Comparison of postexercise and transesophageal atrial pacing two-dimensional echocardiography for detection of coronary artery disease

Feasibility and reproducibility of a cardiovascular magnetic resonance free-breathing, multi-shot, navigated image acquisition technique for ventricular volume quantification during continuous exercise

Background

Cardiovascular magnetic resonance (CMR) image acquisition techniques during exercise typically requires either transient cessation of exercise or complex post-processing, potentially compromising clinical utility. We evaluated the feasibility and reproducibility of a navigated image acquisition method for ventricular volumes assessment during continuous physical exercise.

Methods

Ten healthy volunteers underwent supine cycle ergometer (Lode) exercise CMR on two separate occasions using a free-breathing, multi-shot, navigated, balanced steady-state free precession cine pulse sequence. Images were acquired at 3-stages, baseline and during steady-state exercise at 55% and 75% maximal heart rate (HR_max), based on a prior supine cardiopulmonary exercise test. Intra-and inter-observer variability and inter-scan reproducibility were derived. Clinical feasibility was tested in a separate cohort of patients with severe mitral regurgitation (n=6).

Results

End-diastolic volume (EDV) of both LV and RV decreased during exercise at 55% and 75% HR_max, although a reduction in RVEDV index was only observed at 75% HR_max. Ejection fractions (EF) for both ventricles were significantly higher at 75% HR_max compared to their respective baselines (LVEF 68%±3% vs. 58%±5%, P=0.001; RVEF 66%±4% vs. 58%±7%, P=0.02). Intra-observer and inter-observer reproducibility of LV parameters was excellent at all 3-stages. Although measurements of RVESV were more variable during exercise, the reproducibility of both RVEF and RV cardiac index was excellent (CV <10%). Inter-scan LV and RV ejection fraction were highly reproducible at all 3 stages, although inter-scan reproducibility of indexed RVESV was only moderate. The protocol was well tolerated by all patients.

Conclusions

Exercise CMR using a free-breathing, multi-shot, navigated cine imaging method allows simultaneous assessment of left and right ventricular volumes during continuous exercise. Intra- and inter-observer reproducibility were excellent. Inter-scan LV and RV ejection fraction were also highly reproducible.

MR-compatible treadmill for exercise stress cardiac magnetic resonance imaging

This article describes an MR-safe treadmill that enables cardiovascular exercise stress testing adjacent to the MRI system, facilitating cardiac MR imaging immediately following exercise stress. The treadmill was constructed of nonferromagnetic components utilizing a hydraulic power system. Computer control ensured precise execution of the standard Bruce treadmill protocol commonly used for cardiovascular exercise stress testing. The treadmill demonstrated no evidence of ferromagnetic attraction and did not affect image quality. Treadmill performance met design specifications both inside and outside the MRI environment. Ten healthy volunteers performed the Bruce protocol with the treadmill positioned adjacent to the MRI table. Upon reaching peak stress (98 ± 8% of age-predicted maximum heart rate), the subjects lay down directly on the MRI table, a cardiac array coil was placed, an intravenous line connected, and stress cine and perfusion imaging performed. Cine imaging commenced on average within 24 ± 4 s and was completed within 40 ± 7 s of the end of exercise. Subject heart rates were 86 ± 9% of age-predicted maximum heart rate at the start of imaging and 81 ± 9% of age-predicted maximum heart rate upon completion of cine imaging. The MRI-compatible treadmill was shown to operate safely and effectively in the MRI environment.

Cardiac function and myocardial perfusion immediately following maximal treadmill exercise inside the MRI room

Treadmill exercise stress testing is an essential tool in the prevention, detection, and treatment of a broad spectrum of cardiovascular disease. After maximal exercise, cardiac images at peak stress are typically acquired using nuclear scintigraphy or echocardiography, both of which have inherent limitations. Although CMR offers superior image quality, the lack of MRI-compatible exercise and monitoring equipment has prevented the realization of treadmill exercise CMR. It is critical to commence imaging as quickly as possible after exercise to capture exercise-induced cardiac wall motion abnormalities. We modified a commercial treadmill such that it could be safely positioned inside the MRI room to minimize the distance between the treadmill and the scan table. We optimized the treadmill exercise CMR protocol in 20 healthy volunteers and successfully imaged cardiac function and myocardial perfusion at peak stress, followed by viability imaging at rest. Imaging commenced an average of 30 seconds after maximal exercise. Real-time cine of seven slices with no breath-hold and no ECG-gating was completed within 45 seconds of exercise, immediately followed by stress perfusion imaging of three short-axis slices which showed an average time to peak enhancement within 57 seconds of exercise. We observed a 3.1-fold increase in cardiac output and a myocardial perfusion reserve index of 1.9, which agree with reported values for healthy subjects at peak stress. This study successfully demonstrates in-room treadmill exercise CMR in healthy volunteers, but confirmation of feasibility in patients with heart disease is still needed.

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.

A meta-analytic comparison of echocardiographic stressors

BACKGROUND

The relative performance of alternative stressors for stress echocardiography for the diagnosis of coronary artery disease (CAD) is not well established.

METHODS

All studies published between 1981 to December 2001 who met inclusion criteria were included in this analysis. We performed a summary receiver operator characteristic (SROC) analysis and calculated weighted mean of the likelihood ratio and sensitivity/specificity. A covariate analysis using meta-regression methods was also performed.

RESULTS

Forty-four studies presented data on Exercise, 11 on Adenosine, 80 on Dobutamine, 40 on Dipyridamole, 16 on transatrial pacing transesophageal echocardiography (Tap-TEE), and 7 on transatrial pacing transthorasic echocardiography (Tap-TTE). SROC analysis showed that the following order of most discriminatory to least: Tap-TEE, Exercise, Dipyridamole, Dobutamine and Adenosine. Weighted means sensitivity/specificity were Exercise: 82.6/84.4%, Adenosine: 68.4/80.9%, Dobutamine: 79.6/85.1%, Dipyridamole: 71.0/92.2%, Tap-TTE: 90.7/86.1%, and Tap-TEE: 86.2/91.3%. Covariate analysis showed that the discriminatory power of Exercise decreased with increasing mean age.

CONCLUSIONS

Tap-TEE is a very accurate test for both ruling in and ruling out CAD although its invasiveness may limit its clinical acceptability. Exercise is a well-balanced satisfactory test for both ruling in and ruling out but performance might be lower for the elderly. Dobutamine offers a reasonable compromise for Exercise. Dipyridamole might be good for ruling in but not for ruling out CAD. The incapability in ruling-out CAD was a major problem in clinical application of the stress. Adenosine was the least useful stressor in diagnosing CAD.

Long-term Prognostic Value of Transesophageal Atrial Pacing Stress Echocardiography

OBJECTIVE

The aim of our study was to evaluate the long-term prognostic value of transesophageal atrial pacing stress echocardiography (TAPSE) for the prediction of cardiovascular events (myocardial infarction) and mortality at 10-year follow-up.

METHODS

TAPSE was applied as a diagnostic modality in 93 consecutive patients (mean age 45 +/- 8 years) who were diagnosed for the cause of chest pain. Long-term follow-up data were obtained from 87 (94%) patients with a mean duration of follow-up of 92 +/- 4 months. Stress echocardiography was performed using TAPSE with a mean pacing rate of 142 +/- 18/min.

RESULTS

Predefined cardiac events occurred during the follow-up period in 45 (52%) patients, including 24 (28%) with hard end points: 10 (12%) with nonfatal myocardial infarction and 17 who died (events overlap). Positive result of TAPSE was found in 47 (54%) patients and among those with positive TAPSE result, 16 died (94% of total mortality) and 21 had a hard event (death or infarction-88% of total prevalence). Survival free from hard events was noted in 37 (92%) patients with negative TAPSE and only in 26 (55%) of those with positive TAPSE ( P = .001). Independent predictive factors for mortality were TAPSE positivity (relative risk with 95% confidence interval [RR/CI] = 39.6 [36.3-42.9], P = .0006) and diabetes (RR/CI = 10.2 [8.6-11.8], P = .0026). Independent predictive factors for myocardial infarction were diabetes (RR/CI = 8.1 [6.3-9.9], P = .0186) and significant coronary stenosis in angiography (RR/CI = 9.0 [6.8-11.2], P = .0479). Independent predictive factors for death or nonfatal myocardial infarction were TAPSE positivity (RR/CI = 12.3 [11.1-13.3], P = .0001) and diabetes (RR/CI = 7.0 [5.8-8.2], P = .0018).

