Transesophageal atrial pacing or pharmacologic stress testing in detection of coronary artery disease in patients who are unable to undergo exercise stress testing

Systematic overview and clinical applications of pacing atrial stress echocardiography

Pacing atrial stress echocardiography (PASE) has been studied over the past 3 decades for the evaluation of myocardial ischemia. Published studies suggest that PASE may be used as an alternative to exercise or pharmacologic stress imaging. The recent introduction of improved pacing electrodes, together with use of accelerated and shortened pacing protocols and improvements in transthoracic echocardiographic imaging techniques, makes PASE an appealing stress imaging method. A critical analysis of the diagnostic accuracy of PASE shows equivalence with other imaging stress modalities. PASE has been found to be highly feasible and accurate technique that may expedite the diagnosis and risk stratification of patients with coronary artery disease. This review addresses the history, hemodynamics, protocols, accuracy, clinical utility, and cost-effectiveness of PASE as well as elucidating its place among other stress modalities.

Pacing stress echocardiography: an alternative to pharmacologic stress testing

OBJECTIVES

We sought to evaluate the diagnostic accuracy and feasibility of bedside pacing stress echocardiography (PASE) as a potential substitute for pharmacologic stress echocardiography in patients admitted to the hospital with new-onset chest pain or worsening angina pectoris.

BACKGROUND

Accurate and rapid noninvasive identification and evaluation of the extent of coronary artery disease (CAD) is essential for optimal management of these patients.

METHODS

Bedside transthoracic stress echocardiography was performed in 54 consecutive patients admitted to a community hospital with new-onset chest pain, after acute myocardial infarction had been excluded. We used 10F transesophageal pacing catheters and a rapid and modified pacing protocol. The PASE results were validated in all patients by coronary angiography performed within 24 h of the test. Significant CAD was defined as > or =75% stenosis in at least one major epicardial coronary artery.

RESULTS

The sensitivity of PASE for identifying patients with significant CAD was 95%, specificity was 87% and accuracy was 92%. The extent of significant CAD (single- or multivessel disease) was highly concordant with coronary angiography (kappa = 0.73, p<0.001). Pacing stress echocardiography was well tolerated, and only 4% of the patients had minor adverse events. The mean rate-pressure product at peak pacing was 22,313+/-5,357 beats/min per mm Hg, and heart rate >85% of the age-predicted target was achieved in 94% of patients. The average duration of the bedside PASE test, including image interpretation, was 38+/-6 min.

CONCLUSIONS

Bedside PASE is rapid, tolerable and accurate for identification of significant CAD in patients admitted to the hospital with new-onset chest pain or worsening angina pectoris.

Transthoracic stress echocardiography with transesophageal atrial pacing for bedside evaluation of inducible myocardial ischemia in patients with new-onset chest pain

To date, there are no data on the feasibility and accuracy of bedside pacing stress echocardiography in patients admitted to the hospital with new-onset chest pain or unstable angina. We evaluated the feasibility of pacing stress echocardiography and examined its correlation with myocardial perfusion stress scintigraphy (rest thallium-201/stress technetium-99m sestamibi dual-isotope myocardial perfusion single-photon emission computerized tomography) performed within 24 hours of the pacing stress echocardiography test. We studied 70 consecutive patients after acute myocardial infarction had been excluded. The bedside pacing stress echocardiography test was performed with 10Fr transesophageal pacing catheters. We found pacing stress echocardiography to be feasible and safe (3% minor adverse event rate) at the patients' bedside. Target heart rate of >85% of the age-predicted heart rate was achieved in 96% of patients, and the mean rate-pressure product was 22,644 +/- 4,520 beats/min/mm Hg. The mean duration of the bedside pacing stress echocardiography test including technical preparations and image interpretation was 41 +/- 7 minutes. Pacing stress echocardiography and myocardial perfusion stress scintigraphy correlated well for identification or exclusion of inducible myocardial ischemia in 63 of 70 patients (90%) (kappa 0.81, p <0.001). The extent of inducible myocardial ischemia by vascular territories correlated with myocardial perfusion stress scintigraphy in 52 of 70 patients (74%) (kappa 0.6, p <0.001). We conclude that bedside pacing stress echocardiography is feasible and safe, and highly correlates with myocardial perfusion stress scintigraphy for identifying inducible myocardial ischemia in patients with new onset of chest pain or unstable angina.

