33 Sudden cardiac death and inherited premature conduction disease – potential role for implantable loop recorder in screening?

Background Cardiac conduction disease (CCD) is a potentially fatal entity. The spectrum ranges from a benign clinical course to severe dysfunction, which may precipitate sudden cardiac death. Permanent pacemaker (PPM) implant may benefit affected individuals but the genetic basis of CCD may be underestimated. No prior study has investigated the utility of screening relatives of victims of Sudden Arrhythmic Death Syndrome (SADS) with implantable loop recorders (ILR). Methods We describe 7 families referred to our inherited cardiac conditions service with a family history of SADS, in whom we identified premature CCD. ILR was utilized in screening the majority of families. Results Of 63 individuals screened, 31 (49%) had ILR insertion with 7 (11%) requiring PPM implant. 2/31 had normal baseline tests, and were identified only after ILR implant. Other CCD not yet meeting clinical significance was detected in 10/31 (32%) individuals. These findings (documented 11 to 330 days post implant) included pauses of 3–5.8 seconds (n=7), nocturnal bradycardia Conclusions Inherited premature CCD with variable penetrance and dynamic clinical manifestation may be an under-recognized cause of SADS. To date 12/31 (39%) of individuals with ILR have findings suggesting inherited CCD. As inheritance pattern suggests autosomal dominant transmission, longer follow up may identify more affected individuals. Clinicians involved in SADS family evaluations should consider adding ILR implantation to routine assessment to improve diagnostic yield. We suggest a larger prospective study of consecutive families whose initial investigations following a SADS death have not identified a cause.