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

Additive prognostic and diagnostic value of diastolic exercise parameters in patients referred for exercise echocardiography

AIMS

Exercise echocardiography (ExE) may evaluate left ventricular (LV) systolic and diastolic function. We aimed to assess the value of diastolic parameters at exercise [early LV inflow velocity to early tissue Doppler annulus velocity (E/e')] in patients with normal or abnormal resting diastolic function (DF) referred for a clinically indicated ExE.

METHODS AND RESULTS

LV systolic and DF according to ASE/EACVI guidelines and mitral regurgitation (MR) were evaluated at rest in 772 patients (age 67 ± 12 years) with preserved LV ejection fraction (LVEF ≥ 50%). We assessed regional/global LV systolic function at peak exercise, while MR and E/e' where evaluated in the immediate post-exercise period. Abnormal ExE was defined as ischaemia or fixed wall motion abnormalities, and raised E/e' values as >15 at rest and at exercise (e' at the septal level). Patients were grouped as complaining or not of dyspnoea. Events were overall mortality, myocardial infarction, admission for unstable angina or cardiac failure, and coronary revascularization. DF was abnormal at rest in 221 patients (29%) and indeterminate in 77 (10%), with similar percentages in patients with and without dyspnoea. Exercise E/e' >15 was found in 37% of patients with abnormal DF, 21% with indeterminate DF, and 6% with normal DF (P < 0.001). Patients with abnormal ExE had more often abnormal resting DF (39% vs. 25%, P = 0.001) and exercise E/e' >15 (25% vs. 13%, P < 0.001) than those with normal ExE. During a median follow-up of 1.68 years, there were 132 events. Independent predictors included peak exercise LVEF [hazard ratio (HR) = 0.93, 95% confidence interval (CI) = 0.91-0.94, P < 0.001], and exercise E/e' (HR= 1.04, 95% CI = 1.01-1.07, P = 0.01). Neither resting E/e' values nor resting abnormal DF by ASE/EACVI guidelines, were independent predictors. Annualized event-rates were 43.2% in patients with (+) ExE plus (+) exercise E/e', 23.8% in those with (+) ExE and (-) exercise E/e', 7.9% in (-) ExE and (+) exercise E/e', and 3.6% with both variables normal.

CONCLUSIONS

The results of diastolic dysfunction at rest and at exercise were similar between patients with or without dyspnoea referred for ExE, but they were associated with abnormal ExE. Exercise E/e' reclassified 21% of patients with indeterminate DF and further predicted outcome on top of ExE results.

Peak treadmill exercise echocardiography for ischemia detection

Of the stress echocardiographic methods, exercise should be the first choice for patients able to exercise, according to guidelines. Among ExE modalities, treadmill ExE with acquisition of images at peak exercise has several advantages, including high sensitivity and prognostic value. Overall, sensitivity of ExE is around 80%-85%, although figures for peak imaging on the treadmill are 85%-90%. Despite it, guidelines do not mention this method.

Exercise cardiovascular magnetic resonance: development, current utility and future applications

Stress cardiac imaging is the current first line investigation for coronary artery disease diagnosis and decision making and an adjunctive tool in a range of non-ischaemic cardiovascular diseases. Exercise cardiovascular magnetic resonance (Ex-CMR) has developed over the past 25 years to combine the superior image qualities of CMR with the preferred method of exercise stress. Presently, numerous exercise methods exist, from performing stress on an adjacent CMR compatible treadmill to in-scanner exercise, most commonly on a supine cycle ergometer. Cardiac conditions studied by Ex-CMR are broad, commonly investigating ischaemic heart disease and congenital heart disease but extending to pulmonary hypertension and diabetic heart disease. This review presents an in-depth assessment of the various Ex-CMR stress methods and the varied pulse sequence approaches, including those specially designed for Ex-CMR. Current and future developments in image acquisition are highlighted, and will likely lead to a much greater clinical use of Ex-CMR across a range of cardiovascular conditions.

Exercise left ventricular ejection fraction predicts events in right bundle branch block

OBJECTIVE

Interpretation of the electrocardiogram (ECG) during exercise is not easy in patients with right bundle branch block (RBBB). Also, the value of exercise echocardiography (ExE) for predicting outcome in them has not been addressed. We sought to assess its prognostic value in patients with RBBB and known/suspected coronary disease.

