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

[The Clinical use of Stress Echocardiography in Ischemic Heart Disease Cardiovascular Ultrasound (2017)15:7. Translation authors: Arystan A.Zh., Fettser D.V.]

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows detecting myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependence on operator expertise, the lack of outcome data (a widespread problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

The clinical use of stress echocardiography in ischemic heart disease

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows to detect myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician.

The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependance on operator expertise, the lack of outcome data (a widesperad problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

Prognostic value of myocardial ischemic electrocardiographic response in patients with normal stress echocardiographic study

The prognostic value of ST-segment depression on exercise electrocardiogram (eECG) in the setting of a normal wall motion response in a stress echocardiographic study is not well defined. The aim of the study was to compare outcomes among patients with normal wall motion during stress echocardiography with and without ischemic exercise electrocardiographic changes. A total of 4,233 patients underwent stress echocardiography from 2007 to 2010. The primary outcomes were a composite of all-cause mortality and myocardial infarction. Coronary revascularization was a secondary outcome. A Cox regression model was used for the primary analysis. Ischemic exercise electrocardiographic changes were defined as ST-segment depression of at least 1 mm, on at least 3 consecutive beats, and in at least 2 contiguous leads. A normal stress echocardiogram was present in 2,975 patients; of them, 2,228 (74%) had a normal eECG and 747 (26%) had ischemic changes on eECG. Patients with and without ischemic changes during exercise electrocardiography were similar in age and gender. At 4-years follow-up, 36 patients (2.8%) with a normal eECG experienced a primary end point versus 12 patients (1.9%) in the group with an ischemic exercise electrocardiographic response (p = 0.56). The rate of coronary revascularization was similar between the groups (7.0% and 5.7%, respectively, p = 0.2). There were no differences in the primary outcomes of patients with and without exercise electrocardiographic changes and normal stress echocardiogram (hazard ratio 1.33, 95% confidence interval 0.69 to 2.58). In conclusion, a normal wall motion response even in the setting of an ischemic exercise electrocardiographic response portends a benign prognosis in patients undergoing stress echocardiography.

How to identify the asymptomatic high-risk patient?

Worldwide, cardiovascular diseases are among the leading causes of mortality and morbidity with ever-increasing prevalence. Early targeted initiation of preventive measures would be of great benefit and can provide a major opportunity in reducing mortality and morbidity. To this end, accurate identification of individuals who are still asymptomatic but at elevated risk is essential. However, traditional risk assessment fails to recognize a substantial proportion of patients at high risk while a large proportion of individuals are classified as having intermediate risk, leaving management uncertain. Additional strategies to further refine risk assessment are therefore highly needed. To this end, the use of biomarkers and noninvasive imaging modalities has been proposed. The aim of this review is to provide an overview of the different approaches that are available or under development to improve the identification of asymptomatic individuals at elevated risk for cardiovascular diseases events.

Stress echocardiography expert consensus statement: European Association of Echocardiography (EAE) (a registered branch of the ESC)

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. Among different stresses of comparable diagnostic and prognostic accuracy, semisupine exercise is the most used, dobutamine the best test for viability, and dipyridamole the safest and simplest pharmacological stress and the most suitable for combined wall motion coronary flow reserve assessment. The additional clinical benefit of myocardial perfusion contrast echocardiography and myocardial velocity imaging has been inconsistent to date, whereas the potential of adding - coronary flow reserve evaluation of left anterior descending coronary artery by transthoracic Doppler echocardiography adds another potentially important dimension to stress echocardiography. New emerging fields of application taking advantage from the versatility of the technique are Doppler stress echo in valvular heart disease and in dilated cardiomyopathy. In spite of its dependence upon operator's training, stress echocardiography is today the best (most cost-effective and risk-effective) possible imaging choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

In search of the false-negative exercise treadmill testing evidence-based use of exercise echocardiography

BACKGROUND

Controversy exists regarding the role of exercise treadmill testing (ETT) versus exercise stress echocardiography (ESE) as the appropriate initial noninvasive test to risk-stratify patients with chest pain. The majority of studies to date that evaluated these methodologies included patients with poor functional status and baseline electrocardiogram (ECG) abnormalities, potentially limiting the sensitivity of ETT.

HYPOTHESIS

We examined the hypothesis that given stringent standards of exercise duration and ECG interpretability, the ETT would have a high diagnostic sensitivity for the presence of significant coronary artery disease (CAD).

METHODS

Results of concurrent ETT and ESE in 3,098 patients were examined, and the subset of patients with a negative ETT and positive ESE (-ETT/ + ESE) were reviewed for the presence of CAD as a function of exercise duration (< or > or = 6 min) and baseline ECG normality.

