Bring chicken broth and garlic to a boil in a small saucepan over high heat. Reduce the heat to medium to simmer. Stir in artichoke hearts, lemon juice, and capers; simmer for 3 minutes. Add butter and whisk until melted.
Whisk water and cornstarch together in a small bowl; stir mixture into the sauce and continue cooking until thickened and bubbly, about 30 seconds.
