Detection of cardiac small vessel disease by adenosine-stress magnetic resonance.

Background: Patients testing positive for myocardial ischemia but without significant coronary artery (CA) stenosis in coronary angiography (CXA) are characterized as having "small vessel disease" (SVD). The aim of our study was to identify these patients by stress perfusion cardiac magnetic resonance (CMR).

Methods: 317 patients with suspected myocardial ischemia and clinical indication for CXA were scanned < 72 h before CXA in a whole-body 1.5T scanner. After 3 min of adenosine infusion (140 microg/kg/min), a myocardial first-pass perfusion sequence in 4-5 contiguous short-axis orientations using a Gadolinium-based contrast agent (0.1 mmol/kg) was performed. Images were analyzed qualitatively by two independent and blinded investigators.

Results: Perfusion deficits were detected in 93% of our patients. In 78% of patients with relevant perfusion delay, perfusion deficits extended to > 1/3 of the wall thickness in > or = 2 myocardial segments, persisted for > 5 heartbeats and were regarded as relevant coronary macroangiopathy. All of these patients had significant CA stenosis (60% had luminal narrowing > 70% and 18% had 50-70%). 22% of the patients had perfusion deficits affecting < or = 1/3 of wall thickness with persistence for < or = 5 heartbeats and were regarded as having SVD. None of these patients had a CA stenosis of > 50% or received CA revascularization. These patients more frequently had hypertension (p<0.0001), diabetes (p<0.05) and circumferential perfusion deficits (p<0.0001) than other patients.

Conclusion: Stress perfusion CMR allows non-invasive differentiation between patients with significant CA stenosis and patients with SVD caused by hypertension and/or diabetes based on the temporal and spatial extent of perfusion deficits. Patients with SVD more often have diffuse perfusion deficits with shorter persistence than patients with significant CA disease.