False Positive Results on Dobutamine Stress Echocardiography: A New Marker of Risk for Ischemic Events

Abstract

Background: Although dobutamine stress echocardiography (DSE) has a high specificity, there is still a subset of patients with false positive tests (FP); whether these results have prognostic value remains unclear. Aims: To identify the clinical and echocardiographic predictors of FP on DSE and to evaluate the prognostic impact of FP on DSE. Methods: Retrospective study of 355 consecutive patients who underwent DSE for ischemia assessment over a one-year period: 134 (37,7%) women, 70,3 ± 0,57 years. Demographics, risk factors, clinical and laboratorial parameters and DSE variables were evaluated. Patients were divided into 2 groups regarding the presence (FP+) or the absence (FP0) of a FP result on DSE and a comparative analysis was performed to characterize the groups and identify potencial predictors of FP results. Patients were followed for 2 years to assess acute myocardial infarction, hospitalization for acute heart failure (HF) and mortality. Results: The FP rate was 4,5%. Comparing to FP0, patients in group FP+ were younger, baseline wall motion abnormalities were more frequent, had higher mean blood pressure values at rest and at peak stage and more often hypertensive response. There were no significant differences regarding previous coronary artery disease, medication or complete left bundle branch block. By multivariate analysis, only mean blood pressure values at rest (OR 0,01; 95%CI 0,005-0,02; p=0,003) and at peak stage (OR 0,02; 95%CI 0,000-0,004; p=0,003) were independent predictors of FP. During follow-up was observed: acute myocardial infarction (FP+: 12,5% vs FP0: 1,8%, p=0,046), HF (FP+: 6,3% vs FP0: 11,5%, p=0,44) and mortality (FP+: 6,3% vs FP0: 6,2%, p=0,65). After adjustment for age, sex and comorbidities, there were no diferences between the groups regarding HF and mortality, but the group FP+ mantained a higher rate of acute myocardial infarction (OR 0,21; 95%CI 0,065-0,354; p=0,005). Conclusion: A FP result on DSE was associated with higher mean blood pressure values during the test and with higher rates of acute myocardial infarction during follow-up. This result on DSE should therefore be faced as a risk marker for ischemic events and can identify patients that may benefit from aggressive risk factor control and careful clinical follow-up.