CONCLUSIONS

Positive TAPSE result carries long-term prognostic information regarding mortality and risk of myocardial infarction that can be used to identify patients requiring more aggressive treatment. Negative TAPSE allows highly accurate definition of low-risk population with discriminating power maintained during the 10-year period. TAPSE result and diabetes are the strongest independent predictors for long-term mortality in multivariate analysis.

Feasibility and safety of transeophageal atrial pacing stress echocardiography in patients with known or suspected coronary artery disease

To investigate the feasibility and safety of the transesophageal atrial pacing stress test combined with echocardiography (TAPSE) 1,727 TAPSE tests were performed on 1,641 patients consecutively referred to our echocardiographic laboratory for nonexercise stress testing (1,319 men; mean age 60 +/- 9 years; 34% of whom were outpatients). Wall motion abnormalities were present at baseline echocardiography in 975 cases (56%). TAPSE was feasible in 1,648 cases (95.4%). It was not feasible in 79 patients due to failure of positioning the transnasal catheter (n=11), the patient's intolerance of esophageal stimulation (n=24), failure to obtain any or stable atrial capture (n=36), or because the echocardiogram could not be evaluated at the peak of the test (n=8). TAPSE was diagnostic in 1,584 cases (96% of the feasible tests, 92% of all attempts). TAPSE was nondiagnostic in 64 cases (4% of the feasible tests) due to second-degree atrioventricular type I block resistance to atropine administration with failure to achieve 85% of the age-predicted maximum heart rate (n=59) or due to side effects, such as arrhythmias (n=3) or hypertension (n=2), which required premature interruption of the test. There were no major complications (death, myocardial infarction, or life-threatening arrhythmias). There were 28 instances of minor complications that comprised transient arrhythmias, including atrial fibrillation (n=8), paroxysmal supraventricular tachycardia (n=6), automatic atrial tachycardia (n=1), sinus arrest (n=1), atrioventricular junctional rhythm (n=2), ectopic atrial rhythm (n=2), nonsustained ventricular tachycardia (maximum 6 beats, n=3), hypotension (n=1), and hypertension (n=4) leading to interruption of the test. Only 5 complications hampered a diagnostic result, whereas 18 occurred during or after a positive test and 5 during a negative, but diagnostic, test. Thus, TAPSE is a highly feasible and very safe stress test. It gives high percentage of diagnostic tests and may represent a valid alternative to pharmacologic stressors.

Diagnosis of ischemic heart disease with exercise echocardiography: Comparison of images obtained at peak- and post-exercise

Peak-and post-exercise stress echocardiography were compared with respect to ability to detect coronary artery disease in 138 consecutive patients undergoing supine bicycle stress echocardiography. Sixty of these patients had single-vessel disease; 37, double-vessel disease; and 19, triple-vessel disease. Exercise was performed in the 20- to 30-degree left decubitus position on an echo-bed with an ergometer. Exercise started at 50 watts and was increased in 25-watt every 3 minutes and to a maximum of 150 watts. Two-dimensional echocardiographic images were digitized and assigned in a quad-screen format for nonbiased interpretation. Total wall motion score (TWMS) was the sum of the wall motion score, from normokinesis (0) to dyskinesis (4), of 16 segments. Image quality score index (IQSI) was the mean of the image quality scores in all views. All of the patients underwent coronary arteriography. Significant coronary stenosis was defined as≧75% stenosis of the large coronary arteries. Two-dimensional echocardiographic studies were adequate for analysis in 133 patients during the peak-exercise stage (peak-exercise) and in 137 patients 30 to 60 seconds after the end of exercise (post-exercise). TWMS at peak-exercise was higher than at post-exercise, while IQSI at peak-exercise was lower than at post-exercise. Sensitivity at peak-exercise versus that at post-exercise was 91% versus 79% (p<0.05); specificity, 76% versus 85%; and diagnostic accuracy, 88% versus 80% (p<0.05), respectively. We conclude that despite poor image quality on exercise echocardiography, better diagnostic accuracy was attained by assessing wall motion changes at peak-exercise than at post-exercise.

Head-to-head comparison of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia in an animal model of coronary artery stenosis

To compare the sensitivity of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia we produced a physiologically significant stenosis in the left circumflex artery of 14 open-chest dogs (range: 50 to 89% reduction in luminal diameter). In each study, dobutamine (5 to 40 microg kg(-1) min(-1) in 3-min stages) and pacing (20 bpm increments, each 2 min, up to 260 bpm) were performed randomly, and then followed by dipyridamole (up to 0.84 mg/kg over 10 min). The positivity of stress echocardiography tests was quantitatively determined by a significant (P<0.05) reduction of or failure to increase absolute and percent systolic wall thickening in the stenotic artery supplied wall, as compared to the opposite wall (areas related to the left anterior descending artery). Systolic and diastolic frozen images were analyzed off-line by two blinded observers in the control and stress conditions. The results showed that 1) the sensitivity of dobutamine, dipyridamole and pacing stress tests was 57, 57 and 36%, respectively; 2) in animals with positive tests, the mean percent change of wall thickening in left ventricular ischemic segments was larger in the pacing (-19 +/- 11%) and dipyridamole (-18 +/- 16%) tests as compared to dobutamine (-9 +/- 6%) (P = 0.05), but a similar mean reduction of wall thickening was observed when this variable was normalized to a control left ventricular segment (area related to the left anterior descending artery) (pacing: -16 +/- 7%; dipyridamole: -25 +/- 16%; dobutamine: -26 +/- 10%; not significant), and 3) a significant correlation was observed between magnitude of coronary stenosis and left ventricular segmental dysfunction induced by ischemia in dogs submitted to positive stress tests. We conclude that the dobutamine and dipyridamole stress tests showed identical sensitivities for the detection of myocardial ischemia in this one-vessel disease animal model with a wide range of left circumflex artery stenosis. The pacing stress test was less sensitive, but the difference was not statistically significant. The magnitude of segmental left ventricular dysfunction induced by ischemia was similar in all stress tests evaluated.

Cost-effectiveness and accuracy of exercise stress echocardiography in the non-invasive diagnosis of coronary heart disease

BACKGROUND

Exercise stress echocardiography (ESE) is a more recent form of totally non-invasive stress testing which like exercise thallium SPECT scintigraphy (ETS) was developed to overcome the known limitations of ECG stress testing, namely the limited diagnostic accuracy and the inability of ECG stress testing to site the region of coronary artery disease (CAD) induced ischaemia.

AIMS

To determine the sensitivity and specificity (and overall accuracy) of ESE in a group of patients referred for ETS imaging and compare the relative costs of each technique.

METHODS

One hundred and fifteen patients referred for ETS consented to a simultaneous ESE. Of this group, 59 patients underwent coronary angiography which was utilised as the gold standard.

RESULTS

The feasibility of ESE was 97% (112 of 115 patients of the total study population and 57 of the 59 patients who underwent coronary angiography). Of the 59 patients undergoing coronary angiography, the sensitivity of ESE and ETS were not significantly different (84.1% versus 91.3% respectively). However, despite the apparent marked difference in specificity (92.3% versus 61.5% respectively), p = NS (Fisher's exact test) as there were only 13 normals in the group who underwent coronary angiography. Overall accuracy was also closely similar (86.0% versus 84.7% respectively) and therefore also not significantly different. By contrast, agreement with coronary angiography as measured by the kappa statistic (kappa +/- SEk) was good for ESE (0.66 +/- 0.11) but only moderate for ETS (0.54 +/- 0.13). Moreover, there was a cost saving of at least $594.00 per patient in favour of ESE.

