Radial global strain by cardiac magnetic resonance imaging predicts arrhythmic outcomes in hypertrophic cardiomyopathy

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Hypertrophic cardiomyopathy (HCM) is a relatively prevalent condition associated with arrhythmic events and sudden cardiac death. Several tools are currently available to identify which HCM patients are at risk of developing these events. Purpose We aimed to evaluate the association of Tissue Tracking strain analysis by cardiac magnetic resonance (CMR) and the development of arrhythmic events in patients with HCM. Methods We prospectively analyzed 136 consecutive patients with HCM diagnosis (established according to current clinical practice guidelines) from January 2006 to October 2017. Every routine 24 hours ECG-monitoring test was registered and looked for sustained or non-sustained ventricular tachycardia (any VT). CMR studies were performed following our predefined CMR protocol for HCM with 1.5T magnets. Cine images were obtained with standard, retrospectively gated, steady-state free-precession (SSFP) sequences in 2, 3 and 4 chambers views and in 10–15 contiguous short-axis slices covering the ventricles from the base to the apex, with breath holding. The strain evaluation was performed by a commercially available Tissue Tracking analysis software, manually defining the endocardial border in short axis, 4, 3 and 2 chambers views and, after verifying adequate identification of the different structures, running the strain analysis (Figure 1, displaying myocardium identification by the strain analysis software). Results Mean follow-up was 49 ± 45 months. Mean age was 61 ± 15 years old (p for the comparation between the group with arrhythmic and the group without arrhythmic events 0.212) and 31% of patients were women (p 0.420). Mean ejection fraction was 69 ± 9.21% (p 0.223) and mean HCM-SCD (hypertrophic cardiomyopathy sudden cardiac death) risk score was 2.20 ± 1.34 (p <0.001). Median percentage of total myocardium showing late gadolinium enhancement (LGE) was 0.61 (interquartile range 2.9; p 0.170). Mean global radial strain (GRS) was 26.23 ± 8.78% (p <0.001). 21 VT episodes were recorded during follow-up. GRS showed an area under de ROC curve of 0.75 predicting VT during follow-up, selecting the value of 27% as the best sensitivity/specificity cutoff point. Statistically significant differences were not found when analyzing global circumferential strain (GCS) and global longitudinal strain (GLS) as VT predictors after adjusting for possible confusion factors (GRS, GCS and GLS distributions depicted in Figure 2). A binary GRS ≥27%/<27% variable was included in a logistic regression model adjusted by age, percent of total myocardium mass showing LGE and HCM-SCD risk score. Significantly more arrhythmic events were found to occur in patients with a GRS <27% (OR 7.33; 95% confidence interval 1.07 – 50.41; p 0.043) after adjusting by age, percent of total myocardium mass showing LGE, and HCM-SCD risk score Conclusions A GRS value of <27% on CMR appears to be a good predictor of worse arrhythmic prognosis in patients with HCM.