Table 3.
Risk factors for sudden cardiac death in childhood HCM.
| Major risk factor | Clinical risk factor | Comment |
|---|---|---|
| Major risk factors | Previous VF/VT | Pooled HR 5.4 (95% CI 3.67–7.95, P < 0.001). Pooled OR 5.06 (95% 2.11–12.17, P < 0.001) |
| Unexplained syncope | Pooled HR 1.89 (0.69–5.16, p 0.22). Pooled OR 2.64 (1.21–5.79, p 0.02) | |
| NSVT | Pooled HR 2.13 (95% CI 1.21–3.74, p 0.0009). Pooled OR 2.05 (96% CI 0.98–4.28, p 0.06). | |
| Extreme LVH | Pooled HR 1.8 (95% CI 0.75–4.32, p 0.19). Pooled OR 1.70 (95% CI 0.85–3.40, p 0.13). The most useful measure of LVH for risk stratification is unknown. | |
| Other putative risk factors | LA dilatation | Left atrial size was not included as a major risk factor in the meta-analysis but a significant association has subsequently been reported in four studies (32, 42, 43, 80). |
| LVOT gradient | The definition of LVOT obstruction varies in the literature. Increasing LVOT gradient has been linked to SCD (32, 45) and two large studies have described an inverse relationship between LVOT gradient and risk in childhood (42, 43). | |
| Family history of SCD | Only 1/10 studies reported a significant association between a family history of SCD and SCD event (81). Limited evidence to support its use as a risk factor during childhood. | |
| Age | The role of age in SCD is not fully understood. SCD risk has been reported to be increased in pre-adolescent years (9–14 yrs) (30) and children presenting in infancy are believed to be at lower risk (27, 58) | |
| 12 lead ECG | Proposed 12 lead ECG features include; measures of LV hypertrophy (82) and abnormal repolarisation (83). An ECG risk score has been developed by Ostman-Smith et al. (83) but this was shown to have only moderate discriminatory ability in an external validation study (84). | |
| LGE on CMRI | LGE has been shown to increase during childhood and is associated with left ventricular hypertrophy (51). It is unclear if LGE is an independent risk factor for SCD (85, 86). | |
| Genotype | The role of genotype in SCD risk during childhood is not fully understood. In small cohorts, the presence of a pathogenic sarcomeric mutation has been described to be associated with worse prognosis (61) and certain genotypes associated with higher arrhythmic risk (87). |
Adapted from Norrish et al. (78).