CONCLUSION

ESE is a totally non-invasive, sensitive, specific and cost-effective imaging modality for the detection and localisation of CAD.

Exercise echocardiography in the diagnosis of coronary artery disease

The purpose of this study was to test the applicability of exercise echocardiography in the diagnosis of coronary artery disease. The results were compared to findings of coronary angiography. 118 patients, 100 males and 18 females, who were all referred to coronary angiography for suspected ischaemic heart disease, underwent exercise echocardiography using a cycle ergometer. At coronary angiography 108 patients had significant stenosis in at least one coronary artery. Ten patients had angiographically normal coronary arteries. A new or increased wall motion abnormality detected by echocardiography after the exercise was considered an ischaemic response. Of the 108 patients with coronary artery disease, 101 had abnormal exercise echocardiograms, and the overall sensitivity of exercise echocardiography in detecting ischaemic heart disease was 94%. Among the 10 patients without coronary artery disease, seven had normal and three had abnormal exercise echocardiograms, and the specificity of the test was 70%. In conclusion, exercise echocardiography is a reliable diagnostic method in screening of ischaemic heart disease, and it can be combined relatively easily with the exercise examinations.

Usefulness of combined two-dimensional echocardiography and transesophageal atrial stimulation early after acute myocardial infarction

Transesophageal atrial stimulation (TRAS) was combined with 2-dimensional echocardiography in 69 consecutive patients on days 3 to 5 (mean 3.3) of their first, uncomplicated myocardial infarction, to determine if inducible remote asynergy (i.e., not directly adjacent to the infarcted area and supposedly related to another vascular territory) provides information regarding (1) extent of coronary artery disease, and (2) future ischemic events. Uncomplicated, adequate stress studies were performed in 59 of 69 patients (86%); all these patients had regional asynergy at rest. Remote asynergy at rest was present in 7 patients and during TRAS in 26 patients. Coronary angiography was performed within 2 to 3 weeks after the acute phase. Multivessel disease was present in 23 of these patients and absent in 3. Of the 33 patients without remote asynergy during TRAS, 5 had multivessel disease. Sensitivity of remote asynergy during TRAS for detecting multivessel CAD was 82%, specificity 90%, and predictive accuracy 86%. New ischemic events, defined as recurrent infarction, cardiac death, or revascularization within 12 to 18 months (mean 12.6) occurred in 24 patients (41%); remote asynergy during TRAS was present in 16 of these patients (67%). It is concluded that TRAS combined with 2-dimensional echocardiography can safely be performed in the early days of acute myocardial infarction; remote asynergy during TRAS reliably identifies patients with multivessel disease and future ischemic events.

Effects of nicorandil on regional perfusion and left ventricular function

Left ventricular function and regional perfusion were evaluated by two study designs in patient groups with stable ischemic coronary artery disease (CAD): (1) using conventional left ventricular angiographies and (2) applying myocardial contrast echocardiography. The aim of the studies was to establish the effects of sublingually or orally applied nicorandil (N) on pacing-induced myocardial ischemia (MIS). In the first angiographic study, in nine patients with ischemic CAD and with pacing-inducible MIS, the effect of N, 20 mg sublingually, on hemodynamics and regional wall motion (RWM) were studied. There were no parameter changes without MIS being induced when comparing measurements at the 7th and 14th minute after N application to control values (p > 0.05). In the 15th and 16th minutes after N, pacing-induced MIS could no longer be elicited but left ventricular pump function improved; comparing MIS with N versus MIS without N: ejection fraction improved by 21%, cardiac index by 37%, and RWM by 21%, while filling pressure fell by 41% and systemic vascular resistance fell by 29%. Thus, N-mediated "protection from ischemia" with rather improved hemodynamics and RWM corresponds with alterations that theoretically could have been expected after nitroglycerin given under the above conditions. In the second echocardiographic study, regional perfusion was assessed in 10 patients by intracoronary injection of a newly developed echo contrast medium (ECM) and measurement of ECM washout halftime (t1/2) over opacified myocardial regions of interest, which displayed wall motion abnormalities already at rest.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of coronary artery disease by digital stress echocardiography: comparison of exercise, transesophageal atrial pacing and dipyridamole echocardiography

OBJECTIVES

This study assessed and compared the diagnostic potential of exercise, transesophageal atrial pacing and dipyridamole stress echocardiography in a clinical setting.

BACKGROUND

Although they have been widely studied, no data exist with regard to comparisons of these procedures in a head-to-head study in different clinical settings.

METHODS

One hundred four consecutive patients with suspected coronary artery disease undergoing coronary angiography and with no previous myocardial infarction or rest left ventricular wall motion abnormalities underwent digital posttreadmill, transesophageal atrial pacing and dipyridamole echocardiography.

RESULTS

Feasibility of digital exercise echocardiography was 84%; 8 of 88 remaining patients had a nondiagnostic exercise echocardiographic test (inadequate exercise or imaging). In 80 patients with feasible and diagnostic digital exercise echocardiography, sensitivity, specificity and accuracy were, respectively, 89%, 91% and 90%. Eighty of the 104 patients underwent transesophageal atrial pacing and dipyridamole echocardiography. Feasibility of the alternative stress procedures was 77% for transesophageal atrial pacing and 96% for dipyridamole. In 60 patients successfully undergoing both alternative stress procedures, sensitivity and specificity were 83% and 76% for atrial pacing and 43% and 92% for dipyridamole echocardiography, respectively. In the group of 24 patients with nondiagnostic exercise echocardiography and consequent indication to alternative stress procedures, accuracy of transesophageal atrial pacing was higher than that of dipyridamole echocardiography (73% vs. 45%, p = 0.06).

CONCLUSIONS

Because of its higher diagnostic potential and additional functional information, exercise is the stress of choice when stress echocardiography is used to detect the presence of coronary artery disease. Alternative stresses can be used in patients with nondiagnostic exercise echocardiography. Transesophageal and dipyridamole echocardiography differ in feasibility and diagnostic reliability (higher sensitivity of transesophageal atrial pacing, higher specificity of dipyridamole). These characteristics must be considered when selecting procedures to be used as alternatives to exercise.

Usefulness of radionuclide ventriculography during transesophageal atrial pacing in the diagnosis of coronary artery disease

Radionuclide ventriculography before, during, and after atrial transesophageal pacing was carried out in 15 patients with suspected coronary artery disease (CAD) and without myocardial infarction. All patients underwent coronary angiography. Ten patients (group 1) had a coronary lesion > 50% on at least one of the main coronary arteries. Five patients (group 2) had normal coronary arteries. Radionuclide left ventricular ejection fraction (LVEF) before pacing was 56 +/- 3% in group 1 and 59 +/- 3% in group 2 (NS). Radionuclide ventriculography during pacing was 45 +/- 4% in group 1 (P < 0.0001 vs basal in group 1) and 45 +/- 6% in group 2 (P < 0.01 vs basal in group 2, NS vs group 1 during pacing). Immediate postpacing ejection fraction did not differ in the two groups and was identical to the prepacing value. A quantitative regional wall motion analysis was performed in 105 segments. Regional radionuclide ventriculography was calculated in each segment as follows: end-diastolic counts-end-systolic counts/end-diastolic counts. The relative decrease in regional LVEF during pacing was more important in the 39 segments related to a narrowed vessel than in the 66 segments related to normal coronary artery (32 +/- 13% vs 13 +/- 10%, P < 0.0001). A more than 20% relative decrease in at least one segment during pacing occurred in 10 patients in group 1 (sensitivity 100%) and in 2 patients in group 2 (specificity 60%). In conclusion, global radionuclide ventriculography during transesophageal atrial pacing decreases in patients with and without CAD.(ABSTRACT TRUNCATED AT 250 WORDS)

Does the myocardium become "stunned" after episodes of angina at rest, angina on effort, and coronary angioplasty?

