Influence of novel risk markers on defibrillator implantation in hypertrophic cardiomyopathy

Abstract

Abstract Background/Introduction To guide implantable defibrillator (ICD) use in hypertrophic cardiomyopathy (HCM), European Society of Cardiology (ESC) guidelines recommend using individualised sudden death (SCD) risk scores based on quantitative clinical data. Newly published American guidelines are based on the accumulation of binary risk markers, which include imaging-based novel risk markers (NRMs) that were absent from the development of the ESC's algorithm. These NRMs are ejection fraction <50%, apical aneurysm, and extensive late gadolinium enhancement on cardiac magnetic resonance (CMR) imaging. Purpose To assess how NRMs may have altered ICD prescription across ESC-based SCD risk status prior to publication of current American guidance. Methods We examined electronic records (2013–2020) of a subset of HCM patients with contemporaneous (within 12 months) CMR and echocardiography data for NRMs, ESC risk status, and ICD prescription. Differences in categorical data were assessed by Fisher's exact test. Results We studied 334 HCM patients (74% male; age: 58±14 years), of whom 83 (25%) were referred for ICD. ESC risk status was considered low, medium (4–6% 5-year SCD risk), or high in 264, 26, and 20 patients, for whom ICDs were recommended in 40 (15%), 20 (77%), and 18 (90%) patients, respectively. In patients with low SCD risk status, rate of ICD recommendation was significantly higher when ≥1 NRMs were present (34/126 – 27% vs. 0 NRMs: 6/138 – 4%; p<0.0001). NRMs did not appear to influence ICD recommendation in patients with medium (≥1 NRMs: 14/17 – 82% vs. 0 NRMs: 6/9 – 67%; p=0.6) or high (≥1 NRMs: 14/15 – 93% vs. 0 NRMs: 4/5 – 80%; p=0.4) SCD risk status (Figure 1). NRMs were less frequent in low risk patients than in high risk patients (126/264 – 48% vs. 15/20 – 75%; p<0.05), suggesting interaction between ESC status and NRMs (Figure 2). Conclusion NRMs have disproportionate influence on ICD prescription in low ESC risk HCM patients. However, NRMs are not independent of ESC risk status, suggesting iterative development of the ESC's algorithmic approach will be the most effective way of predicting SCD. Funding Acknowledgement Type of funding sources: None.