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

CT coronary angiography: a paradigm shift for functional imaging tests

The UK National Institute for Health and Care Excellence (NICE) have just updated their guideline on new-onset stable chest pain, recommending that all patients should be investigated with a CT coronary angiography (CTCA). In a separate guideline, NICE recommended CT fractional flow reserve (CT-FFR), to assess coronary stenoses, found on CTCA, stating that this would reduce the need for invasive coronary angiography and hence reduce cost. We discuss the evidence base for CT-FFR and emphasise that we already have established functional imaging tests, with extensive evidence base for efficacy and prognosis and that CT-FFR should be compared with this standard of care and not with the much more expensive and invasive fractional flow reserve undertaken during invasive coronary angiography.

The prognostic role of stress echocardiography in a contemporary population and the clinical significance of limited apical ischaemia

INTRODUCTION

In this study, we aim to reassess the prognostic value of stress echocardiography (SE) in a contemporary population and to evaluate the clinical significance of limited apical ischaemia, which has not been previously studied.

METHODS

We included 880 patients who underwent SE. Follow-up data with regards to MACCE (cardiac death, myocardial infarction, any repeat revascularisation and cerebrovascular accident) were collected over 12 months after the SE. Mortality data were recorded over 27.02 ± 4.6 months (5.5-34.2 months). We sought to investigate the predictors of MACCE and all-cause mortality.

RESULTS

In a multivariable analysis, only the positive result of SE was predictive of MACCE (HR, 3.71; P = 0.012). The positive SE group was divided into 2 subgroups: (a) inducible ischaemia limited to the apical segments ('apical ischaemia') and (b) ischaemia in any other segments with or without apical involvement ('other positive'). The subgroup of patients with apical ischaemia had a significantly worse outcome compared to the patients with a negative SE (HR, 3.68; P = 0.041) but a similar outcome to the 'other positive' subgroup. However, when investigated with invasive coronary angiography, the prevalence of coronary artery disease (CAD) and their rate of revascularisation was considerably lower. Only age (HR, 1.07; P < 0.001) was correlated with all-cause mortality.

CONCLUSION

SE remains a strong predictor of patients' outcome in a contemporary population. A positive SE result was the only predictor of 12-month MACCE. The subgroup of patients with limited apical ischaemia have similar outcome to patients with ischaemia in other segments despite a lower prevalence of CAD and a lower revascularisation rate.

Echocardiographic assessment of myocardial ischemia

Over the last 60 years, echocardiography has emerged as a dominant and indispensable technique for the detection and assessment of coronary heart disease (CHD). In this review, we will describe and discuss this powerful tool of cardiology, especially in the hands of an experienced user, with a focus on myocardial ischemia. Technical development is still on-going, and various new ultrasound techniques have been established in the field of echocardiography in the last several years, including tissue Doppler imaging (TDI), contrast echocardiography, three-dimensional echocardiography (3DE), and speckle tracking echocardiography (i.e., strain/strain rate-echocardiography). High-end equipment with harmonic imaging, high frame rates and the opportunity to adjust mechanical indices has improved imaging quality. Like all new techniques, these techniques must first be subjected to comprehensive scientific assessment, and appropriate training that accounts for physical and physiological limits should be provided. These limits will constantly be redefined as echocardiographic techniques continue to change, which will present new challenges for the further development of ultrasound technology.

Hypertension is strongly associated with false-positive bicycle exercise stress echocardiography testing results

INTRODUCTION

Exercise echocardiography is a reliable routine test in patients with known or suspected coronary artery disease. However, in ∼15% of all patients, stress echocardiography leads to false-positive stress echocardiography results. We aimed to investigate the impact of hypertension on stress echocardiographic results.

METHODS

We performed a retrospective study of patients with suspected or known stable coronary artery disease who underwent a bicycle exercise stress echocardiography. Patients with false-positive stress results were compared with those with appropriate results.

RESULTS

126 patients with suspected or known coronary artery disease were included in this retrospective study. 23 patients showed false-positive stress echocardiography results. Beside comparable age, gender distribution and coronary artery status, hypertension was more prevalent in patients with false-positive stress results (95.7% vs. 67.0%, p = 0.0410). Exercise peak load revealed a borderline-significance with lower loads in patients with false-positive results (100.0 (IQR 75.0/137.5) vs. 125.0 (100.0/150.0) W, p = 0.0601). Patients with false-positive stress results showed higher systolic (2.05 ± 0.69 vs. 1.67 ± 0.39 mmHg/W, p = 0.0193) and diastolic (1.03 ± 0.38 vs. 0.80 ± 0.28 mmHg/W, p = 0.0165) peak blood pressure (BP) per wattage. In a multivariate logistic regression test, hypertension (OR 17.6 [CI 95% 1.9-162.2], p = 0.0115), and systolic (OR 4.12 [1.56-10.89], p = 0.00430) and diastolic (OR 13.74 [2.46-76.83], p = 0.00285) peak BP per wattage, were associated with false-positive exercise results. ROC analysis for systolic and diastolic peak BP levels per wattage showed optimal cut-off values of 1.935mmHg/W and 0.823mmHg/W, indicating false-positive exercise echocardiographic results with AUCs of 0.660 and 0.664, respectively.

CONCLUSIONS

Hypertension is a risk factor for false-positive stress exercise echocardiographic results in patients with known or suspected coronary artery disease. Presence of hypertension was associated with 17.6-fold elevated risk of false-positive results.

Diagnostic accuracy of exercise stress testing for coronary artery disease: a systematic review and meta-analysis of prospective studies

BACKGROUND

Exercise stress testing offers a non-invasive, less expensive way of risk stratification prior to coronary angiography, and a negative stress test may actually avoid angiography. However, previous meta-analyses have not included all exercise test modalities, or patients without known Coronary artery disease (CAD).

