Early Detection of Genetic Cardiomyopathies in Relatives | 133 contributed to the inconsistent findings.53 While GLS has an unequivocal prognostic value in patients with overt HCM,18 its prognostic value in relatives represents a knowledge gap based on these results. A large multicentre study with in-depth multi-modality phenotyping could elucidate the precise role of GLS in genotype-positive HCM relatives. Global circumferential and rotational function was investigated in five studies. Forsey et al.26 and Williams et al.28 reported enhanced systolic LV rotational function in mutation carriers without hypertrophy (Figure 3). This may be a consequence of increased Ca2+affinity due to genetic variants in sarcomeres, as indicated in previous experimental studies.54 However, Ho et al.27, Yiu et al.30, and Kauer et al.31 showed no systolic differences in rotation/twist. On the basis of available data, the added clinical value of circumferential and rotational function is unclear. Six studies reported segmental strain parameters, of which four reported significantly lower strain in the basal septum (Figure 3).29,30,32,34 This was most pronounced in the basal anteroseptum. Early mechanical dysfunction in the basal septum is conceivable, as it has previously been identified as the most affected region in HCM.55 Only one study found no difference in strain in the basal anteroseptum.24 Forsey et al.26 found no differences in 14 children who had an HCM-related genetic variant, but only the inferoseptum was evaluated. Reduced basal (antero)septal strain appears to be an early sign of disease in HCM relatives. This may not directly translate into reduced GLS in the early stage, presumably due to the typical focal character of the disease. Figure 3. Reported early findings in relatives of HCM patients The findings with echocardiographic defromation imaging that are reported in relatives of HCM patients are reduced basal septal strain and alterations in LV rotation. HCM, hypertrophic cardiomyopathy; LV, left ventricle/ ventricular. 7
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