Alessandra Dagianti

Stress echocardiography: Comparison of exercise, dipyridamole and dobutamine in detecting and predicting the extent of coronary artery disease

OBJECTIVES This study was designed to compare exercise, dipyridamole and dobutamine echocardiography in the same patients and to evaluate, by measuring physiologic and echocardiographic variables, the mechanisms by which exercise and dobutamine induce ischemia. BACKGROUND The diagnostic value of stress echocardiography has been widely reported, but the specific effects of exercise, dipyridamole and dobutamine have not been directly compared. Furthermore, no echocardiography study has evaluated left ventricular volume changes at ischemic threshold during exercise and dobutamine administration. METHODS One hundred patients with suspected (Group A, n = 60) or known (Group B, n = 40) coronary artery disease underwent all three tests in random order. RESULTS In Group A, the sensitivities of exercise (mean 76%, 95% confidence interval [CI] 58% to 94%) and of dobutamine echocardiography (72%, 95% CI 53% to 91%) were higher than that of dipyridamole (52%, 95% CI 31% to 73%; p = 0.01 and p = 0.02, respectively). Specificity did not differ significantly among tests (94% for exercise [95% CI 86% to 100%] and 97% for dipyridamole and dobutamine [95% CI 91% to 100%]). Accuracy was identical for exercise and dobutamine (87%) and higher than that for dipyridamole (78%, p = 0.06). In Group B, the accuracy in predicting coronary disease extent was 71% for exercise, 33% for dipyridamole and 75% for dobutamine. At ischemic threshold, end-systolic volume index and the ratio of systolic blood pressure to end-systolic volume, a variable related to myocardial contractility, were significantly lower and higher, respectively, with dobutamine than during exercise (p < 0.05). CONCLUSIONS In a clinical setting, exercise echocardiography should represent the first diagnostic approach because it has high diagnostic efficacy and provides additional information on exercise capacity; pharmacologic stress, particularly that of dobutamine, provides a pivotal diagnostic tool when exercise is not feasible or its results are nondiagnostic. Our preliminary data on echocardiographic evaluation at ischemic threshold support the view that myocardial contractility is a major factor in inducing ischemia during dobutamine infusion.

Usefulness of transesophageal echocardiography in the assessment of aortic dissection.

The acute dissection of the ascending aorta requires prompt and reliable diagnosis to reduce the high risk of mortality; in addition, prognosis is influenced by long-term complications. The aim of this article is to discuss transesophageal echocardiography (TEE) and (1) its diagnostic accuracy in the presurgical evaluation of patients, (2) its role in reducing time of diagnosis and surgery, and (3) its ability to reduce hospital mortality. TEE has also been tested as a screening method in the postsurgical follow-up of these patients. The retrospective investigation concerns a sample of 80 cases of acute dissection of the aorta, submitted for surgical intervention from April 1986 to February 1999. TEE has allowed a precise estimation of aortic diameters and optimal visualization of intimal flap and tear entry with a fine distinction between true and false lumen. A direct comparison of the results of TEE and of transthoracic echocardiography has demonstrated that some elements (visualization of flap and diameters in descending aorta, sites of entry and reentry, direction of jet trough intimal tears, phasic intimal flap movement, diastolic collapse of flap on the valvular plane, false lumen thrombosis, coronary involvement, intramural hematoma, and aortic fissuration) were identified only by TEE, whereas other additional diagnostic elements (cardiac tamponade, aortic valve insufficiency, left ventricular function) show a similar pattern of significance. Routine employment of this method has confirmed a reduction of hospitalization time (about 1.5 hours of waiting time), and hospital mortality has changed from 42.8% to 17.3%. In the follow-up of patients operated on for aortic dissection, fundamental information may be obtained from TEE (assessment of the progression of thrombosis in the false lumen with its complete obliteration and modifications in aortic diameter with a consequent, possible worsening of aortic valve insufficiency). In conclusion, our study demonstrated that TEE may provide fast and efficient detection of acute aortic dissection. In the postsurgical follow-up, TEE has confirmed detection of major complications that can influence long-term prognosis and may be proposed as a method with easy access-one that is repeatable and inexpensive for the screening of aortic dissection surgical patients.

