Evaluation of left ventricular outflow tract area after septal reduction in obstructive hypertrophic cardiomyopathy: A real-time 3-dimensional echocardiographic study

Background The comparative impact of percutaneous alcohol septal reduction (ASR) and surgical myectomy on the left ventricular outflow tract (LVOT) area in patients with obstructive hypertrophic cardiomyopathy (HC) is not well defined. Real-time 3-dimensional echocardiography (RT3DE) provides accurate information about the LVOT geometry and shape. We aimed to analyze the change in LVOT area after septal reduction interventions in patients with obstructive HC using RUDE. Methods Thirty-one HC patients (mean age 53 +/- 17 years) undergoing ASR (n=14) or myectomy (n=17) were studied at baseline and during follow-up with RT3DE. LVOT area was measured after observing the LVOT in the 3D space as the smallest area during midsystole. LVOT pressure gradients were determined by conventional continuous wave Doppler. Results Overall, LVOT area increased from 0.86 +/- 0.20 to 2.50 +/- 0.88 cm(2) (P<.01), and the resting LVOT pressure gradient decreased from 64 +/- 41 to 16 +/- 10 mm Hg (P<.01) after a median follow-up of 3 months after intervention (range 1-24 months). A similar significant decrease in LVOT pressure gradients was seen in myectomy and ASR groups (from 62 +/- 39 to 12 +/- 5 mm Hg and from 67 +/- 43 to 21 +/- 14 mm Hg, respectively, P<.01 in between each group, and P=NS between both groups). However, the increase in LVOT area was greater in myectomy than in ASR group (from 0.81 +/- 0.22 to 2.90 +/- 0.64 cm(2) and 0.93 to 0.16 to 2.02 +/- 0.92 cm(2), respectively, P<.01 between both groups). Conclusion RT3DE demonstrated an effective increase in LVOT area after both ASR and myectomy. This technique may be useful for assessing the results of septal reduction in patients with obstructive HC.