Predictive value greater in nonobstructive CAD
When evaluated in nonobstructive disease, the predictive value of FAI was even greater. In obstructive CAD patients, the increased risk of MACE for the fourth relative to the first quartile was increased threefold (HR 3.15; P < .001), but it was increased almost fivefold among those with nonobstructive CAD (HR 4.77; P < .001). The increases for cardiac mortality were fivefold (HR 5.15; P < .001) and more than 10-fold (HR 10.49; P < .001) in these groups, respectively.
When a risk model based on AI that incorporated FAI plus other cardiovascular risk factors was applied retrospectively to the ORPHAN data, the predicted and actual event graph lines were nearly superimposable over a follow-up to 10 years at risk levels ranging from low to very high.
When this inflammation-based AI model was evaluated against standard risk prediction in patients with nonobstructive CAD, 30% of patients were reclassified to a higher risk category and 10% to a lower risk category.
When the AI-risk calculations were provided to clinicians at four hospitals over a recent 1-year period, it resulted “in changes of management in approximately half of patients,” Dr. Antoniades said.
Overall, Dr. Antoniades said these data provide evidence that coronary inflammation is an important driver of residual risk in patients who have nonobstructive CAD on CCTA, and he believes that the AI-enhanced interpretation of the FAI-based inflammatory burden has the potential to become an important management tool.
“AI-risk assessment may transform risk stratification and management of patients undergoing routine CCTA,” Dr. Antoniades said.
Imaging has potential for expanded risk assessment
The AHA-invited discussant, Viviany R. Taqueti, MD, director of the cardiac stress laboratory at Brigham and Women’s Hospital, Boston, agreed with the promise of evaluating inflammatory infiltrate in the coronary arteries as well as looking at fat in other tissues, such as skeletal muscle, to better risk stratify patients, but she cautioned about the limitations of conclusions based on observational data.
“A registry is not a randomized trial,” she said.
Characterizing AI as a “black box” in terms of understanding methodology, she also recommended further studies to validate the relative contribution of AI to inflammation alone in risk stratification.
Still, she believes that the “explosive growth” in imaging has created new opportunities for more precisely evaluating cardiovascular risk. She said these might be particularly helpful in the context of the “changing landscape” in CAD driven by less smoking, more obesity, and increased statin use. Overall, she endorsed the basic questions Dr. Antoniades is exploring.
“This is an incredibly intriguing idea that deserves continuing research,” she said.
Dr. Antoniades reported financial relationships with Amarin, AstraZeneca, Caristo Diagnostics, Covance, Mitsubishi Tanabe, MedImmune, Novo Nordisk, Sanofi, and Silence Therapeutics. Dr. Taqueti reported no potential conflicts of interest.