Are intraventricular gradients a cause of false positive treadmill exercise tests

Background: Treadmill exercise testing has low specificity for the detection of significant epicardial coronary artery disease (CAD). A possible mechanism to explain some of the false positives is transient subendocardial ischemia induced by intraventricular gradients (IVG) during stress. The development of IVG during dobutamine stress echocardiography (DSE) occurs in 8-38% of non-selected populations. Objectives: To determine: 1. the prevalence of IVG in a selected population of false positives on treadmill stress testing; 2. whether this prevalence is different from that described for non-selected populations; 3. whether patient characteristics are related to the presence of IVG; 4. the relation between the presence of IVG and the occurrence of ECG abnormalities, symptoms and blood pressure. Methods and Results: We evaluated 50 consecutive patients with false positive treadmill stress tests (normal CT coronary angiography, nuclear perfusion tests or angiography) with DSE (2D and Doppler evaluation). All DSE exams were negative for ischemia. Stress-induced IVG was seen in 34 of the 50 patients (68%) and 16 patients (32%) did not develop IVG (p 0.05). However, the presence of IVG was associated with the occurrence of ischemic ST depression during dobutamine stress echo (p < 0.05). Conclusions: 1. The prevalence of IVG during dobutamine stress echocardiography in a selected population of false positives on treadmill stress testing is very high, occurring in more than two-thirds of patients.