Multiplane Transesophageal Echocardiography with Dobutamine in Patients with Biventricular Inferior Myocardial Infarction

The purpose of this study was to evaluate the alterations of ventricular wall movement in patients with acute posteroinferior myocardial infarction with extension to right cavities with multiplane transesophageal echocardiography (TEE), as well as the utility of dobutamine with this technique to analyze myocardial viability. Nine men with a mean age of 51 years fulfilled the inclusion criteria. Myocardial TEE was performed in all the men 72 hours after the acute event with long- and short-axis transgastric images of both ventricles under basal conditions and with dobutamine infusions of 5 and 10 µg/kg per minute. Results were compared with myocardial perfusion findings obtained with Tc-99m Sestamibi SPECT. Left ventricular myocardial viability was demonstrated in 28 of 45 altered segments with dobutamine stress myocardial TEE and Tc-99m Sestamibi SPECT. Right ventricular myocardial viability was identified in 27 of 30 altered segments with dobutamine stress myocardial TEE in transgastric short and long axes, and with Tc-99m Sestamibi SPECT in 23 of 25 segments only in short-axis images. Multiplane TEE provided excellent image resolution and better definition of endocardial and epicardial borders, which facilitated detailed evaluation of ventricular segmental wall movement. Infusion of low doses of dobutamine made it possible to identify viable tissue in both ventricles, and results were comparable to those of nuclear medicine.

Usefulness of dipyridamole transesophageal echocardiography in the evaluation of myocardial ischemia and coronary artery flow

High-dose dipyridamole transesophageal stress echocardiography has recently been proposed as a useful and safe method to assess myocardial ischemia in patients with poor transthoracic acoustic window. It has also been shown that transesophageal echocardiography (TEE) allows the study of coronary blood flow reserve (CBFR) in the left anterior descending artery (LAD). The aim of our study was to assess whether the morphologic information and pathophysiologic data on CBFR and myocardial ischemia can be collected by a single stress TEE without comprimizing its feasibility, safety and accuracy. We studied, 29 patient with known or suspected CAD (previous myocardial infarction or angina) (Group A), and as a control group, we studied 11 patients with mitral disease or mitral prostheses (Group B). All patients underwent the coronary angiography. None of Group B patients showed significant coronary artery stenosis (> 70%). In baseline conditions left ventricular wall motion and LAD coronary blood flow velocity (CBFV) were also evaluated. The following CBFV parameters were measured: maximal diastolic velocity (MaxDV), mean diastolic velocity (MnDV), maximal systolic velocity (MaxSV), mean systolic velocity (MnSV). The ratios of dipyridamole to rest maximal and o mean to diastolic velocities (MaxDV-Dip/Max DV-rest; MnDv-Dip/MnDV-rest) were measured as indexes of CBFR. No side effects were observed and the test could be completed in all patients (feasibility 100%). Wall motion analysis was adequate in all patients (feasibility 100%). Comparison between wall motion analysis was obtained and angiographic findings shown that the overall sensitivity and specificity of TEE were 84% and 93% respectively. Sensitivity for one, two and three vessel disease was 60%, 70% and 100%, respectively. LAD CBFV was adequately recorded in 85% of patients. CBFR parameters showed a significant difference between the two groups (Max DV-Dip/Max DV-rest: 1.67 +/- 0.7 vs. 2.73 +/- 0.6, P < 0.001); comparison between Group B patients and those of Group A with angiographically documented LAD stenosis showed a statistically significant difference in CBFR parameters (MaxDV-Dip/MnDV-rest, 2.73 +/- 0.6 vs. 1.65 +/- 0.7, P < 0.001, MnDV-Dip/MnDV-rest, 2.56 +/- 0.5 vs. 1.69 +/- 0.6 < 0.001). We conclude that transesophageal stress echocardiography is a useful method to study CAD and that it is possible to assess both morphologic and pathophysiologic information during a single examination.

