Influence of dynamic obstruction and hypertrophy location on diastolic function in hypertrophic cardiomyopathy

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a disease with marked genetic and phenotypic heterogeneity. It is well known that obstructive septal forms of this disease entail worse clinical outcome compared with nonobstructive septal and apical forms. The objective of this study was to analyze the differences in left ventricular diastolic function in different subgroups of HCMs and to assess the influence of the location of myocardial hypertrophy and the presence of dynamic obstruction on impairment of diastolic function and its correlation with the clinical status. METHODS: We studied 86 patients with HCM; 27 with the obstructive asymmetric septal type (OAS), 37 with the nonobstructive asymmetric septal type (NOAS) and 22 with apical hypertrophic cardiomyopathy (ApHCM). Patients underwent conventional and tissue Doppler echocardiography and were assessed applying the latest recommendations regarding diastolic dysfunction. Cardiac magnetic resonance was used to study the various morphologic subtypes and quantify left ventricular mass (LVM). RESULTS: The early diastolic annular velocity (e') was significantly lower in OAS with a median of 5 cm/s compared with NOAS with 7 cm/s and ApHCM with 7.5 cm/s (P = 0.0002), and the E/e' ratio was 8.5 in ApHCM, 10 in NOAS and 14 in OAS (P = 0.0001); no significant differences were found in LVM or maximal wall thickness. CONCLUSION: In HCM, the location of left ventricular hypertrophy and the presence of dynamic obstruction affect the degree of diastolic dysfunction; impairment is greater in patients with the OAS type, and markedly less in patients with apical involvement.