RESULTS

In those patients with a - ETT/ + ESE who exercised > or = 6 min, 54 had a normal baseline ECG, 22 underwent angiography and 6 had CAD (all of whom had either small, grafted or collateralized vessels). Patients with a - ETT/ + ESE who were incapable of exercising 6 min were more frequently older and female. Mortality was significantly greater in the < 6 min exercise duration group (31.4 versus 3.1%).

CONCLUSIONS

These findings support the use of the ETT without imaging as the initial test in patients with chest pain who have a normal baseline ECG and are able to exercise 6 min. Using these criteria, false negative findings are generally seen in patients without critical large vessel epicardial disease. The ESE should be reserved as the initial test for patients with an abnormal baseline ECG or reduced functional capacity.

Reliability and validity of the combined heart rate and movement sensor Actiheart

Accurate quantification of physical activity energy expenditure is a key part of the effort to understand disorders of energy metabolism. The Actiheart, a combined heart rate (HR) and movement sensor, is designed to assess physical activity in populations.

OBJECTIVE

To examine aspects of Actiheart reliability and validity in mechanical settings and during walking and running.

METHODS

In eight Actiheart units, technical reliability (coefficients of variation, CV) and validity for movement were assessed with sinusoid accelerations (0.1-20 m/s(2)) and for HR by simulated R-wave impulses (25-250 bpm). Agreement between Actiheart and ECG was determined during rest and treadmill locomotion (3.2-12.1 km/h). Walking and running intensity (in J/min/kg) was assessed with indirect calorimetry in 11 men and nine women (26-50 y, 20-29 kg/m(2)) and modelled from movement, HR, and movement + HR by multiple linear regression, adjusting for sex.

RESULTS

Median intrainstrument CV was 0.5 and 0.03% for movement and HR, respectively. Corresponding interinstrument CV values were 5.7 and 0.03% with some evidence of heteroscedasticity for movement. The linear relationship between movement and acceleration was strong (R(2) = 0.99, P < 0.001). Simulated R-waves were detected within 1 bpm from 30 to 250 bpm. The 95% limits of agreement between Actiheart and ECG were -4.2 to 4.3 bpm. Correlations with intensity were generally high (R(2) > 0.84, P < 0.001) but significantly highest when combining HR and movement (SEE < 1 MET).

CONCLUSIONS

The Actiheart is technically reliable and valid. Walking and running intensity may be estimated accurately but further studies are needed to assess validity in other activities and during free-living.

SPONSORSHIP

The study received financial support from the Wellcome Trust and SB was supported by a scholarship from Unilever, UK.

Stress Echocardiography

Stress echocardiography is commonly employed for the clinical management of known or suspected coronary artery disease. This review discusses the accuracy of the technique, which is equivalent to that of competing imaging techniques, as well as its overall role in patient management. The utilization of stress echocardiographic modalities in clinical presentations, such as chest pain, congestive heart failure, and valvular heart disease, and preoperative risk assessment, as well as determining myocardial viability, are discussed.

A clinical and echocardiographic score for assigning risk of major events after dobutamine echocardiograms

OBJECTIVES

We sought to develop and validate a risk score combining both clinical and dobutamine echocardiographic (DbE) features in 4890 patients who underwent DbE at three expert laboratories and were followed for death or myocardial infarction for up to five years.

BACKGROUND

In contrast to exercise scores, no score exists to combine clinical, stress, and echocardiographic findings with DbE.

METHODS

Dobutamine echocardiography was performed for evaluation of known or suspected coronary artery disease in 3156 patients at two sites in the U.S. After exclusion of patients with incomplete follow-up, 1456 DbEs were randomly selected to develop a multivariate model for prediction of events. After simplification of each model for clinical use, the models were internally validated in the remaining DbE patients in the same series and externally validated in 1733 patients in an independent series.

RESULTS

The following score was derived from regression models in the modeling group (160 events): DbE risk = (age.0.02) + (heart failure + rate-pressure product <15000).0.4 + (ischemia + scar).0.6. The presence of each variable was scored as 1 and its absence scored as 0, except for age (continuous variable). Using cutoff values of 1.2 and 2.6, patients were classified into groups with five-year event-free survivals >95%, 75% to 95%, and <75%. Application of the score in the internal validation group (265 events) gave equivalent results, as did its application in the external validation group (494 events, C index = 0.72).

CONCLUSIONS

A risk score based on clinical and echocardiographic data may be used to quantify the risk of events in patients undergoing DbE.