1 Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.
2 Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam University Medical Centers, Amsterdam, The Netherlands; European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart (ERN GUARD-Heart). Electronic address: p.g.postema@amsterdamumc.nl.
3 Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam University Medical Centers, Amsterdam, The Netherlands; European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart (ERN GUARD-Heart).