Introduction/background The prevalence of Sudden Cardiac Death (SCD) in the Irish people aged 15–35 years is estimated at 2.68 per 100,000/yr. Over 1/3 of SCD deaths are attributed to cardiomyopathies which are frequently inherited in an autosomal dominant pattern, meaning 1st degree relatives have a 50% chance of being affected. Population screening for these conditions is challenging due to low prevalence, genetic heterogeneity and variable penetrance, along with insensitive diagnostic tools. Conventional echocardiography is an accepted tool in screening, however sensitivity varies considerably. Gadolinium contrast cardiac MRI (gCMR) in this population has not previously been evaluated.
Hypotheses The addition of gCMR as standard evaluation of 1st degree relatives of SCD victims will aid in identification of affected relatives at an earlier stage and improve our ability to prevent further deaths.
Methods This is a single center observational study of first degree relatives of SCD victims due to Cardiomyopathy. Assessment compromised a history, family pedigree, electrocardiogram (ECG), ambulatory ECG monitoring (Holter), exercise testing (EST), 2-Dimensional Echocardiogram (ECHO), signal average ECG (SAECG), and gCMR. All results interpreted by experienced physicians, and where necessary expert opinion from relevant specialities was sought. Patients were excluded from the study if they were aged below 16 years, pregnant or breastfeeding, or had renal impairment GFR < 30 ml/min/1.73 m2).
Results 102 individuals were included.
41 had abnormal gCMR (A-gCMR). Of these 54% had only structural abnormalities and almost 1/3 had structural abnormality with fibrosis as demonstrated by late gadolinium enhancement (LGE). 6 individuals had fibrosis only – ie no other structural findings.
CMR and ECHO agreed on 68% of results.
gCMR changed the diagnosis completely in 30 individuals.
gCMR identified a new diagnosis in 14% of individuals whose ECHO was reported as being normal. 38% of these new diagnoses were based on the identification of LGE.
gCMR was normal in 17% whose ECHO was reported to be abnormal (false positive ECHO) with most common issue being over-diagnosis of diastolic dysfunction.
A-gCMR positively correlated with abnormalities on the other non-imaging investigations compared with A-ECHO (an additional 14% had abnormal ECG and 7% had abnormalities on all 3 of ECG, EST and Holter).
Conclusion Addition of contrast enhanced CMR improves diagnostic accuracy and sensitivity compared to ECHO used in conventional screening in the 1st degree relatives of SCD due to Cardiomyopathy.
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