Collateral Circulation Linked to Ischemic Burden and Chest Pain in Stable Angina

A placebo-controlled, n-of-1 study suggested that coronary collateralization may lessen the intensity of ischemic chest pain. The study included 51 participants with stable single-vessel coronary artery disease and angina. After discontinuing antianginal medications, participants recorded daily angina using a smartphone app for 14 days before undergoing invasive pressure wire studies and coronary flow reserve assessment. Each participant then received four 60-second balloon occlusions paired with indistinguishable placebo inflations in randomized order, during which pain intensity was rated on a 10-point scale. Results showed little correlation between daily angina frequency and ischemic severity measured by fractional flow reserve or instantaneous wave-free ratio. However, lower ischemic indices were strongly associated with greater collateral flow, and higher collateral flow was linked to lower pain intensity. Collateral flow and pain responses remained stable across repeated occlusions, showing no evidence of ischemic preconditioning. The findings offer insight into the nonlinear relationship between coronary stenosis, ischemia, and angina. Source: https://www.ahajournals.org/