Transthoracic echocardiographic detection of coronary atherosclerosis

Recent-onset of rheumatoid arthritis leads to increase in wall thickness of left anterior descending coronary artery. An evidence of subclinical coronary artery disease

OBJECTIVES

To explore the atherosclerotic changes of the left anterior descending coronary artery (LADCA) in patients with early onset of rheumatoid arthritis (RA).

METHODS

Transthoracic echocardiographic scans were performed on 15 early RA patients and 20 control subjects, free of rheumatological diseases, diabetes mellitus (DM), and cardiovascular disease (CVD). Out of 15 RA patients, 10 were matched for age and gender with control. Left anterior descending coronary artery wall thickness was compared between RA subjects and their matched control. Among early RA patients, correlation was assessed between LADCA wall thickness and the demographic features, RA activity features, and cardiovascular risk factors.  Results: Left anterior descending coronary artery wall thickness was significantly increased (p=0.001) in early RA compared to controls, as it was reported to be 0.61±0.04 mm (CI: 0.52-0.7); and 0.48±0.08 mm (CI: 0.44-0.51) respectively. Within early RA, LADCA wall thickness was related to the disease activity score (p=0.025, ß-coefficient 0.066, CI: 0.01-0.122) as well as to the patient global assessment of disease activity (PGADA) at RA onset (p=0.006, ß-coefficient 0.003, CI: 0.001-0.005), in a positive linear relationship. Left anterior descending coronary artery  wall thickness was found to be thicker among RA patients with rheumatoid factor (RF) positive (p=0.015, CI: 0.53-0.66). Conclusion: Early RA patients have increased coronary arteries atherosclerotic burden compared to healthy subjects matched for age, and gender. Rheumatoid factor positivity, high disease activity score and PGADA were found to be associated with coronary artery wall thickness.

High echogenic thickening of proximal coronary artery predicts the far advanced coronary atherosclerosis

BACKGROUND

Detection of subclinical, nonobstructive coronary artery disease will require the evaluation of coronary arterial walls and external coronary diameter in order to detect increases in arterial wall thickness and compensatory remodeling before luminal narrowing. We assessed the meaning of high echogenic thickening (HET) on transthoracic coronary echogram of proximal coronary arteries and evaluated whether HET predicts the severity of coronary artery disease on angiogram.

METHODS

Ninety-seven patients (M:F = 61:36, mean age = 61+/-8 years) referred for coronary angiography were included in this study. We detected proximal coronary artery using transthoracic coronary echogram. We defined that HET is more than 1.5 mm in thickness with high echogenicity and persistence. Of these patients, 29 vessels were examined by IVUS (intravascular ultrasound).

RESULTS

(1) HET on coronary echogram had a sensitivity of 44.4% and specificity of 95% for identifying calcification on IVUS. (2) HET had a sensitivity of 73.5% and specificity of 85.7% for identifying the significant stenosis of proximal left coronary artery. (3) HET was observed more frequently in three-vessel diseases and more complex lesion compared to normal and one- or two-vessel diseases (P < 0.05, respectively).

CONCLUSION

HET may be related to the presence of calcification and predicts far advanced coronary atherosclerosis.

Significance of the distal to proximal coronary flow velocity ratio by transthoracic Doppler echocardiography for diagnosis of proximal left coronary artery stenosis

OBJECTIVE

This study was designed to evaluate the significance of accelerated coronary flow velocity in the proximal left coronary artery by transthoracic Doppler echocardiography for detecting coronary stenosis.

METHODS

Seventy subjects with suspected coronary artery disease underwent successful coronary flow velocity measurement in both proximal and distal lesions by transthoracic Doppler echocardiography and coronary angiography.

RESULTS

On the basis of the coronary angiography results, 23 patients had significant (> or =50%) stenosis in the proximal left coronary artery (Group S) and 47 patients had no stenosis (Group N). The distal averaged diastolic peak velocity to proximal averaged diastolic peak velocity ratio (DAPAR) in Group S was significantly lower than that in Group N. A cutoff value of DAPAR < or = 0.5 for DAPAR predicted significant coronary stenosis with a sensitivity of 91% and a specificity of 72%.

