Causes of an increased pressure gradient through the left ventricular outflow tract: a West Coast experience

BACKGROUND Left ventricular outflow tract obstruction (LVOTO) occurs from not only obstructive hypertrophic cardiomyopathy but also other conditions such as sigmoid septum or post mitral valve repair. However, the changes of the LVOT pressure gradient (LVOT PG) in LVOTO with various conditions remain unclear. METHODS The clinical characteristics and echocardiographic parameters of 73 patients with LVOT PG ≥50 mmHg at rest on Doppler ultrasound were retrospectively investigated. RESULTS In these patients (age 69 ± 15 years, 38% male), high prevalences of hypertension (66%) and anemia (43%) were observed. The most frequent clinical disease causing LVOTO was hypertrophic obstructive cardiomyopathy (HOCM) (74%). There were other conditions, including hypertensive left ventricular hypertrophy (9%), post-open heart surgery (7%), sigmoid septum (4%), hyperkinetic LV (3%), takotsubo cardiomyopathy (1.5%), and discrete subaortic membrane (1.5%). Significant improvement or reduction of LVOTO was observed in 93% of cases at follow-up (mean 44 months) echocardiography compared with the initial one with the use of medications and transcatheter procedures. CONCLUSIONS The causes of LVOTO are diverse. However, the occurrence of LVOTO might depend on the coexistence of primary morphological LV characteristics and hemodynamic LV status. Specific factors causing LVOTO need to be investigated, and efforts for improvement of each individual status by the appropriate approach are required.