DESIGN

Retrospective analysis of data on 703 patients with RBBB who were submitted to a clinically-indicated ExE. The end points were overall mortality and combined myocardial infarction and cardiovascular mortality.

RESULTS

During follow-up (4.1 ± 4.5 years) there were 130 deaths and 108 combined events. Independent predictors of combined events were history of coronary artery disease (hazard ratio [HR] = 2.37, 95% Confidence Interval [CI] = 1.24-4.52, p = 0.009) resting wall motion score index (HR = 2.14, 95% CI = 1.12-4.10, p = 0.02), metabolic equivalents (HR = 0.89, 95% CI = 0.93-0.97, p = 0.007), Δ in double product with exercise (HR = 0.96, 95% CI = 0.92-1.00, p = 0.036) and Δ in left ventricular ejection fraction (LVEF) with exercise (HR = 0.97, 95% CI = 0.94-0.99, p = 0.01). Neither positive clinical nor ECG exercise testing was predictive. Combined event rates were 3.3% in patients with ΔLVEF > 5%, 4.7% in those with ΔLVEF between 1-5% and 8.2% in those with no increase (Δ < 1%).

CONCLUSIONS

A decrease in LVEF during exercise is predictive of serious events in patients with RBBB.

Incremental value of exercise echocardiography over exercise electrocardiography in a chest pain unit

BACKGROUND

Limited data are available on the added value of exercise echocardiography (ExEcho) over exercise electrocardiography (ExECG) in patients with suspected acute coronary syndromes (ACS) referred to a chest pain unit. We aimed to assess the incremental value of ExEcho over ExECG in this setting.

METHODS

ExECG and ExEcho were performed in parallel in 1052 patients with suspected ACS, nondiagnostic but interpretable electrocardiograms, and negative serial troponin results. The primary outcome was a composite of coronary death, nonfatal myocardial infarction or unstable angina with angiographic documentation of significant coronary artery disease within 6 months.

RESULTS

The primary outcome occurred in 2/614 patients (0.3%) with both negative ExECG and ExEcho, 3/60 (5%) with positive ExECG and negative ExEcho, 73/135 (54.1%) with negative ExECG and positive ExEcho, 106/136 (77.9%) with both positive ExECG and ExEcho, and 8/107 (7.5%) with inconclusive results. The addition of ExEcho data to a model based on clinical and ExECG data significantly increased the c statistic from 0.898 to 0.968 (change +0.070, 95% confidence interval 0.052-0.092), with a continuous net reclassification improvement of 1.56 and an integrated discrimination improvement of 22% (p<0.001). Decision curve analysis showed that a strategy of referral to coronary angiography based on ExEcho was associated with the highest net benefit and with the largest reduction in unnecessary coronary angiographies.

CONCLUSION

ExEcho provides significant incremental prognostic information and higher net clinical benefit than a strategy based on ExECG in patients referred to a chest pain unit for suspected ACS and negative troponin levels.

Need for a standardized protocol for stress echocardiography in provoking subaortic and valvular gradient in various cardiac conditions

(Semi) supine exercise testing has an established role in the evaluation of patients with valvular heart disease and can help clinical decision making. Stress echocardiography has the advantages of its wide availability, low cost, and versatility for the assessment of disease severity. However, exercise-induced changes in valve hemodynamics, left ventricular outflow obstruction and pulmonary artery pressure depended on load variation. Changing position from supine to upright rapidly decreases load conditions for the ventricles. Therefore several cardiac centers have proposed exercise stress echocardiography in the upright position with gradient monitoring sometimes also in post-exercise recovery. Doppler measurement of subaortic gradient has been a very helpful and informative examination in several heart diseases (especially in hypertrophic cardiomyopathy, valve heart diseases, prosthesis dysfunction).

Clinical applications of exercise stress echocardiography in the treadmill with upright evaluation during and after exercise

Exercise stress echocardiography is the most frequently used stress test in our laboratory. Exercise echocardiography is used mainly in the study of patients with coronary artery disease. However, the technique is increasingly being used to study other diseases. In our centre, we use an original methodology, published by us in 2000, in which we evaluate heart function during exercise in the treadmill. After the exercise, patients are maintained in orthostatic position when appropriate or lying down in left lateral decubitus for further evaluation. Since this method seems to increase the quality and the quantity of information obtained in so many clinical arenas, we now present a detailed review of this methodology and its applications.

