Role of Different Low-Density Lipoprotein-Lowering Medications on Secondary Prevention of Atherosclerotic Cardiovascular Disease in Patients With Diabetes Mellitus

Purpose The objective of this study was to explore the optimal cholesterol-lowering therapy for diabetic patients categorized as having a very high risk for future atherosclerotic cardiovascular disease (ASCVD) events. The primary medications under investigation were statins, ezetimibe, and proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors (PCSK9-Is). The efficacy of different medication regimens helped to draw conclusions regarding the evolution of cholesterol management recommended under the American College of Cardiology's (ACC) 2013 and 2018 guidelines. Methods A retrospective chart review was conducted on a cohort of patients from a large, community-based cardiology practice. Inclusion criteria specified patients aged 30-82 with a past medical history of two or more ASCVD events or one ASCVD event and at least two high-risk comorbidities. Acquired data included demographics, all lipid panels, medications used, and ASCVD events between December 1, 2013, and December 31, 2019. The data were stored and encrypted on a REDCap account. Sub-group analysis was conducted on only diabetic patients, who were then categorized by medication regimen. The statistical analysis was completed using Fisher's exact test. A p-value <0.05 was considered significant. Results A total of 102 diabetic patients met the inclusion criteria. Our primary analysis determined the percentage of patients who achieved their goals on each medication regimen. The goal was defined as a low-density lipoprotein cholesterol (LDL-C) level of less than 70 mg/dL or at least a 50% reduction from baseline levels. The results are as follows: none (0%), statin (33.9%), ezetimibe (21.1%), statin + ezetimibe (73.5%), PCSK9-Is +/- statin (83.3%), and PCSK9-Is and ezetimibe +/- statin (100%). There proved to be a significant difference favoring all combination regimens over statins alone; however, there was no significant difference between these advanced regimens. A follow-up analysis determined if these patients were able to maintain their goals in the subsequent lipid panel after achieving their goals. The results are as follows: none (0%), statin (61.5%), ezetimibe (50%), statin + ezetimibe (77.8%), PCSK9-Is +/- statin (100%), and PCSK9-Is and ezetimibe +/- statin (66.6%). The only significant difference found was between PCSK9-Is +/- statins and statins alone. Conclusions Our study revealed that regimens using PCSK9 inhibitors and ezetimibe, in addition to maximally tolerated statin therapy, were more effective than statin therapy alone in achieving the goal. On extended analysis, only PCSK9 inhibitors showed superior ability in terms of maintaining the goals for diabetic patients at very high risk for future ASCVD events. This implies that statins alone may be inadequate to properly treat this specific patient population. In the context of clinical practice, physicians could have heightened consideration for dual therapy consisting of maximally tolerated statins and a secondary agent in accordance with the 2018 ACC guidelines.