Relative Coronary Flow Velocity Reserve Research Articles

P1594 Relationship between left ventricular morphology and systolic performance and coronary microcirculatory dysfunction in hypertrophic cardiomyopathy

Abstract Background Myocardial ischemia constitutes one of the most important pathophysiological features in hypertrophic cardiomyopathy (HCM). Chronic and recurrent myocardial ischemia leads to fibrosis, which may culminate in myocardial dysfunction. Objective To analyse the relationship between left ventricular (LV) morphology and systolic performance and coronary microcirculatory dysfunction in HCM. Methods The present study prospectively included HCM patients (P) who underwent transthoracic echocardiography. Left ventricular (LV) function was evaluated by ejection fraction (LVEF), global longitudinal strain (GLS) and tissue Doppler septal and lateral s’. The evaluation of coronary flow velocity reserve (CFVR) was performed in apical three chambers view for the left anterior descending (LAD) artery and in an apical three chambers view for the posterior descending (PD) artery. Diastolic coronary flow velocity was measured in basal conditions and in hyperemia, induced by adenosine perfusion (0.14 mg/kg/min intravenously, during 2 minutes). Absolute CFVR was calculated as the ratio of hyperemic to basal peak diastolic flow velocities; relative CFVR was calculated as the ratio between CFVR LAD and CFVR PD. Results 23 P were enrolled (57% male, mean age 57.9 ± 13.7 years). Asymmetric septal hypertrophy was verified in 70% of P, with maximal wall thickness of 21.6 ± 4.3mm. Obstructive HCM was documented in 35% of patients. CFV was successfully measured in the LAD in all patients, but only in 70% of patients in the PD due to technical issues related to poor acoustic window and anatomical constraints. 78% of P (n = 18) presented CFVR <2, denoting microcirculatory dysfunction. Relative CFVR (LAD CFVR/ PD CFVR) was ≥1 in 43% of P. P with maximal wall thickness (MWT)>20mm presented higher CFV PD at baseline (46.5 ± 17.4 vs 32.5 ± 12.6 cm/s; p = 0.072), lower CFVR PD (1.3 ± 0.3 vs 2.5 ± 0.8; p = 0.003) and greater regional difference of microcirculation (relative CFVR 1.4 ± 0.6 vs 0.8 ± 0.3; p = 0.048). At baseline conditions, CFV LAD was higher in obstructive HCM (44.0 ± 4.8 vs 35.3 ± 10.6 cm/s; p = 0.040). P with impairment in global longitudinal strain (GLS>-18%) had higher basal CFV LAD (40.1 ± 8.6 vs 30.0 ± 12.2 cm/s; p = 0.059) and PD (44.5 ± 15.2 vs 20.0 ± 5.0 cm/s; p = 0.015) but lower CFVR PD (1.5 ± 0.5 vs 2.8 ± 1.1; p = 0.039). The reduction in CFVR PD was also noted in P with time to peak longitudinal strain dispersion >90mseg (CFVR PD 1.2 ± 0.2vs1.9 ± 0.9;p = 0.012). Conclusion Higher CFV at baseline was noted in P with greater MWT, obstructive HCM and worse GLS. Coronary microcirculatory dysfunction was associated with the degree of LV hypertrophy and impairment in LV systolic performance.

P1827 Impact of coronary microcirculatory dysfunction in the impairment of left ventricular deformation parameters by 4D echocardiographic techniques in hypertrophic cardiomyopathy patients

