Coronary Calcium Scanning Enters the Conversation for Women Missed by Traditional Risk Tools
Cardiovascular risk assessment in women has long been constrained by tools built around male-dominant data and conventional atherosclerotic predictors. The CAC-WOMEN Trial was designed to test whether coronary artery calcium scoring can correct that blind spot in Australian women who carry female-specific or otherwise under-recognized risk enhancers, including hypertensive disorders of pregnancy, gestational diabetes, and premature menopause.
The protocol centers on a simple clinical premise: calcified plaque can be detected on CT long before angina, infarction, or heart failure forces the diagnosis. In women whose standard risk calculators place them in a low-to-intermediate category, a visible coronary calcium burden could justify earlier lipid-lowering treatment, tighter blood pressure control, and more forceful prevention counseling. Aboriginal and Torres Strait Islander women are especially relevant to that question, given the higher burden of cardiovascular disease and the earlier age at onset described in the trial rationale.
This is not a screening exercise in the abstract. It is a direct attempt to see whether imaging shifts treatment decisions, improves adherence, and closes a gap that routine calculators continue to miss.
Trial Design Centers on Risk Reclassification and Behavior Change
The study is a multisite, single-blind, randomized controlled trial with a 1:1 allocation scheme and a planned sample of 700 women. Participants will be women without established cardiovascular disease, aged 40 to 65 years, or 35 to 65 years for Aboriginal and Torres Strait Islander women. Eligibility also requires a low-to-intermediate estimated cardiovascular risk on standard calculators and at least one risk-enhancing factor such as hypertensive disorders of pregnancy, gestational diabetes, or premature menopause.
The intervention arm will receive a coronary artery calcium score-guided approach, while the control arm will receive standard care. The trial will examine whether access to calcium imaging improves cardiovascular risk factor control and healthy lifestyle adherence over 6 months. Low-density lipoprotein cholesterol and systolic blood pressure serve as the coprimary outcomes, anchoring the study in two modifiable variables that map directly onto future event risk.
Those endpoints are clinically sensible because imaging alone does not prevent infarction. Risk stratification only matters if it changes what happens next in clinic: initiation of statins, intensification of antihypertensive therapy, and a more urgent conversation about weight, exercise, diet, and long-term follow-up. A visible calcium score can make subclinical disease tangible, especially for patients who have been told they are not sick enough to need medication despite carrying a meaningful obstetric or reproductive risk history.
Why Female-Specific Risk Enhancers Matter Here
Standard prediction tools such as Framingham remain imperfect for women and for Indigenous populations. The protocol directly addresses a recurring failure of cardiovascular prevention: patients with meaningful biological risk are often labeled low or borderline risk because their hazard emerged through pathways not fully captured by the calculator. Hypertensive disorders of pregnancy and gestational diabetes are not historical curiosities; they are vascular signals that may reflect endothelial dysfunction, metabolic injury, and a higher lifetime propensity to atherosclerosis.
Premature menopause adds another layer. Early loss of ovarian function alters lipid biology, vascular tone, and potentially inflammatory signaling, all of which can accelerate plaque development. In that context, coronary artery calcium scoring serves as a structural readout of cumulative exposure. It does not measure every dangerous plaque phenotype, but when calcification is present it provides concrete evidence that atherosclerosis is already underway.
One sentence captures the clinical stakes: risk has to be seen before it is treated aggressively.
Indigenous Recruitment and Health Equity Are Built Into the Protocol
Aboriginal and Torres Strait Islander women are not an afterthought in this trial. The investigators aim to recruit approximately 10% of the total sample from this group, reflecting the recognized cardiovascular burden and earlier disease onset in Indigenous women. That decision is important because a trial of risk reclassification loses much of its real-world relevance if it is studied only in populations already well served by routine prevention pathways.
The age range also reflects equity-aware design. Starting eligibility at 35 years for Aboriginal and Torres Strait Islander women acknowledges the earlier onset of cardiovascular disease described in the protocol background. If coronary calcium scoring proves useful in this setting, the result could support a more tailored prevention strategy that starts earlier and uses anatomy, not just calculators, to guide care.
The study will also collect barriers and enablers, which matters because implementation often fails where diagnostic logic succeeds. Patients may accept imaging but decline medication, or clinicians may agree with the result but struggle to act on it within short visits, competing priorities, or reimbursement constraints. Health services research belongs in the same trial because the path from CT scanner to prevention therapy is never automatic.
Outcomes Will Test Whether Imaging Changes Risk-Factor Management
At 6 months, the trial will compare the two groups on LDL cholesterol and systolic blood pressure. Those are pragmatic endpoints with immediate bedside meaning. LDL reduction generally reflects whether statin initiation or intensification occurred and whether patients adhered to therapy; systolic pressure captures the success of antihypertensive management and lifestyle change over a short but meaningful window.
The protocol also includes a health economic analysis. That is essential because calcium scoring adds cost, imaging infrastructure, and follow-up demand. If the scan meaningfully shifts treatment patterns, the next question becomes whether the downstream reduction in preventable events, medication use patterns, or inefficient overtesting justifies the investment. If it does not, the scan may still have value in selected groups, but the threshold for broad implementation would need to stay high.
Safety, Governance, and Real-World Data Linkage
Ethics approval was granted by the Western Sydney Local Health District Research Ethics Committee, and written informed consent will be obtained before randomization. Participants will also be asked to permit linkage with Medicare Benefits Schedule claims, Pharmaceutical Benefits Scheme claims via Medicare Australia, and the Admitted Patient Data Collection. That linkage could provide a more grounded picture of service use and downstream care than a self-reported questionnaire alone.
The use of administrative data is clinically useful because it can show whether imaging truly changes prescribing, attendance, and hospitalization patterns. It also allows investigators to observe whether the intervention affects medication uptake in a way that simple baseline and follow-up visits might miss. In prevention trials, the administrative footprint can be as informative as the trial visit itself.
What This Protocol Can and Cannot Answer
Because this is a protocol, no efficacy findings are available yet, and the study does not claim that coronary calcium screening should already be routine in all women with pregnancy-related or reproductive risk enhancers. It does define a clear and testable question: will coronary artery calcium scoring improve risk factor control better than standard care in women who are likely to be underestimated by conventional tools?
The answer will matter most if it changes behavior at the point of care. Imaging that identifies plaque but fails to move LDL, blood pressure, or adherence will have limited preventive value. If the opposite occurs, the trial could support a more anatomically informed approach to cardiovascular prevention in Australian women, especially those whose risk has been hidden by formulas that never fully captured their biology.