Fabry disease (FD) is an X-linked lysosomal storage disorder caused by mutations of the GLA gene that result in a deficiency of the enzymatic activity of α-galactosidase A and consequent accumulation of glycosphingolipids in body fluids and lysosomes of the cells throughout the body. GB3 accumulation occurs in virtually all cardiac cells (cardiomyocytes, conduction system cells, fibroblasts, and endothelial and smooth muscle vascular cells), ultimately leading to ventricular hypertrophy and fibrosis, heart failure, valve disease, angina, dysrhythmias, cardiac conduction abnormalities, and sudden death. Despite available therapies and supportive treatment, cardiac involvement carries a major prognostic impact, representing the main cause of death in FD. In the last years, knowledge has substantially evolved on the pathophysiological mechanisms leading to cardiac damage, the natural history of cardiac manifestations, the late-onset phenotypes with predominant cardiac involvement, the early markers of cardiac damage, the role of multimodality cardiac imaging on the diagnosis, management and follow-up of Fabry patients, and the cardiac efficacy of available therapies. Herein, we provide a comprehensive and integrated review on the cardiac involvement of FD, at the pathophysiological, anatomopathological, laboratory, imaging, and clinical levels, as well as on the diagnosis and management of cardiac manifestations, their supportive treatment, and the cardiac efficacy of specific therapies, such as enzyme replacement therapy and migalastat.

Mavacamten is approved to treat adults with symptomatic obstructive hypertrophic cardiomyopathy (HCM). However, its effects in nonobstructive HCM remain uncertain. We conducted a phase 3, international, double-blind, placebo-controlled, clinical trial to determine whether mavacamten improves functional capacity and patient-reported health status among adults with symptomatic nonobstructive HCM. Patients were randomly assigned in a 1:1 ratio to receive mavacamten (starting at 5 mg per day and adjusted up to a maximum of 15 mg per day on the basis of left ventricular ejection fraction) or placebo (with sham dose adjustment) for 48 weeks. The two primary end points were the change from baseline to week 48 in peak oxygen uptake and in the 23-item Kansas City Cardiomyopathy Questionnaire clinical summary score (KCCQ-CSS; scores range from 0 to 100, with higher scores indicating better health status). We randomly assigned 289 patients to receive mavacamten and 291 to receive placebo. The mean (±SD) age of the patients was 56±15 years, and 46% were women. From baseline to week 48, the least-squares mean change in peak oxygen uptake was 0.52 ml per kilogram of body weight per minute (95% confidence interval [CI], 0.09 to 0.95) in the mavacamten group and 0.05 ml per kilogram per minute (95% CI, -0.38 to 0.47) in the placebo group (between-group difference, 0.47 ml per kilogram per minute; 95% CI, -0.03 to 0.98; P = 0.07). The least-squares mean change in the KCCQ-CSS was 13.1 points (95% CI, 10.7 to 15.5) in the mavacamten group and 10.4 points (95% CI, 8.0 to 12.8) in the placebo group (between-group difference, 2.7 points; 95% CI, -0.1 to 5.6; P = 0.06). Reductions in ejection fraction and interruptions in the trial regimen were more common with mavacamten than with placebo. Among patients with nonobstructive HCM, mavacamten did not result in a significantly greater improvement in peak oxygen uptake or decrease in symptoms than placebo. (Funded by Bristol Myers Squibb; ODYSSEY-HCM ClinicalTrials.gov number, NCT05582395.).

Fabry disease (FD) is a lysosomal storage disorder caused by mutations of the GLA gene that lead to a deficiency of the enzymatic activity of α-galactosidase A. Available therapies for FD include enzyme replacement therapy (ERT) (agalsidase alfa and agalsidase beta) and the chaperone migalastat. Despite the large body of literature published about ERT over the years, many issues remain unresolved, such as the optimal dose, the best timing to start therapy, and the clinical impact of anti-drug antibodies. Migalastat was recently approved for FD patients with amenable GLA mutations; however, recent studies have raised concerns that “in vitro” amenability may not always reflect “in vivo” amenability, and some findings on real-life studies have contrasted with the results of the pivotal clinical trials. Moreover, both FD specific therapies present limitations, and the attempt to correct the enzymatic deficiency, either by enzyme exogenous administration or enzyme stabilization with a chaperone, has not shown to be able to fully revert FD pathology and clinical manifestations. Therefore, several new therapies are under research, including new forms of ERT, substrate reduction therapy, mRNA therapy, and gene therapy. In this review, we provide an overview of the state-of-the-art on the currently approved and emerging new therapies for adult patients with FD.