CONCLUSION

Measurement of the DAPAR by transthoracic Doppler echocardiography is a promising method in the noninvasive diagnosis of stenosis in the proximal left coronary artery lesion.

Vasodilation of epicardial coronary artery can be measured with transthoracic echocardiography

Transthoracic Doppler echocardiography (TTE) has been introduced as a noninvasive tool to measure coronary flow velocity reserve (CFVR). Velocity measurement, however, fails to take into account epicardial coronary artery vasodilation during hyperemia and this may cause underestimation of CFVR measurements. Therefore, we sought to determine whether the vasodilation of epicardial coronary artery can be measured during cold pressor test (CPT) and adenosine infusion simultaneously with the flow velocity measurement using TTE. We studied 41 healthy nonsmoking men with a linear high-frequency 8.0-MHz transducer. The CPT and adenosine infusion dilated the diameter of the distal left anterior descending coronary artery (LAD) from 1.4 +/- 0.4 mm to 1.5 +/- 0.4 mm (14 +/- 13%, p < 0.01) and from 1.4 +/- 0.4 mm to 1.8 +/- 0.5 mm (31 +/- 19%, p < 0.01), respectively. The CPT increased flow velocity and calculated coronary blood flow rate (velocity time integral x cross-sectional area) from 0.23 +/- 0.05 m/s to 0.36 +/- 0.13 m/s (31 +/- 34%, p < 0.01) and from 8.1 +/- 4.2 mL/min to 11.4 +/- 6.0 mL/min (47 +/- 51%, p < 0.01). CFVR and calculated coronary blood flow rate reserve were 3.9 +/- 1.0 and 6.0 +/- 1.9, respectively. In Bland-Altman analysis, velocity measurements underestimated the vasodilation response of the CPT and adenosine compared with the measurements where epicardial diameter dilation was taken into account. Intra- and interobserver variability of diameter measurements was low (coefficient of variation [CV] 2.6 to 6.5%). Day-to-day, within-day and intersonographer variabilities were of similar magnitude (CV 4.6 to 8.2%), suggesting good reproducibility. This study demonstrates that TTE can be used to assess changes in both epicardial coronary artery diameter and flow velocity simultaneously in the distal LAD artery.

Relationship between the number of coronary risk factors and coronary atherosclerosis assessed by high-frequency transthoracic echocardiography

Atherosclerosis is a diffuse process and can be evaluated in the distal part of the left anterior descending coronary artery (LAD). We evaluated whether 2-dimensional high-frequency transthoracic echocardiography could detect changes in coronary wall thickness and size associated with coronary risk factors. In all, 312 patients without a history of coronary artery disease and 40 patients with LAD disease proven by coronary angiography underwent transthoracic echocardiography evaluation of the distal LAD using high-frequency transducer. LAD wall thickness, luminal diameter, external diameter, and coronary flow velocity were measured, and these values were compared according to the number of coronary risk factors (hypertension, hypercholesterolemia, diabetes, smoking, and family history). The feasibility of measuring coronary thickness and coronary flow velocity was 86% and 90%, respectively. LAD wall thickness and external diameter significantly increased according to the increase in the number of risk factors. Patients with 3 or more coronary risk factors showed similar LAD wall thickness (0.82 +/- 0.2 vs 0.89 +/- 0.2 mm) and external diameter (3.4 +/- 0.8 vs 3.3 +/- 0.9 mm) compared with those obtained in patients with LAD disease. High-frequency transthoracic echocardiography is feasible to measure coronary artery wall thickness and external diameter in the distal LAD. This approach has a potential for noninvasive evaluation of the arterial remodeling and the changes in these variables after risk factor modification and intensive drug therapy.