METHODS AND RESULTS

We systematically reviewed the literature to determine the diagnostic accuracy of exercise stress testing for CAD on angiography. MEDLINE (January 1966 to November 2009), MEDION (1966 to July 2009), CENTRAL (1966 to July 2009) and EMBASE (1980-2009) databases were searched for English language articles on diagnostic accuracy of exercise stress testing. We included prospective studies comparing exercise stress testing with a reference standard of coronary angiography in patients without known CAD. From 6,055 records, we included 34 studies with 3,352 participants. Overall, we found published studies regarding five different exercise testing modalities: treadmill ECG, treadmill echo, bicycle ECG, bicycle echo and myocardial perfusion imaging. The prevalence of CAD ranged from 12% to 83%. Positive and negative likelihood ratios of stress testing increased in low prevalence settings. Treadmill echo testing (LR+ = 7.94) performed better than treadmill ECG testing (LR+ = 3.57) for ruling in CAD and ruling out CAD (echo LR- = 0.19 vs. ECG LR- = 0.38). Bicycle echo testing (LR+ = 11.34) performed better than treadmill echo testing (LR+ = 7.94), which outperformed both treadmill ECG and bicycle ECG. A positive exercise test is more helpful in younger patients (LR+ = 4.74) than in older patients (LR+ = 2.8).

CONCLUSIONS

The diagnostic accuracy of exercise testing varies, depending upon the age, gender and clinical characteristics of the patient, prevalence of CAD and modality of test used. Exercise testing, whether by echocardiography or ECG, is more useful at excluding CAD than confirming it. Clinicians have concentrated on individualising the treatment of CAD, but there is great scope for individualising the diagnosis of CAD using exercise testing.

Right ventricular pressure dynamics and stress echocardiography in pharmacological and exercise stress testing

REASONS FOR PERFORMING STUDY

There is interest in using pharmacological stress testing (PST) as a substitute for exercise stress testing (EST) to evaluate cardiac function in horses.

OBJECTIVES

To compare the effect of PST and EST on right ventricular pressure dynamics and stress echocardiography.

METHODS

Five horses completed a PST and EST in a randomised crossover design. High fidelity pressure transducers were placed in the right ventricle. Continuous pressure signals were digitally collected and stored, and dP/dtmax, dP/dtmin and tau calculated from these measurements. ECGs were recorded continuously for 20 h. Echocardiography was performed prior to EST and PST, during and after PST, and immediately post EST. Plasma cardiac troponin I concentrations were measured pre- and 3-4 h post stress testing. For PST, 5 microg/kg bwt glycopyrrolate i.v. followed after 10 min by 5 microg/kg bwt/min dobutamine infusion over 10 min was given. EST consisted of a 2 min gallop at 110% speed required to elicit VO2max.

RESULTS

Both EST and PST resulted in a significant increase in right-ventricular dP/dtmax and dP/dtmin over baseline (P<0.05) and a significant decrease in tau compared with baseline (P<0.05). EST dP/dtmax and dP/dtmin were significantly greater than PST dP/dtmax and dP/dtmin (P<0.05) and EST tau was significantly less than PST tau (P<0.05). Two minutes post EST and 5 min post PST dP/dtmax were not significantly different, but were significantly less than end-EST and during PST. Tau was also not significantly different between post EST and post PST, but was significantly decreased end-EST compared with during PST. FS were not significantly different between PST and post EST, but during PST and post EST all FS were significantly higher than baseline. Cardiac troponin I concentrations were significantly elevated post PST and were greater than post EST. The clinical relevance of this is unknown.

CONCLUSIONS

PST had a similar, although less marked effect on the cardiac parameters related to right-ventricular pressure dynamics and a similar effect on echocardiography as exercise stress testing.

POTENTIAL RELEVANCE

PST deserves further evaluation in normal horses and those with cardiac disease, and may be complementary to EST to better identify exercise-induced cardiac dysfunction.

Current status of stress echocardiography

Stress echocardiography is a widely applied technique for the evaluation of individuals with known or suspected coronary artery disease. The technique combines echocardiographic imaging with exercise testing or pharmacologic stress. Advances in digital image acquisition and harmonic imaging have substantially improved the quality of echocardiographic images, and have therefore increased general applicability of stress echocardiography.

Strain rate imaging pre- and post-percutaneous coronary intervention: a potential role in the objective detection of ischaemia in exercise stress echocardiography

AIMS

To determine the feasibility of strain rate imaging (SRI) in the objective detection of exercise-induced ischaemia.

METHODS AND RESULTS

Sixteen patients undergoing elective percutaneous coronary intervention (PCI) underwent treadmill exercise stress echocardiography (ESE) pre- and post-PCI. Measurement of systolic SRI parameters was attempted in all myocardial segments at baseline, peak stress, and in recovery. Segments were divided into those supplied by target (Group 1) and non-target vessels (Group 2). Percutaneous coronary intervention was successful in all patients. In Group 1, there was no significant difference in post-systolic strain rate (SRps) at baseline or at peak stress but there was significantly greater SRps pre-PCI compared with post-PCI at 30 min into recovery (-0.37 +/- 0.53 vs. -0.07 +/- 0.44 s(-1), P = 0.004). There were similar findings with the SRps index [ratio of SRps:peak systolic strain rate (SRsys)]. Group 2 segments did not demonstrate any significant differences in SRI parameters pre- and post-PCI. At peak exercise pre-PCI, Group 1 segments had significantly delayed time to SRsys compared with Group 2 (0.12 +/- 0.05 vs. 0.09 +/- 0.05 s, P = 0.013), a difference that was abolished post-PCI.

CONCLUSION

This suggests a potential role for SRI in the objective detection of exercise-induced ischaemia by echocardiography at peak stress and during recovery at the time of improved image quality.

Assessment of Diastolic Function During Exercise Echocardiography: Annulus Mitral Velocity or Transmitral Flow Pattern?

OBJECTIVES

We hypothesize that the change in the left ventricular (LV) diastolic pattern (DP) may be measured with high reproducibility and correlates with exercise echocardiography (EE) better than the ratio of early LV inflow velocity to early diastolic annulus velocity (E/e' index).

