Angiographic correlations of patients with small vessel disease diagnosed by adenosine-stress cardiac magnetic resonance imaging

Cardiac magnetic resonance imaging (CMR) with adenosine-stress
myocardial perfusion is gaining importance for the detection and
quantification of coronary artery disease (CAD). However, there is
little knowledge about patients with CMR-detected ischemia, but
having no relevant stenosis as seen on coronary angiography (CA).
The aims of our study were to characterize these patients by CMR
and CA and evaluate correlations and potential reasons for the
ischemic findings. 73 patients with an indication for CA were first
scanned on a 1.5T whole-body CMR-scanner including adenosine-stress
first-pass perfusion. The images were analyzed by two independent
investigators for myocardial perfusion which was classified as
subendocardial ischemia (n = 22), no perfusion deficit (n = 27,
control 1), or more than subendocardial ischemia (n = 24, control
2). All patients underwent CA, and a highly significant correlation
between the classification of CMR perfusion deficit and the degree
of coronary luminal narrowing was found. For quantification of
coronary blood flow, corrected Thrombolysis in Myocardial
Infarction (TIMI) frame count (TFC) was evaluated for the left
anterior descending (LAD), circumflex (LCX) and right coronary
artery (RCA). The main result was that corrected TFC in all
coronaries was significantly increased in study patients compared
to both control 1 and to control 2 patients. Study patients had
hypertension or diabetes more often than control 1 patients. In
conclusion, patients with CMR detected subendocardial ischemia have
prolonged coronary blood flow. In connection with normal resting
flow values in CAD, this supports the hypothesis of underlying
coronary microvascular impairment. CMR stress perfusion
differentiates non-invasively between this entity and relevant CAD.