controls had a lower baseline DPFV (SMD; 0.69 95%CI; [0.35, 1.04], p-value<0.01) than the IBD group. Conclusions: IBD was associated with Coronary Microvascular Disease assessed as impaired CFVR and hyperemic DPFV. This suggests reduced myocardial perfusion in IBD patients and the need for regular cardiovascular risk assessment and targeted interventions to mitigate the increased risk of cardiovascular events.

Abstract 14798: NAMPT Inhibition Restores Coronary Microvascular Dysfunction in Diabetes

Introduction: Nicotinamide phosphoribosyltransferase (NAMPT) is a multitask peptide; extracellular NAMPT acts as a proinflammatory cytokine, and intracellular NAMPT participates in energy metabolism through NAD + production. Serum NAMPT level is increased in diabetic patients; however, the pathophysiological role of NAMPT in diabetic cardiovascular complications is poorly understood. This study aims to investigate the effect of NAMPT inhibition on coronary microvascular function in diabetes. Materials and Methods: We used two diabetic mouse models: inducible type 2 diabetic (T2D) mice generated by a single injection of low-dose STZ (75 mg/kg, i.p.) with a high-fat diet feeding, and spontaneous T2D mice, TALLYHO/JngJ. Cardiac endothelial cells (CECs) were isolated for molecular biological experiments. Coronary flow velocity reserve (CFVR) was used to determine coronary microvascular function. Results: T2D mice exhibited elevated NAMPT expression in CECs. There was no difference in glucose tolerance and body weight in diabetic NAMPT hetero knockout mice and FK866 (NAMPT inhibitor)-administered diabetic mice compared to their controls. However, CFVR was significantly increased by NAMPT inhibition in T2D mice, accompanied by increased capillary density and augmented endothelium-dependent relaxation (EDR). Chronic administration of neutralizing NAMPT antibody (Ab) also improved CFVR in T2D mice toward the level in control mice. RNA sequencing data in CECs revealed that NAMPT-Ab administration in T2D mice significantly restored the levels of genes related to angiogenesis. NAMPT (100 ng/ml) or NAD + (100 nM) treatment attenuated cell migration in control CECs and reduced EDR in control CAs. Furthermore, NAMPT or NAD + treatment increased mitochondrial ROS formation and decreased Gap junction activity in control CECs. Conclusion: Our data suggest that NAMPT inhibition increases capillary density via enhancing endothelial migration, arguments EDR through reducing mitochondrial ROS production and increasing gap junction activity, and results in restoration of coronary microvascular function in diabetic mice. Therefore, NAMPT inhibition could be a new therapeutic strategy for coronary microvascular disease in diabetes.

The Differences of Quantitative Flow Ratio in Coronary Artery Stenosis with or without Atrial Fibrillation.

Quantitative flow ratio (QFR) is a new method for the assessment of the extent of coronary artery stenosis. But it may be obscured by the cardiac remodeling and abnormal blood flow of the coronary artery when encountering atrial fibrillation (AF). The present study aimed to examine the impact of these changed structures and blood flow of coronary arteries on QFR results in AF patients. Methods and Results. We evaluated QFR in 223 patients (112 patients with AF; 111 non-AF patients served as controls) who had undergone percutaneous coronary intervention (PCI) due to severe stenoses in coronary arteries. QFR of the target coronary was determined according to the flow rate of the contrast agent. Results showed that AF patients had significantly higher QFR values than control (0.792 ± 0.118 vs. 0.685 ± 0.167, p < 0.001). We further analyzed local QFR around the stenoses (0.858 ± 0.304 vs. 0.756 ± 0.146, p=0.002), residual QFR (0.958 ± 0.055 vs. 0.929 ± 0.093, p=0.005), and index QFR (0.807 ± 0.108 vs. 0.713 ± 0.152, p < 0.001) in these two groups of patients with and without AF. Further analysis revealed that QFR in AF patients was negatively correlated with coronary flow velocity (R = -0.22, p=0.02) and area of stenosis (R = -0.70, p < 0.001) but positively correlated with the minimum lumen area (MLA) (R = 0.47, p < 0.001). Conclusion. AF patients with coronary artery stenosis have higher QFR values, which are associated with decreased blood flow velocity, smaller stenosis, and larger MLA in AF patients upon cardiac remodeling.

