Knut Hegbom

Coronary flow velocity reserve in the three main coronary arteries assessed with transthoracic Doppler: a comparative study with quantitative coronary angiography.

BACKGROUND 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. METHODS 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%. RESULTS 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. CONCLUSIONS 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.

Coronary Atheroma Regression and Plaque Characteristics Assessed by Grayscale and Radiofrequency Intravascular Ultrasound After Aerobic Exercise

The aim of the present study was to investigate effects of aerobic interval training (AIT) versus moderate continuous training (MCT) on coronary atherosclerosis in patients with significant coronary artery disease on optimal medical treatment. Thirty-six patients were randomized to AIT (intervals at ≈ 90% of peak heart rate) or MCT (continuous exercise at ≈ 70% of peak heart rate) 3 times a week for 12 weeks after intracoronary stent implantation. Grayscale and radiofrequency intravascular ultrasounds (IVUS) were performed at baseline and follow-up. The primary end point was the change in plaque burden, and the secondary end points were change in necrotic core and plaque vulnerability. Separate lesions were classified using radiofrequency IVUS criteria. We demonstrated that necrotic core was reduced in both groups in defined coronary segments (AIT -3.2%, MCT -2.7%, p <0.05) and in separate lesions (median change -2.3% and -0.15 mm(3), p <0.05). Plaque burden was reduced by 10.7% in separate lesions independent of intervention group (p = 0.06). No significant differences in IVUS parameters were found between exercise groups. A minority of separate lesions were transformed in terms of plaque vulnerability during follow-up with large individual differences between and within patients. In conclusion, changes in coronary artery plaque structure or morphology did not differ between patients who underwent AIT or MCT. The combination of regular aerobic exercise and optimal medical treatment for 12 weeks induced a moderate regression of necrotic core and plaque burden in IVUS-defined coronary lesions.

Transthoracic echocardiography for imaging of the different coronary artery segments: a feasibility study

BackgroundTransthoracic echocardiography (TTE) may be used for direct inspection of various parts of the main coronary arteries for detection of coronary stenoses and occlusions. We aimed to assess the feasibility of TTE to visualise the complete segments of the left main (LM), left descending (LAD), circumflex (Cx) and right (RCA) coronary arteries.MethodsOne hundred and eleven patients scheduled for diagnostic coronary angiography because of chest pain or acute coronary syndrome had a TTE study to map the passage of the main coronary arteries. LAD, Cx and RCA were each divided into proximal, middle and distal segments. If any part of the individual segment of a coronary artery with antegrade blood flow was not visualised, the segment was labeled as not satisfactorily seen.ResultsComplete imaging of the LM was achieved in 98% of the patients. With antegrade directed coronary artery flow, the proximal, middle and distal segments of LAD were completely seen in 96%, 95% and 91% of patients, respectively. Adding the completely seen segments with antegrade coronary flow and segments with retrograde coronary flow, the proximal, middle and distal segments of LAD were adequately visualised in 96%, 96% and 93% of patients, respectively. With antegrade directed coronary artery flow, the proximal, middle and distal segments of Cx were completely seen in 88%, 61% and 3% and in RCA in 40%, 28% and 54% of patients. Retrograde coronary artery flow was correctly identified as verified by coronary angiography in seven coronary segments, mainly in the posterior descending artery (labeled as the distal segment of RCA) and distal LAD.ConclusionsTTE is a feasible method for complete demonstration of coronary flow in the LM, the proximal Cx and the different segments of LAD, but less suitable for the RCA and mid and distal segments of the Cx. (ClinicalTrials.gov number NTC00281346.)

