Coronary Remodeling and Biomechanics: Are We Going with the Flow in 2020?

Under normal conditions, coronary blood flow (CBF) provides critical blood supply to the myocardium so that it can appropriately meet the metabolic demands of the body. Dogmatically, there exist several known regulators and modulators of CBF that include local metabolites and neurohormonal factors that can influence the function of the coronary circulation. In disease states such as diabetes and myocardial ischemia, these regulators are impaired or shifted such that CBF is reduced. While functional considerations have and continued to be well studied, more recent evidence builds upon established studies that collectively suggest that the relative roles of coronary structure, biomechanics, and the influence of cardiac biomechanics via extravascular compression may also play a significant role in dictating CBF. In this mini review, we discuss these regulators of CBF under normal and pathophysiological conditions and their potential influence on the control of CBF.

Abstract P321: Coronary Artery Remodeling and Subclinical Atherosclerosis: the CARDIA study

Atherosclerosis related inflammation and plaque result in expansive remodeling of the coronary artery, a finding associated with plaque rupture and clinical events. The extent of expansive coronary remodeling in adults prior to the development of clinical disease is largely unknown. We tested the hypothesis that middle-aged adults who have subclinical coronary artery disease also have larger coronary artery diameters. Methods: Submillimeter thin slice, non-contrast cardiac CT images were obtained in 1197 black and white men and women in the Coronary Artery Risk Development in Young Adults (CARDIA) Study during the year 25 examination (2010-2011, mean age 50 years). Average coronary artery diameter(mm) and cross sectional area (mm2) were measured sequentially along the length of each vessel and averaged for the left main (LM) and proximal circumflex (LCX), left anterior descending (LAD), and right coronary (RCA) arteries. Presence/absence of coronary artery calcifications [CAC (0 versus >0 AU)] was measured independently. Multivariable linear regression models were used to examine the association of CAC with artery size. Results: Coronary diameter was larger in blacks compared to whites (p<0.05) and in men compared to women (p<.0001) following adjustment for age and study center. Presence of CAC was associated with larger diameter coronary arteries after adjustment for age, race, sex, education, height, and study center (Table, model 1). These associations remained following additional adjustment for established cardiovascular risk factors, with the exception of the left main segment (Table, model 2), and were similar for vessel area as for vessel diameter (not shown). Conclusion: Coronary arteries are larger in middle-age individuals with vs without CAC, supporting the hypothesis that atherosclerosis leads to expansive coronary remodeling. Coronary remodeling by non-contrast CT is a measure that may provide new information on cardiovascular risk and prediction of clinical cardiovascular events.