Implications of three different testing strategies in the diagnostic approach to patients with stable chest pain and low pretest probability of obstructive coronary artery disease

Introduction: The clinical implications of a widespread adoption of guideline recommendations for patients with stable chest pain and low pretest probability (PTP) of obstructive coronary artery disease (CAD) remain unclear. We aimed to assess the results of three different testing strategies in this subgroup of patients: A) defer testing; B) perform coronary artery calcium score (CACS), withholding further testing if CACS ​= ​0 and proceeding to coronary computed tomography angiography (CCTA) if CACS>0; C) perform CCTA in all. Methods: Two-center cross-sectional study assessing 1328 symptomatic patients undergoing CACS and CCTA for suspected CAD. PTP was calculated based on age, sex and symptom typicality. Obstructive CAD was defined as any luminal stenosis ≥50% on CCTA. Results: The prevalence of obstructive CAD was 8.6% (n ​= ​114). In the 786 patients (56.8%) with CACS ​= ​0, 8.5% (n ​= ​67) had some degree of CAD [1.9% (n ​= ​15) obstructive, and 6.6% (n ​= ​52) nonobstructive]. Among those with CACS>0 (n ​= ​542), 18.3% (n ​= ​99) had obstructive CAD. The number of patients needed to scan (NNS) to identify one patient with obstructive CAD was 13 for strategy B vs. A, and 91 for strategy C vs. B. Conclusions: Using CACS as gatekeeper would decrease CCTA use by more than 50%, at the cost of missing obstructive CAD in one in 100 patients. These findings may help inform decisions on testing, which will ultimately depend on the willingness to accept some diagnostic uncertainty.