Comparison of high-frequency two-dimensional transthoracic echocardiography versus intravascular ultrasound for evaluation of the left anterior descending coronary artery

The purpose of this study was to evaluate the feasibility of high-frequency transthoracic echocardiography for measuring the wall thickness and luminal area of the left anterior descending coronary artery (LAD). Fifteen patients underwent simultaneous high-frequency transthoracic echocardiography and intravascular ultrasound (IVUS) examinations. There were good agreements for wall thickness (0.38 +/- 0.05 vs 0.38 +/- 0.06 mm, p = 0.0004) and luminal area (3.24 +/- 1.05 vs 3.32 +/- 1.34 mm2, p <0.0001) between high-frequency transthoracic echocardiography and IVUS measurements. High-frequency transthoracic echocardiography was reliable in the measurement of the wall thickness and luminal area of the LAD.

Potential use of high-resolution two-dimensional transthoracic echocardiography for visualization of the left anterior descending coronary artery

High-resolution, two-dimensional transthoracic echocardiography (HR-2DTTE) can detect the difference in the left anterior descending coronary artery (LAD) wall thickness between patients with coronary artery disease and patients with normal coronary arteries. However, HR-2DTTE measurements of the LAD wall thickness are larger than measurements obtained by intravascular ultrasound and histology. This difference may be due to the inclusion of adventitia by HR-2DTTE. We evaluated the contribution of adventitia to the wall thickness of the normal and atherosclerotic LAD by comparing HR-2DTTE with high-frequency epicardial echocardiography. The LAD wall thickness was significantly greater in patients with coronary artery disease by both HR-2DTTE and high-frequency epicardial echocardiography. Both an increase in the intima plus media thickness and an increase in the thickness of adventitia contributed to the increase in the LAD wall thickness in patients with coronary artery disease. Adventitia represents a significant portion of the LAD wall thickness imaged by HR-2DTTE and its thickness increases significantly with the development of atherosclerosis.

Coronary artery diameter can be assessed reliably with transthoracic echocardiography

We studied whether diameters of coronary arteries can be measured accurately with the use of transthoracic echocardiography (TTE). By knowing the anatomic diameter of the coronary artery together with coronary flow velocity it is possible to measure coronary flow volume more precisely by TTE. However, the suitability of TTE for measurement of diameters of all main epicardial coronary arteries has not been systematically validated. We measured the diameters of the left main (LM), left anterior descending (LAD), left circumflex (LCX), and right coronary arteries (RCA) with the use of TTE [manual two-dimensional (2D), color-Doppler, and automated 2D analysis] in 30 patients who had normal coronary anatomy. We compared these diameters to those measured with quantitative coronary angiography (QCA). We could measure diameters of LM, LAD, LCX, and RCA by TTE in up to 37%, 63%, 7%, and 60% of patients, respectively. The overall correlation coefficients between TTE and QCA measurements were 0.83 ( P < 0.01) with manual 2D analysis, 0.82 ( P < 0.01) with automated 2D analysis, and 0.94 ( P < 0.01) with a color-Doppler-based analysis. Interobserver variability of TTE measurements was low (coefficient of variation 5.4 ± 4.6–7.5 ± 8.8%). TTE is an accurate method to evaluate coronary artery diameter in patients with healthy coronary arteries.

Left anterior descending coronary artery wall thickness measured by high-frequency transthoracic and epicardial echocardiography includes adventitia

High-frequency, 2-dimensional transthoracic echocardiography (HR-2DTTE) measurements of the left anterior descending (LAD) coronary artery wall thickness are larger than measurements obtained by intravascular ultrasound. We hypothesize that this difference is due to inclusion of the third vascular layer, which may represent adventitia by HR-2DTTE, and that this layer must be increasing in thickness with the development of atherosclerosis. We evaluated the contribution of this third layer to the wall thickness of the normal and atherosclerotic LAD artery imaged by HR-2DTTE using high-frequency epicardial echocardiography (HFEE) as the reference standard. Eighteen patients (10 men, mean age 62 years), 13 with coronary atherosclerosis and 5 with normal coronary arteries, referred for open-heart surgery, underwent preoperative HR-2DTTE evaluation of the LAD artery (SONOS 5500; 3- to 8-MHz transducer) and intraoperative HFEE of the LAD artery (SONOS 5500; 6- to 15-MHz transducer). Wall thickness was greater in patients with coronary atherosclerosis than in those with normal coronary arteries by both HR-2DTTE (1.9 +/- 0.3 vs 1.0 +/- 0.1 mm, p = <0.001) and HFEE (1.8 +/- 0.2 vs 1.0 +/- 0.2 mm, p = <0.001). On HFEE, the average intima plus media thickness was greater in patients with coronary atherosclerosis than in those with normal coronary arteries (0.78 +/- 0.3 vs 0.34 +/- 0.1 mm, p = 0.005). The average thickness of adventitia was also greater in patients with coronary atherosclerosis than in those with normal coronary arteries (0.92 +/- 0.2 vs 0.54 +/- 0.2 mm, p = 0.0005). HR-2DTTE and HFEE measurements of the wall thickness correlated well (r = 0.83 [reader 1], p <0.001; r = 0.61 [reader 2], p <0.01). A third vascular layer, which likely included adventitia, represents a significant portion of the LAD wall thickness imaged by HR-2DTTE and HFEE, and it significantly increases in thickness with the development of atherosclerosis.