To assess whether myocardial stunning occurs after brief periods of ischemia, global and regional ventricular function assessed by radionuclide angiography was studied in 52 patients. Patients were divided into 3 groups according to the type of ischemic episodes. Group 1 consisted of 15 patients studied before, during and after episodes of angina at rest. Seventeen patients studied immediately before and after coronary angioplasty constituted group 2. Group 3 consisted of 20 patients with stable angina studied before, during and after exercise-induced ischemia. Medical therapy was discontinued 48 hours before the study in all patients except those undergoing coronary angioplasty who were receiving diltiazem 180 mg/day. No difference in baseline ejection fraction was found between groups, whereas peak filling rate was statistically lower in group 3 patients. Evidence of left ventricular dysfunction during ischemia was seen in patients in groups 1 and 3, whereas transient ischemia was documented by ST-segment displacement and/or typical chest pain during balloon inflation in group 2. Persistence of systolic or diastolic dysfunction was not observed in any of the 3 groups in the recovery phase after ischemia. In conclusion, transient ischemia caused either by a primary reduction in oxygen supply (angina at rest, coronary angioplasty) or by an increase in oxygen demand (angina on effort) did not reproduce the phenomenon of systolic and diastolic stunning observed in animal experiments, although in all patients the ischemia was of sufficient duration and severity to induce marked ventricular dysfunction. The search for stunned myocardium should be extended to other different clinical models characterized by prolonged ischemia such as unstable angina or myocardial infarction.

Peak exercise left ventricular performance in normal subjects and in athletes assessed by first-pass radionuclide angiography

The role of Frank-Starling law of the heart in determining the increase in cardiac output during exercise in humans is still controversial (e.g., the mechanisms responsible for the enhancement of left ventricular [LV] filling during the shortened diastolic interval). Ten weight lifters, 12 swimmers and 12 sedentary subjects who underwent maximal upright bicycle exercise testing were studied. First-pass radionuclide angiography was performed both at rest and at peak exercise using a multicrystal gamma camera. Compared with resting values, heart rate and cardiac index at peak exercise increased by 101 +/- 16 beats/min (p less than 0.001) and 6.7 +/- 2.8 liters/min/m2 (p less than 0.001) in weight lifters, by 96 +/- 9 beats/min (p less than 0.001) and 9.5 +/- 2 liters/min/m2 (p less than 0.001) in swimmers, and by 103 +/- 9 beats/min (p less than 0.001) and 7.3 +/- 1.8 liters/min/m2 (p less than 0.001) in sedentary subjects. Stroke volume increased by 20.5 +/- 9.8 ml/m2 (p less than 0.001) in swimmers only. End-diastolic volume at peak exercise did not change in weight lifters and in swimmers; it decreased by 8.2 +/- 8.6 ml/m2 (p less than 0.01) in sedentary subjects. A significant correlation was found between the decrease in end-systolic volume and the increase in peak rapid filling rate at peak exercise in all 3 groups (r = 0.65, p less than 0.05 in weight lifters; r = 0.59, p less than 0.05 in swimmers; r = 0.67, p less than 0.05 in sedentary subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between exercise echocardiography and perfusion single-photon emission computed tomography in patients with single-vessel coronary artery disease

The aim of this study was to assess the relative value of exercise echocardiography and perfusion single-photon emission computed tomography (SPECT) in identifying the presence and severity of coronary artery stenosis. Accordingly, 44 consecutive patients with stenosis in one vessel performed simultaneous postexercise echocardiography and perfusion SPECT (with either thallium-201 [n = 19] or 99m-Tc-methoxyisobutyl isonitrile [n = 25]) in conjunction with symptom-limited bicycle exercise testing. Positive test results were based on the presence of new or worsened exercise-induced wall motion abnormalities and transient perfusion defects, respectively. Moreover, an "ischemic" score index was derived for semiquantitative assessment of both echocardiography (with a 14-segment model of left ventricular wall on a 4-point scale) and SPECT (47-segment model on a 5-point scale). All patients underwent correlative coronary arteriography, assessed by digital caliper. Significant coronary artery disease (diameter stenosis greater than or equal to 50%) was present in 30 patients. There was a good overall concordance between the two tests in terms of result (79%); compared with patients with positive results of both tests, in the seven patients with positive SPECT and negative echocardiography the time of recording echocardiographic images was longer (p = 0.05). When analyzing patients according to the percent diameter stenosis (greater than 70%, 50% to 70%, and less than 50%) for both echocardiography and SPECT, the prevalence of an ischemic response was directly related to the severity of the coronary stenosis (p less than 0.001); moreover, a negative test result was highly predictive of a diameter coronary stenosis less than 70%.(ABSTRACT TRUNCATED AT 250 WORDS)

Dobutamine stress echocardiography for detection and assessment of coronary artery disease

Stress echocardiography with dobutamine infusion for detection of coronary artery disease is a potential alternative to exercise stress testing with some theoretic advantages. Fifty patients who were not receiving cardioactive medication were prospectively studied with two-dimensional echocardiography and 12-lead electrocardiography (ECG) during incremental dobutamine infusion (5, 10, 15 and 20 micrograms/kg body weight per min, each dose for 8 min). Images were analyzed by using an 11-segment left ventricular model. All patients underwent correlative exercise ECG and coronary angiography, which revealed normal coronary arteries in 14 and significant disease (greater than or equal to 70% diameter stenosis) in 36. Peak rate-pressure product during dobutamine infusion was 18,845 +/- 4,156 versus 23,740 +/- 6,158 mm Hg/min on exercise (p less than 0.01). Interobserver concordance for wall motion analysis was good (kappa coefficient = 0.77). The use of baseline (n = 14) or reversible (n = 24) regional asynergy to define an abnormal dobutamine echocardiogram resulted in a sensitivity for detecting coronary artery disease of 78% and a specificity of 93%. Corresponding data for the dobutamine ECG were 47% and 71% and for the exercise ECG were 72% and 71%, respectively. The development of new mitral regurgitation on Doppler color flow imaging (n = 4) improved sensitivity to 81% without loss of specificity. Inducible asynergy or new mitral regurgitation was observed in 6 (50%) of 12 patients with single-, 6 (60%) of 10 with double- and 12 (86%) of 14 with triple-vessel disease. The site of transient asynergy provided additional localizing information. Exercise duration and time to diagnostic ST segment shift were shorter in patients with coronary artery disease with versus those without echocardiographic evidence of ischemia (both p less than 0.05). Side effects during dobutamine infusion were mild and short-lived. Dobutamine stress echocardiography is well tolerated, is useful for detection and assessment of coronary artery disease and is applicable to patients unable to exercise.

A comparison of dobutamine infusion and exercise during radionuclide ventriculography in the evaluation of coronary arterial disease

Twenty-six patients with "chest pain" syndrome were subjected to radionuclide ventriculography during exercise and dobutamine infusion. All 10 patients with normal coronaries were identified correctly by normal ventriculographic responses to both tests. Of 16 patients with significant coronary arterial disease, dobutamine stress identified 15 patients correctly, whereas only 12 of these had an abnormal exercise response. Three patients with one-vessel disease with a normal exercise response had an abnormal dobutamine stress response. Dobutamine radionuclide stress testing is an acceptable alternative to exercise testing in patients who cannot exercise and its incremental diagnostic yield in patients with one-vessel disease requires further evaluation.

Stress echocardiography versus radionuclide stress techniques

The different modalities of stress echocardiography and stress thallium-201 imaging have comparable sensitivity, specificity, and overall predictive accuracy in the diagnosis and prognosis of coronary artery disease. They are also comparable in the assessment and follow-up of patients treated with thrombolytic therapy or who have undergone percutaneous transluminal coronary angioplasty and coronary artery bypass graft surgery. Stress radionuclide ventriculography has a lower sensitivity and specificity as compared to stress echocardiography and stress thallium. Dipyridamole thallium has a higher sensitivity as compared to dipyridamole echocardiography in the diagnosis and prognosis of coronary artery disease. New techniques such as dobutamine echocardiography, adenosine stress thallium-201, and adenosine echocardiography have individually shown high sensitivities, specificities, and accuracy. However, further studies are needed on their comparative value. The major advantages of stress echocardiography over radionuclide stress techniques are: lack of radiation exposure; less expense; less time consumption; less personnel required; and greater availability. Its major disadvantage, however, is the inability to obtain adequate studies in all patients.

