Introduction Hypertrophic cardiomyopathy (HCM) is an autosomally transmitted cardiomyopathy with an estimated gene prevalence of 1:500, and an important cause of sudden cardiac death. Screening to identify at risk first degree relatives is therefore recommended. The British Heart Foundation (BHF) recently funded nine Nationwide cardio-genetic nurses to support local initiatives. Our application for a nurse was successful and we present our 12-month experience of HCM screening.
Methods We mapped the course of patients with suspected HCM referred to our tertiary heart muscle clinic which serves a population of 1.4million. Following phenotype confirmation, a family tree and contact details from the index case were recorded by the cardio-genetic nurse. The index case was given literature to pass onto at risk relatives. The information pack included an open invitation (referral via primary care) to attend for screening. For relatives residing outside our catchment area screening was arranged via links with the BHF cardio-genetic network and other health care providers. Relatives domiciled outside UK were given our details with offers to support screening. Throughout, strict adherence to patient confidentiality was maintained.
Results Over 12 months, 64 index HCM cases presented to our heart muscle clinic. Pedigree analysis identified 221 first degree relatives at risk of carrying the HCM gene; mean index-to-at RR: 1-to-3.4 (range 0–14 subjects). Of the 221 at risk subjects, 71 (19 through paediatrics) have undergone screening through clinical assessment at our unit with plans for long-term 2–5 yearly follow-up in view of variable gene penetrance. Of the 71 screened subjects, 15 were newly diagnosed with HCM. Newly diagnosed HCM patients underwent further risk stratification for sudden cardiac death; where we identified 3 patients at high risk (≥2 conventional high sudden death risk factors). After appropriate counselling, these 3 patients have received primary prevention defibrillators. Despite our approach, 52 subjects remain unscreened (Abstract 77 table 1), either due to complex family relationships (n=14), personal preference (n=28) and/or geographical/logistical reasons (n=10).
Conclusions Proactive screening for HCM can be effectively facilitated by cardio-genetic nurse services. Each new index case generates 3–4 at risk relatives who require long-term surveillance. Of 71 asymptomatic at risk subjects screened in our unit, we diagnosed 15 new cases of HCM, and 3 patients at high risk of sudden cardiac death who subsequently received primary prevention defibrillator implantation.
- Hypertrophic cardiomyopathy