Impact of electrocardiographic interpretability on outcome in patients referred for stress testing

BACKGROUND

There is limited insight into the association of electrocardiographic interpretability with outcome in patients referred for stress testing.

METHODS

Exercise echocardiography was performed in 8226 patients with known or suspected coronary artery disease. Electrocardiograms were considered uninterpretable in the presence of left bundle-branch block (LBBB), left ventricular hypertrophy (LVH) with strain, repolarization abnormalities because of digitalis therapy, ventricular paced rhythm, preexcitation or ST depression ≥ 0.1 mV because of other causes. End points were all-cause mortality, cardiac death and hard cardiac events (i.e. cardiac death or nonfatal myocardial infarction).

RESULTS

A total of 2450 patients had uninterpretable electrocardiograms. During a follow-up period of 4.1 ± 3.5 years, there were 1011 deaths (of which 478 were cardiac deaths) and 1069 patients experienced a hard cardiac event. The 5-year rates of death, cardiac death and hard cardiac events were, respectively, 18.7%, 10.9% and 18.8% in patients with uninterpretable ECGs, compared with 9.5%, 4.1% and 10.9% in those with interpretable ECGs (P < 0.001). After covariate adjustment, lack of ECG interpretability remained an independent predictor of all-cause mortality (hazard ratio [HR] 1.25, 95% confidence interval [CI] 1.08-1.44, P = 0.002), cardiac death (HR 1.63, 95% CI 1.32-2.01, P < 0.001) and hard cardiac events (HR 1.28, 95% CI 1.11-1.47, P < 0.001). When the specific ECG abnormalities were included as covariates, LBBB, LVH and digitalis therapy remained predictors of cardiac death; LBBB and LVH were predictors of hard cardiac events, and LVH remained predictive of all-cause mortality.

CONCLUSION

Uninterpretable ECGs portend a worse prognosis in patients referred for stress testing.

Recent advances in stress echocardiography

PURPOSE OF REVIEW

This article reviews the recent advances in stress echocardiography, with particular attention to articles published in 2010 and 2011. It summarizes the developments in the diagnostic and prognostic capabilities of stress echocardiography, discusses new data regarding the safety of stress echocardiography, and highlights emerging roles for stress echocardiography in the areas of left ventricular assist devices, cardiac transplantation, strain-rate echocardiography, and myocardial perfusion imaging.

RECENT FINDINGS

Stress echocardiography represents a well validated tool in the diagnosis and assessment of patients with known or suspected coronary artery disease. Recently, data have emerged supporting the prognostic capabilities of stress echocardiography in patients with various levels of systolic dysfunction, diastolic abnormalities, and valvular heart disease. New studies continue to document the safety of stress echocardiography, particularly with regard to arrhythmias, neuropsychiatric symptoms, dosing of dobutamine, and intravenous contrast. Studies are now suggesting that stress echocardiography may play novel roles in the evaluation of patients with left ventricular assist devices or potential donors for cardiac transplantation. Technologic developments in myocardial contrast perfusion imaging, three-dimensional imaging, and strain-rate echocardiography will continue to advance the field.

SUMMARY

Stress echocardiography represents a dynamic, versatile, and well validated tool for the noninvasive assessment of patients with a wide spectrum of cardiovascular diseases.

Detection of prolonged regional myocardial systolic dysfunction after exercise-induced myocardial ischemia by strain echocardiography with high frame rate tissue Doppler echocardiography

BACKGROUND

Strain echocardiography has enabled quantification of regional myocardial systolic function objectively and is less influenced by tethering effects and cardiac translational artifact than Doppler tissue imaging. Although strain echocardiography has been applied for the detection of inducible ischemia during dobutamine stress, it has not been fully applied to exercise stress echocardiography (ESE) because of technical difficulties. Prolonged myocardial systolic dysfunction after exercise-induced ischemia has been shown previously. Thus, we designed this study to evaluate whether the myocardial strain analysis can detect myocardial ischemia by the assessment of prolonged regional left ventricular (LV) dysfunction in ESE.