Clinical and Prognostic Usefulness of Supine Bicycle Exercise Echocardiography in the Functional Evaluation of Patients Undergoing Elective Percutaneous Transluminal Coronary Angioplasty

BACKGROUND Supine bicycle exercise echocardiography (SBEE) has never been used before and early after percutaneous transluminal coronary angioplasty (PTCA) for assessing the functional outcome of the procedure and predicting late restenosis. METHODS AND RESULTS We selected 76 subjects with stable angina, normal wall motion at rest, and exercise-induced wall-motion abnormalities before PTCA. SBEE with peak exercise imaging and the use of a 16-segment, four-grade score model was performed 54 +/- 15 hours after PTCA. No exercise-related adverse events occurred. Patients were grouped according to SBEE results: group 1 (n = 35, 46%) with negative exercise ECG and echo; group 2 (n = 19, 25%) with a positive exercise ECG but normal echo; and group 3 (n = 22, 29%) with a positive exercise echo with either a positive (n = 7, 32%) or negative (n = 15, 68%) ECG. Exercise performance significantly improved in all groups. In group 3, peak wall-motion score index decreased from 1.27 +/- 0.11 before to 1.15 +/- 0.06 after PTCA (P < .05), and duration of wall-motion abnormalities went from 81 +/- 24 to 47 +/- 19 seconds (P < .05). The rate of clinical restenosis (ie, angina recurrence or positive 6-month SBEE in asymptomatic patients, both associated with angiographic restenosis > 50%) was 37%. By multiple logistic regression analysis, clinical restenosis was associated with a positive post-PTCA exercise echo (odds ratio [OR] 3.08, 95% confidence interval [CI] 1.66 to 5.72; P = .0004) and with increasing values of pre-PTCA wall-motion score index (OR 2.86, 95% CI 1.92 to 4.27; P = .005) and duration of wall-motion abnormalities (OR 2.12, 95% CI 1.07 to 4.20; P = .04). CONCLUSIONS SBEE is a safe and reliable tool to demonstrate changes in exercise-induced wall-motion abnormalities after PTCA and provides prognostic information in the risk assessment of clinical restenosis.

Clinical application of exercise stress echocardiography: supine bicycle or treadmill?

Although exercise stress echocardiography is currently used to evaluate coronary artery disease (CAD) patients, the best exercise methodology is still undefined. The objectives of the study were: (1) to compare supine bicycle stress echocardiography (SBSE) and treadmill in the evaluation of CAD; and (2) to define, in normal subjects, the different behavior of factors determining MVO2 with treadmill and SBSE. We selected 10 male patients with CAD (group A), and 10 male control subjects (group B). Each patient underwent SBSE and treadmill testing in random order. We studied heart rate, systolic blood pressure, heart rate x systolic blood pressure, and end-diastolic and end-systolic volume indexes. In group A, we also studied wall motion score index (according to the American Society of Echocardiography) and in group B, systolic blood pressure/end-systolic volume index. The results were as follows: Group A: SBSE resulted in significantly lower work load, heart rate, and significantly higher systolic blood pressure, heart rate x systolic blood pressure, end-diastolic volume index, end-systolic volume index, and wall motion score index. SBSE showed wall motion abnormalities in each patient, whereas treadmill did not detect wall motion abnormalities in 4 patients (3 single-vessel; 1 multivessel); of the other 6 patients, 2 showed a lower wall motion score index and 4 did not show any difference in left ventricle kinetics with the 2 methodologies of exercise. Mean acquisition time for postexercise images was 72 +/- 6 seconds. Group B: SBSE resulted in lower work load, heart rate, heart rate x systolic blood pressure, systolic blood pressure/end-systolic volume index, and higher end-diastolic volume index and end-systolic volume index. Systolic blood pressure was similar with SBSE and treadmill testing. In conclusion, our experience suggests SBSE is a highly accurate diagnostic tool for evaluating CAD compared with treadmill testing; the maximum cardiovascular performance can be achieved with lower values of heart rate, suggesting the echo test is more feasible. Treadmill testing could lose important information about the existence, extension, and location of CAD; in contrast, SBSE detects even small, quickly reversible wall motion abnormalities.

Assessment of regional left ventricular function during exercise test with pulsed tissue Doppler imaging.

To investigate whether mitral annular velocity, measured by tissue Doppler imaging (TDI), is able to get a feasible quantitative evaluation of global and regional left-ventricular function during exercise test, 29 patients with previous uncomplicated myocardial infarction were studied by exercise echocardiography. All patients underwent coronary arteriography within 10 days of stress echocardiography. All of them were in sinus rhythm and had no right or left bundle branch block or significant mitral regurgitation as observed by left ventriculography. A total of 12 patients had anteroseptal and/or posteroseptal wall asynergies and left anterior descending involvement; 9 patients had lateral and/or posteroinferior asynergies and left circumflex coronary artery involvement; 8 patients had inferior and posteroseptal wall asynergies and right coronary artery involvement. Twelve subjects of same age and sex with normal cardiovascular findings were selected as a control group. TDI sample volumes were set on the mitral annuli corresponding to anteroseptal, posterior, posteroseptal, lateral, anterior, and inferior wall in 4-chamber, 2-chamber, and long-axis views. There was a significant correlation between the left-ventricular ejection fraction (0.41 +/- 0.8) and the means of the systolic (S) values (6.1 +/- 0.9 cm/sec, r = 0.83, p < 0.01). The mean S at the sites corresponding to the infarct regions (5.5 +/- 0.4 cm/sec) was significantly lower than the control group (11 +/- 0.8 cm/sec, p < 0.001). After stress, in patients with multivessel disease, S values corresponding to remote regions were significantly lower (p < 0.01) compared with control subjects. Thus, the parameters obtained from mitral annular velocities with pulsed TDI in patients with previous myocardial infarction reflect left ventricular asynergy corresponding to the infarct regions and reversible regional dysfunction after exercise.

