Isuru Ranasinghe1, Chadi Ayoub1, Chaitu Cheruvu1, Saul B Freedman1, John Yiannikas2. 1. Department of Cardiology & The University of Sydney, Sydney Medical School, Level 3 West, Concord Repatriation General Hospital, Hospital Road, Concord, Sydney, NSW 2139, Australia. 2. Department of Cardiology & The University of Sydney, Sydney Medical School, Level 3 West, Concord Repatriation General Hospital, Hospital Road, Concord, Sydney, NSW 2139, Australia. Electronic address: john.yiannikas@yahoo.com.au.
Abstract
BACKGROUND: Isolated basal septal hypertrophy (IBSH) of the left ventricle (LV) is not a well understood phenomenon, particularly in the presence of concomitant left ventricular outflow tract obstruction (LVOTO). We evaluated the prevalence of IBSH and compared those with and without LVOTO. METHODS: Retrospective observational study of 4104 consecutive patients undergoing echocardiography at a community cardiology practice and a hospital without specialized Hypertrophic Cardiomyopathy (HCM) service to determine prevalence of IBSH, defined as isolated hypertrophy (>15 mm) of the basal LV septum (BS) without hypertrophy elsewhere. Clinical, ECG and echocardiographic characteristics were compared in IBSH with and without LVOTO. RESULTS: Prevalence of IBSH was 5.8% (240/4104): mean (SD) age was 76.0y (10.4) with equal gender distribution. Prevalence increased with age (p<0.001 for trend), reaching 7.8% over 70y. None had a family history of HCM, and HCM-associated ECG changes were uncommon. Mean BS thickness (SD) was 17.8mm (0.24) with a BS/posterior wall ratio (SD) of 1.76 (0.31). Resting peak LVOT gradient (>20mmHg) was present in 8/240 (3.3%), mean (SD) 69.6mmHg (59.3). Patients with LVOTO had hypercontractile LV function (fractional shortening [SD] 51.8% [9.5] vs. 40.5% [10.9], p=0.012) compared to those without LVOTO, but had similar BS thickness [SD] (17.8mm [3.0] vs. 17.8mm [2.8], p=0.996) and ECG characteristics. Greater apical and septal displacements of the mitral valve co-aptation point characterized those with IBSH and LVOTO. CONCLUSIONS: IBSH is common in elderly patients referred for echocardiography. LVOTO occurs only when concomitant mitral valve co-aptation and LV hypercontractility facilitate development of a gradient, rather than through differences in the degree of BS myocardial hypertrophy.
BACKGROUND: Isolated basal septal hypertrophy (IBSH) of the left ventricle (LV) is not a well understood phenomenon, particularly in the presence of concomitant left ventricular outflow tract obstruction (LVOTO). We evaluated the prevalence of IBSH and compared those with and without LVOTO. METHODS: Retrospective observational study of 4104 consecutive patients undergoing echocardiography at a community cardiology practice and a hospital without specialized Hypertrophic Cardiomyopathy (HCM) service to determine prevalence of IBSH, defined as isolated hypertrophy (>15 mm) of the basal LV septum (BS) without hypertrophy elsewhere. Clinical, ECG and echocardiographic characteristics were compared in IBSH with and without LVOTO. RESULTS: Prevalence of IBSH was 5.8% (240/4104): mean (SD) age was 76.0y (10.4) with equal gender distribution. Prevalence increased with age (p<0.001 for trend), reaching 7.8% over 70y. None had a family history of HCM, and HCM-associated ECG changes were uncommon. Mean BS thickness (SD) was 17.8mm (0.24) with a BS/posterior wall ratio (SD) of 1.76 (0.31). Resting peak LVOT gradient (>20mmHg) was present in 8/240 (3.3%), mean (SD) 69.6mmHg (59.3). Patients with LVOTO had hypercontractile LV function (fractional shortening [SD] 51.8% [9.5] vs. 40.5% [10.9], p=0.012) compared to those without LVOTO, but had similar BS thickness [SD] (17.8mm [3.0] vs. 17.8mm [2.8], p=0.996) and ECG characteristics. Greater apical and septal displacements of the mitral valve co-aptation point characterized those with IBSH and LVOTO. CONCLUSIONS:IBSH is common in elderly patients referred for echocardiography. LVOTO occurs only when concomitant mitral valve co-aptation and LV hypercontractility facilitate development of a gradient, rather than through differences in the degree of BS myocardial hypertrophy.
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