borderline significantP = 0.05
In contrast, among patients who underwent surgical treatment, BB exposure was associated with a borderline significant reduction in ACM (HR = 0.65; 95% CI: 0.42–1.00; Z = 1.95; P = 0.05), although the heterogeneity within this subgroup remained high (I 2 = 98%, P < 0.00001).