P379The value of T1 mapping in the presentation of chest pain with left ventricular hypertrophy

Abstract

Clinical Case: A 54-year old gentleman presented with chest pain and light-headedness and had a history of one episode of suspected myocarditis, diagnosed on the basis of epicardial late gadolinium enhancement (LGE) on cardiac MRI (CMR), in 2011. On the current presentation, ECG showed intermittent Mobitz II and complete A-V block, and Troponin T elevation (94ng/L). Consequently, he underwent coronary angiography with stenting to a (small) second diagonal (D2) vessel. However, intermittent brady arrhythmias and non-sustained ventricular tachycardia persisted and an inpatient CMR was obtained. Several abnormalities were similar to 2011, including a mildly dilated left ventricle (LV), severe diffuse LV hypertrophy (maximal wall thickness 22mm), sub-epicardial LGE (basal-mid lateral) and sub-endocardial LGE (basal inferoseptal). Despite a mild decline in LV ejection fraction (65 to 50%) and the D2 stent, there was no evidence of a new MI (Figure). T1 mapping with a MOLLI 5s(3s)5s sequence showed reduced T1 values (typically 890-950msec) but T2 mapping values were normal (44-50msec) (Figure). Low T1 values suggested possible diagnoses of Fabry's disease or haemochromatosis, but the other features were more suggestive of hypertensive heart disease as well as forms of hypertrophic cardiomyopathy (HCM). This included HCM caused by mutations in AMPKinase where intracellular glycogen accumulation may conceivably result in altered T1 values. Following implantation of a dual chamber ICD, he was discharged pending additional tests. Very low alpha-galactosidase activity levels have subsequently been found and confirmatory genetic testing for Fabry disease will follow. This case highlights the role of CMR in the evaluation of undiagnosed heart muscle disorders. In this case, the incremental importance of parametric mapping is illustrated, as is the need to exercise caution in the interpretation of epicardial LGE or any other imaging finding in isolation. Finally, increased T2 values were not detected, as might be expected in an inflammatory presentation of Fabry's disease.