Assessment of diastolic left ventricular filling by echocardiographic automated border detection and comparison with radionuclide ventriculography

To determine whether indexes obtained from a newly developed echocardiographic automated border detection (ABD) technology provide a reliable estimate of left ventricular (LV) diastolic filling, ABD variables of LV filling were compared with volumetric measurements determined by radionuclide angiography. Forty-two patients with a variety of heart diseases (age range, 11 to 76 years) underwent ABD echocardiographic studies on the same day as the radionuclide examination. Technically adequate ABD data could be obtained in 31 patients (74%). Nineteen healthy subjects served as normal controls. Area-time and volume-time waveforms for echocardiographic measurements were obtained from LV short-axis views at the level of the papillary muscles and four-chamber apical views. Both the diastolic indexes derived from the waveform of area change (short-axis view) and volume change (four-chamber apical view) correlated with radionuclide variables. Values measured from the ABD area-time waveform showed the following correlations: peak filling rate (r = 0.86; standard error of the estimate [SEE] = 0.62), time to peak filling rate (r = 0.85; SEE = 23.11), rapid filling phase fractional change (r = 0.79; SEE = 5.51), and atrial filling phase fractional change (r = 0.71; SEE = 5.82). Correlations of indexes derived from the ABD volume-time waveform were as follows: peak filling rate (r = 0.87; SEE = 0.50), time to peak filling rate (r = 0.90; SEE = 22.03), rapid filling fractional change (r = 0.83; SEE = 5.33), and atrial filling fractional change (r = 0.77; SEE = 4.68). ABD LV filling parameters in patients with heart disease and normal control subjects were significantly different. Thus ABD data from short-axis and apical views have a strong linear relation with radionuclide ventriculographic measurements and may be used as a method to assess LV diastolic filling.

Influence of reperfusion induced by thrombolytic treatment on natural history of left ventricular regional wall motion abnormality in acute myocardial infarction

Although several studies have investigated left ventricular (LV) function after reperfusion interventions, it is still unclear whether benefits result from successful therapy or whether such benefits only reflect the natural history of a subgroup of patients with acute myocardial infarction (AMI). This study evaluates the unique effect of thrombolytic therapy on the natural history of regional LV wall motion dysfunction. One hundred seventy-six patients with AMI were studied: 82 patients (group A) underwent conventional treatment and 94 (group B) thrombolytic therapy. LV regional improvement, evaluated by changes in echo score between admission and predischarge examination, was present more frequently in group B (28%) than in group A (17%). Furthermore, improved patients in group B had higher admission echo scores (7.5 +/- 3.5 vs 6.3 +/- 3.1), a prevalence of anterior AMI (68 vs 30.1%) and a higher rate of coronary patency (92 vs 58% in patients who had no improvement). In group A patients the rate of coronary patency was similar in those who did (46.1%) and did not have (36.1%) improvement. Observations at 12 to 18 months showed similar data in group A patients and in group B patients without improvement, whereas a marginal additional improvement was observed in group B patients who had in-hospital improvement. These observations demonstrate that LV function recovery is more frequent and marked in treated than in untreated patients. Follow-up results suggest a prolonged beneficial effect of thrombolytic treatment on LV function. The highest rate of coronary patency in improved group B patients underline the role of reperfusion on natural history of LV dysfunction after AMI.

Assessment of left ventricular dyssynergy by color kinesis.

Color kinesis is a new echocardiographic technique based on acoustic quantification. It has been developed to facilitate the ability to identify contraction abnormalities and has been incorporated into a commercially available ultrasound imaging system. The potential of this technique to improve the qualitative and quantitative assessment of wall motion abnormalities is described. Evaluation of color-encoded images allows detection of decreased amplitude of endocardial motion in abnormally contracting segments as well as a shorter time of endocardial excursion in segments with severely decreased motion. Compared with off-line quantitative studies, color kinesis has the advantage to be used on-line, without time-consuming manual tracing of endocardial boundaries. In addition, a single end-systolic color image contains the entire picture of spatial and temporal contraction and can be digitally stored and retrieved. In patients with proven coronary artery disease, color kinesis had a sensitivity of 88%, a specificity of 77%, and an overall accuracy of 86% in identifying the presence of segmental dysfunction. The practical application of color kinesis might be to improve our ability to distinguish normal from hypokinesis, something that has always been difficult in clinical echocardiography. Segmental analysis of color kinesis images allows objective detection of dobutamine-induced regional wall motion abnormalities in agreement with conventional visual interpretation of the corresponding 2-dimensional views. A method for objective assessment of wall dynamics during dobutamine stress echocardiography would be of particular clinical value, because these images are even more difficult to interpret than conventional echocardiograms. Quantitative assessment of diastolic function may allow objective evaluation of segmental relaxation abnormalities, especially under conditions of pharmacologic stress testing. Acquisition of color kinesis images during dobutamine stress echocardiography, both transthoracic and transesophageal, may facilitate the assessment of hybernating but viable myocardium and enhance the sensitivity in the detection of coronary artery disease.

