Assessment of Myocardial Fibrosis Using Multimodality Imaging in Severe Aortic Stenosis: Comparison With Histologic Fibrosis.

OBJECTIVES: This study assessed diffuse myocardial fibrosis (MF) by cardiac magnetic resonance (CMR) imaging and speckle-tracking echocardiography (STE) in patients with severe aortic stenosis (AS) and validated findings by using histologic confirmation of MF. BACKGROUND: MF is a concomitant pathologic finding related to hypertrophic response in severe AS. It would be beneficial to have reliable imaging methods to assess MF. METHODS: CMR and STE were performed in 71 consecutive patients with severe AS before aortic valve replacement. The extracellular volume (ECV) and native T1 values obtained by CMR and global longitudinal strain (GLS) values by STE were measured. The degree of MF was quantified by using Masson trichrome stain in myocardial biopsy specimens obtained intraoperatively. The study population was divided into 3 groups according to the degree of MF on histology (mild, moderate, and severe MF). RESULTS: The severe MF group had a higher incidence of heart failure (HF) and diastolic dysfunction than the mild and moderate MF groups. The ECV (r = 0.465; p < 0.0001), GLS (r = 0.421; p = 0.0003), and native T1 (r = 0.429; p = 0.0002) values were significantly correlated with the degree of MF. GLS was moderately correlated with ECV (r = 0.455; p = 0.0001) and less with the native T1 (r = 0.372; p = 0.0014) value. The model using ECV (R2 = 0.44; Akaike Information Criterion [AIC] = 55.8) was found to predict the degree of MF most accurately than that with GLS (R2 = 0.35; AIC = 66.84) and the native T1 (R2 = 0.36; AIC = 66.18) value. The secondary endpoint of interest was clinical outcome of a composite of total mortality, admission for HF, or development of HF symptoms. During follow-up (median: 4.6 years), and there were 16 clinical events. Although statistically insignificant, ECV is more closely related to prediction of the clinical outcome than native T1 or GLS. CONCLUSIONS: ECV as assessed by CMR could be an ideal surrogate marker for diffuse MF in patients with severe AS among all 3 models considered.

Predicting Left Ventricular Dysfunction after Surgery in Patients with Chronic Mitral Regurgitation: Assessment of Myocardial Deformation by 2-Dimensional Multilayer Speckle Tracking Echocardiography.

BACKGROUND AND OBJECTIVES: The development of postoperative left ventricular (LV) dysfunction is a frequent complication in patients with chronic severe mitral valve regurgitation (MR) and portends a poor prognosis. Assessment of myocardial deformation enables myocardial contractility to be accurately estimated. The aim of the present study was to evaluate the predictive value of preoperative regional LV contractile function assessment using two-dimensional multilayer speckle-tracking echocardiography (2D MSTE) analysis in patients with chronic severe MR with preserved LV systolic function. SUBJECTS AND METHODS: Forty-three consecutive patients with chronic severe MR with preserved LV systolic function scheduled for mitral valve replacement (MVR) or MV repair were prospectively enrolled. Serial echocardiographic studies were performed before surgery, at 7 days follow-up, and at least 3 months follow-up postoperatively. The conventional echocardiographic parameters were analyzed. Global longitudinal strain (GLS) was obtained quantitatively by 2D MSTE. RESULTS: The mean age of patients was 51.7±14.3 years and 25 (58.1%) were male. In receiver-operating characteristic curve analysis, the most useful cutoff value for discriminating postoperative LV remodeling in severe MR with normal LV systolic function was -20.5% of 2D mid-layer GLS. Patients were divided into two groups by the baseline GLS -20.5%. Preoperative GLS values strongly predicted postoperative LV remodeling or LV dysfunction. The postoperative degree of decrease in LV end-diastolic dimension might be an additive predictive factor. CONCLUSION: STE can be used to predict a decrease in LV function after MVR in patients with chronic severe MR. This promising method could be of use in the clinic when trying to decide upon the optimum time to schedule surgery for such patients.

Noninvasive assessment of left ventricular stroke work index in patients with severe mitral regurgitation: correlation with invasive measurement and exercise capacity.

BACKGROUND: Noninvasively measured left ventricular stroke work index (LVSWI) may be an ideal indicator that can provide more relevant information about cardiac performance in severe mitral regurgitation (MR). We sought to correlate the noninvasive LVSWI with invasive measure of LVSWI and validate its clinical usefulness by comparing the noninvasive LVSWI with exercise capacity. METHODS: Twenty-nine patients with severe MR who underwent cardiac catheterization and 61 patients with severe MR who underwent cardiopulmonary exercise test were evaluated for comparison of noninvasive LVSWI with invasive LVSWI via cardiac catheterization and peak exercise capacity, respectively. RESULTS: Mean noninvasive LVSWI was 33.1 ± 9.7 g·m/m², which was in a good agreement with invasive LVSWI (34.9 ± 15.1 g·m/m², intraclass correlation coefficient = 0.72, P < 0.001). Noninvasive LVSWI (ß= 0.35, P = 0.001) was independently related with peak exercise capacity. Indexed left atrial volume (ß=-0.27, P = 0.042), mean blood pressure (ß=-0.21, P = 0.030), age (ß=-0.47, P < 0.001) estimated pulmonary artery systolic pressure (ß=-0.21, P = 0.030) and male gender (ß= 0.36, P = 0.001) were also independently associated with exercise capacity. CONCLUSIONS: Noninvasive LVSWI has a good correlation with invasively measured LVSWI and is a clinically useful parameter for evaluating true cardiac performance in patients with severe MR.