Nonobstructive CAD on Cardiac CTA a Golden Opportunity to Boost Statin Prescribing

Subclinical atherosclerosis identified on coronary computed tomography angiography (CTA) in the emergency department (ED) translates into an increase in statin therapy in the ensuing 6 months for patients with nonobstructive coronary artery disease, a new study shows. The findings, while reassuring, speak to the importance of acting on CTA findings, even if patients are discharged home without needing further interventions, its authors say.

Indeed, nearly one-third of high-risk individuals found to have nonobstructive CAD in the ED still weren’t treated with the lipid-lowering medications.

“People with nonobstructive plaque are getting more statin prescriptions and their LDL cholesterol is appropriately lowered,” said senior investigator Pradeep Natarajan, MD (Massachusetts General Hospital, Boston, MA). “Separately, though, there is still an opportunity. It’s not like everybody that has plaque and an abundance of risk factors is being prescribed statins. Even among the highest-risk patients based on their clinical risk factors, one in three of those individuals who also have plaque is not being prescribed a statin.”

For the new study, published online July 17, 2019, in JACC: Cardiovascular Imaging, the researchers included 510 patients with nonobstructive CAD (defined as a maximal luminal stenosis ranging from 1% to 49% on cardiac CTA) and 510 controls without CAD. To TCTMD, Natarajan said they approached the study more as preventive cardiologists and less as CTA researchers. For patients with chest pain presenting to the emergency department, cardiac CT is frequently used to noninvasively diagnose CAD, and while some patients go on to invasive angiography and PCI, a large percentage have negative CT tests.

“Although a large fraction of them have negative cardiac CTs, negative cardiac CTs can come in a couple of different flavors,” said Natarajan. “There can be absolutely no plaque, or there could be some plaque but not enough to explain the symptoms the patients present with. Both of those are fine for discharge from the emergency department, but that latter represents an opportunity for prevention.”

Incidental Cardiac CTA Findings From the ED

The 2018 cholesterol guidelines provide support for the use of CT-derived measures of subclinical disease, specifically coronary artery calcification screening, but cardiac CTA is not often covered by insurers to assess subclinical atherosclerosis in asymptomatic individuals. In the current study, patients presented with chest pain to the emergency department, where they underwent CTA. This gave the researchers the opportunity to study whether the presence of nonobstructive CAD on imaging altered primary prevention prescribing patterns, specifically the optimization of statin therapy.

Individuals with nonobstructive CAD were older, more likely to be male, and had higher body mass index than the healthy control arm. They were also more likely to have hypertension, diabetes, and impaired glucose levels. The mean 10-year risk of atherosclerotic cardiovascular disease (ASCVD) using the clinical risk score was 10.6% among patients with nonobstructive disease and 4.4% among the controls without CAD. Overall, 36% and 14% of patients with nonobstructive CAD were considered intermediate and high risk for ASCVD, respectively.

After identification of nonobstructive CAD on cardiac CTA, the prevalence of statin use increased from 38.8% to 56.1% over 6 months (P < 0.001). In the control group, statin use increased from 18.0% to 20.4% (P = 0.01). In the multivariate analysis, there was a more than sevenfold increase in statin prescriptions when nonobstructive CAD was documented on cardiac CTA compared with when no disease was found (OR 7.1; 95% CI 4.4-23.0). For those with nonobstructive CAD, statins were newly started for 90 patients and the dose was increased in another 36 patients. In contrast, among controls, just 15 people were newly started on statins and just eight had their dose increased.

Aspirin use also increased during follow-up in both arms, but to a greater extent among those with nonobstructive CAD. Those with subclinical disease were more likely to be referred to a nutritionist for weight management.

At baseline, the mean LDL cholesterol level in the control and nonobstructive CAD groups was 121.0 mg/dL and 115.7 mg/dL, respectively. Nearly 2 years into follow-up, the mean LDL cholesterol level was 116.8 mg/dL in the control arm and 101.9 mg/dL in patients with nonobstructive CAD. Additionally, those with nonobstructive CAD were more likely than those without CAD to have LDL cholesterol levels less than 100 mg/dL and less than 70 mg/dL, respectively. 

Still, despite evidence that longitudinal outpatient caregivers responded to the additional data from cardiac CTA, Natarajan pointed to the fact that among high-risk patients with nonobstructive CAD (10-year risk ASCVD risk ≥ 20%), 30% were not prescribed a statin. One in three intermediate-risk patients with nonobstructive disease also were not taking a statin in follow-up.    

“There is still an opportunity, even among patients where we have a sense that statins would be helpful, including in the primary prevention setting,” said Natarajan. The incidental information gleaned from a cardiac CTA can be used by primary-care physicians to really “hammer the point home in the shared decision-making conversation” that statins can be beneficial, he added.