The clinical use of stress echocardiography in chronic coronary syndromes and beyond coronary artery disease: a clinical consensus statement from the European Association of Cardiovascular Imaging of the ESC.

Since the 2009 publication of the stress echocardiography expert consensus of the European Association of Echocardiography, and after the 2016 advice of the American Society of Echocardiography-European Association of Cardiovascular Imaging for applications beyond coronary artery disease, new information has become available regarding stress echo. Until recently, the assessment of regional wall motion abnormality was the only universally practiced step of stress echo. In the state-of-the-art ABCDE protocol, regional wall motion abnormality remains the main step A, but at the same time, regional perfusion using ultrasound-contrast agents may be assessed. Diastolic function and pulmonary B-lines are assessed in step B; left ventricular contractile and preload reserve with volumetric echocardiography in step C; Doppler-based coronary flow velocity reserve in the left anterior descending coronary artery in step D; and ECG-based heart rate reserve in non-imaging step E. These five biomarkers converge, conceptually and methodologically, in the ABCDE protocol allowing comprehensive risk stratification of the vulnerable patient with chronic coronary syndromes. The present document summarizes current practice guidelines recommendations and training requirements and harmonizes the clinical guidelines of the European Society of Cardiology in many diverse cardiac conditions, from chronic coronary syndromes to valvular heart disease. The continuous refinement of imaging technology and the diffusion of ultrasound-contrast agents improve image quality, feasibility, and reader accuracy in assessing wall motion and perfusion, left ventricular volumes, and coronary flow velocity. Carotid imaging detects pre-obstructive atherosclerosis and improves risk prediction similarly to coronary atherosclerosis. The revolutionary impact of artificial intelligence on echocardiographic image acquisition and analysis makes stress echo more operator-independent and objective. Stress echo has unique features of low cost, versatility, and universal availability. It does not need ionizing radiation exposure and has near-zero carbon dioxide emissions. Stress echo is a convenient and sustainable choice for functional testing within and beyond coronary artery disease.

Diagnostic value of coronary flow acceleration measured by transesophageal echocardiography in coronary artery bypass graft surgery

Background: Transesophageal echocardiography as a method of intraoperative coronary flow assessment is largely unstudied.Objective: To evaluate the potential of intraoperative transesophageal echocardiography in diagnosing proximal coronary artery stenoses, to reveal the correlation between stenoses found on coronary angiography and coronary flow velocity in the corresponding area measured by intraoperative transesophageal echocardiography, and to study how coronary flow velocity changes before and after coronary artery bypass graft surgery and how it is related to postoperative myocardial injury.Methods: Our prospective cohort study included 186 patients scheduled for coronary artery bypass graft surgery. All the patients underwent intraoperative transesophageal echocardiography: coronary flow velocity was measured in the area of its acceleration (proximal parts of the left coronary artery) before and after the surgery. Troponin I was measured on the first postoperative day.Results: The areas of accelerated coronary flow before the procedure were detected in the left main coronary artery (88 patients, 47.3%), left anterior descending artery (146 patients, 78.5%), and left circumflex artery (28 patients, 15.1%). ROC analysis showed that coronary flow velocity of &gt;73 cm/s in the left main coronary artery and of &gt;91 cm/s in the left circumflex artery was associated with a stenosis of 50% and 70% in the respective arteries measured by coronary angiography. Furthermore, an increase in coronary flow velocity in the left anterior descending artery or its decrease by 4 cm/s after coronary artery bypass graft surgery are predictors of a 10-fold increase in troponin I concentration in the postoperative period.Conclusion: Coronary flow velocity assessment during intraoperative transesophageal echocardiography can offer added value in detecting clinically significant coronary artery stenoses, while assessment of changes in velocity may predict perioperative myocardial injury. Received 16 January 2023. Revised 16 May 2023. Accepted 31 August 2023. Funding: The study did not have sponsorship. Conflict of interest: The authors declare no conflict of interest. Contribution of the authorsConception and study design: S.M. Efremov, M.A. Novikov, A.V. ZagatinaData collection and analysis: S.M. Efremov, M.A. Novikov, A.A. Trofimov, A.V. ZagatinaStatistical analysis: S.M. Efremov, A.A. TrofimovDrafting the article: S.M. Efremov, A.A. TrofimovCritical revision of the article: S.M. Efremov, M.A. Novikov, A.A. Trofimov, D.V. Shmatov, M.S. Kamenskih, A.V. ZagatinaFinal approval of the version to be published: S.M. Efremov, M.A. Novikov, A.A. Trofimov, D.V. Shmatov, M.S. Kamenskih, A.V. Zagatina

