Abstract 2481: Myocardial Viability Determined by Myocardial Contrast Echocardiography is Superior to 99mTechnetium Sestamibi Single Photon Emission Computed Tomography in Predicting Hard Cardiac Events Following Acute Myocardial Infarction
Introduction: The extent of residual myocardial viability (MV) following acute myocardial infarction (AMI) is an important determinant of outcome. 99mtechnetium sestamibi single photon emission computed tomography (SPECT) is widely used to assess MV following AMI.
Hypothesis: We hypothesised that myocardial contrast echocardiography (MCE) which has a better spatial and temporal resolution compared to SPECT will be superior for predicting outcome following AMI.
Methods: Accordingly, 99 patients who underwent simultaneous resting low-power MCE & nitrate enhanced SPECT 7 days after AMI were followed up for cardiac death (CD) and AMI. Both SPECT (0=normal;1=mild reduction ;2=moderate reduction;3=severe reduction;4=absent tracer uptake) & MCE perfusion (1=normal;2=reduced;3=absent) were scored on a 16 segment left ventricular (LV) model. Contrast perfusion index (CPI) on MCE and SPECT perfusion index (SPI), both measures of MV, were calculated by adding the respective scores in the 16 LV segments divided by 16.
Results: Ninety five patients were available for the follow up (mean 46 months). There were 15 (16%) events (8 CDs & 7 AMIs). Area under the receiver operator characteristic curves for predicting CD and CD or AMI with MCE (0.82 and 0.80 respectively) were higher compared to SPECT (0.76 and 0.74 respectively). Amongst the clinical, biochemical, echocardiographic and SPECT markers of prognosis, only independent predictors of cardiac death and cardiac death or AMI were age and MV determined by MCE (p=0.01 & p=0.002 respectively).
Conclusion: MV determined by resting MCE is superior to nitrate enhanced SPECT for the prediction of hard cardiac events following AMI.