METHODS

We performed ESE with myocardial strain imaging system in 20 consecutive patients who had exercise Tl-201 single photon emission computed tomography (SPECT). Myocardial strain curves were obtained at six segments in mid LV walls from the apical approach before and 5 min after ESE. We measured the duration from the R wave in the electrocardiogram to the timing of peak systolic strain corrected by the square root of the RR interval (TPSc). We finally calculated the differences of TPSc (ΔTPSc) before ESE and 5 min after ESE. The results were compared with SPECT as a reference standard.

RESULTS

A receiver operating characteristic curve demonstrated that a ΔTPSc cutoff value of 70 ms had a sensitivity of 80% and a specificity of 84% for the detection of myocardial ischemia.

CONCLUSIONS

Prolonged regional LV systolic dysfunction assessed by ESE with strain analysis was useful for the detection of myocardial ischemia.

Value of exercise echocardiography for predicting mortality in elderly patients

BACKGROUND

Elderly patients with suspected or known coronary artery disease are often referred for pharmacological stress testing. Data on the value of exercise echocardiography (ExEcho) for predicting outcome (particularly all-cause mortality) in these patients are scarce.

METHODS

Peak treadmill ExEcho was performed in 2159 patients ≥ 70 years of age with known or suspected coronary artery disease. Left ventricular wall motion was evaluated at baseline and with exercise, and the increase in wall motion score index from rest to peak exercise (ΔWMSI) was calculated. Ischaemia was diagnosed when new or worsening wall motion abnormalities developed with exercise. The end points were all-cause mortality and major cardiac events (cardiac death or myocardial infarction).

RESULTS

Ischaemia developed in 844 patients (38·6%) during exercise. Over a mean follow-up of 3·5 ± 3·1 years, 439 deaths occurred. The cumulative 5-year mortality rate was 29·3% in patients with ischaemia versus 16·8% in those without ischaemia (P < 0·001). After covariate adjustment, ΔWMSI remained an independent predictor of mortality [hazard ratio (HR) 2·37, 95% confidence interval (CI) 1·66-3·39, P < 0·001] and major cardiac events (HR 3·48, 95% CI 2·11-5·74, P < 0·001). These results remained significant even in patients with chronotropic incompetence. When added to a model with clinical, resting echocardiographic and exercise electrocardiogram variables, ExEcho results provided incremental value for the prediction of both end points (P < 0·001).

CONCLUSIONS

ExEcho is feasible in elderly patients with suspected or known coronary artery disease and provides useful information for risk stratification in these patients.

Exercise echocardiography

Exercise echocardiography has been used for 30 years. It is now considered a consolidated technique for the diagnosis and risk stratification of patients with known or suspected coronary artery disease (CAD). Of the stress echocardiography techniques, it represents the first choice for patients who are able to exercise. Given that the cost-effectiveness and safety of stress echocardiography are higher than those of other imaging techniques, its use is likely to be expanded further. Recent research has also proposed this technique for the evaluation of cardiac pathology beyond CAD. Although the role of new technology is promising, the assessment of cardiac function relies on good quality black and white harmonic images.

Prognostic value of exercise echocardiography in patients with atrial fibrillation

AIMS

Non-invasive imaging techniques for the detection of coronary artery disease (CAD) may have technical problems in patients with atrial fibrillation (AF). Although the prognostic value of exercise echocardiography (ExEcho) has been well established in several subgroups of patients, it has not yet been specifically evaluated in these patients.

METHODS AND RESULTS

From a population of 8095 patients with known or suspected CAD referred for ExEcho, 419 had AF at the time of the tests. Ischaemia was defined as the development of new or worsening wall motion abnormalities with exercise. Endpoints were hard cardiac events (i.e. cardiac death or non-fatal myocardial infarction). Mean age was 68.4 +/- 8.5 years, and 256 patients (61.1%) were men. Ischaemia was detected in 92 patients (22%). Over a mean follow-up of 3.10 +/- 2.98 years, 59 hard cardiac events occurred. The 5-year hard cardiac event rate was 37.3% in patients with ischaemia, when compared with 14.5% in patients without ischaemia (P < 0.001). In multivariate analysis, ischaemia on ExEcho remained an independent predictor of hard cardiac events (hazard ratio 1.99, 95% confidence interval 1.06-3.74, P = 0.03), and also provided incremental value over clinical, resting echocardiographic and treadmill exercise data for the prediction of hard cardiac events (P = 0.04).

