Family Screening in Dilated Cardiomyopathy: Prevalence, Incidence, and Potential for Limiting Follow-Up.

BACKGROUND: According to patterns of inheritance and incomplete penetrance, fewer than half of relatives to dilated cardiomyopathy probands will develop disease. OBJECTIVES: The purpose of this study was to investigate the prevalence and incidence, and to identify predictors of developing familial dilated cardiomyopathy (FDC) in relatives participating in family screening. METHODS: The study was a retrospective, longitudinal cohort study of families screened and followed from 2006 to 2020 at a regional assembly of clinics for inherited cardiomyopathies. RESULTS: In total, 211 families (563 relatives, 50% women) were included. At baseline, 124 relatives (22%) were diagnosed with FDC. Genetic sequencing identified the etiology in 37% of screened families and classified 101 (18%) relatives as unaffected carriers (n = 43) or noncarriers (ie, not at risk of FDC [n = 58]). The combined clinical and genetic baseline yield was 30%. During follow-up (2,313 person-years, median 5.0 years), 45 developed FDC (incidence rate of 2.0% per person-year; 95% CI: 1.4%-2.8%), increasing the overall yield to 34%. The incidence rate of FDC was high in relatives with baseline abnormalities on electrocardiogram or echocardiography compared with relatives with normal findings (4.7% vs 0.4% per person-year; HR: 12.9; P < 0.001). In total, baseline screening identified 326 (58%) relatives to be at low risk of FDC. CONCLUSIONS: Family screening identified a genetic predisposition to or overt FDC in 1 of 3 relatives at baseline. Genetic and clinical screening was normal in more than half of relatives, and these relatives had a low risk of developing FDC during follow-up. Thus, baseline screening identified a large proportion, in whom follow-up may safely be reduced, allowing focused follow-up of relatives at risk.

Screening relatives in arrhythmogenic right ventricular cardiomyopathy: yield of imaging and electrical investigations.

AIMS: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease and presymptomatic screening of relatives is recommended. In 2010, the Task Force Criteria (TFC2010) introduced specific diagnostic imaging parameters. The aim of the study was to evaluate the diagnostic yield of family screening and the value of different diagnostic modalities. METHODS AND RESULTS: Family evaluation, including cardiac magnetic resonance (CMR), is routinely offered to ARVC relatives at our institution. We retrospectively registered baseline characteristics, symptomatology, and results of non-invasive examinations from 2010 to 2016 and assessed the findings according to TFC2010. A total of 286 relatives (150 females; age 12-76 years; 251 first-degree) were included. A total of 103 (36%) individuals reported cardiovascular symptoms. The non-invasive workup showed that 101 (35%) relatives had ≥1 positive parameter on signal-averaged electrocardiogram (ECG), 40 (14%) had abnormal findings on Holter monitoring, 36 (13%) fulfilled an ECG criterion, six (2%) fulfilled CMR criteria, and echocardiographic abnormalities was seen in one (0.3%) relative. In total, 21 (7% overall; 13% among gene-positive subgroup) relatives were diagnosed with ARVC and 78 (27% overall; 49% among gene-positive subgroup) with borderline ARVC based on the combined non-invasive evaluations. Family history and electrical investigations alone diagnosed 20 out of 21 (95%) ARVC cases and 73 out of 78 (94%) borderline cases. CONCLUSION: Consecutive evaluation of ARVC relatives diagnosed 7% with definite and 27% with borderline ARVC according to the TFC2010. Screening relatives for electrical abnormalities with 12 lead ECG, signal-averaged ECG, and Holter monitoring was more sensitive than imaging modalities.