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

Clinical outcomes of discordant exercise electrocardiographic and echocardiographic findings compared with concordant findings in patients with chest pain and no history of coronary artery disease: An observational study

The aim of this study was to evaluate comparative clinical outcomes of discordant electrocardiographic (ECG) and echocardiographic (Echo) findings compared with concordant findings during treadmill exercise echocardiography in patients with chest pain and no history of coronary artery disease (CAD).A total of 1725 consecutive patients who underwent treadmill echocardiography with chest pain and no history of CAD were screened. The patients were classified into 4 groups: ECG-/Echo- (negative ECG and Echo), ECG+/Echo- (positive ECG and negative Echo), ECG-/Echo+, and ECG+/Echo+. Concomitant CAD was determined using coronary angiography or coronary computed tomography. Major adverse cardiac events (MACEs) were defined as a composite of coronary revascularization, acute myocardial infarction, and death.MACEs were similar between ECG-/Echo- and ECG+/Echo- groups. Compared with ECG+/Echo- group, ECG-/Echo+ group had more MACEs (adjusted hazard ratio [HR] adjusted by clinical risk factors [95% confidence interval {CI}], 3.57 [1.75-7.29], P < .001). Compared with ECG+/Echo+ group, ECG-/Echo+ group had lower prevalence of concomitant CAD and fewer MACEs (HR, 0.49 [0.29-0.81], P = .006).Positive exercise Echo alone during treadmill exercise echocardiography had worse clinical outcomes than positive ECG alone, and the latter had similar outcomes to both negative ECG and Echo. Positive exercise Echo alone also had better clinical outcomes than both positive ECG and Echo. Therefore, exercise Echo findings might be superior for predicting clinical outcomes compared with exercise ECG findings. Additional consideration of ECG findings on positive exercise Echo will also facilitate better prediction of clinical outcomes.

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.

"Hands-Free" continuous echocardiography during treadmill exercise using a novel ultrasound transducer

BACKGROUND

Echocardiographic imaging using a handheld transducer in conjunction with treadmill exercise testing is commonly used for the diagnosis of coronary artery disease. Motion of the hand and the transducer during peak exercise preclude optimal imaging. To circumvent the limitations of handheld transducers, we developed a low profile transducer (CONTISON) which can be attached to the chest wall for continuous cardiac imaging.

METHODS AND RESULTS

This feasibility study was performed in 10 normal male subjects (28 to 36 years). The ultrasound transducer was placed in the third or fourth intercostal space at the left sternal border to permit imaging of the left ventricle in its short axis. The transducer was interfaced with a commercially available ultrasound machine. The left ventricle was imaged at rest and while subjects exercised according to a standard Bruce protocol. All segments of the left ventricular short axis were seen at rest and peak exercise. Increased left ventricular wall thickening and wall motion were seen at peak exercise. There were no complications from the procedure.

CONCLUSION

We demonstrated the feasibility of hands-free left ventricular imaging during treadmill exercise using the CONTISON transducer. Further evaluation of the technique to detect stress-induced wall motion abnormalities, as a means of diagnosing myocardial ischemia, appears warranted. (ECHOCARDIOGRAPHY 2010;27:563-566).

Prediction of mortality and major cardiac events by exercise echocardiography in patients with normal exercise electrocardiographic testing

OBJECTIVES

We sought to assess the value of exercise echocardiography (EE) for predicting outcome in patients with known or suspected coronary artery disease and normal exercise electrocardiogram (ECG) testing.

BACKGROUND

The prognostic value of EE in patients with normal exercise ECG testing has not been characterized.

METHODS

We studied 4,004 consecutive patients (2,358 men, mean age [+/- SD] 59.6 +/- 12.5 years) with interpretable ECG who underwent treadmill EE and did not develop chest pain or ischemic ECG abnormalities during the tests. Wall motion score index (WMSI) was evaluated at rest and with exercise, and the difference (DeltaWMSI) was calculated. Ischemia was defined as the development of new or worsening wall motion abnormalities with exercise. End points were all-cause mortality and major cardiac events (MACE).

RESULTS

Overall, 669 patients (16.7%) developed ischemia with exercise. During a mean follow-up of 4.5 +/- 3.4 years, 313 patients died, and 183 patients had a MACE before any revascularization procedure. The 5-year mortality and MACE rates were 6.4% and 4.2% in patients without ischemia versus 12.1% and 10.1% in those with ischemia, respectively (p < 0.001). In the multivariate analysis, DeltaWMSI remained an independent predictor of mortality (hazard ratio [HR]: 2.73, 95% confidence interval [CI]: 1.40 to 5.32, p = 0.003) and MACE (HR: 3.59, 95% CI: 1.42 to 9.07, p = 0.007). The addition of the EE results to the clinical, resting echocardiographic and exercise hemodynamic data significantly increased the global chi-square of the models for the prediction of mortality (p = 0.005) and MACE (p = 0.009).

CONCLUSIONS

The use of EE provides significant prognostic information for predicting mortality and MACE in patients with interpretable ECG and normal exercise ECG testing.