Imaging of the left anterior descending coronary artery by high-frequency transthoracic and epicardial echocardiography

Left anterior descending coronary artery (LAD) wall thickness and external diameter are significantly increased in patients with coronary artery disease compared with normal subjects. High-resolution, 2-dimensional transthoracic echocardiography (HR-2DTTE) can be used to measure LAD wall thickness and is sensitive enough to detect these differences. However, HR-2DTTE measurements of the LAD wall thickness are larger than measurements obtained by intravascular ultrasound and histology. We hypothesize that this difference is due to inclusion of the third vascular layer, which may represent adventitia, by HR-2DTTE, and that this layer must be increasing in thickness with the development of atherosclerosis. We evaluated the contribution of this third layer to the wall thickness of the normal and atherosclerotic LAD imaged by HR-2DTTE using high-frequency epicardial echocardiography (HFEE). Thirteen patients with coronary atherosclerosis and 5 patients with normal coronary arteries underwent preoperative HR-2DTTE and intraoperative HFEE. HR-2DTTE and HFEE measurements of the wall thickness correlated well. The wall thickness was significantly greater in patients with coronary atherosclerosis than in patients with normal coronary arteries by both HR-2DTTE and HFEE. With HFEE, the average intima plus media thickness and the average thickness of adventitia were greater in patients with coronary atherosclerosis than in patients with normal coronary arteries. A third vascular layer, which likely includes adventitia, represents a significant portion of the LAD wall thickness imaged by HR-2DTTE and HFEE, and its thickness increases significantly with the development of atherosclerosis.

Detection of subclinical coronary atherosclerosis using two-dimensional, high-resolution transthoracic echocardiography

OBJECTIVES

We evaluated whether two-dimensional high-resolution transthoracic echocardiography (HR-2DTTE) can detect changes in arterial wall thickness and size associated with subclinical coronary artery disease (CAD).

BACKGROUND

Arterial wall thickening, compensatory arterial enlargement and a preserved arterial lumen characterize subclinical atherosclerosis. Detection of these changes during the asymptomatic stage of CAD may allow early treatment and prevention of acute coronary events.

METHODS

Twenty-six patients with angiographically proven CAD and 29 normal volunteers underwent HR-2DTTE evaluation of the left anterior descending coronary artery (LAD) using an ATL 5000 echograph (Advanced Technology Laboratories, Bothell, Washington) with a 4 to 7 MHz transducer. Significant (>70%) LAD stenosis was present in 15 patients (mean 82%); 11 patients did not have significant LAD stenosis (mean 26%) and represented a surrogate for subclinical LAD disease. Wall thickness, maximal luminal diameter and external diameter of the LAD were measured.

RESULTS

Left anterior descending coronary artery wall thickness was larger in patients (1.9 +/- 0.4 mm) than it was in volunteers (0.9 +/- 0.1 mm, p < 0.001). The external diameter of the LAD was (6.0 +/- 1.1 mm) in patients and (3.9 +/- 0.7 mm) in volunteers (p < 0.001). Luminal diameter was 2.2 +/- 0.5 mm in patients and 2.1 +/- 0.6 mm in volunteers (p = NS). There was no difference in wall thickness (1.9 +/- 0.4 mm vs. 2.0 +/- 0.4 mm), luminal diameter (2.2 +/- 0.5 mm vs. 2.2 +/- 0.4 mm) and external diameter (5.9 +/- 1.0 mm vs. 6.2 +/- 1.2 mm) between the patients with <70% and >70% LAD stenosis.