Abstract Background Coronary microvascular dysfunction has been described as an important pathophysiologic feature in hypertrophic cardiomyopathy (HCM). Objective To analyse the impact of coronary microcirculatory dysfunction on left ventricular (LV) deformation parameters obtained by 4D echocardiography in HCM. Methods HCM patients (P) prospectively underwent dedicated transthoracic echocardiogram for microcirculation study. The evaluation of coronary flow velocity reserve (CFVR) was performed in apical three chambers view for the left anterior descending (LAD) artery and in an apical two chambers view for the posterior descending (PD) artery. Diastolic coronary flow velocity (CFV) was measured at basal conditions and during hyperaemia, induced with adenosine perfusion (0.14 mg/kg/min intravenously, during 2 minutes). Absolute CFVR was calculated as the ratio of hyperaemic to basal peak diastolic flow velocities. By 4D TTE (GE E95 equipment) LV global longitudinal strain (GLS), global circumferential stain, global radial strain, area strain, twist and torsion were analysed. Results 23 P were enrolled (57% male, mean age 57.9 ± 13.7 years). Asymmetric septal hypertrophy was verified in 70% of patients, with maximal wall thickness of 21.6 ± 4.3mm. Obstructive HCM was documented in 35% of patients. CFV was successfully measured in the LAD in all patients, but only in 70% of patients in the PD due to technical issues related to poor acoustic window and anatomical constraints. 78% of P (n = 18) presented CFVR <2, denoting microcirculatory dysfunction. Relative CFVR (CFVR LAD / CFVR PD) was ≥1 in 43% of P. At baseline conditions, 4D GLS < -8% was associated with lower LAD flow (34.3 ± 8.3 vs 42.7 ± 9.7cm/s; p = 0.037), trend to lower PD flow (35.3 ± 17.8 vs 49.9 ±18.4 cm/s; p = 0.066). 4D GLS < -8% P presented higher CFVR PD (2.0 ± 0.8 vs 1.1 ± 0.2; p = 0.009), with no significant difference in CFVR LAD. Global circumferential stain <-13% seemed to be associated with lower basal CFV LAD (32.5 ± 8.8 vs 40.4 ± 9.5 cm/s; p = 0.089) and PD (29.8 ± 9.0 vs 45.6 ± 17.4 cm/s; p = 0.054). P with better global circumferential stain (<-13%) presented higher CFVR PD (2.3 ± 0.7 vs 1.4 ± 0.7; p = 0.005), as well as P with an area strain <-18% (CFVR PD 2.0 ± 0.8 vs 1.4 ± 0.8; p = 0.038). P with LV twist >4deg presented higher CFV PD at baseline (49.6 ± 16.5 vs 33,8 ± 12.9 cm/s; p = 0.039) and during hyperemia (68.0 ± 12.2 vs 52.9 ± 12.1cm/s; p = 0.032). Conclusion HCM P with greater impairment in LV deformation parameters by 4D echocardiography presented increased basal diastolic CFV, which can be explained by increased coronary vascular resistance and a higher oxygen demand at baseline conditions. Worse LV performance was also associated with decreased CFVR, mainly in PD.

Regional Difference of Microcirculation in Patients with Asymmetric Hypertrophic Cardiomyopathy: Transthoracic Doppler Coronary Flow Velocity Reserve Analysis

To evaluate, by noninvasive coronary flow velocity reserve (CFVR), whether patients with asymmetric hypertrophic cardiomyopathy (HC), with or without left ventricular outflow tract obstruction, demonstrate significant regional differences of CFVR. We evaluated 61 patients with HC (27 men; mean age 49 ± 16 years), including 20 patients with hypertrophic obstructive cardiomyopathy (HOCM) and 41 patients without obstruction (HCM). The control group included 20 age- and sex-matched subjects. Transthoracic Doppler echocardiography CFVR of the left anterior descending coronary artery (LAD) and the posterior descending coronary artery (PD) were performed, including calculation of relative CFVR as the ratio between CFVR LAD and CFVR PD. Compared with the controls, all the patients with HC had lower CFVR LAD (2.12 ± 0.53 vs 3.34 ± 0.67; P < .001) and CFVR PD (2.29 ± 0.49 vs 3.21 ± 0.65; P < .001). CFVR LAD in HOCM group in comparison with the HCM group was significantly lower (1.93 ± 0.42 vs 2.22 ± 0.55; P = .047), due to higher basal diastolic coronary flow velocities (0.40 ± 0.09 vs 0.33 ± 0.07 m/sec; P = .002), with similar hyperemic diastolic flow velocities (0.71 ± 0.16 vs 0.76 ± 0.19 m/sec; P = .330), respectively. There was no significant difference in CFVR PD between patients with HOCM and those with HCM (2.33 ± 0.46 vs 2.27 ± 0.50; P = .636), respectively. Relative CFVR was lower in the HOCM group compared with the HCM group (0.84 ± 0.16 vs 0.98 ± 0.14; P = .001). By multivariable regression analysis, left ventricular outflow tract gradient was the independent predictor of CFVR LAD (B = -0.24; P = .008) and relative CFVR (B = -0.34; P = .016). CFVR LAD and relative CFVR were significantly lower in patients with HOCM compared with patients with HCM. Regional differences of CFVR are present only in patients with significant left ventricular outflow tract obstruction, which suggests that obstruction per se, by increasing wall stress in basal conditions, leads to higher basal diastolic coronary flow velocities and results in lower CFVR in LAD compared with PD.

