Improved specificity of transesophageal dobutamine stress echocardiography compared to standard tests for evaluation of coronary artery disease in women presenting with chest pain

The diagnostic role of stress echocardiography in women with coronary artery disease: evidence based review

1) Coronary artery disease in women differs from men in several ways, including their response to many diagnostic tests.2) Strong comparative data on stress echocardiography for detecting coronary artery disease in women are lacking, but existing data consistently show sensitivity comparable with other high-sensitivity tests and superior specificity, increasing its diagnostic accuracy.3) Pharmacological stress echocardiography appears to provide superior specificity to exercise stress echocardiography due to difficulties in test execution with the latter that increase the number of false positive results.4) Current evidence suggests that stress echocardiography should be the first-line diagnostic tool for detecting coronary artery disease in women with chest pain, but other noninvasive imaging tests may be valuable in some patient subgroups.

Dobutamine stress echocardiography for the detection of coronary artery disease in women

Dobutamine stress echocardiography (DSE) has good diagnostic accuracy for the diagnosis of coronary artery disease (CAD). However, in most published diagnostic studies, patients are predominantly men. In women, diagnostic accuracy may be lower because of a lower prevalence and extent of CAD, a higher incidence of dobutamine stress-induced hypotension (resulting in less stress or even nondiagnostic test results), smaller left ventricular chamber size, and the beneficial effects of estrogens on the induction of myocardial ischemia. To determine the diagnostic accuracy of DSE in women, 14 diagnostic studies published through 2006 were identified through a Medline search. For a total of 901 patients, the weighted mean sensitivity and specificity were 72% and 88%, respectively. In 7 studies directly comparing results in women and men, conflicting results were reported. However, pooled data showed nearly identical values for sensitivity and specificity in women and men. Additionally, in 6 studies directly comparing DSE results in women with those of stress nuclear scintigraphy, DSE was as sensitive and more specific to detect CAD (90% vs 70%, p <0.0001). The excellent specificity of DSE in women was also confirmed by excellent normalcy rates, ranging from 92% to 100% in women, with a <5% pretest probability of CAD. In conclusion, despite some theoretical limitations, DSE has reasonable sensitivity and excellent specificity for the detection of CAD in women. Considering the diagnostic problems of exercise electrocardiography and nuclear scintigraphy in women, stress echocardiography may be the stress modality of choice in women because of its superior diagnostic specificity.

Noninvasive evaluation of women with coronary artery disease

Coronary artery disease (CAD) is the leading cause of death in women. More women than men die of CAD each year, and unlike men, the death rate has not declined for women but has remained stable over the last 20 years. Despite these statistics, much less is known about the prevention, diagnosis, or treatment of CAD in women. The noninvasive diagnosis of CAD in women is difficult secondary to differences in physiology, etiology, presenting symptoms, risk factor prevalence, comorbid conditions, hormonal status, and body habitus between women and men. Echocardiography and Tc-99m sestamibi single photon emission computed tomography imaging are two noninvasive imaging techniques commonly combined with exercise or pharmacologic agents (dobutamine, adenosine, dipyridamole) that have recently evolved to address these differences. These evolutions and the role of both techniques in the diagnosis and prognosis of women with CAD will be reviewed in this article.

Transesophageal dobutamine stress echocardiography with tissue Doppler imaging for detection and assessment of coronary artery disease

BACKGROUND

Transesophageal dobutamine stress echocardiography (T-DSE) has been shown to be a sensitive and specific technique for the detection of myocardial ischemia. A major limitation of echocardiographic study interpretation, however, is the subjective visual analysis of endocardial motion and wall thickening, which is only semiquantitative.

METHODS

To analyze whether T-DSE with the use or tissue Doppler imaging (TDI) during graded dobutamine infusion may be useful to detect and quantify stress-induced myocardial ischemia by changes in myocardial velocities, 70 patients undergoing coronary arteriography were studied with T-DSE and TDI. Midesophageal and transgastric short- and long-axis images were obtained at each level of dobutamine infusion. T-DSE was successful in 67 patients (96%). Baseline resting pulsed and color peak systolic (S) and early diastolic (E) velocities of the anterior, septal, lateral, and inferior walls were examined.

RESULTS

Pulsed and color TDI correlated well at rest and after stress. Fifteen patients had a normal response to dobutamine, and 52 patients had inducible ischemia by two-dimensional criteria. In the normal group, there was a significant dose-dependent increase in S and E velocities. Compared with those in the normal group, patients with coronary artery disease (CAD) had lower resting S and E velocities and blunted S wave increase or E wave decrease during DSE.