CONCLUSION

ExEcho provides significant prognostic information for predicting hard cardiac events in patients with AF.

Prognostic value of peak and post-exercise treadmill exercise echocardiography in patients with known or suspected coronary artery disease

AIMS

Although peak may have higher sensitivity than post-treadmill exercise echocardiography (EE) for the detection of coronary artery disease (CAD), its prognostic value remains unknown. We sought to assess the relative values of peak and post-EE for predicting outcome in patients with known/suspected CAD.

METHODS AND RESULTS

We studied 2947 patients who underwent EE. Wall motion score index (WMSI) was evaluated at rest, peak, and post-exercise. Ischaemia was defined as the development of new or worsening wall motion abnormalities with exercise. Separate analyses for all-cause mortality and major cardiac events (MACE) were performed. Ischaemia developed in 544 patients (18.5%). Among them, ischaemia was detected only at peak exercise in 124 patients (23%), whereas 414 (76%) had ischaemia at peak plus post-exercise imaging and six patients (1%) had ischaemia only at post-exercise. During follow-up, 164 patients died. The 5-year mortality rate was 3.5% in patients without ischaemia, 15.3% in patients with peak ischaemia alone, and 14% in patients with post-exercise ischaemia (P < 0.001 normal vs. ischaemic groups). In the multivariate analysis, post-exercise WMSI was an independent predictor of MACE [hazard ratio (HR) 1.87, 95% confidence interval (CI) 1.09-2.19, P = 0.02]. Peak exercise WMSI was an independent predictor of MACE (HR 2.19, 95% CI 1.30-3.69, P = 0.003) and mortality (HR 1.58, 95% CI 1.07-2.35, P = 0.02). The addition of peak EE results to clinical, resting echocardiography, exercise variables, and post-EE provided incremental prognostic information for MACE (P = 0.04) and mortality (P = 0.04).

CONCLUSION

Peak treadmill EE provides significant incremental information over post-EE for predicting outcome in patients with known or suspected CAD.

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.

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.

Prognostic value of exercise echocardiography in patients with diabetes mellitus and known or suspected coronary artery disease

To assess the prognostic value of exercise echocardiography in subjects who had diabetes, we studied 214 patients who had 28 hard cardiac events (cardiac death in 15, myocardial infarction in 13) during a follow-up of 44 +/- 16 months. Independent risk factors for predicting cardiac events were insulin therapy (odds ratio 2.313), peak left ventricular ejection fraction (odds ratio 0.973), and ischemia detected by exercise echocardiography (odds ratio 2.513).

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.

Exercise echocardiography with addition of atropine

Exercise echocardiography with the addition of atropine was performed in 31 patients who had a very small probability of achieving submaximal heart rate. Conclusive tests were obtained in 77% of the patients with this protocol.

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.

Comparison of exercise echocardiography to exercise electrocardiographic testing added to echocardiography at rest for risk stratification after uncomplicated acute myocardial infarction

Recommendations for risk assessment after acute myocardial infarction (AMI) include electrocardiographic (ECG) exercise testing. We hypothesized that a more sensitive technique, exercise echocardiography (EE), would refer a greater number of patients to invasive procedures. Therefore, we compared a strategy based on EE with a strategy based on ECG exercise testing for patients with uncomplicated AMI. A series of 164 patients referred for exercise testing after AMI were randomized to treadmill EE (strategy 2) or baseline echocardiography and ECG treadmill exercise testing (strategy 1). Ischemic response was more frequently detected with strategy 2 (59% vs 27%, p <0.001), and consequently angiography and revascularization procedures were more commonly performed (59 vs 32 procedures, p <0.01 and 46 vs 19 procedures, p <0.001, respectively). Fourteen percent and 15% of patients experienced soft events (unstable angina, heart failure, or late revascularization) after strategy 1 and strategy 2, respectively (p = NS); 6% and 9% of patients had hard events (nonfatal AMI or cardiovascular death) at follow-up (p = NS). In conclusion, a strategy based on EE detected more patients with ischemia; therefore, more patients were submitted to coronary angiography and revascularization procedures. No differences were detected in cardiac events when we compared this strategy with the less expensive ECG exercise testing after uncomplicated AMI.

