Abstract Body (Do not enter title and authors here): Background: The ISCHEMIA trial questioned revascularization in chronic coronary syndrome (CCS) patients, but excluding subjects with left main (LM) coronary artery disease (CAD). A widely available diagnostic method excluding LMCAD would expand the implementation of an initial noninvasive strategy.
Objective: Assessing the ability of excluding LMCAD through clinical and ECG stress testing (EST) variables in patients undergoing coronary angiography (CAG) for CCS.
Methods: In a multicenter retrospective case-control study we evaluated CCS subjects undergoing CAG after a maximal EST. Cases were patients with angiographic ≥50% LM stenosis or ≥70% stenoses of both proximal left anterior descending and proximal circumflex arteries; we matched them with similar patients without LMCAD (Controls) in a 1:3 ratio. Models were internally validated through logistic regressions.
Results: 219 Cases were matched with 554 Controls. The c-statistic was 0.80 (optimism-adjusted: 0.73). Assuming LMCAD prevalence of 5% and a misclassification cost ratio of 1:100 (ratio of the cost of performing CAG in a subject without LMCAD to the cost of not performing CAG in a patient with LMCAD), the negative predictive value was 98.6%, correctly classifying 84.5% of Cases. CAG could be spared in 57.0% of subjects, missing one LMCAD diagnosis every 70 CAGs spared in patients without LMCAD (Figure).
Conclusions: Among patients with CCS, LMCAD can be predicted with acceptable diagnostic accuracy and a very high negative predictive value through a model based on clinical and EST parameters, allowing an initial noninvasive management of most patients able to perform an EST, reducing the costs of routine coronary imaging. Such results should enlarge the applicability of the ISCHEMIA results when coronary computed tomography angiography, used in ISCHEMIA, is not available, limiting the referral to invasive CAG.