Usefulness of a New Proposed Tissue Doppler Imaging Global Function Index in Hypertrophic Cardiomyopathy

Tissue Doppler imaging and plasma N-terminal probrain natriuretic peptide for the identification of hypertrophic cardiomyopathy mutation carriers

Previous studies have shown that tissue Doppler imaging (TDI) is able to identify mutation carriers of hypertrophic cardiomyopathy (HC) before the development of the clinical phenotype. However, data are scarce and have sometimes been controversial. We performed a systematic study that included conventional echocardiography, TDI, and plasma NT-probrain natriuretic peptide (NT-proBNP) measurement to evaluate the parameters that could identify HC mutation carriers. A total of 138 genotyped subjects were included and divided into 3 groups: group 1, those with HC (n = 62); group 2, mutation carriers (first-degree relatives with a positive genotype but negative phenotype; n = 34); and group 3, controls (first-degree relatives with a negative genotype and phenotype; n = 42). An echocardiographic study, including TDI, was performed on all subjects, and a TDI-derived index (global function index) was also determined. The age-adjusted mean differences in the echocardiographic and TDI parameters and NT-proBNP levels were compared among the 3 groups. Compared with the HC group, the carriers had significantly higher mean E' velocities, lower mean E/E' ratio, higher mean S' velocities, and lower mean global function index and NT-proBNP values. The carriers and controls did not differ significantly either in the echocardiographic parameters studied or in the NT-proBNP levels. In conclusion, the echocardiographic and TDI parameters and NT-proBNP levels cannot be used to identify the HC mutation carrier state and therefore do not appear to be reliable for the purpose of making a preclinical diagnosis of the disease.

Impaired myocardial function in hypertrophic cardiomyopathy

BACKGROUND

Tissue Doppler imaging (TDI) parameters of peak myocardial velocities (S', E', and A') has been employed to assess the regional left ventricular myocardial function. The global function index (GFI) derived from TDI has been recently employed to distinguish the different etiologies of left ventricular hypertrophy.

OBJECTIVE

To analyze whether the GFI or individual TDI parameters of peak myocardial velocities (S', E', and A') allows detecting different degrees of regional myocardial dysfunction in the most frequent forms of hypertrophic cardiomyopathy (HCM).

METHODS

GFI = (E/E')/S' (where E is the peak transmitral flow velocity, E' is the early diastolic myocardial velocity, and S' is the peak systolic myocardial velocity) and TDI peak myocardial velocities was measured in the septal and lateral mitral annulus in 101 patients with HCM (mean age 47.5 +/- 14 years, 58 women) and in age-matched group of 30 healthy controls (mean age 46 +/- 6 years, 16 women).

RESULTS

Forty-five patients had nonobstructive asymmetric septal HCM, 20 patients had a subaortic gradient >or= 30 mm Hg, 21 p. had apical HCM, and 15 p. had other forms of HCM (midventricular, symmetric, and biventricular). All patients with HCM exhibited a decrease in early diastolic (E') and systolic (S') myocardial velocities, both in the lateral and septal-mitral annulus border, but more pronounced in septal-mitral annulus. Septal GFI was higher in HCM patients than in healthy subjects (1.8 (1.1-2.5) and (0.57 (0.31-0.92), respectively, P < 0.001), but no differences were seen when different forms of HCM were compared.

CONCLUSIONS

In a selected population of patients with HCM and a preserved left ventricular(LV) systolic function, GFI and individual TDI parameters of peak velocity (S', E', and A') and E/E' ratio were similar in different forms of HCM, indicating that in all patients with HCM there is regional systolic and diastolic myocardial dysfunction, regardless of the location of hypertrophy.

Relationship between outflow obstruction and left ventricular functional impairment in hypertrophic cardiomyopathy: a Doppler echocardiographic study

Left ventricular outflow tract (LVOT) obstruction is predictive of a worse outcome in hypertrophic cardiomyopathy (HCM). In a detailed Doppler echocardiographic study of 178 selected HCM patients, the group of patients (n = 73) with the obstructive form (resting peak gradient > or = 30 mmHg) presented more hypertrophy and poorer systolic and diastolic left ventricular (LV) functions than the HCM group (n = 105) without obstruction. LVOT peak gradient was positively correlated with hypertrophy (P < 0.0001) and negatively to tissue Doppler mitral annulus systolic (P = 0.0001) and early diastolic (P < 0.0001) velocities. The gradient significantly correlated with E/Ea ratio (r = 0.67; P < 0.0001). By multiple regression, LVOT gradient was related to E/Ea, LV maximal thickness and left atrial size. In comparison with patients without obstruction, patients with obstruction presented greater hypertrophy (P < 0.0001), lower systolic and early diastolic mitral annulus velocities (both P < 0.0001), higher E/Ea ratio (P < 0.0001) and higher global function index (P < 0.0001). In HCM, beyond the effects on hypertrophy, LVOT obstruction is an independent determinant of LV functional abnormalities.