ROD2 domain filamin C missense mutations exhibit a distinctive cardiac phenotype with restrictive/hypertrophic cardiomyopathy and saw-tooth myocardium

INTRODUCTION AND OBJECTIVES

Missense mutations in the filamin C (FLNC) gene have been reported as cause of inherited cardiomyopathy. Knowledge of the pathogenicity and genotype-phenotype correlation remains scarce. Our aim was to describe a distinctive cardiac phenotype related to rare missense FLNC variants in the ROD2 domain.

METHODS

We recruited 21 unrelated families genetically evaluated because of hypertrophic cardiomyopathy (HCM)/restrictive cardiomyopathy (RCM) phenotype carrying rare missense variants in the ROD2 domain of FLNC (FLNC-mRod2). Carriers underwent advanced cardiac imaging and genetic cascade screening. Myocardial tissue from 3 explanted hearts of a missense FLNC carrier was histologically analyzed and compared with an FLNC-truncating variant heart sample and a healthy control. Plasmids independently containing 3 FLNC missense variants were transfected and analyzed using confocal microscopy.

RESULTS

Eleven families (52%) with 20 assessed individuals (37 [23.7-52.7]) years showed 15 cases with a cardiac phenotype consisting of an overlap of HCM-RCM and left ventricular hypertrabeculation (saw-tooth appearance). During a median follow-up of 6.49 years, they presented with advanced heart failure: 16 (80%) diastolic dysfunction, 3 heart transplants, 3 heart failure deaths) and absence of cardiac conduction disturbances or skeletal myopathy. A total of 6 families had moderate genotype-phenotype segregation, and the remaining were de novo variants. Differential extracellular matrix remodeling and FLNC distribution among cardiomyocytes were confirmed on histology. HT1080 and H9c2 cells did not reveal cytoplasmic aggregation of mutant FLNC.

CONCLUSIONS

FLNC-mRod2 variants show a high prevalence of an overlapped phenotype comprising RCM, HCM and deep hypertrabeculation with saw-tooth appearance and distinctive cardiac histopathological remodeling.

Clinical Risk Prediction in Patients With Left Ventricular Myocardial Noncompaction

BACKGROUND

Left ventricular noncompaction (LVNC) is a heterogeneous entity with uncertain prognosis.

OBJECTIVES

This study sought to develop and validate a prediction model of major adverse cardiovascular events (MACE) and to identify LVNC cases without events during long-term follow-up.

METHODS

This is a retrospective longitudinal multicenter cohort study of consecutive patients fulfilling LVNC criteria by echocardiography or cardiovascular magnetic resonance. MACE were defined as heart failure (HF), ventricular arrhythmias (VAs), systemic embolisms, or all-cause mortality.

RESULTS

A total of 585 patients were included (45 ± 20 years of age, 57% male). LV ejection fraction (LVEF) was 48% ± 17%, and 18% presented late gadolinium enhancement (LGE). After a median follow-up of 5.1 years, MACE occurred in 223 (38%) patients: HF in 110 (19%), VAs in 87 (15%), systemic embolisms in 18 (3%), and 34 (6%) died. LVEF was the main variable independently associated with MACE (P < 0.05). LGE was associated with HF and VAs in patients with LVEF >35% (P < 0.05). A prediction model of MACE was developed using Cox regression, composed by age, sex, electrocardiography, cardiovascular risk factors, LVEF, and family aggregation. C-index was 0.72 (95% confidence interval: 0.67-0.75) in the derivation cohort and 0.72 (95% confidence interval: 0.71-0.73) in an external validation cohort. Patients with no electrocardiogram abnormalities, LVEF ≥50%, no LGE, and negative family screening presented no MACE at follow-up.

CONCLUSIONS

LVNC is associated with an increased risk of heart failure and ventricular arrhythmias. LVEF is the variable most strongly associated with MACE; however, LGE confers additional risk in patients without severe systolic dysfunction. A risk prediction model is developed and validated to guide management.

Prevalence of wild type ATTR assessed as myocardial uptake in bone scan in the elderly population

BACKGROUND

Myocardial uptake of bone tracers has emerged as useful tool for the early detection of transthyretin amyloidosis (ATTR). The prevalence of wild-type ATTR (ATTRwt) in individuals remains to be established.

METHODS

All whole body bone scans performed in individuals ≥ 75 years with no previous clinical suspicion of ATTR were revised in a population-based university hospital over a 7-year period (1509 studies corresponding to 1114 patients; 80.5 ± 4.1 years, 65% males). Positive cardiac uptake was defined according to Perugini score as grade 2 or 3. Heart failure (HF) hospitalizations during the follow-up were obtained from regional administrative databases.

RESULTS

Thirty-one patients ≥ 75 years (2.78%) showed cardiac uptake; compared with those without uptake, these patients were older (85 ± 5 vs. 80 ± 4, p < 0.001) and predominantly males (90% vs. 64%, p = 0.005). The prevalence of cardiac uptake was 3.88% in males and 0.77% in females, and increased with age, reaching 13.9% in males≥85 years (2.7% among females). The estimated prevalence for the European standard population ≥ 75 years was 4.15% in males, 1.03% in females and 2.59% in the general population. HF hospitalizations rates were 14% in patients without uptake and 29% in those with cardiac uptake (p = 0.034). After adjusting for age and gender, cardiac uptake was associated with a higher risk of HF hospitalization (OR 2.60, 95%CI 1.09-5.74, p = 0.022).

CONCLUSIONS

Myocardial uptake in bone scan is very prevalent with ageing, mainly affects males and is associated with an increased risk of HF hospitalization. These findings reinforce ATTRwt as a relevant cause of HF in the elderly.