Advanced CT Test Simulates Blood Flow to Assess Risk in Patients with Angina

Coronary artery calcium is considered as a surrogate marker for total coronary plaque, a fatty buildup in the arteries that can result in a heart attack in the future. A calcium score above 400 is a warning sign of high plaque levels. Non-contrast enhanced cardiac CT is typically performed prior to CT angiography to determine the amount of coronary artery calcium. However, high calcium content can interfere with CT images, making them tough to evaluate. While CT angiography helps identify coronary artery disease, it does not reveal how this condition impacts blood flow. Disrupted blood flow can create abnormal pressure, making these plaques more likely to break open. Now, an advanced CT test can identify individuals with stable angina who are at a reduced risk for negative outcomes over three years, even if their calcium scores are high.

In a prospective study, researchers from the University Hospital of Southern Denmark (Esbjerg, Denmark) looked at the three-year clinical results of patients who went through CT angiography and another specialized scan known as CT angiography-derived fractional flow reserve (CT-FFR). This advanced test combines CT images, AI algorithms, and fluid dynamics calculations to mimic the blood flow in the coronary arteries. The study involved patients newly diagnosed with stable coronary artery disease, who were part of the ADVANCE clinical trial conducted between December 2015 and October 2017 across three locations in Denmark. To be part of this study, patients needed to have at least one coronary artery narrowed by more than 30% and must not have had a history of irregular heartbeats or previous procedures to improve heart blood flow.

Out of 900 participants, 523 had normal CT-FFR results (average age 64, 318 males) and 377 showed abnormal CT-FFR findings (average age 65, 264 males). The three-year adverse outcome rate, which includes death from any cause and non-fatal heart attacks, was just 2.1% (11 out of 523) in the normal CT-FFR group. On the other hand, this rate was 6.6% (25 out of 377) in the abnormal CT-FFR group. Interestingly, those with a high calcium score but normal CT-FFR results had a 2.2% (4 out of 182) adverse outcome rate over three years. The rate soared to 9% (19 out of 212) for those with both high calcium scores and abnormal CT-FFR results. According to the team, while there are various methods to study the effects of coronary artery disease on blood flow, CT-FFR stands out for its high diagnostic accuracy. It aligns well with fractional flow reserve, a more invasive measurement method. The researchers believe that CT-FFR could help doctors categorize patients by risk level and focus on improving the outlook for those at higher risk.

“Our study provides evidence for the prognostic potential of CT-FFR in patients with high coronary artery calcium scores,” said lead researcher Kristian T. Madsen, M.D. “Regardless of the patient’s baseline risk and extent of coronary artery disease measured by coronary artery calcium, if CT-FFR results are normal, the prognosis is good.”

“In my opinion, CT-FFR is the best option because it provides a blood-flow estimate similar to what you would obtain if you performed invasive heart catheterization. You get a reliable and quick answer without performing additional tests or putting the patient through an invasive procedure,” added Madsen. “CT-FFR provides diagnostic and prognostic information beyond what can be obtained from CT angiography alone across a wide range of coronary artery calcium levels. It’s a tool that offers a lot of exciting prospects for the future.”

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University Hospital of Southern Denmark