Document Type


Date of Degree

Spring 2017

Access Restrictions

Access restricted until 07/13/2019

Degree Name

PhD (Doctor of Philosophy)

Degree In


First Advisor

Daack-Hirsch, Sandra

First Committee Member

Ahmad, Ferhaan

Second Committee Member

Ersig, Anne

Third Committee Member

Paik, Anthony

Fourth Committee Member

Williams, Janet K.


Background: Hypertrophic Cardiomyopathy (HCM) and Long QT Syndrome (LQTS) are genetic cardiovascular diseases that cause sudden cardiac death. When an individual is diagnosed with an inherited disease such as HCM/LQTS it is critical that their biological relatives are notified of their increased risk. Newly diagnosed individuals in turn notify other at-risk family members through a successive process called cascade screening. This facilitates screening of at-risk biological relatives through genetic testing and/or clinical testing, and treatment for HCM/LQTS prior to development of life-threatening complications. However, for cascade screening to detect all potential cases the disease risk must be effectively communicated to all at-risk relatives. The responsibility for notifying family members of this risk largely falls to the first person diagnosed in the family (proband). Empiric evidence suggests that around half of at-risk relatives are not screened in accordance with cascade screening recommendations, potentially due to information about HCM/LQTS risk not being communicated effectively in their families. Factors have been identified that influence communication about genetic risk in families with non-cardiac disease; however, it is not known if or how these factors apply in families with genetic cardiac disease. These include network factors, which describe characteristics of relationships between family members and non-network factors, which describe characteristics of individuals including individual factors, disease factors, and sociocultural factors. There is a critical need to understand communication in families with HCM/LQTS in order to facilitate effective genetic risk communication in families, improve adherence to cascade screening recommendations, and prevent death and complications from cardiovascular diseases.

Objectives: The purpose of this study was to improve our understanding of the relationships among network and non-network factors and communication of genetic risk for HCM/LQTS between probands and their relatives. I proposed the following aims:

Aim 1: Describe family social network structures and communication paths about risk for HCM/LQTS from probands to their relatives.

Aim 2: Identify which network and non-network factors are associated with who is told about risk for HCM/LQTS.

Methods: The sample for this study included individuals with HCM or LQTS recruited through the University of Iowa Cardiology Clinics (UI) and the University of Wisconsin Inherited Arrhythmia Clinic (UW). Data were collected using a structured interview, family pedigree, and survey. Analysis included egocentric social network analysis, descriptive, bivariate, and multilevel logit regression modeling.

Results: Participants in this study had an average of 24 living at-risk relatives in their families. Overall, just over half (52%) of these at-risk relatives had been reported to have been told about their risk. However, within families, the percentage of relatives told about their risk ranged from 0%-100%. Ninety percent of first-degree relatives were told about their risk, 61% of second-degree relatives were told and 33% of third-degree relatives were told. Recruitment site affiliation was determined to be a confounder and so analyses were calculated separately for UI and UW. In both the UI and UW samples, network factors including closer geographic distance, increased emotional closeness, increased relationship quality, increased frequency of communication, higher betweenness centrality, and closer degree of biological relation were independently associated with increased odds of communication of risk.

In the UI sample, non-network factors that were independently associated with increased odds of communication of risk included younger age at diagnosis; having LQTS; having positive genetic test results; having an ICD; younger current age; being female; having increased role limitations due to physical functioning; feeling anxious about telling family members about risk; feeling communication was a burden; feeling that communication was a responsibility or duty; being happy to be able to share important information; and identifying financial issues, pregnancies, or upcoming marriages as playing a role in communication. In a multivariate model, increased frequency of communication, closer degree of biological relation, having an ICD, and identifying financial issues and pregnancies as contributors to communication were significantly associated with communication of genetic risk information.

In the UW sample, non-network factors that were independently associated with increased odds of communication of risk included younger age, decreased emotional wellbeing, increased role limitations due to emotional wellbeing, and decreased energy and fatigue. In a multivariate model, increased frequency of communication and closer degree of biological relation were significantly associated with communication.

Although over half of at-risk relatives were told about their risk, just over half of those (53.8%) were reported to have screened for disease, which represents 27% of all at-risk relatives. Of those tested, 35% were reported as diagnosed with HCM/LQTS.

Conclusion: Communication of genetic risk for HCM/LQTS in families is inadequate and contributes to the problem of relatives not being screened for disease. Insight on the factors that influence communication in families at risk of sudden cardiac death can guide development of interventions, policies, and future research aimed at improving genetic risk communication and cascade screening, and preventing death and complications from inherited cardiac diseases. This research is applicable for genetic conditions where population based screening methods are not effective and rely on families to communicate risk and need for screening.

Public Abstract

Genetic cardiac diseases, including hypertrophic cardiomyopathy (HCM) and long QT syndrome (LQTS) can cause sudden death, heart failure, and stroke. Unfortunately, sudden death may be the first indication of disease. However, if disease is diagnosed early, treatments including medications, implanted defibrillators, and lifestyle changes are effective at reducing the risk of death and other symptoms.

The genetic nature of HCM/LQTS means that diagnosis in one person identifies high risk in their entire biological family for HCM/LQTS. These relatives should be notified of their risk and tested for disease so they can receive treatments to reduce their risk of the life-threatening effects of these diseases. Identification of relatives with disease determines who else in the family should be notified of risk and screened. This process, known as cascade screening, currently results in only half of at-risk relatives being screened for disease. Effective cascade screening relies on communication of genetic risk in families, with the responsibility to initiate this communication largely falling to the first person diagnosed in the family (proband) or to the parent in the case where a child is diagnosed.

This study aimed to understand the relationships among several factors and communication of genetic risk between probands and their relatives in families with HCM/LQTS. Normal communication frequency, biological relationship, the proband’s gender, implanted defibrillator status, and consideration of financial and pregnancy issues were associated with communication to relatives. With this information, clinicians can support improved communication about HCM/LQTS risk in families, thus promoting cascade screening to identify more relatives with HCM/LQTS.


cascade screening, hypertrophic cardiomyopathy, inherited cardiac conditions, long QT syndrome, risk communication


xiii, 201 pages


Includes bibliographical references (pages 192-201).


Copyright © 2017 Lisa Lynn Shah

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