Abstract 19: Ability to Perform Supine Bicycle Exercise Predicts Short-Term Mortality in Patients Undergoing Dobutamine Stress Testing

Background: We studied outcomes associated with ability to perform supine bicycle exercise in patients referred for dobutamine stress testing. Material and Methods: Consecutive unselected patients referred for dobutamine stress echocardiographic testing were grouped by ability to perform supine bicycle exercise (n=85, 37 females, 61+/-12 years old) or not (n=107, 53 females, 57+/-12 years old). Demographic data and medical history were collected. Survival was ascertained through hospital records and Social Security Death index. Follow-up (mean 22+/-7 months) was available in 192 patients Analysis of variance (ANOVA), chi-square, and logistic regression analyses were used. Results: Target heart rate (THR) was achieved in 90% (76 of 85) with supine bicycle dobutamine (SBD) vs. 80% (85 of 107) with standard dobutamine tests (DT), p=0.046. During follow-up, 9% (17 of 192) of patients expired. Abnormal, ischemic response to stress testing was predictive of mortality (18% (6 of 33) in ischemic response vs. 7% (11 of 159) in normal response, p=0.038). When analyzed by ability to perform supine bicycling, there was a trend towards decreased mortality in patients able to exercise (SBD 7% (6 of 85) vs. DT 10% (11 of 107), p=0.435) or reach target heart rate (THR reached - 8% (14 of 171) vs. THR not reached - 15% (3 of 20), p=0.311). Longer exercise time was predictive of decreased mortality (HR 1.1 per minute, 95%CI 1-1.3, p=0.048), but not age (p=0.926) or maximal bicycle resistance (p=0.222). In addition to that, ischemia during test was not predictive of mortality in exercise-capable group (HR 2, 95%CI 0.4-13, p=0.406). On the contrary, in patients unable to exercise, ischemia by echo (HR 4, 95%CI 1-16, p=0.047) and age (HR 1.9 per decade, 95%CI 1-3.5, p=0.043) were associated with increased mortality. Gender, history of CAD, CHF, HTN, DM, PAD, smoking, beta-blocker treatment, or time to heart rate recovery had no effect on mortality in either groups. Conclusion: Similarly to upright exercise, supine bicycle exercise capacity is associated with improved short-term mortality and appears to be more important than age or ischemia during stress testing. In patients unable to perform supine exercise, age and ischemia during stress testing remain significant predictors of poor outcomes. </jats:p

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

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&lt;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&lt;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). </jats:p

Search for DNA of exogenous mouse mammary tumor virus-related virus in human breast cancer samples

Earlier reports of a human exogenous retrovirus (HMTV) related closely to mouse mammary tumor virus (MMTV) led us to search for these viral sequences in breast cancer tissues and normal tissues. A real-time PCR was developed based on MMTV and published HMTV envelope sequences. The real-time PCR method can detect one to ten copies of MMTV target DNA. Tissue samples were collected prospectively from 18 breast cancer patients and 11 non-malignant control cases, as well as peripheral blood leukocytes from the same women. Despite the high sensitivity of the real-time PCR method used, none of the samples were positive for HMTV DNA or RNA. The absence of HMTV DNA in both breast cancer samples and controls indicates either that the concentration of putative HMTV DNA in the breast cancers was too low for detection or that it did not exist there.</p

Abstract 359: Lack Of Blood Pressure Augmentation During Stress Testing Is Associated With Increased Mortality.

Objective: We investigated long-term outcomes associated with hypertensive response to exercise in patients with chest pain referred for stress echocardiography. Methods: Records of 404 patients with normal baseline LV systolic function (45% females, mean age 60+/-11 years, baseline SBP 136+/-20 mmHg, 26% with CAD, 4% with CHF, 39% with hypertension, 13% with diabetes mellitus, 5% with peripheral vascular disease, 21% with history of smoking or active smoking, 43% on beta-blockers, 23% on ACE-inhibitors/ARBs) referred for chest pain evaluation with stress echocardiography at a single tertiary care center were reviewed. Demographics, clinical data, and outcomes were collected. Median length of followup was 35+/-0.3 months. Patients were divided into four groups depending on their maximum blood pressure during exercise (greater or less than 180mmHg) and whether they achieved their age-adjusted target heart rate. Results: Contrary to the expectations, hypertensive response to exercise was not associated with the increased mortality (Table). Instead, lack of blood pressure augmentation during exercise and low double product were predictive of increased mortality. History of CHF (p=0.0003) and/or PVD (p=0.001) were the strongest predictors of failure to augment blood pressure during stress testing. Conclusions: Failure to augment systolic blood pressure during exercise appears to be associated with increased mortality. Although ischemia on echocardiography and reduced exercise capacity are the stress test outcomes traditionally associated with poor prognosis, failure to augment blood pressure during exercise may be an important predictor of mortality as well. Additional studies of this subject are needed. </jats:p