Effect of Time Delay on the Diagnostic Use of Contrast Echocardiography in Patients Presenting to the Emergency Department with Chest Pain and no S-T Segment Elevation

Prognostic value of resting myocardial contrast echocardiography: a meta-analysis

BACKGROUND

Resting myocardial perfusion (MP) and wall motion (WM) imaging during real time myocardial contrast echocardiography (MCE) improves the detection of coronary artery disease (CAD). However, its prognostic role in different clinical settings (emergency department and outpatient setting) remains unclear.

METHODS

A systematic search in PubMed and Embase databases, and the Cochrane library, was conducted to evaluate the role of resting MP and WM in predicting major adverse cardiac events (MACE), including death, nonfatal myocardial infarction (NFMI) and urgent revascularization in patients presenting to either outpatient clinics or emergency departments with suspected symptomatic CAD. Summary receiver operating characteristic (SROC) curves, sensitivity and specificity plots were applied to assess diagnostic performance using RevMan 5.3.

RESULTS

Seven studies met criteria, including 3668 patients (six with follow up ranging from two days to 2.6 years). The relative risk (RR) for predicting MACE in patients with both abnormal resting MP and WM was 6.1 (95% CI, 5.1-7.2) and 14.3 (95% CI, 10.3-19.8) for death/NFMI, when compared to normal resting MP and WM patients. Having both abnormal resting MP and WM was also more predictive of MACE (RR 1.7; 95% CI 1.5-1.9) and death/NFMI (RR, 2.2; 95% CI, 1.8-2.7) when compared to abnormal WM with normal resting MP.

CONCLUSION

In this meta-analysis of both ED and outpatient clinic presentations for suspected CAD, having both a resting regional MP and WM abnormality identifies the highest risk patient for adverse events.

Noninvasive cardiac imaging in suspected acute coronary syndrome

Noninvasive cardiac imaging has an important role in the assessment of patients with acute-onset chest pain. In patients with suspected acute coronary syndrome (ACS), cardiac imaging offers incremental value over routine clinical assessment, the electrocardiogram, and blood biomarkers of myocardial injury, to confirm or refute the diagnosis of coronary artery disease and to assess future cardiovascular risk. This Review covers the current guidelines and clinical use of the common noninvasive imaging techniques, including echocardiography and stress echocardiography, computed tomography coronary angiography, myocardial perfusion scintigraphy, positron emission tomography, and cardiovascular magnetic resonance imaging, in patients with suspected ACS, and provides an update on the developments in noninvasive imaging techniques in the past 5 years.

Patient outcome following 2 different stress imaging approaches: a prospective randomized comparison

OBJECTIVES

The study sought to prospectively compare patient outcome after stress real-time myocardial contrast echocardiography (RTMCE) versus conventional stress echo (CSE), where contrast is used to optimize wall motion (WM) analysis.

BACKGROUND

Myocardial perfusion imaging with RTMCE may improve the detection of coronary artery disease (CAD), and predict patient outcome.

METHODS

Patients with intermediate to high pre-test probability referred for dobutamine or exercise stress echocardiography were prospectively randomized to either RTMCE or CSE. Definity contrast was used for CSE only when endocardial border delineation was inadequate (63% of studies). Studies were interpreted by either an experienced contrast reviewer (R1; n = 1257), or 4 Level 3 echocardiographers (R2) with basic contrast training (n = 806). Death, nonfatal myocardial infarction (MI), and revascularizations were recorded at follow-up.

RESULTS

Follow-up was available in 2,014 patients (median 2.6 years). Mean age was 59 ± 13 years (53% women). An abnormal RTMCE was more frequently observed than an abnormal CSE (p < 0.001), and more frequently resulted in revascularization (p = 0.004). Resting WM abnormalities were also more frequently seen with RTMCE (p < 0.01), and were an independent predictor of death/nonfatal MI (p = 0.005) for RTMCE, but not CSE. The predictive value of a positive study, whether with CSE or RTMCE, was significant for both R1 and R2 reviewers in predicting the combined endpoint, but R1 was better than R2 at predicting patients at risk for death or nonfatal MI.

CONCLUSIONS

Perfusion imaging with RTMCE improves the detection of CAD during stress echocardiography, and identifies those more likely to undergo revascularization following an abnormal study.

Prognostic value of real time dobutamine stress myocardial contrast echocardiography in patients with chest pain syndrome

The aims of this study were (1) to evaluate the prognostic value of negative wall motion (WM) and myocardial perfusion during contrast-dobutamine stress echocardiography (DSE), (2) to determine whether WM-myocardial contrast echocardiography (MCE) had incremental prognostic value over just WM during DSE in patients with chest pain in the emergency room (ER), and (3) to compare the prognostic value of negative DSE-WM, and DSE-WM-MCE to nuclear-myocardial perfusion imaging (N-MPI) in a similar patient population over the same time period. We retrospectively studied 569 patients with real time contrast DSE, and 147 patients underwent N-MPI for evaluation of chest pain. Follow-up for cardiac events was obtained between 12 and 25 months. The cumulative cardiac event-free survival was 94.5% in negative DSE-WM, 97.1% in negative DSE-WM-MCE and 96.7% in negative N-MPI group. Cardiac event-free survival of the negative DSE-WM-MCE group was significantly higher than the DSE-WM group (log rank P < 0.01), and similar in the DSE-WM-MCE group compared to the N-MPI group. Combined WM and perfusion during DSE was the strongest independent predictor for cardiac events. The negative predictive power of DSE-WM-MCE is superior to that of just negative DSE-WM and is comparable to that of N-MPI. Myocardial perfusion and WM analysis during DSE provide independent information for predicting cardiac events in patients with chest pain syndrome in the ER.

