Risk Calculators Miss Many Patients Who Present With First MI

Roughly half of patients who present to the hospital with their first MI would not have been eligible for statin therapy based on two popular risk-assessment tools had they been seen in a cardiology clinic 2 days prior to the event, according to the results of a new study.

Among the study’s 465 MI patients, all age 65 years or younger with no known coronary artery disease, 45% would not have been recommended statin therapy or sent for diagnostic imaging based on their 10-year risk of atherosclerotic cardiovascular disease (ASCVD) on the ASCVD Risk Estimator Plus calculator.

Based on the more contemporary PREVENT equations, which have replaced the older pooled cohort equations for risk assessment, 61% would not have been recommended statins or sent for imaging. Moreover, 54% experienced chest pain for the first time only 24 hours prior to their MI.

Anna Mueller, MD (Icahn School of Medicine at Mount Sinai, New York, NY), lead author of the paper published this week in JACC: Advances, told TCTMD that primary prevention patients are typically seen by physicians who rely on risk- and symptom-based tools to identify those who require more intensive treatment. Patients at intermediate or high risk are prescribed lipid-lowering therapy, such as statins, or might be sent for further diagnostic imaging.

However, clinical events still frequently occur in patients deemed low risk by the current calculators or in those without symptoms, she said.  

Senior investigator Amir Ahmadi, MD (Icahn School of Medicine at Mount Sinai), said that while current screening tools work well at the population level, “they are not optimal for capturing the risk of individual patients.”

Instead, Ahmadi said, the focus should be more on looking for subclinical disease with tools such as CT angiography. “We would be treating the disease,” as opposed to treating risk based on surrogate markers like LDL cholesterol, he said. Even for patients with low LDL cholesterol levels, it’s no guarantee their vessels are free from atherosclerosis.

To reduce the large burden of cardiovascular disease, the researchers write in their paper, “prevention strategies should move beyond focusing on traditionally high-risk individuals and include those often classified as low risk.”

No Signs Just 2 Days Before

In the present study, the researchers wanted to start with patients who presented with a first MI to two large hospitals and work backwards. The aim was to simulate how well the current guideline-directed risk-assessment tools would have performed if applied 2 days before presentation. In this way, they could determine if the patients would been prescribed medication or sent for further testing based on risk scoring.

Of those who presented, 81% were male. One-third had an ASCVD Risk Estimator Plus score below 5%, putting them at low risk. Another 12% were considered low-to-intermediate risk, with a 10-year risk score of 5% to 7.5%. Using the PREVENT risk equations, 45% were considered low risk and another 16% at low-to-intermediate risk. None of these patients would have been recommended a statin based on the 2018 American College of Cardiology/American Heart Association guidelines for the management of cholesterol.

When investigators looked at patient symptoms, 60% did not have chest pain or dyspnea until within 48 hours of presentation.

To TCTMD, Ahmadi said there is evidence showing that imaging-based detection of atherosclerosis, such as coronary artery calcium (CAC) scoring or CT angiography, is superior to traditional risk equations. He pointed out that cardiovascular disease remains the leading cause of death worldwide and that earlier detection with imaging, which is a more personalized approach, might be the most effective way to reduce this burden.

He likened this form of risk assessment to cancer screening by colonoscopy or mammography. Instead of waiting for cancer to develop, or evaluating only patients at high risk for cancer, such screening occurs in everyone to reduce the risk of disease.

For Mueller, the low-to-intermediate patient is where additional screening might be the most cost-effective. Ahmadi agreed that further research is still needed to determine the best timing and impact of imaging-based screening strategies, with several ongoing studies evaluating the role of CT angiography in patients at intermediate risk of cardiovascular events.

“The onus is on us to prove that [screening with imaging] reduces cardiovascular events,” said Ahmadi. However, he imagines that in the next 5 years or so, imaging will be more integrated within cardiovascular risk assessment independent of symptoms, a shift that will allow physicians to treat subclinical disease rather than based on risk estimates.