21 Jul When Should A Coronary CT Scan Be Repeated?
Medical Research: What are the main findings of the study?
Dr. Kumamaru: When a patient does not have diabetes and had no or ≤25% coronary stenosis in his/her previous coronary CT angiography (CCTA) performed within 3 years, the probability of newly developed coronary artery disease (CAD) is very low, suggesting no repeat CCTA necessary, even if the clinical scenario suggested CCTA to be appropriate. Especially, when coronary arteries were completely normal at the prior scan, no patient underwent subsequent revascularization during the study period.
Medical Research: Were any of the findings unexpected?
Dr. Kumamaru: Our cohort was a retrospectively selected population for whom clinicians had a clinical suspicion for the interval development of CAD, with a prior negative CCTA. We were surprised to find that significant stenosis was detected at the time of repeat scan only in 13.3% (74/555).
Medical Research: What should clinicians and patients take away from your report?
Dr. Kumamaru: Although CCTA is less invasive than catheter angiography, it still has radiation exposure and uses iodinated contrast medium. Therefore a comprehensive risk-benefit assessment remains mandatory. The current study identified a criterion to guide clinicians for making a decision about what to do with patients who had a prior CCTA excluding significant coronary stenosis, but have developed new or worsening symptoms. We recommend clinicians to assess identified three factors (diabetes status, time interval, and findings at the prior scan) and take them into consideration before sending patients to repeat CCTA.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Kumamaru: This is a single center study with single ethnicity. Ethnicity can influence the probability of significant stenosis. While we believe that identified predictors are reasonable, an external validation in different settings will be necessary before the guidelines are widely used in routine care.