Inherited cardiovascular conditions generally inherit following an autosomal dominant pattern. When a mutation is detected in the proband, relatives can have predictive DNA testing, and - when they are carrier - be monitored and timely treated if needed. Currently, less than half of relatives attends genetic counselling. With the eCG Family Clinic, an easily accessible virtual clinic which better suits the needs and preferences of relatives will be offered. At the eCG Family Clinic, relatives will receive tailored information to support informed decision-making, a DNA-test at home if desired, and can be referred for local cardiac monitoring if relatives appear to be a carrier. Implementation of the eCG Family Clinic in clinical practice is compared to current practice in this clinical trial.

Background:

Inherited cardiovascular conditions generally inherit following an autosomal dominant pattern. When a mutation is detected in the proband, relatives can have predictive DNA testing, and - when they are carrier - be monitored and timely treated if needed. Currently, less than half of relatives attends genetic counselling. With the eCG Family Clinic, an easily accessible virtual clinic which better suits the needs and preferences of relatives will be offered. At the eCG Family Clinic, relatives will receive tailored information to support informed decision-making, a DNA-test at home if desired, and can be referred for local cardiac monitoring if relatives appear to be a carrier. Implementation of the eCG Family Clinic in clinical practice (intervention group) is compared to current practice (control group) in this clinical trial.

Hypotheses:

It is hypothesized that the eCG Family Clinic can lower practical barriers for at-risk relatives to attend genetic counselling and equally or better suit the needs of probands and relatives in this regard. A higher uptake of presymptomatic counselling in the eCG Family Clinic (intervention) group is expected.

Design:

A non-inferiority randomised controlled trial (RCT) design with two study arms (parallel-group, control- and intervention group) for this study was chosen. In this study, probands, at-risk relatives and genetic healthcare professionals will be recruited for this study. The Medical Ethical Committee of the University Medical Centre Utrecht (UMCU, NedMec) has approved the study design.

Measures:

In this RCT, the following outcome measures will be evaluated: (1) uptake of presymptomatic counselling among at-risk relatives, (2) satisfaction with provided care among healthcare professionals, probands and at-risk relatives, (3) impact on feelings of anxiety and worry among at-risk relatives, (4) time requested for care provision and administration. Uptake of presymptomatic testing will be evaluated using file research. Data on the other outcome measures will be collected using questionnaires. First, probands will be asked to fill out one questionnaire after informing at-risk relatives. In addition, at-risk relatives are asked to fill out a questionnaire twice: (a) shortly after the presymptomatic counselling (time-point 1) and, (b) after two/three months, in which at-risk relatives who chose to have DNA-testing, will have received their results. Finally, healthcare professionals involved in providing counselling will be asked to fill out one questionnaire after study completion. Questionnaires will also be used to administer sociodemographic and clinical characteristics of study participants.

Sample size calculation:

Assuming a two-sided 5% significance level and a power of 80%, 238 at-risk relatives ( 119 per study arm) will be included. Previous literature shows that on average four adult relatives per proband are at 50% risk of inheriting the genetic mutation. Using a conservative estimate of 3.5 relatives per proband, a total of 68 probands (34 per study arm) needs to be included in this study.

Statistical analyses:

Sociodemographic and clinical characteristics will be analysed using descriptive and frequency statistics. Differences in participant characteristics between study arms will assessed with chi-square tests / t-tests, as appropriate. Differences in uptake of genetic counselling will be analysed using chi-square tests; logistic regression analyses will be conducted to assess differences in uptake while controlling for the influence of coviarates. Multilevel analyses will be performed to assess whether the study group has an impact on satisfaction with the care provided and impact on psychological functioning, adjusted for coviarates. SPSS version 29.0.1 will be used to perform statistical analyses. A p-level of p<0.05 will be used.

Inclusion Criteria:

Probands:

• > 18 y/o
• Diagnosed with inherited hypertrophic cardiomyopathy (HCM) or dialted cardiomyopathy (DCM))
• Class 4 or 5 variant identified.
• Access to a working laptop or computer device.

At risk relatives:

• > 18 y/o
• First degree family member, or second degree in case of a deceased first degree relative
• Access to a working laptop or computer device.

Healthcare professionals:

- Genetic counsellors of the genetics department directly involved in the care given to the family.

Exclusion Criteria:

- Insufficient control of the Dutch language or digital skills.