Relationship Between Maximal Left Ventricular Wall Thickness and Sudden Cardiac Death in Childhood Onset Hypertrophic Cardiomyopathy
Gabrielle Norrish, Tao Ding, Ella Field, Elena Cervi, Lidia Ziółkowska, Iacopo Olivotto, Diala Khraiche, Giuseppe Limongelli, Aris Anastasakis, Robert G. Weintraub, Elena Biagini, Luca Ragni, Terrence Prendiville, Sophie Duignan, Karen McLeod, Maria Ilina, Adrián Fernández, Chiara Marrone, Regina Bökenkamp, Anwar Baban, Peter Kubuš, Piers E.F. Daubeney, Georgia Sarquella‐Brugada, Sergi César, Sabine Klaassen, Tiina Ojala, Vinay Bhole, Constancio Medrano, Orhan Uzun, Elspeth Brown, Ferrán Gran, Gianfranco Sinagra, Francisco J. Castro, Graham Stuart, Gabriele Vignati, Hirokuni Yamazawa, Roberto Barriales‐Villa, Luis Garcı́a-Guereta, Satish Adwani, Katie Linter, Tara Bharucha, Pablo García‐Pavía, Ana Siles, Torsten B. Rasmussen, Margherita Calcagnino, Caroline B. Jones, Hans De Wilde, Toru Kubo, Tiziana Felice, Anca Popoiu, Jens Mogensen, Sujeev Mathur, Fernándo Centeno Malfaz, Zdenka Reinhardt, Sylvie Schouvey, Costas O’Mahony, Rumana Omar, Perry Elliott, Juan Pablo Kaski
Abstract
Background: Maximal left ventricular wall thickness (MLVWT) is a risk factor for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). In adults, the severity of left ventricular hypertrophy has a nonlinear relationship with SCD, but it is not known whether the same complex relationship is seen in childhood. The aim of this study was to describe the relationship between left ventricular hypertrophy and SCD risk in a large international pediatric HCM cohort. Methods: The study cohort comprised 1075 children (mean age, 10.2 years [±4.4]) diagnosed with HCM (1–16 years) from the International Paediatric Hypertrophic Cardiomyopathy Consortium. Anonymized, noninvasive clinical data were collected from baseline evaluation and follow-up, and 5-year estimated SCD risk was calculated (HCM Risk-Kids). Results: MLVWT Z score was <10 in 598 (58.1%), ≥10 to <20 in 334 (31.1%), and ≥20 in 143 (13.3%). Higher MLVWT Z scores were associated with heart failure symptoms, unexplained syncope, left ventricular outflow tract obstruction, left atrial dilatation, and nonsustained ventricular tachycardia. One hundred twenty-two patients (71.3%) with MLVWT Z score ≥20 had coexisting risk factors for SCD. Over a median follow-up of 4.9 years (interquartile range, 2.3–9.3), 115 (10.7%) had an SCD event. Freedom from SCD event at 5 years for those with MLVWT Z scores <10, ≥10 to <20, and ≥20 was 95.6%, 87.4%, and 86.0, respectively. The estimated SCD risk at 5 years had a nonlinear, inverted U-shaped relationship with MLVWT Z score, peaking at Z score +23. The presence of coexisting risk factors had a summative effect on risk. Conclusions: In children with HCM, an inverted U-shaped relationship exists between left ventricular hypertrophy and estimated SCD risk. The presence of additional risk factors has a summative effect on risk. While MLVWT is important for risk stratification, it should not be used either as a binary variable or in isolation to guide implantable cardioverter defibrillator implantation decisions in children with HCM.