MRI-based Multiparametric Strain Analysis Predicts Contractile Recovery after Aortic Valve Replacement for Aortic Insufficiency

Abstract

Background Guidelines for referral of chronic aortic insufficiency (AI) patients for aortic valve replacement (AVR) suggest that surgery can be delayed until symptoms or reduction in left ventricular (LV) contractile function occur. The frequent occurrence of reduced LV contractile function after AVR for chronic AI suggests that new contractile metrics for surgical referral are needed. Methods In 16 chronic AI patients, cardiac MRI tagged images were analyzed before and 21.5 ± 13.8 months after AVR to calculate LV systolic strain. Average measurements of three strain parameters were obtained for each of 72 LV regions, normalized using a normal human strain database (n=63), and combined into a composite index (multi-parametric strain z score [MSZ]) representing standard deviation from the normal regional average. Results Preoperative global MSZ (72-region average) correlated with post-AVR global MSZ (R2 = .825, p < .001). Preoperative global MSZ also predicts improvement of impaired regions (N=271 regions from 14 AI patients, R2 = .392, p < .001). Preoperative MRI-based left ventricular ejection fraction (LVEF) is also predictive (r = .410, p < .001). Although global preoperative MSZ had a significantly higher correlation than preoperative LVEF with improvement of injured regions (p < .001), both measures convey the same phenomenon. Conclusions Global preoperative MRI-based multi-parametric strain predicts global strain postoperatively, as well as improvement of regions (n=72/LV) with impaired contractile function. Global contractile function is an important correlate with improvement in regionally impaired contractile function, perhaps reflecting total AI volume-overload burden (severity/duration of AI).

Preliminary investigation of multiparametric strain Z‐score (MPZS) computation using displacement encoding with simulated echoes (DENSE) and radial point interpretation method (RPIM)

“…The terms ε c -μ n,c and ε l -μ n,l yield positive values and the negative of ε r -μ n,r yields a positive value. Ultimately, a computed z-score greater than zero implies a dysfunctional sub-region where it would be less than or equal to zero in a normally performing region [5, 14, 19–21]. MPZS therefore compares contractility to an established normal in the same myocardial sub-region in a database of healthy subjects.…”

“…The second step involved automated image-based boundary detection using the MR Analytical Software System (MASS) (Leiden University, Leiden, NL) and 3D reconstruction using an in-house C++ algorithm [14–18]. The third and last step was the development of an automated, high resolution LV myocardial function-based metric, the MRI-based Multiparametric Strain Z-Score (MPZS) [14, 19–21]. While a number of well-validated scoring methods for assessing clinical HF risks exist [22–28], a validated model of risk assessment based on an individual patient’s LV biomechanics is yet to become mainstream in clinical HF diagnosis [5, 14, 20, 21].…”

Quantifying “normalized” regional left ventricular contractile function in ischemic coronary artery disease

“…This testing has confirmed not only its accuracy in detecting regional wall motion abnormalities, but also the applicability of this high-resolution, dynamic cardiac geometric data acquisition in the clinical setting frequented by patients with advanced atherosclerotic coronary occlusive disease. We have in fact already applied this same methodology effectively in multiple other patient populations including those with aortic valvular disease, 12, 26 mitral valvular disease, 27 and non-ischemic dilated cardiomyopathy. 9 …”

Myocardial performance assessment in neonates by one-segment strain and strain rate analysis by tissue Doppler - a quality improvement cohort study

“…Only in three-dimensional datasets the deformation can be assessed independent of angle. Such three-dimensional datasets can be obtained by ultrasound49 and by MRI 50. The temporal resolution is low (frame rate by MRI typically 30/s and by 3D-echocardiography typically 20/s), in addition 3D ultrasound has extremely low-line density and such deformation analyses have so far to our knowledge only been used in adults.…”