Abstract 85: Target Heart Rate Determinants, ECG and Echocardiographic Responses to Supine Bicycle Dobutamine Testing in Chest Pain Evaluation

Abstract

Background: We investigated the impact of the addition of supine bicycle exercise to standard dobutamine stress echocardiography in patients referred for evaluation of chest pain. Material and Methods: Results of 210 consecutive dobutamine stress echocardiographic tests with (SBDT group: 93 patients, 43% females, 61+/-12 years old) or without (DT group: 117 patients, 49% females, 57+/-12 years old) supine bicycle were reviewed. One patient was unable to perform supine bicycling and in one patient test was stopped due to hypertensive response. Analysis of variance (ANOVA), chi-square, and logistic regression analyses were used. Results: Supine bicycling was associated with increased double product (24838+/-5291 vs. 21936+/-5522 in DT, p<0.001), while test time (12+/-4 vs 14+/- 4 min in DT, p=0.008) and maximum dobutamine dose were decreased (30+/-11 vs. 35+/-11 mcg/kg/min in DT, p=0.004). Abnormal, ischemic ECG (17% vs. 8% in DT, p=0.035) and ECHO responses (19 vs. 14% in DT, p=0.267) were more common in SBDT. When ECG and echo results were compared, false-positive ECG response was significantly more common in SBD (10% vs. 1%, p=0.01), likely due to augmented venous return or LVEDP rise. Target heart rate (THR) was achieved in 90% of tests with supine bicycle vs. 80% in DT, p=0.046. Supine bicycle retained THR predictive significance (5.5, 95%CI 1.9-15, p<0.002) after adjustment for history of CHF (0.04, 95%CI 0-0.6, p=0.021), smoking (20, 95%CI 1-425, p=0.06), diabetes (0.01, 95%CI 0-0.4, p=0.004), and baseline diastolic DP (1.05, 95%CI 1-1.1, p=0.038). Age, gender, history of hypertension, coronary artery disease, baseline systolic BP and heart rate were not predictive of whether patient has achieved THR. Conclusion: Addition of supine bicycle exercise to standard dobutamine testing is well tolerated and results in more patients achieving THR. Supine bicycle exercise with dobutamine testing should be strongly considered in patients with history of heart failure, smoking, diabetes, or diastolic hypertension. Using combined stress test is associated with better resource utilization (shorter test time and lower peak dobutamine dose) and increased test sensitivity (higher double product).