Assessment of regional myocardial wall stress before and after surgical correction of functional ischaemic mitral regurgitation using multidetector computed tomography and novel software system☆☆☆
The objective of this study was to assess changes in left ventricular (LV) volume, function and regional myocardial wall stress in non-infarcted segments following restrictive mitral annuloplasty (RMA) in patients with ischaemic cardiomyopathy (ICM) and severe functional mitral regurgitation (MR).Twenty-two patients with ICM (ejection fraction <35%) and severe MR were investigated before and 3 months after RMA using cine-angiographic multidetector row computed tomography (cine-MDCT). For comparative purposes, 38 normal subjects were also studied. Cine-MDCT LV images were reconstructed in a cardiac cycle and regional circumferential wall stress (end-systolic stress (ESS)) was evaluated from the LV end-systolic image using Janz's method. The ESS was determined in six basal and six mid-LV segments of the ventricle based on AHA/ASE criteria. Five apical infarcted segments were not analysed. Mean circumferential fibre shortening (CFS) in both basal and mid-LV regions was determined as a parameter of regional systolic performance.Left ventricular end-diastolic volume (index) (LVEDVI) and left ventricular end-systolic volume (index) (LVESVI) decreased significantly and left ventricular ejection fraction (LVEF) increased after surgery. Neither end-systolic nor end-diastolic sphericity index changed significantly after surgery. Regional ESS significantly decreased in both basal and mid-LV regions after surgery. There was a significant inverse correlation between the change in average value of regional ESS and magnitude of increase in mean CFS of the mid-LV region (r=-0.67, p=0.0018). Postoperative reduction in ESS in the mid-LV region was also correlated with improvement in global EF (r=-0.72, p<0.01).The present cine-MDCT may be useful for assessing regional myocardial stress in patients with ICM. We found that RMA could reduce both end-diastolic and end-systolic volume leading to reduction in regional systolic wall stress, which resulted in improved ejection performance of non-infarcted myocardium in patients with functional MR and ICM.