Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp eft ventricular (LV) remodeling after acute myocardial infarction (AMI) contributes to the development of pump failure and increases the mortality and morbidity of major cardiovascular events. 1,2 Activation of the renin-angiotensin system (RAS) plays an important role in ventricular remodeling after AMI. 3 However, experimental studies have demonstrated that ventricular remodeling after AMI is also associated with enhanced matrix metalloproteinase (MMP) activity. Plasma levels of the MMP subtype, MMP-9, are particularly increased after MI, indicating an association of this enzyme with ventricular remodeling, and suggesting that MMP-9 inhibition prevents LV enlargement in experimental models of MI. 4-6 Animal studies have shown that suppression of RAS with angiotensin-converting enzyme (ACE) inhibitors attenuate MMP activity and LV dilation. 7 Animal studies have also found that angiotensin II type 1 receptor blockers (ARBs) prevent LV remodeling via the modification of MMP-9 expression in ischemic-reperfusion models. 8 However, whether RAS inhibition through use of an ACE inhibitor, ARB or a combination of both can suppress ventricular remodeling in association with MMP-9 expression in human subjects has not been investigated. Whether LV remodeling is suppressed in association with MMP-9 suppression in post-AMI/-percutaneous coronary intervention (PCI) patients treated with ACE inhibitor and/or ARB was examined. The presence of any differences in LV remodeling and MMP-9 levels across the groups was also investigated.