Inclusion Criteria:
* All Canadian patients referred for cardiac investigations related to inherited heart rhythm (IHR) conditions will be invited to participate if they meet the following criteria:
* They understand the registry/bio bank purpose, potential risks and willingly sign consent
* Recognized genetic syndromes; Long QT syndrome (LQT), Short QT Syndrome (SQT), catecholaminergic polymorphic ventricular tachycardia (CPVT), Brugada (BrS), Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC), Familial Cardiac Conduction Disease (FCCD).
* Deceased cases of SCD, suspicious for an inherited heart rhythm condition. Included with signed consent from next of kin (NOK).
* IHR patients referred for risk of SCD enrolled (includes first degree and second degree relatives) SCD syndromes seen in heart rhythm clinics; Unexplained cardiac arrest (UCA), Early Repolarization (ER), Idiopathic Ventricular Fibrillation (IVF), Short Coupled IVF (SCIF), Polymorphic Ventricular Tachycardia Not Otherwise Diagnosed (PMVT, NYD), Sudden Arrhythmic Death Syndromes (SADS) that are SCD cases with negative autopsy results.
* Mendelian cardiomyopathies (hypertrophic cardiomyopathy (HCM), Mendelian Dilated Cardiomyopathy (DCM) including Lamin and Phosopholambin (LMNA, \& PLN), and Left Ventricular Non -Compaction (LVNC).
\*\*Must have either a probable or definite clinical diagnosis, first degree relative (FDR) with a known diagnosis, gene carrier (disease causing or likely disease causing by American College of Medical Genetics (ACMG 2015), or may be second degree relative (SDR) with inability to screen intervening relative
* Carriers of a pathogenic or likely-pathogenic variant for an inherited arrhythmia or cardiomyopathy related gene, not otherwise fitting inherited or cardiomyopathy diagnostic criteria
Exclusion:
Patients referred for cardiac investigations related to inherited heart rhythm conditions will be excluded from participating if they meet the following criteria:
* Unwilling or are unable to provide informed consent
* Known sarcoidosis
* Mitral valve Prolapse unless unexplained cardiac arrest or syncope with documented PMVT
* Heart Failure/Non-Familial Dilated Cardiomyopathy DCM without a positive family history of affected FDRs or SDRs
* Aortopathies including Marfan Syndrome, Ehlers Danlos, Familial Thoracic Aortic Aneurysm and Dissection
* Neuromuscular disease
* Familial hypercholesterolemia
