Resting Echocardiography Identifies Hypertrophic Cardiomyopathy Patients with Latent Left Ventricular Outflow Obstruction

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• 作者：Satoshi Nakatani ; Harry M. Lever ; Thomas H. Marwick ; James D. Thomas
• 刊名：Journal of the American College of Cardiology
• 出版年：1995
• 出版时间：February 1995
• 年：1995
• 卷：25
• 期：2, Supplement 1
• 页码：273A
• 全文大小：115 K

文摘

Latent LV outflow tract (OT) obstruction has important therapeutic and prognostic implications in patients with hypertrophic cardiomyopathy (HCM). However, since its presence can not be known until it is provoked, we investigated the resting echo features of patients with latent LVOT obstruction, aiming to predict it before provocation.

Methods: 48 patients with non-obstructive HCM (resting LVOT pressure gradient (PG) < 40 mmHg) challenged with amyl nitrite inhalation were studied. 23 patients (mean 51 ± 18 years) were nonprovocable and 25 (mean 52 ± 12 years, P = ns) were provocable (LVOT-PG ≥ 40 mmHg with amyl). Echo measurements included assessment of LV shape (asymmetric septal hypertrophy (ASH), concentric hypertrophy (CH) and prominent basal septal bulge (SB), anterior and posterior mitral leaflet length, qualitative assessment of mitral valve systolic anterior motion (SAM, 0 = none to 3 = severe), LVOT-PG, LVOT diameter at the onset of systole (DIA, cm), septal and posterior wall thickness, end-diastolic and end-systolic volume, and ejection fraction determined by Simpson's method. The angle (α, degrees) between the color Doppler-determined ejection streamline in LVOT and the LV long axis was measured to assess the magnitude of the drag force acting on the mitral valve.

Results: 12 of 16 patients (80 % ) with SB showed LVOT obstruction after amyl inhalation, whereas only 3 of 8 patients (38 % ) with ASH and 10 of 25 (40 % ) with CH showed obstruction (p < 0.05). Unpaired t-testing revealed the following:

The sensitivity for predicting provocable patients by combination of small LVOT diameter (≤2 cm) and large α (≥35 degrees) was 64 % and the specificity was 79 % . Wall thickness, leaflet length, ventricular volume, and ejection fraction did not show significant differences between two groups. Multiple stepwise linear regression analysis showed DIA and resting PG are best predictors for PG after amyl inhalation (r = 0.67, p < 0.001).

Conclusions: Non-obstructive HCM patients with 1) prominent septal bulge, 2) narrow LVOT, 3) oblique angle between the ejection flow and the LV long-axis, and 4) higher resting PG appeared to be predisposed for latent LVOT obstruction.