The feasibility of combining low-level exercise with vasodilator stress in patients referred for stress perfusion cardiac MRI

Background Adenosine, an agonist of the A2a receptor, is widely used for stress CMR. However, target receptors for adenosine are heterogeneous in their location and facilitated physiologic effects. A2b and A3 receptors are responsible for bronchospasm and peripheral arteriolar vasodilation; A1 receptors are responsible for AV block. The rate of adverse reactions with adenosine approaches 80%, consisting of dyspnea, headache, flushing, chest/ abdominal discomfort, angina, ST depression, dizziness, nausea, and dysgeusia. In SPECT protocols, use of vasodilators has been previously established as safe during low level exercise, and results in fewer adverse reactions. Our hypothesis is that adenosine administered during low level exercise treadmill stress cardiac MRI is safe, feasible, and results in diagnostic quality imaging.