Background: We sought to evaluate the role of adenosine myocardial contrast echocardiography (MCE) for the determination of functional relevance of coronary stenoses with intermediate angiographic severity and compared the results to single photon imaging (SPECT). We hypothezised that sole assessment of myocardial blood volume changes during adenosine on MCE would indicate functional stensosis relevance when accompanied by increased myocardial oxygen consumption (MVO2).
Methods: Fifty-seven patients with >or=1 coronary stenosis underwent adenosine MCE (ultraharmonic imaging) and exercise SPECT. On MCE, myocardial blood volume was assessed and constant or increased myocardial opacification during adenosine coupled with increased MVO2 was defined as normal and decreased opacification as abnormal.
Results: Rate-pressure product significantly increased during adenosine in all patients due to reflex tachycardia following mild hypotension, indicative of increased MVO2. Concordance between MCE and SPECT for the detection of reversible myocardial perfusion defects was 89% (kappa = 0.83). Comparison of regions between rest and during adenosine as opposed to comparison to remote regions of the same stage was important for accurate assessment because concordance betweenn MCE and SPECT was less on separate assessment at rest (73%, kappa = 0.40) compared to stress (91%, kappa = 0.81, P < 0.05) mainly due to territories scored normal on SPECT and abnormal on MCE.
Conclusions: Assessment of myocardial blood volume changes during adenosine using MCE can be used for the determination of the functional relevance of coronary stenoses of intermediate angiographic severity if MVO2 is increased during adenosine.