BACKGROUND

The E/e' index has been related to LV filling pressures but has not been compared with DP.

METHODS

We selected 179 consecutive patients who were referred for EE. Early (E) and late (A) LV inflow velocities by conventional pulsed Doppler, and septal annulus e' velocity by pulsed Doppler myocardial imaging were measured at rest (R) and post-exercise (PE).

RESULTS

Four LV-DPs were found: abnormal relaxation (AR) at R and PE (E < A) in 110 patients; AR at PE (E > A at R; E < A at PE) in 22 patients; restrictive pattern (RP) at R and PE (E > A) in 18 patients; and RP at PE (E < A at R; E > A at PE) in 29 patients. The more accurate PE cutoff E/e' values to predict abnormal EE, ischemic response, poor functional capacity (< 8 Mets in men; < 6 Mets in women), and lack of increase in left ventricular ejection fraction (LVEF) were 12, 12, 11, and 11 (areas under the curve were 0.53, 0.53, 0.63, and 0.57, respectively). Corresponding areas under the curve for an RP at R + PE or only at PE were 0.57, 0.55, 0.54, and 0.56 (P = not significant). The sensitivity of an RP at R + PE or only at PE was lower and the specificity was higher than those of the different E/e' cutoff values for predicting abnormal EE, functional capacity, ischemic response, and lack of increase in LVEF. Achieved Mets were lower in patients with an RP at R + PE or only at PE irrespectively of the E/e' values, whereas achieved Mets in patients with AR at R + PE or only at PE were lower if the E/e' was > or = 11 (8.2 +/- 2.9 vs. 9.8 +/- 3.1, P = .01). Interobserver and intraobserver concordance were 95% (kappa = 0.86) and 100% (kappa = 1.0) for an RP, and 86% (kappa = 0.73) and 92% (kappa = 0.78) for a PE-E/e' value of > or = 11.

CONCLUSIONS

E/e' does not allow further stratification in patients with exercise RP. We propose both measurement of E/e' and determination of the LV-DP (a quickly assessable variable) for the assessment of diastolic function during EE. However, when an RP persists or develops with exercise, further assessment may not be more informative.

Risk Stratification by Treadmill Exercise Echocardiography in Patients with Excellent Exercise Capacity

BACKGROUND

The incremental value of exercise echocardiography (EE) has been demonstrated to be maximal in patients with moderate pretest probability for coronary artery disease, but there is a lack of data in patients with low pretest probability or patients with good functional capacity.

METHODS

To investigate whether such incremental value is maintained in patients with excellent exercise capacity, we studied 1,433 patients who had excellent exercise capacity (>or=8 METs for women, >or=10 METs for men).

RESULTS

During a follow-up of 2.3 +/- 1.5 years, 42 hard events occurred (cardiac death or nonfatal myocardial infarction). Variables independently associated to hard events were male gender (P = 0.04), % of the age-predicted maximum heart rate (P = 0.02), chronotropic reserve (P = 0.002), and abnormal EE (P = 0.03; incremental P value of EE = 0.03).

CONCLUSIONS

EE has incremental value over clinical variables, resting echocardiography, and exercise testing variables in patients with excellent exercise capacity. EE may be preferable to ECG exercise testing even in patients expected to have good exercise capacity.

Usefulness of a novel ultrasound transducer for continuous monitoring treadmill exercise echocardiography to assess coronary artery disease

BACKGROUND

The feasibility of a novel ultrasound probe, which can be attached to the left ventricular (LV) apex chest wall and allows free rotation around its long axis direction for the continuous monitoring of LV wall motion, was tested.

METHODS AND RESULTS

There were 36 subjects who had coronary artery disease (CAD). By attaching a novel ultrasound probe to the chest wall, the LV apical views were recorded during treadmill exercise stress echocardiography (Echo). The continuous monitoring of LV wall motion was satisfactorily feasible in 30 of 36 patients. The visualization rate of the overall LV segments was higher at rest (90%) compared to that during peak exercise (77%). The segments were better visualized in apical portions (90-100%) than in mid (77-96%) or basal portions (68-87%). The sensitivity, specificity, and accuracy for detecting CAD were 61, 100 and 77%, respectively. The wall motion score index 3 and 6 min after exercise decreased significantly compared to those at peak exercise. The number of segments with dyssynergy was highest at the peak exercise. Ischemic ST-T depression on electrocardiography was observed only at peak stress periods.

CONCLUSIONS

Continuous monitoring treadmill exercise Echo using a novel ultrasound probe seems feasible for the non-invasive and physiological assessment of CAD.

Risk stratification by treadmill exercise echocardiography

BACKGROUND

Although exercise echocardiography (EE) has value for the diagnosis of coronary artery disease (CAD), it's not clear whether it may be useful for risk assessment in all categories of patients. To determine whether: 1) there is an incremental value of EE over clinical, exercise and resting echocardiographic variables for the prediction of events according to the pre-test probability of CAD; and 2) the number, location of the diseased territories, and nature of the disease affect the risk stratification, we studied 2436 patients referred for EE that were followed for 2.1 +/- 1.5 years.

METHODS

Based on a pre-test score, previous myocardial infarction (MI) or revascularizations, 1242 patients were considered as having high, 1038 moderate, and 156 low pre-test probability.

RESULTS

There were 89 hard events (myocardial infarction or cardiovascular death) in the 1203 patients with abnormal EE vs. 31 events in the 1233 with normal EE (p < 0.0001). Gender, Mets, heart rate x blood pressure, resting wall motion score index and number of involved territories at exercise were independently associated to hard events (final Chi-square = 170, incremental p value of exercise echo <0.0001). The incremental value of exercise echo over other variables was found in patients with the different pre-test probabilities.

CONCLUSIONS

Exercise echocardiography has incremental value over clinical, exercise and resting echocardiographic variables in patients with different pre-test probabilities of CAD.

