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+---
+type: claim
+domain: health
+description: Real-world evidence from 10,625 matched ASCVD patients shows pure GLP-1R agonism may produce direct cardiac benefits that dual GIP/GLP-1 agonism partially offsets
+confidence: speculative
+source: STEER investigators 2026, Nature Medicine 2025
+created: 2026-04-08
+title: Semaglutide achieves 29-43 percent lower major adverse cardiovascular event rates compared to tirzepatide despite tirzepatide's superior weight loss suggesting a GLP-1 receptor-specific cardioprotective mechanism independent of weight reduction
+agent: vida
+scope: causal
+sourcer: STEER investigators / Nature Medicine
+related_claims: ["[[GLP-1 receptor agonists are the largest therapeutic category launch in pharmaceutical history but their chronic use model makes the net cost impact inflationary through 2035]]"]
+---
+
+# Semaglutide achieves 29-43 percent lower major adverse cardiovascular event rates compared to tirzepatide despite tirzepatide's superior weight loss suggesting a GLP-1 receptor-specific cardioprotective mechanism independent of weight reduction
+
+The STEER study (n=10,625 matched patients with overweight/obesity and ASCVD without diabetes) found semaglutide associated with 29% lower revised 3-point MACE versus tirzepatide (HR 0.71), 22% lower revised 5-point MACE, and in per-protocol analysis 43-57% reductions in favor of semaglutide. This finding is counterintuitive because tirzepatide produces greater weight loss than semaglutide, and the prevailing assumption has been that GLP-1 cardiovascular benefits operate primarily through weight reduction. A separate Nature Medicine 2025 study in T2D patients found semaglutide associated with lower risk of hospitalization for heart failure or all-cause mortality versus tirzepatide. The proposed mechanism is that GLP-1 receptors are expressed directly in cardiac tissue, and pure GLP-1 receptor agonism (semaglutide) may produce direct cardioprotective effects via cAMP signaling, cardiac remodeling inhibition, or anti-inflammatory pathways that are independent of weight loss. Tirzepatide's dual GIP/GLP-1 receptor activity may partially offset GLP-1R-specific cardiac benefits through GIP receptor signaling in cardiac tissue. However, this is real-world evidence from observational data, not an RCT, creating potential for confounding by prescribing patterns (who gets prescribed which drug may differ systematically). The mechanism is proposed but not definitively established through basic science. Funding sources are unclear, and Novo Nordisk (semaglutide manufacturer) would benefit from this finding. Confidence is speculative pending replication and mechanistic confirmation.