The Clinical Importance of Risk Factor Modification: Looking at Both Myocardial Viability (MV) and Myocardial Perfusion Imaging (MPI)

Abstract

Determination of changes in coronary artery disease (CAD) following risk factor modification (lipid lowering and stress reduction) have focused only on changes in myocardial blood flow (Q)/myocardial perfusion imaging (MPI) and not myocardial viability (MV). To determine the outcome of each and to determine if there are differences in myocardial viability versus coronary blood flow, 31 people were studied for 1 year with comparison of baseline and 1-year PET results. One subject underwent an additional 2-year follow-up study, providing a total of 32 comparisons. A total of 224 myocardial segments were compared with improvement in MPI seen in 58 of 224 segments (25.9%), stabilization in 111 of 224 (49.6%) segments, and progression of disease in 55 of 224 (24.6%) segments. MV improved in 82 of 224 segments (36.6%), showed stabilization in 83 of 224 (37.0%) of the segments, and worsening in 59 (26.3%) of 224 segments. When improvement in either MPI or MV were added together, improvement was seen in 50.9% (p≤0.001) of the segments and stabilization was seen in 30.4% (p≤0.001). Despite RFM as defined above, progression of CAD and loss of myocardial viability was noted in 15% of the myocardial segments studied. This study demonstrated that regardless of whether one looks at MPI alone or a combination of MPI and MV, reduction of serum lipids and stress reduction alone cannot guarantee stabilization or regression of atherosclerosis. Clearly there are additional factors involved which play an important role in reveral of CAD which must be addressed in future studies.