Comparison of exercise echocardiography and the Duke treadmill score for risk stratification in patients with known or suspected coronary artery disease and normal resting electrocardiogram

BACKGROUND

Although exercise echocardiography (EE) is not clearly indicated in patients with normal electrocardiogram (ECG) as the first evaluation, there is a lack of data regarding its superiority over the Duke score for prognosis. We investigate whether EE has incremental value over the Duke score for predicting outcome in patients with normal ECG.

METHODS

One thousand six hundred forty-seven patients with interpretable ECG referred for EE were followed up for 2.5 +/- 1.4 years. There were 58 hard events (myocardial infarction or cardiovascular death).

RESULTS

There were 38 events in 735 patients with abnormal EE versus 20 events in 912 with normal EE (P < .0001). The Duke score, resting wall motion score index, and ischemia were independently associated to events (incremental P value of EE = .03). The Duke score allowed stratification of patients with abnormal EE (P = .001) or ischemia (P = .01) into different risk categories but did not stratify patients without these characteristics. Exercise echocardiography variables stratified patients with the low Duke score (left anterior descending artery territory P = .04, left anterior descending artery ischemia P = .03) and with the intermediate Duke score (abnormal EE P = .005, necrosis P = .0009, ischemia P = .004, resting ejection fraction P < .00001, resting wall motion score index P < .00001, peak ejection fraction P < .00001, peak wall motion score index P < .0001, number of territories P = .002, left anterior descending artery territory P = .001, and left anterior descending artery ischemia P = .002) but did not with the high Duke score.

CONCLUSIONS

Exercise echocardiography has incremental value over clinical variables, the Duke score, and resting echocardiography for the prediction of hard cardiovascular events in patients with normal resting ECG.

Comparison of exercise, dobutamine-atropine and dipyridamole-atropine stress echocardiography in detecting coronary artery disease

Background

Dipyridamole and dobutamine stress echocardiography testing are most widely utilized, but their sensitivity remained suboptimal in comparison to routine exercise stress echocardiography. The aim of our study is to compare, head-to-head, exercise, dobutamine and dipyridamole stress echocardiography tests, performed with state-of-the-art protocols in a large scale prospective group of patients.

Methods

Dipyridamole-atropine (Dipatro: 0.84 mg/kg over 10 min i.v. dipyridamole with addition of up to 1 mg of atropine), dobutamine-atropine (Dobatro: up to 40 mcg/kg/min i.v. dobutamine with addition of up to 1 mg of atropine) and exercise (Ex, Bruce) were performed in 166 pts. Of them, 117 pts without resting wall motion abnormalities were enrolled in study (91 male; mean age 54 ± 10 years; previous non-transmural myocardial infarction in 32 pts, angina pectoris in 69 pts and atypical chest pain in 16 pts). Tests were performed in random sequence, in 3 different days, within 5 day period under identical therapy. All patients underwent coronary angiography.

Results

Significant coronary artery disease (CAD; ≥50% diameter stenosis) was present in 69 pts (57 pts 1-vessel CAD, 12 multivessel CAD) and absent in 48 pts. Sensitivity (Sn) was 96%, 93% and 90%, whereas specificity (Sp) was 92%, 92% and 87% for Dobatro, Dipatro and Ex, respectively (p = ns). Concomitant beta blocker therapy did not influence peak rate-pressure product and Sn of Dobatro and Dipatro (p = ns).

Conclusion

When state-of-the-art protocols are used, dipyridamole and dobutamine stress echocardiography have comparable and high diagnostic accuracy, similar to maximal post-exercise treadmill stress echocardiography.

Efficacy of Ultrasound-assisted Stress Testing Using a Hand-carried Ultrasound Device for Diagnosis of Coronary Artery Disease

BACKGROUND

Exercise echocardiography is an effective means of noninvasively detecting coronary artery disease (CAD), and hand-carried cardiac ultrasound (HCU) devices are now being used to diagnose CAD in emergency rooms and at bedsides.

OBJECTIVE

To compare the efficacies of exercise echocardiography with an HCU device (EchoCG-HCU) and exercise electrocardiography (ECG) in the diagnosis of CAD.

METHODS

Fifty-eight patients underwent symptom-limited treadmill exercise testing. Two-dimensional echocardiographic images were obtained from standard parasternal and apical windows at rest and immediately after exercise using an HCU device (180 PLUS SonoSite Inc, Bothell, Wash). Wall motion was scored for each of 16 left ventricular segments using a 5-point grading system. The development of new or worsening wall motion was considered to be indicative of ischemia.

RESULTS

When identifying CAD using exercise ECG, the sensitivity ws 63%, the specificity was 72%, and the diagnostic accuracy was 69%. By comparison, with exercise EchoCG-HCU the sensitivity was 68%, the specificity was 90%, and the diagnostic accuracy was 83%. Moreover, the specificity of exercise EchoCG-HCU was significantly higher than that of exercise ECG (p < .05).

CONCLUSION

Exercise EchoCG-HCU is at least as useful as exercise ECG for diagnosing CAD.

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.

Usefulness of strain rate imaging in detecting ischemic myocardium during dobutamine stress

BACKGROUND

Tissue Doppler imaging-derived systolic myocardial velocity can detect subtle alterations in contractility during dobutamine stress. However, increased cardiac translation and tethering during dobutamine stress may affect measurements.

METHODS

To examine the hypothesis that regional ischemic myocardium can be sensitively detected during dobutamine stress using myocardial strain rate, a new indicator of regional myocardial contraction that is independent of cardiac translation and tethering, we studied seven closed-chest pig confirmed chronic ischemic models produced by placing an ameroid constrictor on the left circumflex artery. Left ventricular short-axis tissue Doppler imaging was obtained at baseline and during dobutamine stress (10 and 30 microg/kg/min). Peak systolic myocardial velocity and peak systolic myocardial strain rate in anterior and posterior segments were derived offline at each stage.

