Predictive value of the electrocardiogram exercise stress test for the presence or absence of left main disease

Background: The ability of the electrocardiogram exercise stress test (ECG-EST) in excluding the presence of left main (LM) coronary artery disease (CAD) has been poorly investigated. Methods: We retrospectively selected patients who underwent both ECG-EST and elective invasive coronary angiography (ICA) at our Institution between January 2018 and December 2023 due to angina pain suspected of obstructive CAD. Preventively defined individual and combined ECG-EST variables suggesting no/mild myocardial ischemia were assessed as predictors of the absence of LM disease. Some ECG-EST variables suggesting extensive/severe myocardial ischemia were instead assessed as predictors of the presence of LM disease, defined as a stenosis ≥50% of the left main artery. Results: Overall, 515 patients were included (age 66.2 ± 11 years; 74% men). LM disease at ICA was found in 26 patients (5%). Individual and combined ECG-EST variables showed low positive predictive values for LM-CAD [maximum 15% for a combination of ST-segment depression (STD) in ≥ 5 leads and ECG-EST duration <360 s]. The negative predictive value, however, was very high for some combined ECG-EST variables. Very low risk of LM disease (≤2.5%) was particularly shown in patients with peak heart rate (HR) ≥ 75% of maximal predicted HR for age and STD < 2 mm (prevalence 63.1%; risk 2.2%) and peak HR ≥85% of maximal predicted HR for age and maximal STD < 2 mm (prevalence 46.2%; risk 2.5%). Conclusions: Among patients with angina chest pain suspected of obstructive CAD, ECG-EST results can reliably identify those at very low risk of LM disease at coronary angiography.