CONCLUSIONS

T-DSE with TDI is a feasible and accurate test for the quantitative assessment of patients with CAD who have impaired augmentation of systolic and diastolic myocardial velocities during dobutamine infusion.

Milrinone echocardiographic viability test: a pilot study

We assessed the utility of milrinone to predict recovery of function after surgical myocardial revascularization in patients with severe baseline left ventricular systolic dysfunction caused by coronary artery disease (CAD). Prediction of viable myocardial segments that will regain function after revascularization may help in the selection of patients who will benefit from coronary artery bypass graft surgery (CABG) as well as aid in the choice of target sites for coronary revascularization. We investigated 20 consecutive patients with CAD and left ventricular ejection fraction < or = 40% who had evidence of myocardial viability by either thallium scan or dobutamine viability test and were candidates for elective CABG. Left ventricular regional wall motion and global ejection fraction were assessed by transesophageal echocardiography in the operating room. Measurements were done before and 10 minutes after milrinone infusion, and immediately after CABG. Left ventricular wall motion score was derived by means of a 12-segment model. Functional improvement for each segment was defined as a wall motion change > 1. Baseline ejection fraction was 27% +/- 5% (mean +/- SD). Ejection fraction increased to 35% +/- 5% after milrinone infusion (P < .0001) and to 36% +/- 6% after CABG (P < .0001). Post-CABG ejection fraction was significantly correlated with postmilrinone ejection fraction (r = 0.65, P < .0001). Milrinone infusion resulted in augmentation of contraction in 98 of the 209 abnormal segments (wall motion score > or = 2); 91 (92.9%) of these improved after CABG. One hundred nine of the 111 segments that showed no improvement with milrinone did not improve after revascularization (98.2%). Seventy-three segments were akinetic or dyskinetic at baseline; 46 (63.0%) of these improved with milrinone. Improvement in regional wall motion after revascularization was detected in 84.8% of the segments that improved with milrinone versus only 3.7% of the segments that did not improve with milrinone. In patients with ischemic cardiomyopathy, improvement in left ventricular function (segmental wall motion and global ejection fraction) during milrinone infusion is highly predictive of improvement after CABG.

Stress testing for risk stratification of patients with low to moderate probability of acute cardiac ischemia

In summary, this article focused on the use of stress testing to risk-stratify patients at the conclusion of their emergency evaluation for ACI. As discussed, those patients in the probably not ACI category require additional risk stratification prior to discharge. It should be kept in mind that patients in this category are heterogeneous, containing subgroups at both higher and lower risk of ACI and cardiac events. The patients with lower pretest probability for ACI may only need exercise testing in the ED. Patients with higher pretest probability should undergo myocardial perfusion or echocardiographic stress testing to maximize diagnostic and prognostic information. Prognostic information is the key to provocative testing in the ED. Prognostic information is the component that will help emergency physicians identify the patients who may be discharged home safely without having to worry about a 6% annual cardiac death rate and a 10% overall death rate over the next 30 months. Stress testing provides this key prognostic data, and it can be obtained in short-stay chest pain observation units in a safe, timely, and cost-effective fashion.

Value of transesophageal dobutamine stress echocardiography in assessing coronary artery disease

The introduction of digital echocardiography has significantly enhanced our ability to select the best set of frames for analysis. However, despite the beneficial attributes of transthoracic dobutamine stress echocardiography, poor quality 2-dimensional images continue to be a significant limiting factor in patients with chest deformities, severe chronic obstructive lung disease, marked obesity, and previous chest surgery. Transesophageal echocardiography provides a new window to monitor left ventricular contractility without the interference of bone and air-filled structures of the thoracic cage. The transesophageal dobutamine stress test is a logical but poorly explored modality to image/stress the heart in certain patients with known or suspected myocardial ischemia. Overall sensitivity (< or = 85%) and specificity (< or = 95-100%) of transesophageal dobutamine stress echocardiography appear to be similar to that of previous transthoracic studies, although no direct comparison has been accomplished between transthoracic and transesophageal stress images. False negative transesophageal dobutamine stress echocardiography results have been described in patients with single-vessel disease in whom ischemic regions may not have been visualized throughout the entire study. False positive study results may be present in patients with hypertension and myocardial hypertrophy that may have signs and symptoms of myocardial ischemia in absence of obstructive disease of the epicardial coronary arteries, presumably related to either microvascular disease or impaired vasodilatory reserve. The proportion of patients with coronary artery disease who need a transesophageal examination for reliable assessment of echocardiographic response to stress varies depending on the operators' skills, the interpreters' experience, and the use of videotape or digitizing systems for image analysis. Although clinically useful in its present transthoracic and transesophageal form, a major limitation of dobutamine stress echocardiographic study is the subjective visual interpretation of endocardial motion and wall thickening, which is only semiquantitative. Color kinesis and tissue Doppler imaging (TDI) are 2 novel echocardiographic techniques that color code endocardial motion and myocardial velocity online and have the potential to objectively quantify regional left ventricular function. Quantitative standardization of transthoracic and transesophageal data interpretation, such as establishing endocardial motion by color kinesis or velocity thresholds by TDI for an abnormal segmental response to stress, has the potential to decrease interobserver variability and increase interinstitutional agreement.

