In 2016, 17.6 million deaths occurred globally due to cardiovascular disease (CVD) with coronary artery disease (CAD) and ischemic stroke as top contributors.1 Elevated low-density lipoprotein cholesterol (LDL-C) has been linked to greater risk of atherosclerotic cardiovascular disease (ASCVD); therefore, LDL-C reduction is imperative to decrease risk of cardiovascular (CV) morbidity and mortality.2 Since 1987, statin therapy has been the mainstay of treatment for hypercholesterolemia, and current practice guidelines recommend statins as first-line therapy given demonstrated reductions in LDL-C and CV mortality reduction in robust clinical trials.2-4 Although generally safe and well tolerated, muscle-related adverse events (AEs) limit optimal use of statins in up to 20% of individuals who have an indication for statin therapy.5 As a consequence, these patients receive suboptimal statin doses or no statin therapy and are at a higher risk for ASCVD.5
Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors have been shown to significantly lower LDL-C when used as monotherapy or in combination with statins and/or other lipid-lowering therapies.5 These agents are currently approved by the US Food and Drug Administration as an adjunct to diet with or without other lipid-lowering therapies for the management of primary hypercholesterolemia (including heterozygous familial hypercholesterolemia), homozygous familial hypercholesterolemia (evolocumab only), and for use in patients with established CVD unable to achieve their lipid-lowering goals with maximally tolerated statin doses and ezetimibe.4 With the ability to reduce LDL-C by up to 65%, PCSK9 inhibitors offer an alternative option for LDL-C and potentially CV risk reduction in statin-intolerant patients.5
Alirocumab, the formulary preferred PCSK9 inhibitor at the Michael E. DeBakey Veterans Affairs Medical Center (MEDVAMC) in Houston, Texas, has been increasingly used in high-risk statin-intolerant veterans. The primary objective of this case series was to assess LDL-C reduction associated with alirocumab use in statin-intolerant veterans at the MEDVAMC. The secondary objective was to assess the incidence of CV events. This study was approved by the MEDVAMC Quality Assurance and Regulatory Affairs committee.
Methods
In this single-center case series, a retrospective chart review was conducted to identify statin-intolerant veterans who were initiated on treatment with alirocumab for LDL-C and/or CV risk reduction between June 2017 and May 2019. Adult veterans with a diagnosis of primary hypercholesterolemia (including heterozygous familial hypercholesterolemia) and/or CAD with documented statin intolerance were included in the study. Statin intolerance was defined in accordance with the National Lipid Association (NLA) definition as aninability to tolerate ≥ 2 statins with a trial of at least 1 statin at its lowest daily dose.5 Veterans who previously received treatment with evolocumab, those prescribed concurrent statin therapies, and those missing follow-up lipid panels at 24 weeks were excluded from the study. To assess LDL-C reduction, LDL-C at baseline was compared with LDL-C at 4 and 24 weeks. Incident CV events before and after alirocumab initiation were documented. The US Department of Veteran Affairs (VA) Computerized Patient Record System was used to collect patient data.
Data Collection, Measures, and Analysis
Electronic health records of all eligible patients who received alirocumab were reviewed, and basic demographics (patient age, sex, and race/ethnicity) as well as medical characteristics at baseline were collected. To confirm statin intolerance, each veteran’s history of statin use and use of additional lipid-lowering agents was documented. CV history was measured with an index of categorical measures for hypertension, confirmed CAD, hyperlipidemia, heart failure, arrhythmias, peripheral artery disease, stroke, diabetes mellitus, and hypothyroidism. Additionally, concomitant medications, such as aspirin, P2Y12 inhibitors, β-blockers, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers that patients were taking also were collected. Each veteran’s lipid panel at baseline, and at 4 and 24 weeks posttreatment initiation, also was extracted. Continuous variables were summarized with means (SD), and categorical variables were summarized with frequencies and proportions. The paired Wilcoxon signed rank test was used to compare LDL-C at 4 and 24 weeks after alirocumab initiation with patients’ baseline LDL-C.
Results
Between June 2017 and May 2019, 122 veterans were initiated on alirocumab. Of these veterans, 98 were excluded: 35 concurrently received statin therapy, 33 missed follow-up lipid panels, 21 had previously received evolocumab, 6 failed to meet the NLA definition for statin intolerance, 2 did not fill active alirocumab prescriptions, and 1 had an incalculable LDL-C with a baseline triglyceride level of 3079 mg/dL. This resulted in 24 veterans included in the analysis.
Most participants were male (87.5%) and White veterans (79.2%) with a mean (SD) age of 66.0 (8.4) years and mean (SD) baseline LDL-C of 161.9 (74.3) mg/dL. At baseline, 21 veterans had a history of primary hyperlipidemia, 19 had a history of CAD, and 2 had a history of heterozygous familial hypercholesterolemia. Of the 24 patients included, the most trialed statins before alirocumab initiation were atorvastatin (95.8%), simvastatin (79.2%), rosuvastatin (79.2%), and pravastatin (62.5%) (Table).
LDL-C Reduction
Veterans were initially treated with alirocumab 75 mg administered subcutaneously every 2 weeks; however, 11 veterans required a dose increase to 150 mg every 2 weeks. At treatment week 4, the median LDL-C reduction was 78.5 mg/dL (IQR, 28.0-107.3; P < .01), and at treatment week 24, the median LDL-C reduction was 55.6 mg/dL (IQR, 18.6-85.3; P < .01). This equated to median LDL-C reductions from baseline of 48.5% at week 4 and 34.3% at week 24. A total of 3 veterans experienced LDL-C increases following initiation of alirocumab. At week 4, 9 veterans were noted to have an LDL-C reduction > 50%, 7 veterans had an LDL-C reduction between 30% and 50%, and 5 veterans had an LDL-C reduction of < 30%. At week 24, 6 had an LDL-C reduction > 50%, 9 veterans had an LDL-C reduction between 30% and 50%, and 6 had a LDL-C reduction < 30%.