Predictors of diastolic deceleration time of coronary flow velocity of infarct related and reference coronary artery assessed by transthoracic Doppler echocardiography in the chronic phase of successfully reperfused anterior myocardial infarction: relation to infarct size.

High-frequency transthoracic Doppler echocardiography (TDE) enables the assessment of flow velocity and velocity pattern in different coronary arteries, including the assessment of diastolic deceleration time (DDT) of coronary flow velocity. Short DDT of infarct related artery (IRA) (<600 msec) in the acute phase of anterior myocardial infarction (MI) is the predictor of adverse left ventricular (LV) remodeling and prognosis. The significance of DDT of coronary flow velocity assessment in the chronic phase of anterior MI is not well established. Our study aimed to establish the predictors of DDT of the coronary flow velocity of infarct related (left anterior descendent-DDT of LAD) and reference coronary artery, evaluated by TDE, and to assess their relation to infarct size in the chronic phase of successfully reperfused first anterior MI. Our study included 40 consecutive patients (34 men, mean age 52 ± 12 years) one month after the first anterior STEMI and single vessel disease successfully treated with primary PCI. All patients underwent SPECT MPI for the assessment of LV volumes, ejection fraction, and percentage of the myocardium with fixed perfusion abnormalities and echocardiographic examination including the evaluation of DDT of IRA and reference coronary artery TDE. DDT of LAD correlated significantly to the WMSI (r = -0.467, p = 0.002), LV end-systolic volume (r = -0.412, p = 0.008), LV ejection fraction (r = 0.427, p = 0.006), while the strongest correlation was observed between DDT of LAD and the extent of fixed perfusion abnormality (r = -0.627, p < 0.0001), Multivariate analysis revealed percentage of fixed perfusion abnormalities along with DDT of reference coronary artery as the independent predictors of DDT of IRA. DDT of IRA shorter than 886 msec predicts large fixed perfusion abnormalities (>20%) with a sensitivity of 89% and specificity of 62% (AUC 0.842). DDT of LAD assessed by TDE in the chronic phase of successfully reperfused first anterior MI is a usefull variable for the assessment of microcirculatory function that exclusively reflects the extent of microvascular damage and relates to infarct size.

Changes of left atrial morphology and function evaluated with four-dimensional automated left atrial quantification echocardiography in patients with coronary slow flow phenomenon and preserved left ventricular ejection fraction