Assessment of viable myocardium by dobutamine transesophageal echocardiography and comparison with fluorine-18 fluorodeoxyglucose positron emission tomography

OBJECTIVES

The aim of this study was to assess whether dobutamine transesophageal echocardiography can identify viable myocardium in patients with chronic myocardial infarction.

BACKGROUND

Experimental and clinical studies have shown that dobutamine can recruit a contraction reserve in postischemic viable but akinetic segments, indicating that dobutamine-induced functional recovery is a potential ultrasound marker of myocardial viability.

METHODS

Forty patients underwent rest and dobutamine transesophageal echocardiography (dobutamine 5, 10 and 20 micrograms/kg body weight per min) and fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography at rest. Three representative short-axis tomograms and a transverse four-chamber-view were used for wall motion and F-18 fluorodeoxyglucose-uptake analysis in corresponding myocardial regions. A basally asynergic segment was considered viable by transesophageal echocardiography if dobutamine-induced systolic wall motion could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake > or = 50% of the maximal uptake in a region with normal wall motion by left ventriculography.

RESULTS

Functional recovery within the infarct region was found in 21 (53%) of 40 patients during dobutamine infusion. Infarct region-related viability by F-18 fluorodeoxyglucose uptake was diagnosed in 25 (63%) of 40 patients, yielding a diagnostic agreement between both techniques in 90% of patients. In 210 (89%) of 235 akinetic segments at rest, data on myocardial viability were concordant by the two techniques. The positive and negative predictive accuracy of dobutamine transesophageal echocardiography for viability defined by F-18 fluorodeoxyglucose uptake was 81% and 97%, respectively. Such uptake was significantly different (p < 0.001) between segments remaining akinetic (mean +/- SD 45 +/- 9%) during dobutamine infusion and segments with a dobutamine-induced contraction reserve (68 +/- 11%).

CONCLUSIONS

Dobutamine transesophageal echocardiography provides a promising low cost and widely available approach to unmask myocardial viability in patients with chronic myocardial infarction, and results compare favorably with those of F-18 fluorodeoxyglucose positron emission tomography.

Usefulness of transesophageal atrial pacing combined with two-dimensional echocardiography (echo-pacing) in predicting the presence and site of residual jeopardized myocardium after uncomplicated acute myocardial infarction

The usefulness of transesophageal atrial pacing combined with 2-dimensional echocardiography (echo-pacing) in predicting the presence and site of jeopardized myocardium, defined as areas of myocardium perfused by a vessel with a stenosis > or = 75% or by a collateral circulation if the supplying vessel was occluded, was evaluated in 31 patients with uncomplicated acute myocardial infarction who underwent coronary angiography. All 5 patients without jeopardized myocardium had a negative test, whereas 24 of 26 with jeopardized muscle had a positive test (sensitivity 92%; specificity 100%). To identify the site of jeopardized myocardium, tests that were positive for development of new asynergies were analyzed further, distinguishing those positive in the infarct or remote zone. Seven of 8 patients with new asynergies in the remote zone had areas of jeopardized myocardium outside the territory of distribution of the infarct-related vessel, whereas only 2 of 12 with new asynergies in the infarct zone had areas of jeopardized myocardium outside that territory (p < 0.01), correctly predicting the site of jeopardized myocardium in 17 of 20 cases. In conclusion, echo-pacing is useful for detecting the presence and site of jeopardized myocardium after an acute myocardial infarction.

