1 Laboratory of Cardiovascular Fluid Dynamics, Department of Mechanical Industrial and Aerospace Engineering, Concordia University, 1455 de Maisonneuve Blvd. W., Montreal, QC, H3G 1M8, Canada.
2 Department of Mechanical Engineering, McGill University, Montreal, QC, Canada.
3 Division of Pediatric Cardiology, Centre Hospitalier Universitaire Sainte-Justine, Montreal, QC, Canada.
4 Departement of Biomedical Engineering, Faculty of Technology, University of Tlemcen, Tlemcen, Algeria.
5 Department of Mechanical Engineering, McMaster University, Hamilton, ON, Canada.
6 Laboratory of Cardiovascular Fluid Dynamics, Department of Mechanical Industrial and Aerospace Engineering, Concordia University, 1455 de Maisonneuve Blvd. W., Montreal, QC, H3G 1M8, Canada. lcfd@encs.concordia.ca.

The optimal timing for management of pediatric patients with moderate aortic valve disease [moderate aortic stenosis (modAS) or moderate aortic regurgitation (modAR)] remains unknown and largely unexplored. Although usually asymptomatic, the risk of increased left ventricular (LV) wall stress, irreversible myocardial fibrosis and sudden death in untreated moderate conditions warrants clearer risk stratification for appropriate timely intervention. In this study, we explore the use of a patient-specific mathematical model to introduce a new evaluative parameter of LV performance in patients with moderate aortic valve disease. Synthetic patient data (N = 520) representing healthy patients, and patients with modAS or modAR were first generated. Then, data from twenty-five pediatric patients were included in this study (healthy = 9; moderate AS = 8; modAR = 8). The effect of modAS or modAR on LV performance was evaluated by LV stroke work (LVSW) efficiency, a new non-invasive parameter. The results demonstrate that healthy patients possess a very high LVSW efficiency (synthetic data: 91 ± 2%, in vivo data: 92 ± 3%). However, modAS patients have a significant reduction in LVSW efficiency (synthetic data: 78 ± 2%, in vivo data: 76 ± 5%, p < 0.05), whereas modAR patients had the lowest LVSW efficiency (synthetic data: 58 ± 3%, in vivo data: 66 ± 7%; p < 0.05). This highlights that patients with moderate aortic valve disease require careful myocardial assessment, regardless of onset of clinical symptoms as their LV performance is significantly reduced. The evaluation of LVSW efficiency offers a promising avenue for future stratification of mixed aortic valve disease for optimal timing of management and intervention.