[Complications of transesophageal echocardiography with dobutamine]

The transesophageal echocardiographic approach improves the diagnostic power of transthoracic stress echocardiography. However, it is a seminvasive test and its safety is not well established. Our objective was to compare the incidence of complications of transesophageal and transthoracic dobutamine echocardiography. We collected data from 63 patients with inadequate transthoracic window, who underwent transesophageal dobutamine echocardiography and were compared with 100 patients in whom the transthoracic approach was diagnostic. Baseline blood pressure and heart rate were higher in the first group. There were no differences in those parameters at the end of the test. Neither were atropine administration and side effects more frequent in any of the groups. There were no cases of ventricular fibrillation, ventricular tachycardia, acute myocardial infarction, intractable angina or intolerance to the probe. Side effects were equally present in both groups. Transesophageal dobutamine stress echocardiography is a safe test that can be used in patients with coronary artery disease and poor transthoracic window.

Stress echocardiography in women

The diagnosis of coronary heart disease in women has been thought to be more difficult than in men, owing to the overall lower prevalence and severity of disease in women, as well as more subtle clinical presentations. Exercise electrocardiography is associated with a high rate of false-positive results. In contrast, exercise and pharmacologic stress echocardiography have been shown to have high sensitivity, specificity, and prognostic value in women, comparable to that obtained in a male population. Although exercise thallium provides high f disease accuracy, due to its cost, availability, and radiation exposure, it may not be the ideal initial test in women. Thus, compared with other modalities, the advantages of stress echocardiography include its lower cost, availability, and high diagnostic accuracy. In the evaluation of women with chest pain, the initial step should involve clinical stratification into low, moderate, or high-probability groups based on symptoms, age, and cardiovascular risk factors. In women with atypical chest pain and a low probability of coronary heart disease, further testing should be avoided because any positive result is likely to be falsely positive. In those women with a moderate likelihood of disease, the most efficient and cost-effective strategy includes stress echocardiography as the initial test. This approach avoids the high rate of false-positive results with subsequent unnecessary angiography generated by exercise electrocardiography, as well as minimalizing false-negative results, which would lead to delays and potential increase in morbidity and mortality from untreated coronary heart disease. The optimal strategy for women at high clinical risk may be either exercise echocardiography or cardiac catheterization as the initial test. Although the diagnosis of CAD in women is different than in men, it is not necessarily more difficult. Astute clinical evaluation, in conjunction with judicious use of diagnostic testing, yields excellent results.

Transesophageal echocardiography with stress for the evaluation of patients with coronary artery disease

Echocardiography permits a comprehensive assessment of resting regional and global left ventricular function, the presence and extent of inducible myocardial ischemia, and the identification of myocardial viability. Accordingly, stress echocardiography has become a valuable tool for the evaluation of patient with known or suspected coronary artery disease. In some patients however, a suboptimal transthoracic echocardiogram may limit the performance of interpretation of the test. Transesophageal echocardiography in combination with stress has been recently used for the evaluation of patients with coronary artery disease. This technique is semi-invasive, more time-consuming, and requires a greater degree of expertise on the part of the personnel assisting with the test. In general, complications and side-effects are self-limited and rarely affect the diagnostic accuracy of the test. Based on its ability to provide high quality images, transesophageal stress echocardiography should be considered in patients who have suboptimal transthoracic ultrasound window for the quantitative assessment of myocardial wall-thickening in clinical investigations of ischemic heart disease.