Ischemia-induced regional wall motion abnormality is improved after coronary angioplasty: demonstration by dobutamine stress echocardiography

OBJECTIVES

The purpose of this study was to examine whether dobutamine stress echocardiography can detect reversal of ischemia-induced left ventricular regional wall motion abnormality immediately after percutaneous transluminal coronary angioplasty.

BACKGROUND

Although angioplasty is routinely performed as a means of coronary revascularization, at present there is a question whether this results in an immediate improvement in ischemia-induced left ventricular regional function.

METHODS

Thirty-five patients underwent dobutamine stress echocardiography 24 h before and 24 to 48 h after angiographically successful coronary angioplasty. Only patients with normal wall motion at rest were included. Dobutamine infusion was begun at 5 micrograms/kg per min and increased at 5-min intervals (10, 20, 30, 40 micrograms/kg per min). Echocardiographic images were stored into cine loops and analyzed off line with simultaneous comparison of images acquired at baseline, 5 micrograms/kg per min, peak infusion and recovery. Echocardiographic images were interpreted independently, without knowledge of other data, by two experienced cardiologists using the 16-myocardial segment model.

RESULTS

Before angioplasty, dobutamine stress echocardiography induced wall motion abnormalities in 31 patients (88%). Wall motion score at peak dobutamine infusion improved in 28 (90%) of the 31 patients after angioplasty. Wall motion score at peak dobutamine infusion for the group improved from 20 +/- 3 before angioplasty to 17 +/- 2 after angioplasty (p < 0.001). There was no change in the rate-pressure product achieved for the group before and after angioplasty (20,038 +/- 6,415 beats/min x mm Hg before versus 20,775 +/- 5,435 after angioplasty, p = NS). Before angioplasty, dobutamine stress echocardiography induced angina in 13 patients (37%), whereas angina occurred only once after angioplasty. Electrocardiographic changes diagnostic of ischemia occurred seven times, all before angioplasty.

CONCLUSIONS

We conclude that dobutamine stress echocardiography is an excellent method to demonstrate an immediate improvement in stress-induced regional left ventricular dysfunction in the distribution of the vessel undergoing successful angioplasty.

Detection of restenosis with dobutamine stress test after coronary angioplasty

Dobutamine ECG tests were serially performed before, at 15 days, and at 2 and 6 months after successful coronary angioplasty in 58 patients. The dose of dobutamine was progressively increased from 5 micrograms/kg/min to a maximum of 40 micrograms/kg/min every 5 minutes, with ECG and blood pressure control. Coronary angiography was performed at the end of the study. At 15 days after coronary angioplasty, the dobutamine test was of little value for the diagnosis or prediction of restenosis. At the end of the study, both the presence of angina and the results of the dobutamine test were related to coronary angiography, and their accuracy was calculated for the detection of mild (> or = 50%) and severe (> or = 70%) restenosis or new coronary lesions. The accuracy of angina was 68% for the detection of mild lesions and 70% for that of severe lesions, whereas the accuracy of the dobutamine test was 78% for mild lesions and 80% for severe lesions. It is concluded that the dobutamine stress test is a simple and useful method for the detection of restenosis when it is performed at 2 and 6 months after coronary angioplasty. However, it cannot distinguish between restenosis or new coronary lesions.

Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography

Patients undergoing dobutamine stress echocardiography often take beta antagonists which limit heart rate response and sensitivity in the test for detection of coronary artery disease. The aim of this study was to assess the effect of the addition of atropine to dobutamine stress echocardiography on clinical, electrocardiographic and echocardiographic outcomes. Dobutamine stress echocardiography was performed starting at and increasing every 3 minutes with 10 micrograms/kg/min to a maximum of 40 micrograms/kg/min (stage 4), which was continued for 6 minutes. In patients not achieving 85% predicted maximal exercise heart rate and in whom the test was not judged positive on echocardiographic or electrocardiographic criteria, atropine (0.25 mg intravenously, repeated up to a maximum of 1 mg if necessary) was added and dobutamine continued for up to a further 5 minutes, or until an adequate heart rate was achieved or the test was stopped because of chest pain or electrocardiographic changes. Of 80 consecutive patients undergoing dobutamine stress echocardiography within 2 weeks of coronary angiography, 49 required atropine (group A) and 31 required only dobutamine (group B). After dobutamine alone, heart rate (mean +/- SD) was higher in group B than in group A: 129 +/- 20 vs 90 +/- 18 beats/min, p less than 0.0001; but after the addition of atropine, heart rate in group A increased to 120 +/- 20 beats/min. Overall sensitivity for the detection of coronary disease was 70%, 95% confidence interval (CI) 55 to 83%; after the addition of atropine, sensitivity for group A was 65%, 95% CI 45 to 81%; in group B, sensitivity was 81%, 95% CI 54 to 96%.(ABSTRACT TRUNCATED AT 250 WORDS)

Dobutamine stress echocardiography before and after coronary angioplasty

Myocardial function was assessed by stress echocardiography in 28 patients before and after successful elective coronary angioplasty. Dobutamine stress echocardiography was performed using up to 40 micrograms/kg/min, followed by the addition of atropine in 20 patients to achieve 85% of the predicted maximal exercise heart rate. The initial studies were performed 1 day before and the second ones within 3 days (mean 1.3) after angioplasty. Peak heart rates and systolic blood pressures were the same for the 2 studies. The frequency of dobutamine-induced new wall motion abnormalities decreased from 20 (71%) before to 4 (14%) after angioplasty (p less than 0.0001). Before angioplasty, wall motion score index (an indicator of left ventricular wall motion, an increase in which indicates impaired wall motion due to myocardial ischemia) increased from 1.06 at rest to 1.23 at peak stress (p less than 10(-6)), but there was no significant increase in this index in the study after angioplasty. Before angioplasty, 14 patients (50%) developed chest pain during the stress test compared with 6 (21%) after angioplasty (p = 0.05), and before angioplasty, the stress test was stopped before the target heart rate was achieved, because of symptoms, ST-segment change or severe new wall motion abnormality in 14 patients compared with 7 after angioplasty (p = 0.09). Thus, early after angioplasty there is a reduction in myocardial ischemia as assessed by dobutamine stress echocardiography.

Transesophageal dipyridamole echocardiography for diagnosis of coronary artery disease

The value of transthoracic dipyridamole echocardiography has been extensively documented. However, in some patients, because of a poor acoustic window, the rest transthoracic examination is not always feasible and the transesophageal approach is more convenient. Therefore, transesophageal echocardiography with high dose dipyridamole (up to 0.84 mg/kg body weight over 10 min) was performed in 32 patients in whom the transthoracic dipyridamole test either was not feasible (n = 29) or yielded ambiguous results (n = 3). The transesophageal echocardiographic test results were considered abnormal when new dipyridamole-induced regional wall motion abnormalities were observed. All 32 patients underwent coronary angiography; significant coronary artery disease was defined as greater than or equal to 70% lumen diameter narrowing in at least one major vessel. All patients also performed a bicycle exercise test 1 day before transesophageal dipyridamole echocardiography. Transesophageal stress studies were completed in all patients, with a maximal imaging time (in tests with a negative result) of 20 min. No side effects or intolerance to drug or transducer was observed. The left ventricle was always visualized in the four-chamber and transgastric short-axis views. High quality two-dimensional echocardiographic images were obtained in all patients both at rest and at peak dipyridamole infusion and were digitally analyzed in a quad-screen format. Coronary angiography showed coronary artery obstruction in 24 patients: 6 had single-, 9 double- and 9 triple-vessel disease. The transesophageal dipyridamole test showed a specificity of 100% and an overall sensitivity of 92%. The sensitivity of this test for single-, double- and triple-vessel disease was 67%, 100% and 100%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)