RESULTS

In peak systolic myocardial velocity and peak systolic myocardial strain rate, repeated-measures analysis of variance showed significant interaction between nonischemic and ischemic segments during dobutamine stress. Statistical significance between nonischemic and ischemic segments was reached at baseline, 10 microg/kg/min dobutamine, and 30 microg/kg/min dobutamine in peak systolic myocardial strain rate, and at 30 microg/kg/min dobutamine in peak systolic myocardial velocity. By receiver operating characteristic (ROC) analysis for predicting ischemic segments at 30 microg/kg/min dobutamine, a cutoff value of peak systolic myocardial strain rate was 4.84, with a sensitivity of 100% and a specificity of 100%. Peak systolic myocardial velocity was the less discriminating parameter (cutoff, 6.46; sensitivity, 86%; specificity, 86%).

CONCLUSIONS

Myocardial strain rate imaging might represent an accurate parameter for clinical recognition of regional ischemic myocardium during dobutamine stress echocardiography.

Comparison of peak and postexercise treadmill echocardiography with the use of continuous harmonic imaging acquisition

OBJECTIVES

We sought to compare the feasibility and accuracy of peak and postexercise treadmill echocardiography with the use of continuous harmonic imaging capture.

BACKGROUND

Previous work has demonstrated the superiority of peak exercise echocardiography (EE) as compared with post-EE for the diagnosis of coronary artery disease (CAD). However, most of these studies used fundamental imaging and view-per-view acquisition systems. Technical advantages in stress echocardiography include harmonic imaging and continuous imaging capture.

METHODS

The study group included 650 patients (423 men; 60 +/- 12 years) who were submitted to peak and postexercise treadmill echocardiography.

RESULTS

Postexercise images were acquired within 55 seconds after exercise (28 +/- 10). The number of segments visualized in each view were similar at peak and post-EE except for the parasternal short-axis view, which was better qualified at postexercise. For analysis of diagnostic capability we included 312 patients: 195 were included on the basis of having had an EE and a coronary angiography, whereas 117 patients with pretest probability of CAD < 10% who had atypical chest pain or were asymptomatic were also included and considered as having no CAD. CAD (>/=50% stenosis) was confirmed in 159 patients. Positive EE was defined as ischemia or necrosis. Sensitivity for CAD was higher with peak imaging (92% vs 77%, P <.001), with similar specificity (78% vs 87%, P = not significant) and accuracy (85% vs 82%, P = not significant).

CONCLUSION

Peak treadmill EE is technically feasible and has higher sensitivity for CAD than posttreadmill EE. Therefore, in the clinical setting, peak EE should be performed for diagnostic purposes.

Novel stress echocardiographic model incorporating the extent and severity of wall motion abnormality for risk stratification and prognosis

The prognostic value of stress echocardiography to predict future cardiac events using the extent and severity of wall motion abnormalities is not well defined. The objective of this study was to develop and validate a prognostic model for interpretation of stress echocardiographic studies by using the extent and severity of wall motion abnormalities. We evaluated 1,500 patients (59 +/- 13 years old; 51% men) who underwent stress echocardiography (34% on the treadmill exercise and 66% on dobutamine). Left ventricular regional wall motion was assessed by consensus of 2 experienced echocardiographers. Follow-up periods (mean 2.7 +/- 1.0 years) for confirmed myocardial infarction (n = 31) and cardiac death (n = 44) were identified. Multivariate regression analysis identified 2 independent predictors of cardiac events: the number of left ventricular wall segments with new wall motion abnormalities (an index of the extent of ischemia) and the maximal magnitude of new wall motion abnormalities (an index of the severity of ischemia). The ischemic extent (chi-square 48.7, p <0.0001) and maximal severity (chi-square 52.0, p <0.0001) were exponentially correlated with an increase in event rate. On the basis of these data, a prognostic model was defined that uses ischemic extent and maximal severity as stress-dependent orthogonal variables. With this 3-dimensional model, the predicted event rate ranged over sevenfold, from a low of 0.9%/year in patients without any wall motion abnormalities to a high of 6.7%/year in patients with extensive and severe wall motion abnormalities. The extent and severity of wall motion abnormalities by stress echocardiography are independent and cumulative predictors of prognosis in patients who have suspected or known ischemic heart disease.

Relationship between the ischemic threshold at the onset of wall-motion abnormality on semisupine exercise echocardiography and the extent of coronary artery disease

Semisupine exercise echocardiography (SSEE) provides the unique opportunity of continuous monitoring of segmental wall motion during physiologic stress. We evaluated the relationship between the ischemic threshold at the onset of wall-motion abnormality on SSEE and the extent of coronary artery disease (CAD) in a consecutive series of 224 patients who underwent coronary angiography. Ischemic threshold was significantly lower for patients with multivessel disease compared with single-vessel disease: maximal workload was 102 versus 135 W (P = 1.3.10(-6)); percentage of maximal predicted heart rate achieved was 64 versus 70% (P =.004); and double product was 21,335 versus 23,389 (P =.03), respectively. Sensitivity, specificity, and positive and negative predictive values of SSEE for the detection of significant CAD (> or =60% diameter stenosis) were 81%, 74%, 90%, and 56%, respectively. SSEE is an accurate tool to diagnose CAD and the ischemic threshold at the onset of wall-motion abnormality is inversely related to the extent of CAD.

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.

Biplane stress echocardiography using a prototype matrix-array transducer

BACKGROUND

Rapid image acquisition after cessation of exercise is essential for accurate stress echocardiography. Recently, a prototype matrix-array transducer has been developed that allows simultaneous acquisition of 2 imaging planes (biplane [BP] imaging).

METHODS

In all, 19 healthy volunteers underwent 2 separate stress echocardiographic studies. Images were acquired in traditional 2-dimensional or BP format pre-exercise and postexercise.

RESULTS

Total image acquisition time for 2-dimensional stress echocardiography was 38 +/- 8 seconds versus 29 +/- 8 seconds for BP imaging (P <.05). Heart rates were acquired closer to age-predicted maximum with BP imaging in the apical 3- and 2-chamber and parasternal long- and short-axis views (82%, 75%, 70%, 70% for BP vs 76%, 72%, 68%, 66% for 2-dimensional, respectively).