Usefulness of echocardiography in the prognostic evaluation of non-Q-wave myocardial infarction.

Patients with non-Q-wave myocardial infarction (MI) are a heterogeneous population with a wide range of coronary disease severity and extent of myocardial necrosis, showing, therefore, different electrocardiographic findings and different outcomes. To evaluate the role of echocardiography in the management of non-Q-wave MI patients, 192 consecutive patients without previous MI were studied (78 with ST segment elevation, 56 with ST depression and 58 without ST modifications). All patients underwent 2-dimensional echocardiography (16-segment model) within 24 hours of admission to the coronary care unit. Wall-motion abnormalities, wall-motion score index, ejection fraction, and end-diastolic and end-systolic volumes were evaluated. In 35 patients, death, reinfarction, recurrent angina, or severe heart failure occurred during the in-hospital phase, whereas the remaining 157 patients had a good outcome. Patients with a poor prognosis were older (68 +/- 6 vs 59 +/- 5 years, p < 0.01), had a worse left-ventricular function (wall-motion score index 1.4 +/- 0.4 vs 1.25 +/- 0.3, p < 0.05; end-systolic volume 54 +/- 25 vs 38 +/- 12 mL/m2, p < 0.01; ejection fraction 50 +/- 10 vs 58 +/- 8%, p < 0.01), and presented more frequently with ST segment depression (49 vs 25%, p < 0.01). The positive and negative predictive values for early clinical events were, respectively: ST segment depression 0.30 and 0.87; wall-motion abnormalities in > 3 segments 0.28 and 0.86; wall-motion score index > 1.33 = 0.28 and 0.87; end-diastolic volume > 46 mL/m2 = 0.49 and 0.91; ST segment depression and wall-motion abnormalities in > 3 segments 0.60 and 0.88. These results underline the usefulness of echocardiography in the early risk stratification of non-Q-wave MI patients, together with electrocardiographic data. Patients with ST segment depression and more extensive wall-motion abnormalities are at higher risk and their management needs a more aggressive approach.

Clinical impact of echocardiography in prognostic stratification after acute myocardial infarction

Risk stratification is mandatory in the management of the postinfarction period. The identification of high-risk patients, on the basis of clinical data (recurrent angina, overt heart failure, etc.), is quite easy, whereas stratification of uncomplicated subjects needs an accurate noninvasive strategy. In the last 20 years, echocardiography has been gaining an increasing role, allowing increasingly precise evaluation of infarct size. This detection of the extent of infarct size has a definite prognostic value. Since 1980, we have observed that a dysfunctioning left ventricular myocardium >40% marked patients with a poor prognosis. These observations are most important in asymptomatic infarct patients, in whom clinical features may not reflect the amount of left ventricular dysfunction. Our recent results on a large series of patients with acute myocardial infarction (MI) without overt heart failure have shown that the extension of wall motion abnormalities at 2-dimensional (2D) echocardiography was highly predictive of cardiac death or new coronary events in a 3-year follow-up (univariate analysis; p <0.0005). Echocardiography also plays an important role in detecting postinfarct ischemia, as seen by its wide use during stress tests. In our experience, the response to exercise echocardiographic testing has a high prognostic value. In fact, in our series, univariate analysis (Kaplan-Meier) showed that the best predictors of coronary events were the number of markers of ischemia during exercise (p <0.00001), the work load (p <0.00001), a positive exercise echo (p <0.0005), and the echo score at rest (p <0.0005). Multivariate analysis (Cox) confirmed these data: number of markers of ischemia: odds ratio (OR) 4.45, 95% confidence interval (CI) 1.5-13.1; work load: OR 2.46, CI 1.3-4.5; positive exercise echo OR 1.88, CI 1.1-3.2. Thus, serial echocardiography together with predischarge stress echocardiography is recommended for risk stratification after acute MI. In particular, in thrombolytic-treated patients, echo examinations allow the detection of functional recovery of viable reperfused myocardium whereas stress echo may show exercise-induced worsening in the region supplied by the infarct-related vessel, a predictor of a higher rate of coronary events.