Recovery of Function After Acute Myocardial Infarction Evaluated by Tissue Doppler Strain and Strain Rate

BACKGROUND The aim of this study was to investigate the changes and time course of recovery of regional myocardial function within the first week following successful primary coronary intervention in patients with first-time ST-segment elevation myocardial infarctions using myocardial deformation analysis, which is more quantitative and thus more objective than the wall motion score. METHODS Thirty-one consecutive patients admitted with ST-segment elevation myocardial infarctions were studied on days 1, 2, 3, and 7 using strain and strain rate tissue Doppler echocardiography. RESULTS The mean peak troponin T level was 7.0 microg/L, and 15 patients had anterior and 16 had inferior infarct localization. Peak systolic strain rate and end-systolic strain increased significantly on day 2, both in segments with moderately reduced function (-0.6 to -1.0 s(-1) vs -8% to -15%, P < .001) and in severely reduced function (-0.2 to -1.0 s(-1) vs 1% to -12%, P < .001), but there were no further changes. Mean wall motion score in infarct related segments decreased significantly from day 1 to day 2 (2.7 to 2.4, P = .001) and from day 3 to day 7 (2.3 to 2.2, P = .001). CONCLUSIONS Recovery of regional function after ST-segment elevation myocardial infarction occurred within 2 days and could be detected by wall motion score, strain rate, and strain. However, strain and strain rate were better discriminative parameters for the changes in function as well as being better to assess near normalization on day 2. This could have a clinical impact on early management in patients who undergo percutaneous coronary intervention.

Transthoracic Doppler for detection of stenoses in the three main coronary arteries by use of stenotic to prestenotic velocity ratio and aliased coronary flow

AIMS Our aim was to determine the feasibility and accuracy of diagnosing significant coronary artery stenoses using peak stenotic to prestenotic velocity ratio (pSPVR) measurements when compared with results from quantitative coronary angiography and coronary flow velocity reserve (CFVR) assessed by transthoracic echocardiography (TTE). METHODS AND RESULTS One hundred and eight patients scheduled for coronary angiography were studied using transthoracic Doppler echocardiography. Stenoses were identified by local colour aliasing by colour flow Doppler, and further evaluated by pSPVR, using a pSPVR of ≥2.0 as a cut-off for significant stenosis. When pSPVR could not be measured, local mosaic coronary flow pattern at Nyquist limit ≥0.48 m/s was used. Sixty-five lesions suggestive of stenosis were found by TTE. Combining findings of pSPVR ≥2.0 and local mosaic flow at Nyquist limit ≥0.48 m/s, the sensitivity and specificity of demonstrating significant stenoses (diameter stenosis, 50-99%) in the left main coronary artery (LM), left anterior descending coronary (LAD), left circumflex coronary (Cx), and right coronary artery (RCA) were 75 and 98%, 74 and 95%, 40 and 87%, and 34 and 98%, respectively. The pSPVR did not differ significantly between arteries with reduced and normal CFVR, with a cut-off of CFVR <2.0. CONCLUSIONS Findings of pSPVR ≥2.0 or localized colour flow aliasing are useful in the non-invasive diagnosis of significant coronary disease in the three main coronary arteries, with high specificity for detecting significant stenoses. These findings showed high sensitivity for identifying significant stenoses in the LM and LAD, but showed lower ability to detect those lesions in the Cx and RCA.

Transthoracic Doppler Echocardiography for Detection of Stenoses in the Left Coronary Artery by Use of Poststenotic Coronary Flow Profiles: A Comparison with Quantitative Coronary Angiography and Coronary Flow Reserve

BACKGROUND The aim of this study was to determine whether poststenotic diastolic-to-systolic velocity ratio (DSVR) assessed by transthoracic Doppler echocardiography could accurately identify significant stenoses in the left coronary artery. METHODS A total of 108 patients scheduled for coronary angiography because of chest pain or acute coronary syndromes were studied. RESULTS The success rates of peak DSVR (pDSVR) measurements in the distal to mid left anterior descending coronary artery and marginal branches of the left circumflex coronary artery were 85% and 32%, respectively. With peak coronary flow velocity reserve as a reference, pDSVR was significantly higher in arteries with normal coronary flow reserve (peak coronary flow velocity reserve ≥ 2.0) compared with arteries with reduced coronary flow reserve (peak coronary flow velocity reserve < 2.0) (1.86 ± 0.32 vs 1.53 ± 0.31, P < .0001). In comparison with quantitative coronary angiography, pDSVR was significantly higher in lesions with diameter stenosis < 50% compared with those with diameter stenosis of 50% to 75% (1.92 ± 0.32 vs 1.53 ± 0.18, P < .0001) or diameter stenosis of 76% to 100% (1.43 ± 0.13, P < .0001). Receiver operating characteristic curves showed pDSVR < 1.68 to be the optimal cutoff value for identifying both functionally significant stenoses and diameter stenoses ≥ 50%, with sensitivity of 86% and 90%, specificity of 74% and 84%, positive predictive value of 51% and 71%, and negative predictive value of 94% and 95%, respectively. CONCLUSIONS Transthoracic pDSVR measurements in the distal to mid left anterior descending coronary artery and marginal branches of the left circumflex coronary artery had high accuracy for excluding functionally significant stenoses in the left coronary artery, as well as for identifying angiographic significant stenoses.

