The AML and PML lengths were greater in HCM patients compared to controls (26 ± 4 mm vs. 20 ± 4 mm; P < 0.001 and 14 ± 4 mm vs. 11 ± 3 mm; P < 0.001, respectively), including 24 (10%) with substantially increased AML length of ≥32 mm (≥3 SD above control). AML and PML lengths measured in vivo by CMR did not differ significantly from that previously reported valves removed at surgery or postmortem (p = NS).
Although AML length was longer in male patients (26 ± 4 mm vs. 25 ± 4 mm in females, p = 0.04) there was no difference with respect to age, so that HCM patients ≤16 years of age had similar leaflet lengths to those ≥65 years (23 ± 5 mm vs. 26 ± 3 mm; p = 0.05). In addition, there was no difference in AML length in HCM patients with or without LV outflow obstruction (27 ± 4 vs. 26 ± 5 mm; p = 0.10), nor between AML length and maximum LV wall thickness (R = 0.11; p = 0.09) or total LV mass (R = 0.72; p = 0.3). Specifically, in HCM patients with only limited hypertrophy (13-19 mm), 31 patients (14%) had AML lengths which were greatly increased (≥2 SD above controls).