[Exercise echocardiography to differentiate dilated cardiomyopathy from ischemic left ventricular dysfunction]

OBJECTIVES

Previous studies have shown the usefulness of dobutamine echocardiography to differentiate dilated cardiomyopathy (DC) from ischemic left ventricular dysfunction (ILVD), but no studies have been made using exercise echocardiography (EE). We hypothesized that most patients with DC have some contractile reserve and experience an increase in left ventricular ejection fraction (LVEF) during exercise, as opposed to patients with ILVD. Differences in response to EE may be useful to clinically differentiate between these two entities.

PATIENTS AND METHOD

Between 1 March 1995 and 1 March 2001, we performed 4,133 EE studies on 3,830 patients. Of 289 patients (8%) with moderate or severe LV dysfunction (biplane LVEF < 41% and left ventricular end-diastolic diameter > 5.2 cm), 207 were excluded: 111 for a history of myocardial infarction; 28 for scarring on echocardiography (regional akinesia/dyskinesia with thinning and/or increased brightness); 13 for previous revascularization procedures; 9 for aortic valve disease; 11 for a known cause of cardiomyopathy; and 35 for not undergoing angiography. The study group was therefore composed of 82 patients who were encouraged to perform maximal treadmill EE. EE criteria for ILVD were either impaired regional wall motion (RWM) or a decrease/no change in LVEF from baseline to peak exercise, while criteria for DC were RWM improvement/no change and LVEF increase. The ILVD group was formed by 39 patients with stenosis >/= 70% diameter stenosis of a major epicardial coronary artery or major branch vessel. The remaining 43 patients constituted the DC group.

RESULTS

The number of coronary risk factors (ILVD 2.0 1.1; DC 1.9 1.1), baseline LVEF (ILVD 30 7; DC 30 8), and exercise-induced angina (ILVD 23%; DC 14%) did not differ between groups (p = NS). ILVD patients achieved less Mets (6.6 3.1 vs 8.3 2.8; p < 0.05), had a lower heart rate x systolic blood pressure product (22 5 vs 27 7; p < 0.001), and developed regional and/or global LV dysfunction more frequently (79 vs 28%; p < 0.001). Sensitivity, specificity, positive and negative predictive values and global accuracy for ILVD detection were 79% (95% CI: 70-88), 72% (95% CI: 63-81), 72% (95% CI: 63-81), 79% (95% CI: 67-85), and 76% (95% CI: 69-83), respectively.

CONCLUSION

Global and/or regional LV function impairment with exercise is accurate in identifying patients with ILVD. This method could reduce the need for invasive procedures.

[Physiologic evaluation of coronary circulation. Role of invasive and non invasive techniques]

For many years, the evaluation of the extent and severity of coronary artery disease has been mainly anatomical, carried out by coronary angiography. However, this technique has methodological limitations and interobserver variability is considerable. Quantification of coronary reserve with pressure guidewires and intracoronary Doppler now provides more precise physiologic evaluation of coronary circulation. Myocardial perfusion single proton emission computed tomography and echocardiography, combined with stress and/or pharmacological challenge testing, though they are only semiquantitative techniques, also offer appropriate complements to coronary angiography in the functional evaluation of coronary patients. The aim of this paper is to discuss the clinical value of these techniques.

Postexercise left ventricular function: a comparative assessment by different noninvasive imaging modalities

The variety of noninvasive imaging modalities now available permits assessment of different aspects of left ventricular function in the postexercise state. Some of these modalities, such as first-pass radionuclide ventriculography, permit a nearly instantaneous assessment of left ventricular function in the early postexercise state. These modalities indicate that most exercise-induced left ventricular wall motion abnormalities resolve quickly after exercise. Resting wall motion abnormalities may also improve in the postexercise period; this response indicates the presence of hibernating myocardium capable of improving in response to myocardial revascularization procedures. On the other hand, all imaging techniques indicate that a certain percentage of exercise-induced wall motion abnormalities may persist into the postexercise period, and this finding signifies that severe coronary disease subtends the region of persisting wall motion abnormality. Further, if there is increased left ventricular size after exercise, both extensive and severe coronary disease are present. A conceptual framework for unifying these disparate findings is provided. These results underscore the importance of postexercise imaging in enhancing clinical assessment and imply that there are important technical considerations to contemplate when performing certain tests such as postexercise echocardiography.