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Comment & Response
December 23, 2020

Consistency and Generalizability of Trials for Coronary Computed Tomography Angiography—Reply

Author Affiliations
  • 1Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
JAMA Cardiol. 2021;6(4):484. doi:10.1001/jamacardio.2020.6133

In Reply In discussing my Viewpoint,1 Newby and colleagues disagree with my statement that the results of the Scottish Computed Tomography of the Heart Trial (SCOT-HEART) were discordant with results of the Prospective Multicenter Imaging Study for Evaluation of Chest Pain (PROMISE) trial, and present several concerns. (1) SCOT-HEART included a broader population than the PROMISE trial. This is true but does not justify the inclusion in SCOT-HEART of patients with known coronary artery disease (CAD). (2) At 2 years, the trial results were almost identical. They cite a hazard ratio from SCOT-HEART of 0.62 (95% CI, 0.38-1.01; P = .053), which was measured at 1.7 years, and compared it with a hazard ratio of 0.66 (95% CI, 0.44-1.00; P = .049) from the PROMISE trial, which was measured in a secondary analysis at 12 months (8 months earlier). The primary analysis of the PROMISE trial measured a hazard ratio at 25 months (closer to 1.7 years) of 0.88 (95% CI, 0.67-1.13; P = .35), which is very different. (3) Singh et al2 show undeniable superiority of CCTA” compared with stress testing. I agree with the editorial by Douglas3 describing many shortcomings of the article by Singh et al,2 including exclusion of nearly one-third of the randomized patients, inclusion of patients with known CAD, and interpretation of the exercise electrocardiography by the sites as positive or negative without any standardized criteria, consideration of ST-segment changes, or consideration of exercise capacity. (4) The PROMISE score performed even better in SCOT-HEART. I disagree. When the PROMISE minimal risk tool was applied to the SCOT-HEART population, the initial calibration was poor. The model coefficients had to be reestimated for SCOT-HEART, creating a new score. (5) My interpretation of revascularization in SCOT-HEART was misleading. I apologize—my description of the meta-analyses4,5 was potentially misleading. The meta-analyses showed that revascularization after randomization to computed tomography angiography (CTA) was more frequent than revascularization after randomization to usual therapy (odds ratio, 1.77; 95% CI, 1.14-2.75; P = .01), but there was heterogeneity (I2 = 84%; P < .001 for heterogeneity) due to SCOT-HEART. In the PROMISE trial, revascularization was 97% higher in the CTA arm, but in SCOT-HEART, revascularization was only 18% higher in the CTA arm. As I indicated, revascularization was often performed within 1 year in both groups in SCOT-HEART in the absence of prognostically significant CAD. We do not know how these patients were selected.

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