Utility of stress echocardiography for postinfarct prognosis

Although high-risk patients following myocardial infarct are usually identified in the acute stage by clinical assessment and determination of left ventricular function at rest, a significant percentage of infarct patients with increased risks, i.e., presence of residual myocardial ischemia, remain undetected at discharge. Since the yield of adequate images for interpretation stress echocardiograms has been significantly improved with digital technology, stress echocardiography has become a truly practical technique to identify these patients. Presence of remote asynergy, i.e., asynergy not directly adjacent to the infarcted area and supposed to be related to another vascular region, directly following cessation of dynamic exercise appears to be highly related to multivessel disease and an unfavorable follow-up period. Treadmill electrocardiographic findings, however, appeared to be of limited value in this respect. Furthermore, the echocardiographic ejection fraction was also a poor predictor. The versatility of the technique, lack of injections, or radiation hazard, and the relatively low cost will undoubtedly increase the application of stress echocardiography for postinfarct stratification.

Hypotension during dobutamine stress echocardiography: initial description and clinical relevance

Hypotension during exercise treadmill testing is correlated with the presence of coronary artery disease, its severity, and prognosis. The importance of hypotension during dobutamine stress testing has not been previously reported to our knowledge. We reviewed 43 cases of hypotension occurring in 42 patients out of a total of 116 consecutive stress dobutamine echocardiographic procedures performed in a total of 112 patients. Of the 42 patients with hypotension, 20 underwent cardiac catheterization. Regional wall motion abnormalities induced by dobutamine infusion were found in 13 of these patients, all of whom had significant (greater than or equal to 70% diameter reduction) coronary artery disease. The remaining seven patients without regional wall motion abnormalities did not have significant coronary artery disease at catheterization. Of the remaining 22 patients with dobutamine-induced hypotension, 20 had no induced regional wall motion abnormalities, were not catheterized, and were followed clinically. None of these patients had a cardiac event during a mean follow-up period of 11.5 months. We conclude that hypotension during dobutamine stress echocardiography in the absence of regional wall motion abnormalities does not indicate significant coronary artery disease or portend an adverse prognosis.

Stress echocardiographic techniques. An overview

The choice of upright or supine exercise, pharmacological agents, or atrial pacing for the induction of ischemia depends on the goals and the imaging modality. Dynamic stress echocardiography has improved diagnostic accuracy over and above the stress electrocardiogram. Indications include patients with atypical symptoms, prior nondiagnostic stress electrocardiograms, or baseline electrocardiographic abnormalities. Pharmacological agents coupled with echocardiography do well in the high-risk preoperative patient (e.g., abdominal aneurysmectomy) or in those unable to walk due to orthopedic, neurological, or peripheral vascular disease. When there is uncertainty as to the physiological significance of anatomical (angiographic) stenosis, dynamic stress echocardiography in the ambulatory patient or atrial pacing (or beta-agonist pharmacological stressors) in the catheterization laboratory are useful. The accuracy of stress echocardiography for detection of ischemia in the follow-up of interventional procedures or for postmyocardial infarction risk stratification is superior to standard stress electrocardiography alone.

The importance of stress-induced cardiac wall motion abnormalities in the evaluation of drug intervention

Stress-induced wall motion abnormalities are a sensitive marker of myocardial ischaemia. Stress echocardiography has recently been the subject of increasing interest because of its improved feasibility and compatibility with new and effective alternative stresses. Transoesophageal atrial pacing (TAP) with 2-dimensional echocardiography (2-D echo) is a recently developed echo-cardiographic stress procedure that has been shown to be reliable and effective in both the diagnosis and evaluation of stress-induced myocardial ischaemia. TAP with 2-D echo was performed after treatment with placebo and intravenous gallopamil 0.03 mg/kg in 12 patients with stable, reproducible angina of effort. Compared with placebo, gallopamil treatment increased the time to 1 mm ST-segment depression (6.6 vs 5.3 minutes; p less than 0.05) and improved the ventricular wall motion score at a heart rate of 130 beats/min (17 vs 15; p less than 0.01) and 150 beats/min (13 vs 11; p = 0.07). Three patients who developed angina after placebo administration were symptom-free after gallopamil. Thus, gallopamil exerts a beneficial effect on atrial pacing-induced ischaemia, by increasing the pacing time to the ischaemic threshold and reducing the extent of dysfunctional myocardium during ischaemia.

Diagnostic accuracy of peak exercise echocardiography in coronary artery disease: comparison with thallium-201 myocardial scintigraphy

To evaluate the accuracy of exercise two-dimensional echocardiography for the recognition of coronary artery disease, 53 patients (46 men and 7 women, age range 35 to 69 years) without either previous myocardial infarction or resting wall motion abnormalities, were studied. According to coronary angiography 26 had normal coronary arteries, 14 had one-vessel, seven had two-vessel, and six had three-vessel disease. After withdrawal of any therapy, all patients underwent a single exercise stress test with a stress table during which cine-loop digitized echocardiography was acquired and 74 MBq of thallium-201 (TI-201) were injected. Echocardiographic images were evaluated at rest and at peak exercise. Three-view planar scintigraphic images were collected immediately after exercise and 4 hours later. For the overall recognition of coronary artery disease, exercise electrocardiography had 77.8% sensitivity and 65.4% specificity; myocardial scintigraphy had 100% sensitivity and 92.3% specificity; and exercise echocardiography had 92.6% sensitivity and 96.2% specificity (both NS versus myocardial scintigraphy). Global accuracy was 71.7% for exercise electrocardiography, 94.3% for stress echocardiography, and 96.2% for myocardial scintigraphy. For the classification of the individual involved coronary arteries, the sensitivity of myocardial scintigraphy was 84.8% and that of exercise echocardiography was 63% (p less than 0.01); the related specificities were 98% and 98.2% respectively (NS). It may be concluded that exercise echocardiography is highly accurate for the recognition of coronary artery disease, whereas it appears less sensitive in the identification of the involved vessels, particularly in patients with multivessel disease.

Computer analysis of the electrocardiogram during esophageal pacing cardiac stress

It has been estimated that 15 to 30% of patients with suspected or known coronary artery disease are unable to perform an adequate exercise stress test due to a variety of reasons such as obesity, poor physical condition, claudication, etc. Transesophageal atrial pacing has been proposed as a noninvasive alternative for inducing cardiac stress in patients who cannot exercise. Although computer analysis is commonly employed to analyze the electrocardiogram (ECG) during the conventional exercise stress test, the surface ECG recorded during transesophageal atrial pacing is contaminated with large pacing artifacts which confound beat identification by standard computer software. We report the development of a robust signal processing algorithm for interpretation of the surface ECG during transesophageal atrial pacing stress. The algorithm employs novel schemes using both linear and nonlinear transformations to detect and differentiate between the pacing artifact and QRS complex even in difficult situations where the pacing artifact is in proximity to or superimposed on the QRS complex. The algorithm uses sophisticated logic for automatic recognition of sustained capture. It subsequently calculates beat-by-beat and average (over five beats) ST segment amplitude and slope. The algorithm also reports the instantaneous heart rate, RR interval, pace-to-R interval, R-wave amplitude, and estimated sinus node recovery time upon loss of sustained capture. The limitations of present exercise ECG computer methods in processing the ECG during transesophageal atrial pacing stress are evaluated and significantly improved performance by our algorithm is demonstrated.

