P5274Characterization of cardiac involvement in patients with MELAS syndrome in comparison to HCM patients by conventional LGE imaging and novel T1-mapping

Abstract

Abstract Background MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) is a rare clinical subtype of mitochondrial myopathy. Cardiovascular magnetic resonance (CMR) images of MELAS-patients at an advanced state of the disease often show characteristic patterns: septal pronounced left ventricular (LV) hypertrophy and distinct focal myocardial scars in late-gadolinium-enhancement (LGE) images. This specific pattern is different from those seen in patients with hypertrophic cardiomyopathy (HCM) due to sarcomere protein mutations. Besides LGE imaging another method for the assessment of myocardial integrity, T1-mapping, has been established recently. This is the first study comparing native and enhanced T1-mapping (T1-na/en) as well as extracellular volume (ECV) values in HCM and MELAS. Methods 12 patients with confirmed MELAS syndrome at different states of the disease, 13 HCM patients and 15 controls were included. All CMR studies were performed on a 1.5T MR scanner (Ingenia, Philips) using bSSFP cine sequences for the assessment of LV-function and MOLLI sequences for T1-na/en mapping. 15min after IV injection of 0.1mmol/kg BW Gadobutrol for LGE imaging, T1-en maps were acquired. For comparison of groups T1-na/en and ECV values in a basal short axis slice were used. Results Median and interquartile ranges of LV function, T1 and ECV are shown in the table. There was no difference in LV ejection fraction (LVEF) between the groups, but end-diastolic LV-mass was increased in HCM- and MELAS-patients vs. controls (p<0.001, p=0.028). In MELAS-patients, myocardial fibrosis was detected in focal spots clearly defined in both septum and free lateral wall. In HCM patients there was a rather diffuse LGE pattern in the hypertrophic septum and the RV insertion points. Here T1-na/en and ECV significantly differed from those measured in healthy controls (p<0.001, p<0.001, p=0.002). In the MELAS group T1-na values were significantly higher compared to controls (p=0.004) and significantly lower compared to HCM patients (p=0.003). LV-function and mapping parameters of compared groups LV-EF, % LV-EDV, ml/m2 LV-mass, g/m2 T1-na, ms T1-en, ms ECV, % MELAS 57 (44–63) 86 (81–122) 80 (50–131) 969 (940–1033) 409 (381–465) 27 (24–35) HCM 60 (57–65) 50 (73–94) 94 (72–102) 1041 (1021–1074) 362 (346–430) 31 (28–36) Controls 61 (58–65) 72 (67–89) 53 (42–60) 937 (894–951) 464 (446–513) 26 (24–27) Conclusion Compared to healthy controls and HCM-patients, cardiac involvement in MELAS-patients is not only reliably visualized by conventional LGE imaging but also detected without the use of contrast agent by native T1-mapping. MELAS vs. HCM-patients show a different pattern of LGE and higher native T1 values, respectively.