Comparison between Bruce and ramp protocols for exercise testing in the diagnosis of myocardial ischemia

ABSTRACT

BACKGROUND: Exercise tests are an important tool in the investigation of myocardial ischemia. The ramp protocol has gained increasing importance in clinical practice because of the possibility of individualizing its exercise intensity. OBJECTIVE: To assess and compare the sensitivity, specificity, and accuracy of Bruce and ramp protocols for exercise testing in the diagnosis of myocardial ischemia considering myocardial perfusion scintigraphy as the reference standard. Secondary objectives included the assessment of hemodynamic profiles, functional capacity, and the incidence of arrhythmias in each of the protocols. METHODS: Participants underwent exercise testing using the ramp and Bruce protocols, and the tests' diagnostic power was assessed. For testing the difference between data provided by both protocols, we used a paired Student's t-test or Wilcoxon test, depending on the assumption of data normality. The level of significance adopted for all tests was 5%. RESULTS: The ramp protocol showed sensitivity, specificity, and accuracy values of 55.6%, 82.4%, and 76.7%, respectively, whereas the Bruce protocol had results of 77.8%, 64.7%, and 67.4%, respectively. The maximum heart rate and double product at peak exercise were significantly higher in the Bruce protocol (p = 0.043 and p = 0.040, respectively). No differences were observed between the incidence of arrhythmias in both protocols. CONCLUSION: The Bruce protocol presented higher sensitivity for detecting ischemia on the exercise test, while the ramp protocol presented higher specificity and accuracy.