Atrial pacing with two-dimensional echocardiography for evaluation of chest pain: comparison with thallium 201 scintigraphy

Atrial pacing was performed with two-dimensional (2-D) echocardiography and thallium 201 scintigraphy in 40 men with stable chest pain. Coronary angiography showed significant (one or more lesions greater than or equal to 50%) coronary artery disease (CAD) in 36 patients and no or insignificant CAD in 4. Two dimensional echocardiography showed a left ventricular wall motion abnormality (WMA) either at rest or with pacing in 28 (78%) patients with CAD, with 17 (47%) showing a new or worsened WMA with pacing. A thallium scan showing abnormality (reversible or fixed perfusion defect) was seen in 26 (72%) patients with CAD; 18 (50%) had a reversible defect. In all, 34 of the 36 patients with CAD (94%) had a WMA, a perfusion defect, or both (specificity 50%). Occurrence of both a WMA and a perfusion defect in individual segments ranged from 10 of 25 patients with septal abnormalities to 0 of 12 with abnormalities of the lateral segment. Sensitivity of 2-D echocardiography for identifying CAD in specific vessels was 81% for the left anterior descending (LAD) artery, 30% for the right coronary artery, and 20% for the circumflex artery (both p less than .001 compared with the LAD artery). Corresponding sensitivities for thallium 201 imaging were 54% (p less than .05 compared with 2-D echocardiography), 27%, and 8% (both p less than .05 compared with the LAD artery). When combined with atrial pacing, 2-D echocardiography and thallium 201 perfusion imaging are of similar value for diagnosing the presence of CAD in patients with stable chest pain. Two-dimensional echocardiography is superior to thallium 201 imaging for identifying the presence of significant CAD in the LAD artery, but both tests are limited in their ability to detect lesions of the right coronary or circumflex arteries.

Exercise echocardiography and technetium-99m MIBI single-photon emission computed tomography in the detection of coronary artery disease

To compare the relative diagnostic value of exercise echocardiography with perfusion technetium-99m metoxyisobutylisonitrile single-photon emission computed tomography (SPECT) in detecting coronary artery disease (CAD), 75 patients with suspected CAD but a normal electrocardiogram (ECG) at rest were included in a prospective correlative study. Both the exercise echocardiograms and SPECT studies were performed in conjunction with the same symptom-limited bicycle exercise test. The development of either a new wall motion abnormality or a reversible perfusion defect after exercise, or both, were regarded as a positive test for the exercise echocardiographic and SPECT studies, respectively. The results of these 2 diagnostic tests were compared with coronary arteriography. Exercise echocardiography identified 35 (71%) and SPECT 41 (84%, p = 0.13) of the 49 patients with significant CAD (defined as greater than 50% diameter stenosis). Twenty-five of the 26 patients (96%) without significant coronary stenosis had negative exercise echocardiographic results and 23 of 26 (88%) had negative SPECT results. Exercise-induced new wall motion abnormalities showed a good correlation with reversible perfusion defects, and the results of the 2 methods were concordant in 65 of 75 patients (agreement = 88%, kappa = 0.75 +/- 0.14). Both the diagnostic accuracy of exercise echocardiography and SPECT were significantly higher than the exercise ECG (81 vs 64%, p less than 0.02 and 88 vs 64%, p less than 0.005). The sensitivity and specificity for detecting individual diseased vessels were 60 and 95% for exercise echocardiography and 67 and 94% for SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative assessment of transient left ventricular asynergy in coronary artery disease

The purpose of this study was to determine the diagnostic value of quantitative two-dimensional echocardiography during transesophageal atrial pacing in assessing the presence and severity of coronary artery disease. Apical four- and two-chamber views were registered at rest and at different pacing rates. Computerized quantitative evaluation of left ventricle wall motion was performed. On the basis of left ventricle wall motion analysis data of 22 individuals with no coronary pathology, as assessed by angiography and with negative exercise ECG and transesophageal atrial pacing ECG test, nomograms for assessment of wall motion abnormalities and for calculation of asynergy area as a measure of wall motion abnormality extent were obtained. The method revealed new transient wall motion abnormalities during pacing or exacerbation of old ones present at rest in 83 of the 89 patients with angiographically proven coronary artery stenosis greater than or equal to 70% and in 3 of the 32 controls with no changes in their coronary angiograms. Thus, it showed high sensitivity (93%), specificity (91%), predictive value of positive result (96%), predictive value of negative result (83%), and efficiency of the test (93%). These values appeared to be higher than those calculated for transesophageal atrial pacing ECG, recorded simultaneously with echocardiographic images (81, 87, 95, 62, and 83%, respectively) and for exercise ECG test which was performed in 66 coronary patients and in 29 controls (68, 86, 92, 54, and 74%, respectively). The extent of pacing-induced left ventricular regional wall motion abnormalities appeared to be directly correlated to the extent of coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous transesophageal atrial pacing and transesophageal two-dimensional echocardiography: a new method of stress echocardiography

The diagnostic use of exercise echocardiography has been widely reported. However, transthoracic exercise echocardiography is inadequate in up to 20% of patients because of poor image quality related to exercise. In an attempt to overcome these limitations, a system was developed in which transesophageal echocardiography is combined with simultaneous transesophageal atrial pacing by means of the same probe. In a prospective study, transesophageal echocardiography was performed before, during and immediately after maximal atrial pacing in 50 patients with suspected coronary artery disease. Results of transesophageal stress echocardiography were considered abnormal when new pacing-induced regional wall motion abnormalities were observed. Correlative routine bicycle exercise testing was carried out in 44 patients. Cardiac catheterization was performed in all patients. The success rate in obtaining high quality diagnostic images was 100% by transesophageal echocardiography. All nine patients without angiographic evidence of coronary artery disease had a normal result on the transesophageal stress echocardiogram (100% specificity). Thirty-eight of 41 patients with coronary artery disease (defined as greater than or equal to 50% luminal diameter narrowing of at least one major vessel) had an abnormal result on the transesophageal stress echocardiogram (93% sensitivity). The sensitivity of the technique for one, two or three vessel disease was 85%, 100% and 100%, respectively, compared with 44%, 50% and 83%, respectively, for bicycle exercise testing; the 12 lead electrocardiogram (ECG) during rapid atrial pacing showed a sensitivity of 25%, 64% and 86%, respectively. Thus, rapid atrial pacing combined with simultaneous transesophageal echocardiography is a highly specific and sensitive technique for the detection of coronary artery disease. Ischemia-induced wall motion abnormalities were detected earlier than observed ECG changes. The technique appears to be particularly suited to patients who are unable to perform an active stress test or those with poor quality transthoracic echocardiograms.

The divergent recovery of ST-segment depression and radionuclide angiographic indicators of myocardial ischemia

This study evaluated the recovery after exercise of both ST-segment depression on the exercise electrocardiogram (electrical evidence of ischemia) and exercise-induced abnormalities in wall motion or ejection fraction as detected by radionuclide angiography. The study group of 31 patients was selected to undergo prolonged electrocardiographic and radionuclide imaging after exercise because they had persistent ST-segment depression greater than 3 minutes after exercise and radionuclide angiographic evidence of ischemia at peak exercise. In 27 (87%) of the 31 patients, radionuclide evidence of ischemia recovered more quickly than the electrocardiogram. Only 15 of the 31 patients had exercise-induced radionuclide abnormalities after exercise. Compared with the 16 patients without such findings of ischemia after exercise, these 15 patients had a worse wall motion score at peak exercise (5.3 vs 3.9; p less than 0.01) and a smaller increase in systolic blood pressure with exercise (p less than 0.05) and after exercise (p less than 0.01). Radionuclide angiographic evidence of ischemia recovers more quickly after exercise than ST-segment depression. When there is radionuclide evidence of ischemia after exercise, it is associated with more severe ischemia during exercise.

Prediction of cardiac events after uncomplicated myocardial infarction by cross-sectional echocardiography during transesophageal atrial pacing

Atrial pacing can safely be utilized shortly after myocardial infarction. To evaluate the prognostic value of wall motion abnormalities induced by such pacing 83 consecutive patients with recent uncomplicated myocardial infarction underwent transthoracic cross-sectional echocardiography during transesophageal atrial pacing and upright bicycle exercise stress test. Patients were followed-up for 14 +/- 5 months. During the atrial pacing and the echocardiography, patients were defined at high risk if abnormalities of wall motion were detected in left ventricular regions remote from the infarcted area. Then, during the exercise stress test, high risk patients were those with ST segment depression greater than or equal to 1 mm. On the other hand, patients were considered to be at low risk if they had no abnormalities of wall motion during atrial pacing in remote regions or, in the case of the stress test, if they did not develop ST depression greater than or equal to 1 mm. Of the 83 patients, 21 had major cardiac events during the period of follow-up. Cardiac events occurred in 15/23 (65%) and 5/60 (8%, P less than 0.001) patients assigned to the groups adjudged to be at high and low risk, respectively, on the basis of echocardiographic results. Exercise testing was less reliable in identifying patients at risk of future cardiac events. Major events occurred in only 6 of the 19 patients with a positive stress test (32%, P less than 0.05 vs positive stress echocardiography) and in 14 of the 64 patients with a negative exercise stress test (22%, P = NS vs positive exercise stress test, P less than 0.05 vs negative atrial pacing echocardiography).

