Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitor Eligibility and Prescription Rates in Patients Presenting With Recurrent Acute Coronary Syndromes.

Background: Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are novel medications for reducing low-density lipoprotein cholesterol (LDL-C) levels. In 2020, the Australian Pharmaceutical Benefits Scheme (PBS) began subsidising PCSK9 inhibitors for secondary prevention of cardiovascular disease in patients with LDL-C >2.6 mmol/L despite statin and ezetimibe therapy. This criterion was expanded to LDL-C >1.8 mmol/L in 2022.

Method: A retrospective analysis was conducted on patients admitted to a quaternary hospital with acute coronary syndrome (ACS) between 2020-2022. PCSK9 inhibitor eligibility and prescribing patterns were compared between recurrent ACS patients (≥2 events within 5 years) and first-presentation ACS patients. Australian PBS 2020 and 2022 criteria were applied to assess eligibility.

Results: Of 817 ACS patients with LDL-C >1.8 mmol/L, 118 (14.4%) were categorised as recurrent ACS (33.9% female, mean age 67 years, LDL-C 2.9 mmol/L). When compared with first-presentation ACS patients (n=699), recurrent ACS patients had significantly higher proportions already on statin therapy (49.2% vs 6.0%, p<0.001) and ezetimibe (20.3% vs 2.4%, p<0.001). Recurrent ACS patients had significantly higher proportions of 2020 PBS-eligible patients (11.0% vs 1.3%, p<0.001) and 2022 PBS-eligible patients (20.3% vs 2.2%, p<0.001). There were no significant differences in PCSK9 inhibitor prescription rates among eligible patients (four of 13, 30.8% vs four of nine, 44.4%, p=0.51). Univariate binary logistic regression demonstrated that statin intolerance was significantly associated with PCSK9 inhibitor prescription (odds ratio 10; 95% confidence interval 1.3-79.3; p=0.029).

Conclusions: Despite significantly higher eligibility rates, PCSK9 inhibitor uptake remains low in recurrent ACS patients, demonstrating the need to raise further awareness about eligibility criteria and encourage proactive prescription to prevent recurrent cardiovascular events.