Knowledge on clinical profiles of late-onset phenotypes of Fabry disease (FD) is essential to better define their natural history. Our study aims to demonstrate a founder effect of FD due to the GLA gene mutation c.337T>C (p.F113L) in the Portuguese region of Guimarães; and to characterize the clinical profile of this late-onset phenotype in a large cohort of genetically related adult patients, living in the same region. FD screening was performed in 150 adult patients with hypertrophic cardiomyopathy (HCM) and found 25 Fabry patients (16.6%). The p.F113L mutation was found in 21 of them, leading to a genealogy study and haplotype analysis of the p.F113L patients. Genealogy research revealed a 12-generation family tree with a common ancestor to p.F113L patients, suggesting a founder effect that was supported by haplotype findings. Pedigree analysis was performed and 120 consecutive p.F113L patients underwent a predefined diagnostic evaluation of FD multiorgan involvement. This late-onset phenotype was characterized by common and/or potentially severe cardiac manifestations (left ventricular hypertrophy 40.8%, atrial fibrillation 5%, non-sustained ventricular tachycardia 12.5%, atrioventricular block 18.3%, bifascicular block 13.4%). Extracardiac manifestations included albuminuria>30 mg/24 h 36.1%, chronic kidney disease≥G3 7.6%, brain white matter lesions 54.4%, stroke 3.3%, sensorineural deafness 44.5%, cornea verticillata 13.9%. Plasma lyso-GB3 was undetectable in females, regardless of clinical manifestations. A founder effect of FD due to p.F113L mutation was documented by genealogy and genetics in a Portuguese region. In this late-onset phenotype, although cardiac manifestations carry the highest prognostic impact, extracardiac involvement is common.

In the HELIOS-B randomized clinical trial, the RNA interference therapeutic agent vutrisiran reduced the risk of all-cause mortality and recurrent cardiovascular events among patients with transthyretin amyloidosis with cardiomyopathy (ATTR-CM). In this secondary analysis of HELIOS-B, we evaluated vutrisiran’s effects on echocardiographic measures of cardiac structure and function in patients with ATTR-CM receiving vutrisiran or placebo (n = 654, 93% men). At 30 months after treatment, as compared to the placebo group, vutrisiran treatment attenuated increases in mean left ventricular (LV) wall thickness (least squares mean difference: −0.4 mm; 95% confidence interval (CI): −0.8, 0.0; P = 0.03) and LV mass index (−10.6 g m^{− 2}; 95% CI: −18.0, −3.3; P < 0.01). Vutrisiran treatment also attenuated declines in LV ejection fraction (2.0%; 95% CI: 0.3, 3.7; P = 0.02), absolute global longitudinal strain (1.2%; 95% CI: 0.7, 1.7; P < 0.01) and LV stroke volume (4.1 ml; 95% CI: 1.7, 6.4; P < 0.01), and decreased both the average ratio of early diastolic transmitral flow velocity to early diastolic mitral annular tissue velocity (−2.0; 95% CI: −2.9, −1.2; P < 0.01) and the early to late diastolic transmitral flow velocities ratio (−0.3; 95% CI: −0.6, −0.0; P = 0.04), as compared to placebo. Consistent with its clinical benefits, these echocardiographic findings indicate favorable effects of vutrisiran on cardiac structure and function in patients with ATTR-CM. ClinicalTrials.gov registration: NCT04153149.

The common GLA gene mutation p.F113L causes late-onset phenotype of Fabry disease (FD) with predominant cardiac manifestations. A founder effect of FD due to this mutation was found in the Portuguese region of Guimarães. Our study aims to deepen the knowledge on the natural history of this late-onset variant. 203 consecutive adult Fabry patients with p.F113L mutation (79 males; mean age 46 ± 18 years), from this region, were submitted at baseline to a predefined diagnostic protocol. The occurrence of FD manifestations was analyzed in each decade of age in both genders. In males, left ventricular hypertrophy (40.2%) and late gadolinium enhancement (21.4%) arose over 30 years; heart failure (HF) (21.9%), ventricular tachycardia (8.9%) and conduction disorders over 40 years; and bifascicular (13.1%) and complete atrioventricular blocks (5.9%) beyond 50 years of age. Cardiac manifestations occurred more commonly and 1-2 decades earlier in males; their frequency increased with age. Septum and posterior wall thickness, LV mass, QRS interval duration and pro-BNP levels increased with age in both genders. Mean survival free from HF (64 ± 1 vs. 76 ± 2 years) and pacemaker (71 ± 2 vs. 86 ± 1 years) was higher in females (p < .001). Albuminuria A2/A3 (33.7%), brain white matter lesions (50.3%) and sensorineural deafness (44.7%) arose before 30 years of age in both genders, increasing with age. Renal failure and stroke were rare. Lysosomal inclusions were demonstrated in podocytes of patients with proteinuria. This study improves the knowledge on natural history of late-onset variants of FD, carrying major impact on clinical decisions and guidelines.