Subgroup performance according to hypertrophic cardiomyopathy characteristics. Results are shown for algorithm performance in each defined subgroup of patients with hypertrophic cardiomyopathy vs. the entire control population. Significant difference in algorithm performance existed only for the apical vs. non-apical hypertrophic cardiomyopathy subgroups. Note that specificity values are identical in the examined subgroups because the control non-hypertrophic cardiomyopathy group is the same across these subgroups.