FEATURE TRACKING-BASED STRAIN ANALYSIS PREDICTS THE PRESENCE OF MYOCARDIAL FIBROSIS AMONG PATIENTS WITH NON-ISCHEMIC CARDIOMYOPATHY

Abstract

Abnormal myocardial deformation has been described in the presence of regional fibrosis, as detected by late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMR) in patients with previous infarction, Fabry’s disease and hypertrophic cardiomyopathy. Mid-wall striae pattern fibrosis on LGE imaging has been shown to predict adverse cardiovascular outcomes among patients with non-ischemic cardiomyopathy. However, macroscopic mid-wall fibrosis is a late pathologic finding and requires administration of gadolinium based contrast agent. Non-contrast dependent markers heralding adverse remodeling are desired. In this study we describe a novel strain analysis tool employing feature tracking to predict the presence of mid-wall fibrosis in patients with non-ischemic cardiomyopathy. CMR imaging was performed in 117 patients with idiopathic non-ischemic cardiomyopathy, defined as a left ventricular ejection fraction (LVEF) <55% by CMR with no prior history of myocardial infarction and no CMR findings of ischemic or other specific cardiomyopathy states (ie. hypertrophic cardiomyopathy, amyloidosis, sarcoidosis). Blinded quantitative analysis was performed using a prototype version of a commercial software (cvi42, version 4.1.5 M192, Calgary, Alberta, Canada). Left ventricular regional strain analysis was performed to obtain both radial and circumferential strain of a mid-ventricular short axis slice cine image (Figure 1). Volumetric analysis of sequential short axis cine images was also performed. LGE images were visually scored for the presence of mid-wall striae fibrosis. Mean age was 57.8 +/- 14.5 years and 60 % of patients were male. CMR characteristics are summarized in Table 1. Mid-wall striae fibrosis was identified in 48 patients (41 %). These patients had greater indexed LV end diastolic and systolic volumes and total scar volume with lower LV and RV ejection fraction. Compared to patients without midwall striae fibrosis, radial and circumferential strain values were significantly lower in the mid anteroseptal segments among patients with midwall striae fibrosis despite corresponding anterolateral strain values being similar (Table 1). On multivariate analysis, patients with midwall striae fibrosis had a significantly lower anteroseptal to anterolateral strain ratio (AASR) for both radial (0.61±0.41 vs. 0.37±0.32, p=0.024) and circumferential strain (0.66±0.36 vs. 0.42±0.29, p=0.015). Of note, 15 (22%) patients had a low AASR despite having no midwall striae fibrosis on LGE imaging. AASR is strongly associated with the presence of midwall striae fibrosis in patients with non-ischemic cardiomyopathy. The prognostic utility of this novel imaging marker warrants future study within a prospective multi-centre study.View Large Image Figure ViewerDownload (PPT)