CONCLUSION

BP imaging using a recently developed matrix-array probe allows more rapid imaging postexercise, resulting in acquisition of poststress images at higher heart rates without compromising image quality.

Prognostic value of exercise echocardiography: validation of a new risk index combining echocardiographic, treadmill, and exercise electrocardiographic parameters

Exercise (Ex) echocardiography has been shown to have significant prognostic power, independent of other known predictors of risk from an Ex stress test. The purpose of this study was to evaluate a risk index, incorporating echocardiographic and conventional Ex variables, for a more comprehensive risk stratification and identification of a very low-risk group. Two consecutive, mutually exclusive populations referred for treadmill Ex echocardiography with the Bruce protocol were investigated: hypothesis-generating (388 patients; 268 males; age 55 +/- 13 years) and hypothesis-testing (105 patients; 61 males age: 54 +/- 14 years).Cardiac events included cardiac death, myocardial infarction, late revascularization (>90 days), hospital admission for unstable angina, and admission for heart failure. Mean follow-up in the hypothesis-generating population was 3.1 years. There were 38 cardiac events. Independent predictors of events by multivariate analysis were: Ex wall motion score index (odds ratio [OR] = 2.77/Unit; P <.001); ischemic S-T depression > or = 1 mm (OR = 2.84; P =.002); and treadmill time (OR = 0.87/min; P =.037). A risk index was generated on the basis of the multivariate Cox regression model as: risk index = 1.02 (Ex wall motion score index) + 1.04 (S-T change) - 0.14 (treadmill time). The validity of this index was tested in the hypothesis-testing population. Event rates at 3 years were lowest (0%) in the lower quartile of risk index (-1.22 to -0.47), highest (29.6%) in the upper quartile (+0.66 to +2.02), and intermediate (19.2% to 15.3%) in the intermediate quartiles. The OR of the risk index for predicting cardiac events was 2.94/Unit ([95% confidence interval: 1.4 to 6.2]; P =.0043). Echocardiographic and Ex parameters are independent powerful predictors of cardiac events after treadmill stress testing. A risk index can be derived with these parameters for a more comprehensive risk stratification with Ex echocardiography.

Right ventricular pressure dynamics during exercise: relationship to stress echocardiography

Thorough evaluation of myocardial function remains difficult to evaluate under exercising conditions. This study described right ventricular (RV) pressure dynamics during and immediately following exercise. Nine Thoroughbreds without evidence of cardiac disease completed treadmill exercise at 110% of the speed necessary to elicit VO2max while RV pressures were recorded. RV pressure dynamics were calculated at rest, maximal speed and at 10 s intervals for 2 min after exercise. Stress echocardiography was performed at rest and within 120 s after exercise. Mean dP/dtmax and dP/dtmin values were significantly greater at maximal speed and up to 30 s immediately postexercise than at rest and all time points from 60 to 120 s postexercise. Mean dP/dtmax and dP/dtmin were not significantly different from resting values after 60 s postexercise. Tau (the time constant for ventricular relaxation) decreased significantly with exercise, but was not significantly different from rest at time points from 60 to 120 s following exercise. Mean % fractional shortening (FS) increased postexercise; however, the coefficient of variability was large. Wall motion indices also showed large variability postexercise. These temporal changes in normal horses suggest that exercising RV pressure dynamics may provide a better estimation of cardiac function during exercise than postexercise stress echocardiography.

Low-level exercise echocardiography identifies contractile reserve in patients with a recent myocardial infarction: comparison with dobutamine stress echocardiography

Contractile reserve (CR) during dobutamine stress echocardiography (DSE) identifies patients with coronary artery disease whose left ventricular function and prognosis may improve after revascularization. To test the hypothesis that the early stages of upright bicycle-exercise echocardiography (LLEx) result in CR comparable with DSE, 30 patients 1 week after myocardial infarction underwent multistage LLEx and DSE. At low and peak LLEx, heart rate and systolic blood pressure were higher than DSE. Identification of CR by LLEx was concordant with DSE when analyzed by infarct zone or by individual patient. We conclude that CR can be demonstrated during LLEx that correlates with DSE in patients with a recent MI. Low-level exercise is a promising alternative to DSE for identifying contractile reserve after MI.

Can strain rate and strain quantify changes in regional systolic function during dobutamine infusion, B-blockade, and atrial pacing--implications for quantitative stress echocardiography

BACKGROUND

We investigated the ability of ultrasonic strain rate (SR) and strain (epsilon) to quantify the changes in normal myocardial function at varying inotropic states and heart rates (HR) in an attempt to determine whether these new regional function indices are potentially robust enough to quantitate stress echocardiography.

METHODS AND RESULTS

Twenty closed-chest pigs underwent incremental atrial pacing (AP: 120-180/min, n = 7), dobutamine infusion (DI: 2.5-20 microg/kg/min, n = 7) or esmolol infusion with subsequent pacing (EI: 0.5 +/- 0.15 mg/kg/min with pacing 120-180/min, n = 6). Radial deformation of the left ventricular posterior wall was interrogated using the parasternal short-axis view to derive regional systolic SR and epsilon values. At baseline SR and epsilon averaged 5.0 +/- 0.4 s(-1) and 60% +/- 4%, respectively. SR remained unchanged during AP and increased linearly with DI (at 2.5 microg/kg/min = 6.2 +/- 0.3 s(-1), P <.05 vs baseline; at 20 microg/kg/min = 9.9 +/- 0.7 s(-1), P <.0001 vs baseline), whereas EI resulted in a constant decrease of 30% +/- 4% in SR (P <.05). SR and left ventricular dP/dt(MAX) correlated linearly over the induced change in inotropic states and HR (r = 0.82; P <.0001). Conversely, epsilon values decreased during AP (at 180/min = 36% +/- 2%, P <.001). During DI, epsilon initially increased at 2.5 and 5 microg/kg/min (at 5 microg/kg/min = 77% +/- 6%, P <.05) and decreased for higher doses because of increasing HR. EI resulted in a decrease of 30% +/- 4% in epsilon with a further decrease during subsequent pacing. epsilon correlated linearly with left ventricular ejection fraction (r = 0.87; P <.0001).

