Is imaging at intermediate doses necessary during dobutamine stress magnetic resonance imaging?

To determine if visualization of left ventricular contraction throughout the course of a pharmacologic stress test performed with magnetic resonance imaging (MRI) (rather than solely at baseline and peak stress) is necessary, we retrospectively reviewed dobutamine MRI results in 469 consecutively referred patients for diagnosis of inducible ischemia. At each stage of pharmacologic stress, six image planes of the heart were viewed and left ventricular wall motion was scored as normal, hypokinetic, akinetic, or dyskinetic. Inducible ischemia was identified in 102 patients; in 39 patients (38%), evidence of ischemia occurred before receiving high doses of dobutamine. During testing, 103 patients developed chest discomfort consistent with angina, but only 26 of the 103 patients (25%) developed new wall motion abnormalities indicative of ischemia. Continuous image acquisition and review during dobutamine MRI pharmacologic stress testing provides a mechanism to detect ischemia and avoid premature test termination during the early stages of the procedure. Compared with protocols that image only at baseline and at peak stress, continuous acquisition and review may enhance the safety and improve the diagnostic accuracy of pharmacologic stress testing during dobutamine MRI.