Objective To establish the minimum clinical importance difference of the Seattle Angina Questionnaire (SAQ) in patients with coronary heart disease, evaluate its reactivity, and construct a localized efficacy evaluation standard. Methods: A prospective cohort study was conducted. A total of 387 patients with coronary heart disease admitted to the Department of Cardiology of Bozhou People's Hospital from May 2024 to November 2025 were selected, and divided into the drug treatment group and percutaneous coronary intervention group according to the treatment methods. The data of SAQ, SF-36 and Overall Impression of Change Scale for patients were collected at baseline and 2 to 3 months after treatment. In accordance with the COSMIN guidelines, the minimum clinical importance difference (MCID) was determined by combining the anchoring method and distribution method, and the reactivity of SF-36 was compared.

Results The scores of physical limitation, attack frequency and changes in disease cognition dimension of SAQ were strongly positively correlated with PGIC (r = 0.671-0.693, P ＜ 0.01), and the validity of the benchmark was better than that of SF-36. After rounding, the optimal cutoff values of MCID for the dimensions of physical limitation, attack frequency and disease cognition were 11, 10 and 8 points, respectively, and the AUCs were 0.912, 0.923 and 0.953, respectively, all ＞0.90, and the thresholds remained stable between the drug treatment group and percutaneous coronary intervention group. In terms of reactivity, the standardized response mean of each dimension of SAQ (1.82–1.95) was higher than that of SF-36 (0.55–0.61) (P ＜ 0.01).

Conclusions SAQ has excellent longitudinal validity and reactivity in patients with coronary heart disease, and its sensitivity in capturing minor clinical improvements is significantly better than that of the general scale SF-36. The localized MCID threshold defined in this study provides a scientific yardstick for determining substantial clinical improvement, and is recommended as the core tool for evaluating the symptom burden of coronary heart disease.