A predictive instrument using contrast echocardiography in patients presenting to the emergency department with chest pain and without ST-segment elevation

OBJECTIVE

Risk stratification of patients presenting to the emergency department (ED) with suspected cardiac chest pain (CP) and an undifferentiated electrocardiogram (ECG) is difficult. We hypothesized that in these patients a risk score incorporating clinical, ECG, and myocardial contrast echocardiography (MCE) variables would accurately predict adverse events occurring within the next 48 hours.

METHODS

Patients with CP lasting for 30 minutes or more who did not have ST-segment elevation on the ECG, were enrolled. Regional function (RF) and myocardial perfusion (MP) were assessed by MCE. A risk model was developed in the initial 1166 patients (cohort 1) and validated in subsequent 720 patients (cohort 2). Any abnormality or ST changes on ECG (odds ratio [OR] 2.5; 95% confidence interval [CI], 1.4-4.5, P = .002, and OR 2.9, 95% CI, 1.7-4.8, P < .001, respectively), abnormal RF with normal MP (OR 3.5, 95% CI, 1.8-6.5, P < .001), and abnormal RF with abnormal MP (OR 9.6, 95% CI, 5.8-16.0, P < .001) were found to be significant multivariate predictors of nonfatal myocardial infarction or cardiac death.

RESULTS

The estimate of the probability of concordance for the risk model was 0.82 for cohort 1 and 0.83 for cohort 2. The risk score in both cohorts stratified patients into 5 distinct risk groups with event rates ranging from 0.3% to 58%.

CONCLUSION

A simple predictive instrument has been developed from clinical, ECG, and MCE findings obtained at the bedside that can accurately predict events occurring within 48 hours in patients presenting to the ED with suspected cardiac CP and an ECG that is not diagnostic for acute ischemic injury. Its application could enhance care of patients with CP in the ED. For instance, patients with a risk score of 0 could be discharged from the ED without further workup. However, this needs to be validated in a multicenter study.

Cost-efficiency of myocardial contrast echocardiography in patients presenting to the emergency department with chest pain of suspected cardiac origin and a nondiagnostic electrocardiogram

Assessment of patients presenting to the emergency department (ED) with suspected cardiac chest pain and a nondiagnostic electrocardiogram (ECG) is lengthy and costly. It was hypothesized that myocardial contrast echocardiography (MCE) can be cost-efficient in such patients by detecting those with chest pain that is noncardiac in nature. Accordingly, cost-efficiency was evaluated in 957 patients presenting to the ED with suspected cardiac chest pain, but no ST-segment elevation on the ECG, who underwent MCE. Economic outcome calculations were based on costs estimated from national average Medicare charges adjusted by a cost-charge ratio. Based on routine clinical criteria, 641 patients (67%) were admitted to the hospital, whereas 316 (33%) were discharged directly from the ED. The average cost per patient using routine evaluation was $5,000. Patients with normal MCE results (n = 523) had a very low primary event rate (death, acute myocardial infarction) of 0.6% within 24 hours after presentation, making it relatively safe to discharge patients directly from the ED with a normal MCE result. Hence, if MCE had been used for decision making, 523 patients (55%) would have been discharged directly from the ED and 434 (45%) would have been admitted to the hospital. Preventing unnecessary admissions and tests would have saved an average of $900 per patient, in addition to reducing their ED stay. In conclusion, by excluding cardiac causes in patients presenting to the ED with chest pain and a nondiagnostic ECG, MCE can prevent unnecessary admissions and downstream resource utilization, making it a cost-efficient tool in the evaluation of these patients.

Contrast ultrasound in the assessment of patients presenting with suspected cardiac ischemia

Echocardiography is a portable technology that can be used to assess myocardial, pericardial, and valvular structure and function. Doppler echocardiography provides the ability to evaluate blood flow in large vessels and within cardiac chambers. Recently, the advent of microbubble contrast agents, which can opacify the systemic circulation, has improved the ability of echocardiography to evaluate left-ventricular function by improving delineation of the left-ventricular endocardial border. Furthermore, these microbubbles can be used to assess myocardial perfusion and quantify myocardial blood flow. Myocardial contrast echocardiography has been studied in multiple clinical situations, including the acute evaluation of patients presenting with suspected cardiac ischemia. Ongoing research is focused on the development of microbubbles that are capable of detecting molecular and cellular events within the circulation, which may allow distinction of acute vs. remote ischemic insults to the myocardium. This multifaceted technology promises to be of increasing clinical utility--not only for the heart, but for any organ accessible to ultrasound.