Inclusion of study patients. (A) Flowchart summarizing the selection of the study population with the PLN p.(Arg14del) pathogenic variant. Type of presentation and history data should be available for exclusion of PLN p.(Arg14del)-positive subjects with major VA at baseline or in history. Most subjects with no baseline or follow-up data were only genetically counselled in the participating university hospitals with no cardiologic data available and treated by their local cardiologists. Events in history and during a 3-year follow-up period consisted spontaneous VT/VF (n = 51), aborted SCD (n = 19), appropriate ICD intervention (n = 9), death (n = 7), heart transplantation (n = 7), VT-storm (n = 1) and undefined arrhythmic events (n = 10). Tests between 2 and 4 years of follow-up included electrocardiogram, transthoracic echocardiogram, or magnetic resonance imaging and Holter monitor. (B) Landmark at time point 0 (LM-0) represent the cohort for the development of the PLN p.(Arg14del) risk score at time of first presentation, landmark at time point 3 (LM-3) represent the new cohort for the longitudinal evaluation. ICD, implantable cardioverter defibrillator; PLN, phospholamban; SCD, sudden cardiac death; VA, ventricular arrhythmia; VF, ventricular fibrillation; VT, ventricular tachycardia.