Severe bradyarrhythmia linked to left atrial dysfunction in Fabry disease-A cross-sectional study.

BACKGROUND: Fabry disease (FD) is a lysosomal storage disorder caused by an enzymatic deficiency. Conduction abnormalities and bradyarrhythmias are common and can occur prior to the onset of left ventricular (LV) hypertrophy. We aimed to describe the clinical, electrocardiographic and echocardiographic, including left atrial (LA) function, determinants of bradyarrhythmic events in FD. HYPOTHESIS: Bradyarrhythmic events are frequent in patients with FD and are associated with LA dysfunction. METHODS: We designed a cross-sectional study that includes 53 FD patients (mean age, 45 years; 42% male). Clinical characteristics and electrocardiographic and echocardiographic data were collected. LA function was measured using biplane volumes and 2D speckle-tracking echocardiography. Bradyarrhythmic events were defined as pause of more than 2 seconds (sinus pause or atrioventricular block) recorded on Holter, severe bradycardia (≤ 40 bpm on ECG) or implantation of a permanent pacemaker. RESULTS: Six (11%) patients had installation of a pacemaker, 4 (8%) patients had cardiac pause and 2 (4%) patients had an episode of severe bradycardia. Patients with bradyarrhythmic events were older and had a lower resting heart rate. On echocardiography, a significantly higher LV mass, a lower LV ejection fraction, and a more affected LA reservoir function were found in those with bradyarrhythmic events. Patients also experienced tachyarrhythmias frequently. Atrial fibrillation occurred in 11 (21%) patients and ventricular tachycardia in 4 (8%) patients. CONCLUSIONS: Bradyarrhythmia are common manifestations of cardiac involvement in FD. Age, LV mass, LV ejection fraction and LA reservoir dysfunction can be useful markers associated with bradyarrhythmia.

Impaired Left Atrial Function in Fabry Disease: A Longitudinal Speckle-Tracking Echocardiography Study.

BACKGROUND: Fabry disease (FD) is characterized by the accumulation of sphingolipids in multiple organs, including the left atrium. It is uncertain if the left atrial (LA) reservoir, conduit, and contractile functions evaluated by speckle-tracking echocardiography are affected in Fabry cardiomyopathy and whether enzyme replacement therapy can improve LA function. METHODS: In this retrospective cohort study, LA strain, strain rates, and phasic LA volumes were studied in 50 patients with FD and compared with values in 50 healthy control subjects. RESULTS: All three LA phasic functions were altered. Peak positive strain (reservoir function) was 38.9 ± 14.9% versus 46.5 ± 10.9% (P = .004), and late diastolic strain (contractile function) was 12.6 ± 5.9% versus 15.6 ± 5.3% (P = .010). In 15 patients who started enzyme replacement therapy during the study, most of the LA parameters improved at 1-year follow-up (peak positive strain from 32.0 ± 13.5% to 38.0 ± 13.5%, P = .006), whereas there was a trend toward deterioration in 15 patients who never received treatment (peak positive strain from 47.3 ± 10.8% to 41.3 ± 9.3%, P = .058). Nine patients with FD (21%) experienced new-onset atrial fibrillation or stroke during 4-year follow-up. By univariate analysis, peak positive strain and early diastolic strain demonstrated significant associations with clinical events, surpassing conventional echocardiographic parameters and clinical characteristics. CONCLUSIONS: LA reservoir, conduit, and contractile functions by speckle-tracking echocardiography were all affected in FD. Enzyme replacement therapy improved LA function. LA strain parameters were associated with atrial fibrillation and stroke.

A Longitudinal Low Dose µCT Analysis of Bone Healing in Mice: A Pilot Study.

Low dose microcomputed tomography (µCT) is a recently matured technique that enables the study of longitudinal bone healing and the testing of experimental treatments for bone repair. This imaging technique has been used for studying craniofacial repair in mice but not in an orthopedic context. This is mainly due to the size of the defects (approximately 1.0 mm) in long bone, which heal rapidly and may thus negatively impact the assessment of the effectiveness of experimental treatments. We developed a longitudinal low dose µCT scan analysis method combined with a new image segmentation and extraction software using Hounsfield unit (HU) scores to quantitatively monitor bone healing in small femoral cortical defects in live mice. We were able to reproducibly quantify bone healing longitudinally over time with three observers. We used high speed intramedullary reaming to prolong healing in order to circumvent the rapid healing typical of small defects. Bone healing prolongation combined with µCT imaging to study small bone defects in live mice thus shows potential as a promising tool for future preclinical research on bone healing.