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Myocardial perfusion imaging and coronary angiography in patients with known or suspected stable angina pectoris.

INTRODUCTION
The patho-physiological cause of angina pectoris is myocardial ischaemia, which can be objectified by myocardial perfusion imaging (MPI).


METHODOLOGY
MPI was undertaken prior to coronary angiography (CAG) in 86 randomly selected patients with known or suspected stable angina pectoris.


RESULTS
Among 78 adequately stressed patients, MPI was normal in 28 (36%) and showed reversible and irreversible perfusion abnormalities in 30 (38%) and 20 patients (26%), respectively. Coronary angiograms were normal in 28 (36%) and revealed at least one > or = 50% stenosis in 50 patients (64%) (16 with single and 34 with multi vessel disease). Using angiography as a reference, the sensitivity and specificity of MPI in detecting coronary artery disease was 88% and 93%, respectively.


DISCUSSION
MPI demonstrates regional hypoperfusion whereas CAG depicts anatomical stenosis in epicardial arteries. Both modalities are potentially relevant in patients with stable angina pectoris. The functional significance of coronary artery lesions is, however, variable and MPI can demonstrate normal myocardial perfusion in the presence of moderate lesions. MPI exhibited a high sensitivity and specificity regarding significant lesions. More than one third of the subjects had a normal MPI and a normal CAG. Patients with stable angina pectoris and a normal MPI have a very low risk of cardiac events and do usually not require further invasive investigation or therapy. Reversible ischaemia and irreversible ischaemia with demonstration of viable tissue call for coronary revascularisation.