The role of first-pass perfusion deficit in the detection of cardiac subendocardial manifestation in patients with autoimmune vasculitis.

This report describes the potential of cardiac magnetic resonance imaging (cMRI) based on myocardial first-pass perfusion imaging in the visualization of cardiac manifestations in autoimmune vasculitis, which in the heart are typically localized at the level of small subendocardial vessels. Two patients with primary or secondary autoimmune vasculitis were investigated in this study. Myocardial first-pass perfusion imaging was performed using an ECG-gated T1-weighted MRI sequence after the injection of intravenous bolus of gadolinium chelate. In both cases, the cMRI showed findings of subendocardial first-pass perfusion deficit (FPPD), a phenomenon so far described as microvascular obstruction (MVO) only in patients with acute cardiac infarction due to thromboembolic obstruction of small myocardial vessels. The two patients showed local subendocardial and myocardial hypoenhancement (characterized by a darker appearance than normal myocardial tissue), which is the typical morphological stigma of FPPD initially after injection of contrast media. The perfusion deficit, although morphologically very similar to the well-known phenomenon of MVO in acute cardiac infarction, was conceivably caused by different vasculitis-specific mechanisms such as occlusion of the microvasculature with erythrocytes, neutrophils and cellular debris. This study indicates that FPPD is useful for the non-invasive assessment of the microvasculature in patients with acute cardiac involvement in primary and secondary vasculitis.