Abstract 3573: In Search of the False-Negative ETT: Evidence-Based Use of the ESE
Introduction: Exercise stress echocardiography (ESE) is widely used in addition to exercise stress testing (ETT) because of its perceived greater sensitivity and specificity for the diagnosis of significant coronary artery disease (CAD). However, unnecessary use of the ESE in patients with a diagnostic ETT only serves to increase costs. We therefore tested the hypothesis that the ESE provides little incremental diagnostic yield over an ETT in patients with a normal baseline ECG who are able to exercise ≥6 min on a standard Bruce protocol.
Methods: We examined a database of 3129 consecutive patients exercising on a standard Bruce protocol with a diagnostic ESE and defined a group of patients with a negative ETT and a positive ESE (-ETT/+ESE, n = 128) who had subsequent angiographic definition of the presence or absence of CAD.
Results: Patients with a −ETT/+ESE who met the criteria for a normal resting ECG and good exercise tolerance (≥6 min) had a low prevalence of CAD (6/128, 4.7%), with these 6 patients having lesions in either small, collateralized, or grafted vessels. Results were similar irrespective of gender. Patients with a −ETT/+ESE who did not meet these criteria (i.e. either abnormal baseline ECG or inability to exercise 6 min despite reaching 85% MPHR) had a significantly higher incidence of CAD (23.5%, P < 0.05) and a higher mortality over an average 5 year follow-up (20.3% vs. 2.5%, P < 0.05). Patients that could not complete ≥6 minutes on the standard Bruce protocol were more likely to be older (64 vs. 53 years old, P<0.05) and female (68%, P<0.05) with hypertension and diabetes.
Conclusions: In male or female patients with a normal resting ECG and satisfactory exercise capacity (≥6 min), a negative ECG effectively excludes high-risk CAD. Conversely, low exercise capacity identifies a group of patients in whom the ETT can be falsely negative. Older female patients have an increased likelihood of not completing 6 minutes on a standard Bruce protocol and should be considered for ESE testing as the initial test. However, in the absence of poor exercise capacity and an abnormal baseline EKG, ESE provides minimal diagnostic yield above an ETT.