CONCLUSION

Both SR and epsilon can quantify the changes in myocardial function during a range of inotropic challenges and over the range of physiologic HRs encountered during clinical stress echocardiography. SR may reflect regional contractile function, whereas epsilon reflects changes in ventricular geometry. This study would suggest that for quantitative stress echocardiography SR is better in quantification of changes in contractile function being relatively independent of HR.

Hypertensive response to exercise: a potential cause for new wall motion abnormality in the absence of coronary artery disease

OBJECTIVES

We sought to characterize patients with a hypertensive response during exercise echocardiography and its effect on results of the test.

BACKGROUND

A hypertensive response to exercise has been shown to cause false-positive results in perfusion imaging, radionuclide angiography and exercise electrocardiography, but its influence on exercise echocardiography has not been reported.

METHODS

We identified 548 of 6,686 patients who had coronary angiography within four weeks after exercise echocardiography from 1992 through 1996. Echocardiographic results from 132 patients (24%) with a hypertensive response to exercise, defined as systolic blood pressure (SBP) >220 mm Hg for men and SBP >190 mm Hg for women or as an increase in diastolic blood pressure (DBP) >10 mm Hg or DBP >90 mm Hg during exercise echocardiography, were compared with those from 416 patients without a hypertensive response.

RESULTS

Of 132 patients with a hypertensive response to exercise, 108 patients had exercise echocardiographic results positive for ischemia. Of these patients, 24 (22%) were found to have no significant coronary artery disease (CAD). In contrast, of 320 patients with positive exercise echocardiographic results without a hypertensive response, 39 (12%) patients did not have significant CAD. Among the false-positive results, new wall motion abnormalities were extensive in 15 of 24 (63%) hypertensive responders involving >25% of segments compared with 14 of 39 non-hypertensive responders (36%, p = 0.012).

CONCLUSIONS

An excessive rise in blood pressure during exercise is associated with a greater likelihood of new or worsening abnormalities with exercise, which may be observed in the absence of angiographically significant coronary artery stenosis.

Stratification of single-vessel coronary stenosis by ischemic threshold at the onset of wall motion abnormality during continuous monitoring of left ventricular function by semisupine exercise echocardiography

We studied the relation between the ischemic threshold at the onset of wall motion abnormality on exercise echocardiography (EE) and the severity of coronary stenosis in patients with 1-vessel coronary artery disease (CAD). We screened 216 consecutive patients who underwent coronary angiography and EE for suspected CAD. Ninety-five (74 men; age, 56 +/- 12 years) satisfied the study criteria, that is, the presence of 1-vessel disease or no evidence of CAD on angiography and a normal baseline echocardiogram. Eighty-seven patients had 1-vessel CAD on angiography, and exercise-induced wall motion abnormality occurred in 73 (77%). Optimal cutoff values of percent diameter stenosis and minimal lumen diameter for predicting a positive EE were 61% (sensitivity and specificity of 76%) and 1.12 mm (sensitivity and specificity of 74%). Among patients with positive EE, heart rate-blood pressure product at ischemic threshold was correlated with quantitative coronary stenosis (r = -0.72, P <.001). The ischemic threshold from continuous monitoring of left ventricular function during semisupine EE is correlated with the severity of coronary stenosis among patients with 1-vessel disease and a normal resting echocardiogram.

Stress echocardiography and its role in performance assessment

Stress echocardiography in the horse is in its infancy, and investigations need to continue to determine the significance and mechanism of postexercise echocardiographic abnormalities detected in horses. This work should be coupled with investigations on the exercise-induced changes in cardiac isoenzymes, cTnI, arterial oxygen content, and cardiac rhythm that may occur concurrently. With continued investigations into the cardiovascular problems that occur in the exercising horse, the sport horse veterinarian should be better able to accurately diagnose and treat problems causing poor performance in the horse.

Non-invasive investigations

The most commonly used techniques for imaging the effects of coronary artery disease (CAD) on the heart are myocardial perfusion scintigraphy (MPS) and echocardiography. Both tests have been validated during exercise and pharmacological stress and they are valuable for the diagnosis and aiding management decisions in patients with suspected or known CAD. In a proportion of these patients, repetitive episodes of myocardial ischaemia can lead to intracellular and extracellular changes so that myocytes, although viable, have insufficient energy to sustain contraction. This phenomenon is known as myocardial hibernation and it can be detected accurately by both MPS and stress echocardiography. The review that follows highlights the role of these techniques as powerful diagnostic and prognostic tools in clinical cardiology. In order to make the best use of them, attention to detail and planning are required to design the test to suit the clinical problem and to obtain the most accurate data possible.

Stress echocardiography: technical considerations

Stress echocardiography has evolved into a widely practiced and accepted method for the noninvasive assessment of the status of the coronary anatomy. Furthermore, this modality incorporates the ability to assess left ventricular function, valvular structure and function, intracardiac masses, the pericardium, and hemodynamics. The extent to which this tool can reliably provide useful clinical information is dependent, in part, on optimal performance. The purpose of this report is to provide an overview of those technical considerations that can contribute to the successful operation of a stress echocardiography laboratory. Consideration is given to personnel qualifications, functional requirements of the digital acquisition/storage/replay system, functional integration of the various hardware components, characteristics of the software, physical layout of the facility, and alternatives to treadmill exercise as the stressor. A thorough understanding of the physiologic basis of stress echocardiography, coupled with optimization of resources used in its performance, enable this tool to be an extraordinarily useful and cost-efficient method for comprehensive cardiovascular assessment.

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.