BackgroundCoronary slow flow phenomenon (CSFP) can cause left ventricular diastolic dysfunction (LVDD). In multiple studies, the left atrial (LA) strain has been reported to be an excellent parameter for assessing LVDD. The 4-dimensional automated LA quantification (4D Auto LAQ) dedicated to the LA was recently available. Our study aimed to evaluate subclinical changes in LA morphology and function with 4D Auto LAQ in patients with CSFP and preserved left ventricular ejection fraction (LVEF). MethodsForty-eight patients with CSFP confirmed with coronary angiography and 46 age and gender-matched controls with normal coronary flow were enrolled. The thrombolysis in myocardial infarction frame count (TFC) method was used to record coronary blood flow velocities for each major coronary artery. LA volume, LA longitudinal and circumferential strains during each of the three LA phases (reservoir, conduit, and contraction), LA total emptying fraction (LATEF), LA active emptying fraction (LAAEF), and LA passive emptying fraction (LAPEF) were quantified with 4D Auto LAQ analysis. ResultsCompared with controls, LA longitudinal reservoir strain (LASr), LA longitudinal strain during the conduit phase (LAScd), LA contraction strain (LASct), LA conduit circumferential strain (LAScd-c), LATEF, LAPEF decreased significantly in individuals with CSFP. Of the 4D- LAQ parameters, only LASr [odds ratio (OR): 0.773, P < 0.001] and LATEF [OR: 0.762, P < 0.001] were associated with CSFP in multivariate analysis. A LASr ≤23.00% can differentiate CSFP from controls [sensitivity, 66.7%; specificity, 93.5%; area under the curve (AUC), 0.823; P < 0.001]. A LASr of ≤19.00% could predict the elevation of LV filling pressure in the CSFP cohort [sensitivity, 76.9%; specificity, 74.3%; area under the curve (AUC), 0.792; P < 0.001]. LASr was the only index to demonstrate significant changes compared to controls in single-vessel CSFP. Compared to the right coronary artery (RCA) and left circumflex (LCX), TFC of the left anterior descending (LAD) artery was the only independent variable of LASr (Standardized Coefficients: -0.386, P = 0.037). ConclusionsImpairment of LA reservoir function reflected by changes in LASr and LATEF can be seen in patients with CSFP. LASr could predict the elevation of LV filling pressure in CSFP individuals. LASr is more sensitive than LATEF in detecting LA reservoir dysfunction in single-vessel CSFP. CSFP in LAD exerts a more prominent influence on LASr than RCA or LCX.

Normal physiologic coronary flow velocity gradient across the left anterior descending artery in healthy asymptomatic subjects

Aim: Coronary flow velocity (CFV) can be obtained with transthoracic echocardiography (TTE) in the left anterior descending coronary artery (LAD). The physiologic flow velocity gradient across the different segments of LAD has not been established. This study aims to assess the normal values of resting CFV in proximal, mid, and distal LAD. Methods: In a single center, prospective, observational study design, TTE was attempted on 110 consecutive, asymptomatic middle-aged subjects (age = 55 years, 46% males) with a low likelihood of coronary artery disease (&lt; 5%). Resting CFV in the LAD was assessed with high-end machines, dedicated coronary pre-set, and high-frequency transducers by pulsed-wave Doppler under color-Doppler guidance in the proximal, mid, and distal segments. Results: The technical success rate for CFV imaging was lowest for the proximal (101/110, 92%), intermediate for mid (106/110, 96%), and highest for the distal segment (108/110, 98%). All 3 segments were interpretable in 101 subjects. CFV was highest in proximal segments (38.6 cm/s ± 3.9 cm/s), intermediate in mid segments (34.3 cm/s ± 6.04 cm/s, P &lt; 0.01 vs. proximal), and lowest in distal segments (28.1 cm/s ± 1.7 cm/s, P &lt; 0.01 vs. proximal and vs. mid). Conclusions: A resting evaluation of CFV-LAD can be obtained by TTE in the large majority of consecutive subjects referred to the echocardiography laboratory. Feasibility is highest for distal and lowest for proximal-LAD segments. There is a clear physiologic gradient of CFV with decreasing values, of about 10% for each step, going from proximal to mid and distal segments of LAD. When resting CFV is considered, the site of the sampling is important to obtain comparable and physiologically meaningful data.

Dynamic Assessments of Coronary Flow Reserve after Myocardial Ischemia Reperfusion in Mice.

