Disparity Between Dobutamine Stress and Physical Exercise Magnetic Resonance Imaging in Patients with an Intra-atrial Correction for Transposition of the Great Arteries.

Background: In patients with an intra-atrial correction for transposition of the great arteries (TGA) an abnormal response to stress testing is common. However, hemodynamic responses may vary substantially when different stress tests are used. We compared the hemodynamic response to dobutamine stress with the response to physical exercise in patients and controls. Methods: Thirty-nine patients and 25 age/sex-matched control subjects underwent either dobutamine stress (15 µg/kg/min) or submaximal physical exercise cardiovascular magnetic resonance. End-systolic and end-diastolic right ventricular volumes (ESV; EDV) were determined. Five representative patients underwent both stress tests. For these patients, wall thickening reserve was calculated as systolic wall thickening during stress minus systolic wall thickening at rest. Results: In controls, dobutamine stress and physical exercise showed similar responses: stroke volume, cardiac output, and ejection fraction increased significantly, whereas ESV decreased significantly and EDV was unchanged. In patients, stroke volume did not increase with either dobutamine or exercise (- 8.6% vs. 2.9%). Ejection fraction increased significantly with dobutamine (16%, p [ABSTRACT FROM AUTHOR]