CONCLUSIONS

Left anterior descending coronary artery wall thickness and external diameter are significantly increased in patients with CAD as compared with normal subjects, and HR-2DTTE is sensitive enough to detect these differences. Wall thickness and external diameter are increased to the same extent in patients with obstructive and subclinical LAD disease.

Usefulness of topography of coronary calcium by electron-beam computed tomography in predicting the natural history of coronary atherosclerosis

Electron-beam computed tomography (EBCT) allows for accurate noninvasive detection and quantification of coronary calcium that is representative of underlying atherosclerotic disease. The present study quantitatively analyzes the topography and establishes the natural history of coronary calcium in patients with variable degrees of coronary atherosclerosis. EBCT was performed in 330 consecutive patients aged 56 +/- 12 years (70% men) with recent (<3 months) onset of signs or symptoms of coronary artery disease (CAD) or who were evaluated because of a presumed high risk. Total calcium scores, computed by the Agatston method, were positive in 269 patients (82%) (mean age 58 +/- 11 years, 73% men). These patients were classified into 4 groups, with total calcium scores ranging between 1 and 30, >30 and 100, >100 and 400, and >400, respectively. The presence and amount of calcium was additionally assessed in 10 major segments of the coronary arterial tree, including the major coronary arteries. Of the 72 patients with calcium of only 1 of the major coronary arteries, the left anterior descending coronary artery was involved in 39 patients (54%) and the right coronary artery in 18 patients (25%). Left main stem calcium was observed in only 10 of 139 patients (7%) with 1- or 2-vessel calcium and in 17 of 77 patients (23%) with 3-vessel calcium. Calcium was consistent most frequently in the proximal left anterior descending coronary artery, followed by the proximal left circumflex and right coronary artery segments. A significant decrease of frequency and amount of calcium from the proximal to distal segments was observed in the left coronary system but not in the right coronary artery, where the distribution was more even. With increasing total calcium scores, segmental scores in the more distal segments were enhanced, but the increase was most pronounced in the proximal segments and particularly in the proximal left anterior descending coronary artery. EBCT-derived coronary calcium shows an axial distribution that appears comparable to that of atherosclerotic lesions observed in pathologic and angiographic studies, highlighting the potential role of EBCT for studying the natural history of CAD.

Noninvasive coronary artery imaging in the diagnosis and management of patients with ischemic heart disease

The inherent limitations of x-ray coronary angiography have led to the development for both noninvasive and minimally invasive techniques for imaging the coronary arteries to assist in the diagnosis and management of patients with ischemic heart disease. Significant advances in transesophageal echocardiography, electron beam computed tomography, and magnetic resonance imaging now permit imaging of the proximal to mid-coronary arteries. Moreover, results of initial studies demonstrate the promise of these methods to detect coronary artery stenoses. In addition, each of these methods provides biochemical or physiologic data about the stenoses that are not obtainable through x-ray angiography. Quantification of coronary calcification via electron beam computed tomography has shown promise as a surrogate marker of coronary atherosclerosis. Transesophageal echocardiography and magnetic resonance imaging appear useful in evaluating the physiologic significance of angiographically detectable coronary artery stenoses via assessment of coronary blood flow. However, it should be noted that significant improvements in technology or acquisition parameters must occur before these techniques can be used on a routine clinical basis for coronary artery imaging. The relative merits and ultimate clinical potential of each of these techniques are discussed in this article.

Visualization of stents in the left anterior descending coronary artery by transthoracic echocardiography in pigs and humans

In this study, we demonstrate that coronary artery stents can be visualized by transthoracic 2-dimensional echocardiography. We were able to image stents in the left anterior descending coronary artery in 6 of 6 pigs and in 6 of 7 patients studied.