Relation of quantitative coronary lesion measurements to the development of exercise-induced ischemia assessed by exercise echocardiography

To assess the relation of quantitative measures of coronary stenoses to the development of exercise-induced regional wall motion abnormalities, 34 patients with isolated, single vessel coronary artery lesions and normal wall motion at rest underwent exercise echocardiography and quantitative angiography on the same day. Although all 11 patients with a visually estimated stenosis greater than or equal to 75% had an ischemic response and 10 (91%) of 11 patients with a less than or equal to 25% visually estimated stenosis had a normal response by exercise echocardiography, among 12 patients with a visually estimated stenosis of 50%, 6 (50%) had an ischemic response and 6 (50%) had a normal exercise echocardiogram. Quantitative measurements of stenosis severity distinguished patients with ischemic (group 1) from normal (group 2) exercise echocardiographic responses as follows: minimal luminal diameter (mm), group 1 1.0 +/- 0.4 versus group 2 1.7 +/- 0.4, p less than 0.0001; minimal cross-sectional area (mm2), group 1 0.9 +/- 0.6 versus group 2 2.5 +/- 1.1, p less than 0.0001; percent diameter stenosis, group 1 68.3 +/- 14.2 versus group 2 42.2 +/- 12.1, p less than 0.0001; and percent area stenosis, group 1 87.5 +/- 7.8 versus group 2 64.8 +/- 15.9, p less than 0.0001. These data validate the utility of exercise echocardiography by demonstrating that 1) coronary stenosis severity measured by quantitative angiography is closely related to wall motion abnormalities detected by exercise echocardiography, and 2) exercise echocardiography can be used as a noninvasive means to assess the physiologic significance of coronary artery lesions.

Prognostic value of atrial pacing and thallium-201 scintigraphy in patients with stable chest pain

The value of atrial pacing and thallium-201 scintigraphy for assessing risk of subsequent cardiac events was examined in 210 patients with stable chest pain. Follow-up information was complete in 195 patients (mean age 61 years). Over an average follow-up of 19 months, cardiac events occurred in 38 patients--unstable angina in 20, nonfatal acute myocardial infarction in 6 and death from cardiac causes in 12. A history of previous myocardial infarction, diabetes mellitus, systemic hypertension or peripheral vascular disease at the time of pacing was not associated with an increased frequency of subsequent cardiac events. Six of 38 patients with later cardiac events had a history of congestive heart failure, compared with 8 of 157 without cardiac events (p less than 0.05). Neither pacing-induced angina, ST depression, nor the presence of a fixed perfusion defect was significantly more frequent in patients with cardiac events as a whole compared with patients without such events. Reversible defects and abnormal scans (reversible or fixed defects) were present, respectively, in 19 and 31 of 38 patients with cardiac events, compared with 42 and 79 patients, respectively, of the 157 patients without cardiac events (both p less than 0.01). In patients who developed unstable angina, a reversible defect was seen in 13 and an abnormal scan in 16 (both p less than 0.01 compared with patients without cardiac events). In 12 patients who died from a primary cardiac event, fixed defects were present in 8 and an abnormal scan in 11 (p less than 0.05 and p less than 0.01, respectively, compared with patients without cardiac events).(ABSTRACT TRUNCATED AT 250 WORDS)

Nonexercise cardiac stress testing

Many patients who require evaluation for coronary artery disease are unable to undergo exercise stress testing because of physiologic or psychological limitations. Drs Vacek and Baldwin describe three alternative methods for assessment of cardiac function in these patients, all of which have high levels of diagnostic sensitivity and specificity.

High dose dipyridamole echocardiography early after uncomplicated acute myocardial infarction: correlation with exercise testing and coronary angiography

The feasibility, safety and usefulness of dipyridamole echocardiography (two-dimensional echocardiography and 12 lead electrocardiographic monitoring during dipyridamole infusion, up to 0.84 mg/kg over 10 min) were evaluated in 94 asymptomatic patients 8 to 10 days after uncomplicated acute myocardial infarction. The results were compared with those of symptom-limited treadmill exercise testing and correlated with coronary angiography. Two mechanical patterns of positivity of dipyridamole echocardiography could be identified: 1) a new wall motion abnormality confined to the infarct zone or to the adjacent segments (24 patients), and 2) transient remote asynergy (33 patients). The success rate in recording adequate images during dipyridamole infusion was 100%. Interobserver agreement concerning diagnosis occurred in 89 (93%) of 94 patients. Dipyridamole echocardiography was well tolerated; no complication was observed during or after the test. Seventy-three patients underwent coronary angiography within 6 weeks after acute myocardial infarction. Transient remote asynergy on echocardiography was present in 27 of 40 patients with multivessel disease and in none of 33 patients without multivessel disease. Results of treadmill exercise testing were positive in 28 patients with multivessel disease and 8 patients without multivessel disease. Thus, the sensitivity of dipyridamole-induced transient remote asynergy was 68% compared with 52% for treadmill testing (p less than 0.05); specificity was 100% and 72%, respectively (p less than 0.005). The overall accuracy of dipyridamole echocardiography (81%) was higher than that of dipyridamole stress electrocardiography (63%) or exercise electrocardiography (60%) (p less than 0.02). It is concluded that dipyridamole echocardiography is a useful, feasible and inexpensive nonexercise-dependent test for detecting the extent of coronary artery disease early after acute myocardial infarction.

Evaluation of coronary artery disease in the patient unable to exercise: alternatives to exercise stress testing

Exercise stress testing is a well-established method for the diagnostic, prognostic, and functional assessment of patients with known or suspected CAD. A variety of alternative tests have been described in patients unable to perform leg exercise. Atrial pacing and dipyridamole imaging have been evaluated most extensively, and results compare favorably with those of exercise testing for diagnosing the presence of CAD. Both tests may be used to assess prognosis after myocardial infarction, and dipyridamole imaging may be useful in patients undergoing preoperative evaluation. The use of the cold pressor test and isometric handgrip exercise have also been described. However, the value of both tests is limited by a relatively low sensitivity for detecting the presence of CAD. Other testing modalities--arm ergometry, intravenous infusion of beta-adrenergic agonists, and transthoracic pacing--show promise but require further assessment to confirm their value.

Clinical utility of exercise, pacing, and pharmacologic stress testing for the noninvasive determination of myocardial contractility and reserve

The ability of the left ventricle to modulate its performance is an important and integral component in the cardiovascular system's adaptive response to increased workload. Abnormalities in ventricular contractility can blunt this response and thus significantly limit the patient's functional capacity. The accurate determination and quantitation of cardiac contractility and reserve is a difficult task in the symmetrically contracting ventricle and more so when regional contraction abnormalities are present. Moreover, derangements in other physiologic variables, such as ventricular loading conditions, heart rate, systemic vascular tone, cardiac autonomic function, and pulmonary gas exchange, can diminish cardiopulmonary reserve. This report relates the determinants of myocardial oxygen demand and efficiency to the currently available forms of exercise, pacing, and pharmacologic stress testing. Within this framework, commonly used as well as newer approaches to the noninvasive assessment of stress-induced changes in left ventricular performance and contractility are addressed. In addition, several examples are presented in which noninvasive techniques for assessing intracardiac structures, pressures, and flows (eg, echo/Doppler, radionuclide angiography, rapid acquisition computed tomography, and magnetic resonance imaging) are combined with various cardiovascular stress tests to achieve more reliable measures of myocardial contractility and reserve.

