Heart failure–induced cardiovascular morbidity and mortality constitute a major health problem worldwide and result from diverse pathogeneses, including coronary artery disease, nonischemic cardiomyopathies, and arrhythmias. Assessment of cardiovascular performance is important for early diagnosis and accurate management of patients at risk of heart failure. During the past decade, cardiovascular magnetic resonance myocardial feature tracking has emerged as a useful tool for the quantitative evaluation of cardiovascular function. The method allows quantification of biatrial and biventricular mechanics from measures of deformation: strain, torsion, and dyssynchrony. The purpose of this article is to review the basic principles, clinical applications, accuracy, and reproducibility of cardiovascular magnetic resonance myocardial feature tracking, highlighting the prognostic implications. It will also provide an outlook on how this field might evolve in the future.

Cardiovascular Magnetic Resonance myocardial feature tracking (CMR-FT) is a quantitative technique tracking tissue voxel motion on standard steady-state free precession (SSFP) cine images to assess ventricular myocardial deformation. The importance of left atrial (LA) deformation assessment is increasingly recognized and can be assessed with echocardiographic speckle tracking. However atrial deformation quantification has never previously been demonstrated with CMR. We sought to determine the feasibility and reproducibility of CMR-FT for quantitative derivation of LA strain and strain rate (SR) myocardial mechanics. 10 healthy volunteers, 10 patients with hypertrophic cardiomyopathy (HCM) and 10 patients with heart failure and preserved ejection fraction (HFpEF) were studied at 1.5 Tesla. LA longitudinal strain and SR parameters were derived from SSFP cine images using dedicated CMR-FT software (2D CPA MR, TomTec, Germany). LA performance was analyzed using 4- and 2-chamber views including LA reservoir function (total strain [ε_s], peak positive SR [SRs]), LA conduit function (passive strain [ε_e], peak early negative SR [SRe]) and LA booster pump function (active strain [ε_a], late peak negative SR [SRa]). In all subjects LA strain and SR parameters could be derived from SSFP images. There was impaired LA reservoir function in HCM and HFpEF (ε_s [%]: HCM 22.1 ± 5.5, HFpEF 16.3 ± 5.8, Controls 29.1 ± 5.3, p < 0.01; SRs [s^-1]: HCM 0.9 ± 0.2, HFpEF 0.8 ± 0.3, Controls 1.1 ± 0.2, p < 0.05) and impaired LA conduit function as compared to healthy controls (ε_e [%]: HCM 10.4 ± 3.9, HFpEF 11.9 ± 4.0, Controls 21.3 ± 5.1, p < 0.001; SRe [s^-1]: HCM -0.5 ± 0.2, HFpEF -0.6 ± 0.1, Controls -1.0 ± 0.3, p < 0.01). LA booster pump function was increased in HCM while decreased in HFpEF (ε_a [%]: HCM 11.7 ± 4.0, HFpEF 4.5 ± 2.9, Controls 7.8 ± 2.5, p < 0.01; SRa [s^-1]: HCM -1.2 ± 0.4, HFpEF -0.5 ± 0.2, Controls -0.9 ± 0.3, p < 0.01). Observer variability was excellent for all strain and SR parameters on an intra- and inter-observer level as determined by Bland-Altman, coefficient of variation and intraclass correlation coefficient analyses. CMR-FT based atrial performance analysis reliably quantifies LA longitudinal strain and SR from standard SSFP cine images and discriminates between patients with impaired left ventricular relaxation and healthy controls. CMR-FT derived atrial deformation quantification seems a promising novel approach for the study of atrial performance and physiology in health and disease states.

Cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) is a recently described method of post processing routine cine acquisitions which aims to provide quantitative measurements of circumferentially and radially directed ventricular wall strain. Inter-study reproducibility is important for serial assessments however has not been defined for CMR-FT.

To assess intervendor agreement of cardiovascular magnetic resonance feature tracking (CMR-FT) and to study the impact of repeated measures on reproducibility. Ten healthy volunteers underwent cine imaging in short-axis orientation at rest and with dobutamine stimulation (10 and 20 μg/kg/min). All images were analysed three times using two types of software (TomTec, Unterschleissheim, Germany and Circle, cvi(42), Calgary, Canada) to assess global left ventricular circumferential (Ecc) and radial (Err) strains and torsion. Differences in intra- and interobserver variability within and between software types were assessed based on single and averaged measurements (two and three repetitions with subsequent averaging of results, respectively) as determined by Bland-Altman analysis, intraclass correlation coefficients (ICC), and coefficient of variation (CoV). Myocardial strains and torsion significantly increased on dobutamine stimulation with both types of software (p<0.05). Resting Ecc and torsion as well as Ecc values during dobutamine stimulation were lower measured with Circle (p<0.05). Intra- and interobserver variability between software types was lowest for Ecc (ICC 0.81 [0.63-0.91], 0.87 [0.72-0.94] and CoV 12.47% and 14.3%, respectively) irrespective of the number of analysis repetitions. Err and torsion showed higher variability that markedly improved for torsion with repeated analyses and to a lesser extent for Err. On an intravendor level TomTec showed better reproducibility for Ecc and torsion and Circle for Err. CMR-FT strain and torsion measurements are subject to considerable intervendor variability, which can be reduced using three analysis repetitions. For both vendors, Ecc qualifies as the most robust parameter with the best agreement, albeit lower Ecc values obtained using Circle, and warrants further investigation of incremental clinical merit.

Myocardial fibrosis (MF) might represent a key player in pathophysiology of heart failure in aortic stenosis (AS). We aimed to assess its impact on left ventricular (LV) remodelling, recovery, and mortality after transcatheter aortic valve implantation (TAVI) in different AS subtypes. One hundred patients with severe AS were prospectively characterized clinically and echocardiographically at baseline (BL), 6 months, 1 year, and 2 years following TAVI. Left ventricular biopsies were harvested after valve deployment. Myocardial fibrosis was assessed after Masson’s trichrome staining, and fibrotic area was calculated as percentage of total tissue area. Patients were stratified according to MF above (MF+) or below (MF−) median percentage MF (≥11% or <11%). Myocardial fibrosis burden differed significantly between AS subtypes, with highest levels in low ejection fraction (EF), low-gradient AS and lowest levels in normal EF, high-gradient AS (29.5 ± 26.4% vs. 13.5 ± 16.1%, P = 0.003). In the entire cohort, MF+ was significantly associated with poorer LV function, higher extent of pathological LV remodelling, and more pronounced clinical heart failure at BL. After TAVI, MF+ was associated with a delay in normalization of LV geometry and function but not per se with absence of reverse remodelling and clinical improvement. However, 22 patients died during follow-up (mean, 11 months), and 14 deaths were classified as cardiovascular (CV) (n = 9 arrhythmia-associated). Importantly, 13 of 14 CV deaths occurred in MF+ patients (CV mortality 26.5% in MF+ vs. 2% in MF− patients, P = 0.0003). Multivariate analysis identified MF+ as independent predictor of CV mortality [hazard ratio (HR) 27.4 (2.0–369), P = 0.01]. Histological MF is associated with AS-related pathological LV remodelling and independently predicts CV mortality after TAVI.