Diagnostic and prognostic use of stress echocardiography in stable patients

Stress echocardiography is an effective diagnostic and prognostic technique in stable patients with known or suspected coronary artery disease (CAD), myocardial infarction, or chronic left ventricular dysfunction and those undergoing noncardiac surgery. Stress echocardiography is sensitive and specific for the detection and extent of CAD. Negative tests confer a high negative predictive value for cardiac events regardless of the clinical risk. Positive studies confer a high positive predictive value for ischemic events in patients with intermediate to high clinical risk. Stress echocardiography provides incremental prognostic information relative to clinical, resting echocardiographic, and angiographic data. Meta-analysis studies have shown that the diagnostic and prognostic information provided by stress echocardiography is comparable to that from radionuclide scintigraphic stress tests. Stress echocardiography may be more specific for the detection and extent of CAD, whereas radionuclide scintigraphy may be more sensitive for one-vessel disease. Sensitivities are similar for the detection and extent of disease in patients with multivessel CAD.

Accuracy of exercise echocardiography to detect coronary artery disease in left bundle branch block unassociated with either acute or healed myocardial infarction

To search for the value of treadmill exercise echocardiography in the detection of coronary artery disease in noninfarcted patients with left bundle branch block, we studied 35 patients (17 with coronary artery disease). We found high sensitivity, specificity, and accuracy (76%, 83%, and 80%, respectively).

Myocardial ischemia due to coronary artery spasm during dobutamine stress echocardiography

Dobutamine stress echocardiography (DSE) is a useful and safe provocation test for myocardial ischemia. Until now, the test has been focused only on the organic lesion in the coronary artery, and positive DSE has indicated the presence of significant fixed coronary artery stenosis. The aim of the present study is to examine whether myocardial ischemia due to coronary spasm is induced by dobutamine. We performed DSE on 51 patients with coronary spastic angina but without significant fixed coronary artery stenosis. All patients had anginal attacks at rest with ST elevation on the electrocardiogram (variant angina). Coronary spasm was induced by intracoronary injection of acetylcholine, and no fixed coronary artery stenosis was documented on angiograms in all patients. DSE was performed with intravenous dobutamine infusion with an incremental doses of 5, 10, 20, 30, and 40 microg/kg/min every 5 minutes. Of the 51 patients, 7 patients showed asynergy with ST elevation. All 7 patients (13.7%) had chest pain during asynergy, and both chest pain and electrocardiographic changes were preceded by asynergy. These findings indicate that dobutamine can provoke coronary spasm in some patients with coronary spastic angina. When DSE is performed to evaluate coronary artery disease, not only fixed coronary stenosis, but also coronary spasm should be considered as a genesis of asynergy.

Comparison of bicycle, heavy isometric, dipyridamole-atropine and dobutamine stress echocardiography for diagnosis of myocardial ischemia

Several stress echocardiography (SE) modalities have been introduced for diagnosing coronary artery disease (CAD). Exercise and dobutamine SE are considered to have better diagnostic accuracy than vasodilator or isometric SE, but there are no studies in a single group of patients comparing these 3 tests with heavy 2-arm isometric SE. The purpose of this study was to determine the diagnostic characteristics of 4 SE methods in patients with chest pain. Altogether, 60 patients (age +/- SD 55.1 +/- 2.1 years) were tested with bicycle, heavy 2-arm isometric, dipyridamole-atropine and dobutamine SE. CAD (>50% stenosis) was present in 44 patients; 26 patients had 1-vessel disease. During bicycle SE, the double product at peak stress was higher than during dobutamine and dipyridamole-atropine SE (26.5 x 10(3), p <0.005 vs dobutamine and dipyridamole-atropine SE), and peak wall motion score index (1.40) was higher than during dipyridamole-atropine and isometric SE (1.26 and 1.07, respectively, p <0.05 vs bicycle SE). Bicycle, dipyridamole-atropine, and dobutamine SE had higher sensitivity than isometric SE (90%, 93%, 95%, and 30%, respectively, p <0.05 isometric SE vs others). There were no statistically significant differences with regard to specificity. Similarly, bicycle, dipyridamole-atropine, and dobutamine SE had a higher diagnostic accuracy than isometric SE (78%, 88%, 87% and 47%, respectively, p <0.05 isometric SE vs others). We conclude that bicycle, dipyridamole-atropine, and dobutamine SE have an equal diagnostic accuracy in detecting CAD despite higher double product and ischemic burden at peak stress during bicycle and dobutamine SE over dipyridamole-atropine SE. Heavy isometric SE is inaccurate.

Comparison of treadmill exercise echocardiography before and after exercise in the evaluation of patients with known or suspected coronary artery disease

OBJECTIVES

We sought to compare the feasibility and accuracy of peak treadmill exercise echocardiography versus postexercise echocardiography imaging.

BACKGROUND

Although peak exercise echocardiography has been reported for both supine and orthostatic bicycle exercise and has shown higher sensitivity than postexercise imaging, acquiring images at peak exercise with treadmill has not been explored.

METHODS

Peak and post-treadmill exercise echocardiography and coronary angiography were performed on 89 patients with known or suspected coronary artery disease. Positive exercise echocardiography was defined as necrosis or ischemic response. Positive coronary angiography was defined as >/=1 diseased vessels (>/=50% luminal narrowing). Images were analyzed in a blind manner by an expert observer.

RESULTS

Postexercise images were acquired within 80 seconds after exercise (40 +/- 14). Mean heart rate (bpm) was 139 +/- 22 at peak versus 118 +/- 25 at postexercise imaging (P <.001). Interpretable peak and postexercise images were obtained for all 89 patients. Of the 72 classified as having positive exercise echocardiography, 23 had new regional wall motion abnormality at peak (21 with positive angiography), which resolved at postexercise imaging. Sensitivity was higher with peak than with postexercise imaging (94% vs 73%, P <.001). Specificity was similar (68% vs 79%), as was predictive positive value (92% vs 93%). Negative predictive value was again higher with peak imaging (76% vs 44%, P <.05). Total accuracy was higher with peak imaging (89% vs 74%, P <.05).

CONCLUSIONS

Peak treadmill exercise echocardiography is technically feasible and has higher sensitivity and accuracy than post-treadmill exercise echocardiography. Therefore in the clinical setting peak exercise echocardiography should be performed to diagnose ischemia.