Exercise echocardiography: detection of coronary artery disease in patients with normal left ventricular wall motion at rest

Most studies investigating the ability of exercise two-dimensional echocardiography to identify patients with coronary artery disease have included patients with left ventricular wall motion abnormalities at rest. This has the effect of increasing sensitivity because patients with only abnormalities at rest are detected. To determine the diagnostic utility of exercise echocardiography in patients with normal wall motion at rest, 64 patients were studied with exercise echocardiography in conjunction with routine treadmill exercise testing before coronary cineangiography. All 24 patients who had no angiographic evidence of coronary artery disease had a negative exercise echocardiogram (100% specificity). Nine of 40 patients with coronary artery disease (defined as greater than or equal to 50% narrowing of at least one major vessel) also had a negative exercise echocardiogram (78% sensitivity). Of the nine patients with a false negative exercise echocardiographic study, six had single vessel disease. Among 25 patients with single vessel disease, exercise echocardiography was significantly more sensitive (p = 0.01) than treadmill exercise testing alone (76 versus 36%, respectively). Among 15 patients with multivessel disease, the two tests demonstrated similar sensitivity (80%). In conclusion, exercise echocardiography is highly specific and moderately sensitive for the detection of coronary artery disease in patients with normal wall motion at rest. Although exercise echocardiography is significantly more sensitive than treadmill exercise electrocardiographic testing alone in patients with single vessel disease, the two tests are similar in their ability to detect coronary artery disease in patients with multivessel disease and normal wall motion at rest.

The dobutamine stress test as an alternative to exercise testing after acute myocardial infarction

Three weeks after myocardial infarction in 50 patients the effect of the infusion of a graded dose of dobutamine was compared with that of symptom limited treadmill exercise testing. The following variables were measured: blood pressure, heart rate, ST segment changes, Doppler aortic blood flow, and cross sectional echocardiographic dimensions. The heart rate and double product increased more during exercise than during dobutamine infusion, while maximum acceleration in the ascending aorta increased more during dobutamine infusion than during exercise. Significant ST depression was recorded in 22 patients during exercise and in 24 during dobutamine infusion; the concordance between the two tests was 88%. In all cases in which ST segment depression occurred in both tests the site of ST depression was the same. Dobutamine stress testing is an alternative to exercise testing in patients after myocardial infarction.

Doppler echocardiographic evaluation of the effect of atrial pacing-induced ischemia on left ventricular filling in patients with coronary artery disease

Very little is known about the effects of acute myocardial ischemia on left ventricular filling. Previous studies of these effects have been of limited value because they were performed with 1) imaging techniques that, like cineventriculography or radionuclide ventriculography, do not allow beat to beat monitoring of left ventricular filling throughout the entire ischemic attack; and 2) exercise, which, even if effective in inducing myocardial ischemia in patients with coronary artery disease, also considerably shortens cycle length, thus leading to additional nonischemic filling alterations. To overcome these limitations, left ventricular filling was studied by means of Doppler echocardiographic evaluation of transmitral flow velocities before and immediately after rapid atrial pacing in 17 patients. Eight patients had coronary artery disease but did not develop ischemia (ST depression greater than or equal to 1.5 mm) during atrial pacing (Group 1) whereas nine had coronary artery disease and developed ischemia during atrial pacing (Group 2). No differences were observed from rest to postpacing in any of the filling variables considered in Group 1 patients. In contrast, a significant rearrangement of left ventricular filling occurred during ischemia in Group 2 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of echocardiography at peak exercise and after bicycle exercise in evaluation of patients with known or suspected coronary artery disease

To determine if echocardiography done immediately after bicycle exercise provides the same information as imaging at peak exercise, we evaluated 104 consecutive patients being studied for coronary artery disease. Interpretable exercise echocardiograms were obtained in 96 patients (92%), 29 of whom had a new wall motion abnormality detected with exercise echocardiography. Of these 29 patients, 10 had a wall motion abnormality detected in apical views obtained during peak exercise that resolved by the time apical imaging was performed after exercise. Three of these 10 patients, however, had wall motion abnormalities in parasternal views taken after exercise in areas adjacent to the wall motion abnormality imaged at peak exercise. The sensitivity of exercise-induced wall motion abnormality for the detection of significant coronary artery disease in those patients undergoing coronary arteriography was 70% for imaging done after exercise versus 100% for imaging done at peak exercise. Six patients' conditions would have been misclassified as normal if only imaging done after exercise had been performed. We conclude that the addition of echocardiographic imaging at peak exercise on a bicycle enhances the sensitivity for the detection of coronary artery disease with exercise echocardiography.

Echocardiography and coronary artery disease: current and future applications

Echocardiographic techniques are becoming more widespread for evaluating patients with known or suspected coronary artery disease. Because it affords an excellent overall view of the heart, two-dimensional echocardiography, rather than M-mode echocardiography, is the imaging procedure of choice when dealing with coronary artery disease. This technique can be used to make the initial diagnosis of acute myocardial infarction, diagnose complications, and assess prognosis following myocardial infarction. Additionally by combining this test with stress testing, latent coronary artery disease can be detected. Recovery of wall motion can be assessed following interventions such as thrombolysis or balloon angioplasty. Investigational and future uses include tissue characterization, which may allow detection of ischemic but potentially viable myocardium, direct coronary visualization for detection of atherosclerotic involvement of the proximal coronary arteries and myocardial contrast echocardiography. The latter technique allows visualization of perfusion by way of injecting contrast material into the coronary circulation. This has been demonstrated to be an accurate means of determining myocardial infarction size in an animal model and is currently being used in a number of centers in patients at the time of cardiac catheterization. In summary two-dimensional echocardiography currently allows assessment of patients with myocardial infarction from the time of their presentation through their convalescent period with respect to diagnosis, prognosis and presence of complications. Exercise echocardiography can diagnose latent coronary artery disease. The newer investigational techniques show promise for furthering our ability to evaluate patients with coronary artery disease using echocardiography.

Temporary cardiac pacing. Diagnostic and therapeutic indications

Temporary cardiac pacing is a useful tool both diagnostically and therapeutically. A wide array of methods are available for delivering such pacing to the myocardium. Careful patient evaluation, which includes ruling out the use of certain drugs and the presence of certain diseases, will help determine the most desirable pacing therapy. In an emergency situation, transcutaneous pacing is the ideal modality for use by the primary care physician.

Prediction of the extent of coronary artery disease with the evaluation of left ventricular wall motion abnormalities during atrial pacing. A cross-sectional echocardiographic study

In patients with coronary artery disease, left ventricular performance during stress is affected by the degree of coronary stenosis. In order to verify whether there exists a relationship between the extent of wall motion abnormalities detectable during atrial pacing and the degree of coronary obstruction, 76 patients, without previous myocardial infarction, were studied. Each patient underwent cross-sectional echocardiography during transesophageal atrial pacing and exercise electrocardiography before coronary angiography. Of the 76 patients, 46 had significant coronary artery disease (stenosis greater than or equal to 75% of at least one major coronary vessel), while 30 had normal coronaries or a stenosis of less than 75%. Eighteen patients had single-, 14 had two- and 14 had three-vessel disease. For each patient a coronary score was obtained: the score used took into consideration the site, number and severity of the stenosis. This score was then correlated with the wall motion score, obtained from the analysis of 9 segments of the left ventricle. A weak correlation was obtained between wall motion score at rest and coronary score (r = -0.42), while the correlation between coronary score and the difference between wall motion score at rest and during transesophageal atrial pacing was slightly better (r = 0.53); this correlation further improved if wall motion score during pacing was considered (r = -0.63). If the patients with discordant diagnostic tests (echocardiography during transesophageal atrial pacing and exercise electrocardiography) were excluded, the correlation coefficient between coronary score and wall motion score during pacing increased even more (r = -0.77).

IN CONCLUSION

(1) analysis of wall motion of the left ventricle during atrial pacing is useful for the non-invasive evaluation of the severity of coronary disease; (2) cross-sectional echocardiography during atrial pacing, apart from being a useful diagnostic tool, is also a help in judging the degree of severity of coronary artery disease.