Comparative Efficacy and Safety of Vasodilators Used to Prevent Internal Thoracic Artery Spasm in Coronary Artery Bypass Grafting: A Systematic Review.

Internal thoracic artery (ITA) spasm during coronary artery bypass grafting (CABG) can compromise graft flow and perioperative outcomes. This review systematically evaluates the comparative efficacy and safety of vasodilators used to prevent ITA spasm, including papaverine, glyceryl trinitrate-verapamil (GV) solution, systemic diltiazem, and efonidipine. Six studies comprising clinical, ex vivo, and in vitro investigations were included. GV solution consistently demonstrated superior vasodilatory efficacy, rapid onset (2.9 min), and high potency, achieving near-complete ITA relaxation and increasing intraoperative free flow by up to 95%, with minimal adverse events. Papaverine effectively prevented spasm at high concentrations but showed a slower onset. Systemic diltiazem improved graft flow safely, while efonidipine exhibited dose-dependent relaxation in ex vivo models, targeting both L- and T-type calcium channels. Delivery method influenced efficacy, with topical or intraluminal administration providing rapid, direct vasodilation. Overall, combination therapy (GV solution) offers a practical and safe approach for intraoperative ITA spasm prevention.