Aims: On the basis of an MRI study it has been suggested that subendocardial hypoperfusion is present in patients with cardiac syndrome X. However, further work is required to test whether these findings can be generalized.
Methods and results: MRI was used to visually and semi-quantitatively assess subendocardial and subepicardial perfusion, at rest and during an infusion of adenosine, in 20 patients with angina pectoris and normal coronary angiograms. A myocardial perfusion index (MPI) was calculated using the normalized upslope of myocardial signal enhancement. An index for myocardial perfusion reserve (MPRI) was calculated by dividing the MPI values at maximal vasodilatation by the values at rest. The MPI in our study population increased significantly during adenosine infusion in both the subendocardium (from 0.091 +/- 0.020 to 0.143 +/- 0.030; P < 0.001) and the subepicardium (from 0.074 +/- 0.017 to 0.135 +/- 0.03; P < 0.001). The overall MPRI was 1.83 +/- 0.50.
Conclusion: The results show that patients with chest pain and normal coronary angiograms had significant perfusion responses to adenosine in both the subendocardium and subepicardium. In the present study we found no evidence for subendocardial hypoperfusion in these patients.