Predictors of Beneficial Coronary Plaque Changes after Aerobic Exercise.

PURPOSE It has been demonstrated that aerobic exercise induces beneficial changes in coronary atherosclerosis via reduced necrotic core and plaque burden. Clinical factors that may be associated with favorable exercise-induced intracoronary effects are unknown. METHODS This study used post hoc analysis of associations between baseline clinical variables and reductions in coronary necrotic core and plaque burden after aerobic exercise intervention. Coronary plaque characteristics were measured with grayscale and radiofrequency intravascular ultrasound in 36 patients (median age, 58.5 yr; seven women) with stable CAD (SCAD) or non-ST elevation acute coronary syndrome (NSTE-ACS). Screening of clinical variables was performed with random forest analysis followed by multivariate linear regression. RESULTS The only significant clinical variable for necrotic core reduction was clinical presentation of disease (SCAD vs NSTE-ACS, P = 0.011). The changes in necrotic core after exercise were -4.94 mm3 (-10.33; -1.33) in patients with SCAD and 1.03 mm3 (-4.29; 3.71) in patients with NSTE-ACS (P = 0.01). Necrotic core was reduced in 17 patients (94%) with SCAD and eight patients (44%) with NSTE-ACS (P = 0.01). R2 for the model including baseline clinical presentation and baseline necrotic core volume was 0.90. There were no significant explanatory variables for plaque burden reduction. CONCLUSIONS Exercise-induced plaque stabilization via reduced coronary necrotic core may be strongly dependent on clinical presentation of CAD. We hypothesized that an increased proinflammatory load renders patients with NSTE-ACS more resistant to exercise-induced plaque stabilization than patients with SCAD. Furthermore, aerobic exercise may have a particular potential for inducing beneficial effects on coronary atherosclerosis in patients with SCAD compared with patients in the early phase after an acute coronary syndrome.

Pedicled Vein Grafts in Coronary Surgery Exhibit Reduced Intimal Hyperplasia at 6 Months

Despite strong evidence for superior patency and improved clinical endpoints using arterial grafts in coronary artery bypass graft surgery, the saphenous vein (SV) is still the most widely used graft in addition to left internal mammary artery (LIMA) [(1)][1]. Consequently, improving SV patency

Reproducibility of grayscale and radiofrequency IVUS data acquisition in stented coronary arteries

Abstract Objectives. Variability in data acquisition from intervened coronary arteries could represent a source of error that has implications for the design of serial stent studies. We assessed inter-pullback reproducibility of volumetric grayscale and radiofrequency intravascular ultrasound (IVUS) data in stented coronary arteries. Design. Fifteen patients with coronary artery lesions treated with stent implantation were included and examined with two separate pullbacks using the Eagle Eye Gold-phased array 20 MHz IVUS catheter (Volcano). The arteries were divided into five segments, giving a total of 150 sub-segments for analyses. Matching of frames was performed using landmarks that were clearly visible in coronary angiography and intravascular pullbacks. Data were analyzed off-line at an independent Corelab. Results. The inter-pullback reproducibility of geometrical data was very good for non-stented segments with relative differences less than 5% between pullbacks for lumen-, vessel-, and plaque volumes. For stented segments reproducibility was poorer with relative differences between pullbacks in the range of 5–10%. The inter-pullback reproducibility of compositional data demonstrated large standard deviations of relative differences, indicating a weaker agreement. Conclusions. Agreements between pullbacks were weaker in stented than those in non-stented segments. Based on our data, future longitudinal IVUS studies in intervened vessels should account for a variability of 5–10% attributed to the acquisition of images.