Relative Coronary Flow Velocity Reserve Improves Correlation With Stress Myocardial Perfusion Imaging in Assessment of Coronary Artery Stenoses

To evaluate the angiographic and coronary flow velocity parameters that best correlate with the results of stress myocardial perfusion imaging. Criterion standard. Tertiary care center. Forty-eight patients undergoing diagnostic coronary angiography for angina or silent ischemia. We performed angiographic and coronary flow velocity measurements at rest and during hyperemia at the post-stenotic segment and in the adjacent angiographically normal branch of the left coronary artery. Relative coronary flow velocity reserve (RCFVR) was calculated as the ratio of post-stenotic to reference vessel coronary flow velocity reserve (CFVR). The best cutoff points for reversible perfusion defects were calculated using receiver operating characteristic curves. Post-stenotic CFVR showed fairly good correlations with minimal lumen diameter and percentage of diameter stenosis (r = 0.57 and r = 0.55, respectively; p < 0.001). RCFVR showed stronger correlations with these angiographic indexes of stenosis severity (r = 0.66 and r = 0.68, respectively; p < 0.0001). Based on receiver operating characteristic cutoff values (1.67 for post-stenotic CFVR and 0.64 for RCFVR), RCFVR had better agreement with myocardial perfusion imaging results, compared to post-stenotic CFVR (92% vs 75%, respectively). This agreement was more meaningful in patients with moderate coronary artery stenoses (50 to 75%). The area under the curve was 0.65 (not significant) for post-stenotic CFVR and 0.88 (p < 0.01) for RCFVR. RCFVR describes better than post-stenotic CFVR the functional significance of coronary artery stenoses.

P2199 Elevated C reactive protein levels predict inadequate improvement of relative coronary flow velocity reserve after uncomplicated stent implantation because of periprocedural microembolisation

P2199 Elevated C reactive protein levels predict inadequate improvement of relative coronary flow velocity reserve after uncomplicated stent implantation because of periprocedural microembolisation

Agreement between coronary flow velocity reserve and stress echocardiography in intermediate‐severity coronary stenoses

Visual and quantitative assessments of percent diameter stenosis on coronary angiography correlate poorly with functional testing, particularly in intermediate-severity (40%-70%) lesions, yet are frequently relied on to make decisions regarding revascularization. Coronary flow velocity reserve (CFVR) and relative CFVR (RCFVR) are promising methods for on-line functional assessment of lesion severity in the catheterization laboratory. We sought to determine the agreement between maximal, mean, and relative CFVR and stress echocardiography in intermediate-severity stenoses. The results of exercise or dobutamine stress echocardiography and CFVR measured by intracoronary Doppler were compared in 28 patients referred for assessment of intermediate-severity stenoses, using 15 patients with either angiographically normal coronary arteries or diameter stenoses > 70% as reference groups. CFVR was measured at least three times in response to a bolus of adenosine in the target vessel distal to the stenosis. RCFVR (target/normal vessel CFVR) was also measured in 27 patients. Maximal, mean (of three measures), and relative CFVR were calculated. CFVR > or = 2.0 and RCFVR > or = 0.75 were accepted as normal. A minority (29%) of patients in the intermediate-severity stenosis group had a positive test by either method. There was good to very good agreement between stress echocardiography and maximal CFVR (84%, kappa = 0.62, P < 0.0001) and RCFVR (81%, kappa = 0.59, P < 0.001) across the entire patient cohort, though in the intermediate subgroup concordance was only fair. Using the mean (of three measures of) CFVR for the same comparison improved the agreement in the intermediate subgroup to good (86%, kappa = 0.58, P = 0.002), and in the entire cohort the agreement was very good (88%, kappa = 0.74, P < 0.0001). There was only fair correlation between measures of CFVR and percent coronary stenosis. CFVR improved from 1.8 +/- 0.8 to 2.7 +/- 0.7 after percutaneous intervention (n = 12, P < 0.0001). These results suggest that there is good agreement between CFVR and stress echocardiography across a wide range of coronary lesion severity. The mean of three CFVR measurements distal to the target vessel stenosis increases diagnostic accuracy. Intracoronary Doppler flow velocity measurements at the time of cardiac catheterization may facilitate improved decision-making by providing the ability to assess the functional significance of coronary stenoses on-line.