After cardiac ischemia, there is often insufficient myocardial perfusion, even if flow has been successfully and completely restored in an upstream artery. This phenomenon, known as the "no-reflow phenomenon," is attributed to coronary microvascular dysfunction and has been associated with poor clinical outcomes. In clinical practice, a reduction in coronary flow reserve (CFR) is frequently used as an indicator of coronary artery disease. CFR is defined as the ratio of the peak flow velocity induced by pharmacologic or metabolic factors to the resting flow velocity. This protocol focused on assessing the dynamic changes in CFR before and after ischemia-reperfusion (IR) using pulse wave Doppler measurements. In this study, normal mice exhibited the ability to increase the peak velocity of coronary blood flow up to two times higher than the resting values under isoflurane stimulation. However, after ischemia-reperfusion, the CFR at 1 h significantly decreased compared to the pre-operation baseline. Over time, the CFR showed gradual recovery, but it remained below the normal level. Despite the preservation of systolic function, early detection of microvascular dysfunction is crucial, and establishing a practical guide could aid doctors in this task, while also facilitating the study of cardiovascular disease progression over time.

Incremental value of non-invasive myocardial work for the evaluation and prediction of coronary microvascular dysfunction in angina with no obstructive coronary artery disease.

Evidence suggests that patients suffering from angina with no obstructive coronary artery disease (ANOCA) experience coronary microvascular dysfunction (CMD). We aimed to understand the diagnosis value of noninvasive myocardial work indices (MWIs) with left ventricular pressure-strain loop (LV PSL) by echocardiography in ANOCA patients with CMD. 97 patients with ANOCA were recruited. All subjects underwent standard echocardiography with traditional ultrasound parameters, two-dimensional speckle-tracking echocardiography with global longitudinal strain (GLS), LV PSL with MWIs include global work index (GWI), global constructive work (GCW), global waste work (GWW) and global work efficiency (GWE). In addition, all enrolled cases underwent high-dose adenosine stress echocardiography (SE) with coronary flow velocity reserve (CFVR). CMD was defined as CFVR <2.0. Of the 97 patients with ANOCA, 52 were placed in the CMD group and 45 in the control group. GWI and GCW were decreased significantly in the CMD group compared with the control group (P < 0.001 for both). GWI and GCW were moderately correlated with CFVR (r = 0.430, P < 0.001 and r = 0.538, P < 0.001, respectively). In the multiple logistic regression analyses, GCW was identified as the only independent echocardiography parameter associated with CMD after adjusting for age and baseline APV [OR (95%CI) 1.009 (1.005-1.013); P < 0.001]. Moreover, the best predictor of CMD in patients with ANOCA using receiver operating characteristic (ROC) curve was GWI and GCW, with an area under the curve (AUC) of 0.800 and 0.832, sensitivity of 67.3% and 78.8%, specificity of 80.0% and 75.6%, respectively. MWIs with LV PSL is a new method to detect LV systolic function noninvasively in ANOCA patients with CMD.

Assessment of coronary microcirculation alterations in a porcine model of no-reflow using ultrasound localization microscopy: a proof of concept study.

