Background: The thickness of coronary fibrous caps is a major determinant of vulnerable plaques. Several clinical trials have suggested that statin therapy could stabilize vulnerable plaques. Recently, optical coherence tomography (OCT) has been proposed as an effective histology-resolution imaging modality for assessing such micro-structural changes.
Methods: Forty AMI patients with hyperlipidemia were enrolled and underwent percutaneous coronary intervention (PCI). They were divided into two groups; statin treatment group (n=23) or control group (n=17). Serial OCT analyses were performed at baseline and 9-month follow-up for a non-PCI lipid-rich plaque lesion.
Results: The LDL-cholesterol level in the statin group was significantly lower than that in the control group at follow-up. Although the fibrous-cap thickness was significantly increased in both the statin treatment group (151+/-110 to 280+/-120 microm, p<0.01) and the control group (153+/-116 to 179+/-124 microm, p<0.01) during follow-up period, the degree of increase was significantly greater in the statin treatment group than in the control group (188+/-64% vs. 117+/-39%, p<0.01). Furthermore, when the patients in the statin treatment group were divided into two subgroups (fibrous-cap thickness <median and >or=median), the thin fibrous-cap group (<median) increased their thickness much more than the thick fibrous-cap group (>or=median).
Conclusion: The lipid-lowering therapy with statin for 9 months after the onset of acute myocardial infarction significantly increased the fibrous-cap thickness in patients with hyperlipidemia.