Fractional flow reserve, absolute and relative coronary blood flow velocity reserve in relation to the results of technetium-99m sestambi single-photon emission computed tomography in patients with two-vessel coronary artery disease

OBJECTIVESWe sought to perform a direct comparison between perfusion scintigraphic results and intracoronary-derived hemodynamic variables (fractional flow reserve [FFR]; absolute and relative coronary flow velocity reserve [CFVR and rCFVR, respectively]) in patients with two-vessel disease.BACKGROUNDThere is limited information on the diagnostic accuracy of intracoronary-derived variables (CFVR, FFR and rCFVR) in patients with multivessel disease.METHODSDipyridamole technetium-99m sestambi (MIBI) single-photon emission computed tomography (SPECT) was performed in 127 patients. The presence of reversible perfusion defects in the region of interest was determined. Within one week, angiography was performed; CFVR, rCFVR and FFR were determined in 161 coronary lesions after intracoronary administration of adenosine. The predictive value for the presence of reversible perfusion defects on MIBI SPECT of CFVR, rCFVR and FFR was evaluated by the area under the curve (AUC) of the receiver operating characteristics curves.RESULTSThe mean percentage diameter stenosis was 57% (range 35% to 85%), as measured by quantitative coronary angiography. Using per-patient analysis, the AUCs for CFVR (0.70 ± 0.052), rCFVR (0.72 ± 0.051) and FFR (0.76 ± 0.050) were not significantly different (p = NS). The percentages of agreement with the results of MIBI SPECT were 76%, 78% and 77% for CFVR, rCFVR and FFR, respectively. Per-lesion analysis, using all 161 measured lesions, yielded similar results.CONCLUSIONSThe diagnostic accuracy of three intracoronary-derived hemodynamic variables, as compared with the results of perfusion scintigraphy, is similar in patients with two-vessel coronary artery disease. Cut-off values of 2.0 for CFVR, 0.65 for rCFVR and 0.75 for FFR can be used for clinical decision-making in this patient cohort. Discordant results were obtained in 23% of the cases that require prospective evaluation for appropriate patient management.

Coronary Physiology as an important adjunct to coronary intervention.

The direct physiologic influence of a coronary stenosis, prior to an intervention for either de novo or restenotic lesions, can be easily and safely determined with sensor-tipped angioplasty guidewires, employing poststenotic absolute coronary flow velocity reserve (CVR), the relative CVR and the pressure-derived fractional flow reserve. This information supports decisions regarding planned interventions on restenotic or de novo lesions of intermediate angiographic severity. Following percutaneous interventions, these measurements provide prognostic information that may not only direct the need for repeat balloon dilatation, stent implantation or high-pressure expansion, but also predict long-term clinical outcome.

Abnormal coronary flow velocity reserve after coronary artery stenting in patients: role of relative coronary reserve to assess potential mechanisms.

Absolute coronary flow velocity reserve (CVR) after stenting may remain abnormal as a result of several different mechanisms. Relative CVR (rCVR=CVR(target)/CVR(reference)) theoretically normalizes for global microcirculatory disturbances and facilitates interpretation of abnormal CVR. To characterize potential mechanisms of poststent physiology, CVR was measured using a Doppler-tipped angioplasty guidewire in 55 patients before and after angioplasty, after stenting, and in an angiographically normal reference vessel. For the group, the percent diameter stenosis decreased from 75+/-13% to 40+/-18% after angioplasty and to 10+/-9% (all P<0.05) after stent placement. After angioplasty, CVR increased from 1.63+/-0.71 to 1.89+/-0.55 (P<0.05) and after stent placement, to 2.48+/-0.75 (P<0.05 versus pre- and postangioplasty). After angioplasty, rCVR increased from 0.64+/-0.26 to 0.75+/-0.23 and after stent placement to 1.00+/-0.34. In 17 patients with CVR(stent) < or = 2.0, increased basal coronary flow, rather than attenuated hyperemia, was responsible in large part for the lower CVR(stent) compared with patients having CVR(stent) >2.0. In 8 patients with CVR(stent) <2.0, a normal rCVR supported global microvascular disease. The subgroup of 9 patients with CVR(stent) <2.0 and abnormal rCVR (16% of the studied patients) may require a pressure-derived fractional flow reserve to differentiate persistent obstruction from diffuse atherosclerotic disease or microvascular stunning. Although a majority of patients after stenting normalize CVR for the individual circulation (ie, normal CVR or normal rCVR), in those with impaired CVR(stent), the analysis of coronary flow dynamics suggests several different physiological mechanisms. Additional assessment may be required to fully characterize the physiological result for such patients to exclude remediable luminal abnormalities.

The Absolute and Relative Coronary Flow Velocity Reserve After Lumen Enlargement by Ultrasound-guided Balloon Angioplasty and Stent Implantation

The Absolute and Relative Coronary Flow Velocity Reserve After Lumen Enlargement by Ultrasound-guided Balloon Angioplasty and Stent Implantation

The absolute and relative coronary flow velocity reserve after lumen enlargement by ultrasound-guided balloon angioplasty and stent implantation

The absolute and relative coronary flow velocity reserve after lumen enlargement by ultrasound-guided balloon angioplasty and stent implantation