Coronary microvascular obstruction also known as no-reflow phenomenon is a major issue during myocardial infarction that bears important prognostic implications. Alterations of the microvascular network remains however challenging to assess as there is no imaging modality in the clinics that can image directly the coronary microvascular vessels. Ultrasound Localization Microscopy (ULM) imaging was recently introduced to map microvascular flows at high spatial resolution (∼10μm). In this study, we developed an approach to image alterations of the microvascular coronary flow in exvivo perfused swine hearts. A porcine model of myocardial ischemia-reperfusion was used to obtain microvascular coronary alterations and no-reflow. Four female hearts with myocardial infarction in addition to 6 controls were explanted and placed immediately in a dedicated preservation and perfusion box manufactured for ultrasound imaging. Microbubbles (MB) were injected into the vasculature to perform Ultrasound Localization Microscopy (ULM) imaging and a linear ultrasound probe mounted on a motorized device was used to scan the heart on multiple slices. The coronary microvascular anatomy and flow velocity was reconstructed using dedicated ULM algorithms and analyzed quantitatively. We were able to image the coronary microcirculation of exvivo swine hearts at a resolution of tens of microns and measure flow velocities ranging from 10mm/s in arterioles up to more than 200mm/s in epicardial arteries. Under different aortic perfusion pressures, we measured in large arteries of a subset of control hearts an increase of flow velocity from 31±11mm/s at 87mmHg to 47±17mm/s at 132mmHg (N=3 hearts, P<0.05). This increase was compared with a control measurement with a flowmeter in the aorta. We also compared 6 control hearts to 4 hearts in which no-reflow was induced by the occlusion and reperfusion of a coronary artery. Using average MB velocity and average density of MB per unit of surface as two ULM quantitative markers of perfusion, we were able to detect areas of coronary no-reflow in good agreement with a control anatomical pathology analysis of the cardiac tissue. In the no-reflow zone, we measured an average perfusion of 204±305MB/mm2 compared to 3182±1302MB/mm2 in the surrounding re-perfused area. We demonstrated this approach can directly image and quantify coronary microvascular obstruction and no-reflow on large mammal perfused hearts. This is a first step for noninvasive, quantitative and affordable assessment of the coronary microcirculation function and particularly coronary microvascular anatomy in the infarcted heart. This approach has the potential to be extended to other clinical situations characterized by microvascular dysfunction. This study was supported by the French National Research Agency (ANR) under ANR-21-CE19-0002 grant agreement.

Comparing the hemodynamic effect of a large arteriovenous fistula during high and low cardiac output states.

Background: A large arteriovenous fistula (AVF) is a low-resistant circuit that affects organ perfusion and systemic hemodynamics even in standard conditions. The extent of its' effect in critical states has not been elucidated yet. We used norepinephrine to create systemic vasoconstriction, dobutamine to create high cardiac output, and rapid right ventricle pacing as a model of acute heart failure in a porcine model of high-flow AVF circulation. Methods: The protocol was performed on nine domestic female pigs under general anesthesia. AVF was created by connecting two high-diameter ECMO cannulas inserted in the femoral artery and vein. Continuous hemodynamic monitoring was performed throughout the protocol. Three interventions were performed-moderate dose of norepinephrine (0.25ug/kg/min), moderate dose of dobutamine (10ug/kg/min) and rapid right ventricle pacing to simulate low cardiac output state with mean arterial pressure under 60mmHg. Measurements were taken with opened and closed arteriovenous fistula. Results: Continuous infusion of norepinephrine with opened AVF significantly increased mean arterial pressure (+20%) and total cardiac output (CO) (+36%), but vascular resistance remained virtually unchanged. AVF flow (Qa) rise correlated with mean arterial pressure increase (+20%; R = 0.97, p = 0.0001). Effective cardiac output increased, leading to insignificant improvement in organ perfusion. Dobutamine substantially increased cardiac output with insignificant effect on AVF flow and mean arterial pressure. Carotid artery blood flow increased significantly after dobutamine infusion by approximately 30%, coronary flow velocity increased significantly only in closed AVF state. The effective cardiac output using the heart failure model leading to decrease of carotid artery flow and worsening of brain and peripheral tissue oximetry. AVF blood flow also dropped significantly and proportionally to pressure, but Qa/CO ratio did not change. Therefore, the effective cardiac output decreased. Conclusion: In abovementioned extreme hemodynamic conditions the AVF flow was always directly proportional to systemic perfusion pressure. The ratio of shunt flow to cardiac output depended on systemic vascular resistance. These experiments highlight the detrimental role of a large AVF in these critical conditions' models.

Blunted Coronary Flow Velocity Reserve After Anthracycline Therapy in Breast Cancer Patients

Blunted Coronary Flow Velocity Reserve After Anthracycline Therapy in Breast Cancer Patients