Patients who received a protocol-driven recommendation to initiate statin therapy for primary prevention of cardiovascular disease based upon their CT angiography coronary artery calcium score were twice as likely to actually start on the drug than those whose recommendation was guided by the American College of Cardiology/American Heart Association Pooled Cohort Equations Risk Calculator, according to the results of the randomized CorCal Vanguard study.
These results suggest that patients – and their primary care physicians – find the conventional method of screening for cardiovascular risk using the Pooled Cohort Equations to estimate the 10-year risk of MI or stroke, as recommended in ACC/AHA guidelines, to be less persuasive than screening for the presence or absence of actual disease as captured by CT angiography images and the associated coronary artery calcium (CAC) score,, said at the joint scientific sessions of the ACC and the World Heart Federation. The meeting was conducted online after its cancellation because of the COVID-19 pandemic.
The CorCal Vanguard study included 601 patients with an average baseline LDL cholesterol of 120 mg/dL, an average age of 60 years, and no history of cardiovascular disease, diabetes, or prior statin therapy. They were randomized to decision-making regarding statin therapy based on either the ACC/AHA guideline–endorsed Pooled Cohort Equations, which use an estimated 10-year risk of 7.5% or more as the threshold for statin initiation, or their CAC score.
If a patient’s CAC score was 0, the recommendation was against starting a statin. Everyone with a CAC greater than 100 received a recommendation for high-intensity statin therapy. And for those with a CAC of 1-100, the decision defaulted to the results of the Pooled Cohort Equations. The screening results were provided to a patient’s primary physician so they could engage in joint decision-making regarding initiation of statin therapy. Adherence to a screening-based recommendation to start on a statin was assessed at 3 and 12 months of follow-up, explained Dr. Muhlestein, a cardiologist at the Intermountain Medical Center Heart Institute in Salt Lake City.
He noted that CorCal Vanguard was merely a feasibility study. Based on the study results he presented at ACC 2020, the full 9,000-patient CorCal primary prevention trial is now enrolling participants. CorCal is the first randomized trial to pit the Pooled Cohort Equations against the CAC score in a large study looking for differences in downstream clinical outcomes.
The rationale for this line of clinical research lies in the known limitations of the ACC/AHA risk calculator. “It may overestimate risk in some populations, patients aren’t always adherent to Pooled Cohort Equations Risk Calculator recommendations, and it doesn’t include novel risk markers such as C-reactive protein that some consider important for risk assessment. And the big question: Should we continue risk screening to determine potential benefit from drug therapy, or should we switch to disease screening?” the cardiologist commented.
The CorCal Vanguard results
A recommendation to start statin therapy was made in 48% of patients in the Pooled Cohort Equations group, versus 36% of the group randomized to CAC. However, only 17% of patients in the Pooled Cohort Equations group actually initiated a statin, a significantly lower rate than the 26% figure in the CAC arm. Fully 70% of patients who received a recommendation to start taking a statin on the basis of their CAC score actually did so, compared to just 36% of those whose recommendation was based upon their Pooled Cohort Equations Risk Calculator.
At 3 months of follow-up, 61% of patients who received an initial recommendation to start statin therapy based upon their CAC screening were actually taking a statin, compared with 41% of those whose recommendation was based upon the Pooled Cohort Equations. At 12 months, the figures were 64% and 49%.
In both groups, at 12 months of follow-up, the No. 1 reason patients weren’t taking a statin as recommended was that their personal physician had advised against it or never prescribed it. That accounted for roughly half of the nonadherence. Another quarter was because of a preference to try lifestyle change first. Fear of drug side effects was a less common reason.
Putting the CorCal Vanguard study results in perspective, Dr. Muhlestein observed that, prior to the screening study, none of the participants had ever been on a statin, yet 37% of them were found by one screening method or the other to be at high cardiovascular risk. Of those high-risk patients, 51% actually initiated statin therapy and the majority of them were still taking their medication 12 months later.
“That has to be a good thing. It emphasizes what can be done when proactive primary prevention is practiced,” the cardiologist said.
He reported having no financial conflicts regarding the CorCal study, which was funded by a grant from the Dell Loy Hansen Cardiovascular Research Fund.
SOURCE: Muhlestein JB et al. ACC 2020, .