Cardiac Cycle-Dependent Variations in Mitral Annulus Size in Mitral Regurgitation: An ECG-gated CT Analysis

Mitral regurgitation, caused by backward blood flow in the heart, can lead to heart failure and arrhythmias. In severe cases, mitral valve replacement is necessary. However, mitral valve replacement carries risks of complications and prolonged recovery periods, highlighting the increasing use of transcatheter mitral valve replacement as an alternative. The prosthetic valve used in transcatheter mitral valve replacement is selected based on the maximum size of the mitral annulus, and accurate measurement of the annulus size is crucial to minimize procedural complications. This study analyzes the dynamic changes of the mitral annulus throughout the cardiac cycle using electrocardiocram gated computed tomography and proposes the optimal cardiac phase for selecting prosthetic valves in transcatheter mitral valve replacement. A retrospective analysis was conducted on patients diagnosed with mitral regurgitation who underwent electrocardiocram gated computed tomography between January 2023 and February 2025. The study population consisted of 30 patients with normal sinus rhythm and 30 patients with arrhythmias. The circumference, area, anteroposterior distance, and intercommissural distance of the mitral annulus were measured at various phases of the cardiac cycle. The results showed that the maximum mitral annulus size occurred at the 40% phase of systole, while the minimum size was observed at the 0% phase of diastole. Significant differences were found across all measured parameters (p<0.05), and inter-observer reliability was high (ICC >0.8). Therefore, measuring the mitral annulus at the 40% phase of the cardiac cycle, when the annulus reaches its maximum size, is recommended to minimize complications in transcatheter mitral valve replacement.