• cmr
• hcm
• strain

ABSTRACT
Background and aims: Hypertrophic Cardiomyopathy (HCM) is characterized by various clinical expression, from early onset of atrial fibrillation to malignant ventricular arrhythmias and end-stage forms. Cardiac magnetic resonance (CMR) is nowadays considered one of the main imaging techniques for morphological, functional and tissue evaluation of the cardiomyopathy. Myocardial strain analysis by CMR has increasingly been performed to assess the cardiac dysfunction in a variety of myocardial diseases. It is established that a reduction of contractile indexes, expressed by strain values, predicts worse prognosis in HCM [1] [2]. However, there are no studies in Literature investigating the myocardial strain variance (Δ global strain) obtained by two CMR scan during follow-up. This study aims to retrospectively examine the Δ global strain over time and the correlation with other CMR parameters, particularly myocardial fibrosis expressed as late gadolinium enhancement (LGE).
Methods: The CMR examinations were performed using 1.5 Tesla CMR scan (GE 1.5T MRI SIGNA Artist). 412 HCM patients that underwent a CMR scan were screened to detect those with two consecutive examinations. Every data analysis was performed using cvi42® (circle cardiovascular imaging) software. Indexes of left atrial and ventricular function including myocardial global strain, mass and extent of LGE (grams and percentage of LV mass) in both examinations were calculated as previously published [1].
Strain parameters intra and inter-operator reproducibility was confirmed by matching obtained data for a randomly selected subset of patients.
Results: Of 412 HCM patients in our clinical records, 94 had performed a follow-up CMR. Among these, 64 had adequate acquisitions for strain analysis in both the first and second scan. Our study population was therefore constituted of 64 HCM patients (45 males, 19 females). The median age of the study group at the time of the first CMR was 50,5 ± 16,9 years with a medium follow-up time for the second scan of 5,1 ± 2,6 years. Over time a worsening of every global strain (circumferential, p = 0.009; longitudinal p = 0.001; radial short axis, p = 0.03; radial long axis, p = 0.007), extent of LGE (p < 0.001) and left atrial ejection fraction (p < 0.001) was observed. A significant relationship of Δ global strain with Δ LGE (circumferential, r = 0.41, p < 0.001; longitudinal r = 0.28, p < 0.05; radial short axis, r = 0.37, p < 0.05; radial long axis, r = 0.27, p < 0.05) as well as with Δ left atrial function (circumferential, r = 0.43, p < 0.001; longitudinal r = 0.29, p < 0.05; radial short axis, r = 0.39, p < 0.001; radial long axis, r = 0.27, p < 0.05) was detected. Neither inter nor intra-operator results differed significantly; inter-operator reproducibility largely exceeded established cut-off of 0,8 average interclass correlation coefficient.
Conclusions: In HCM, we first demonstrated a worsening of Δ global strain over time and its correlation with progression of myocardial fibrosis. Δ global strain over time may be used in follow-up of HCM patients in a multimodality approach to predict LGE progression and potentially clinical consequences.