The correlation between isolated interventricular septal hypertrophy and 24-h ambulatory blood pressure monitoring in apparently healthy air crew

BACKGROUND: Interventricular septal (IVS) hypertrophy is considered to affect prognosis in hypertensive patients. However, the natural history of isolated septal hypertrophy, identified by echocardiography in otherwise healthy subjects is not well defined. METHODS: The study population included 51 apparently healthy pilots with septal hypertrophy (septal thickness > 11 mm) defined by routine echocardiography, with a calculated normal left ventricular (LV) mass. All pilots underwent casual blood pressure (BP) measurements and a 24-h ambulatory BP monitoring (ABPM). Hypertension (HTN) was defined as a casual measurement of > 140/90 mmHg. RESULTS: The mean age of the pilots was 38 +/- 11 years and the body mass index (BMI) 26.3 kg/m(2). The 17 pilots found to be hypertensive had a higher septal thickness than the 34 counterparts with normal BP measurements (13.8 +/- 2.0 mm versus 12.6 +/- 1.7 mm, P < 0.04, respectively). The mean ambulatory daytime systolic and diastolic BP were higher in comparison to non-hypertensive pilots (142 +/- 6.2 versus 128 +/- 5.0 mmHg, P < 0.0001 for systolic BP and 91 +/- 5.3 versus 78 +/- 4.1 mmHg, P = 0.001 for diastolic BP), respectively. The adjusted relative risk (RR) of a subject with an IVS thickness P > 12 mm to be hypertensive by ABPM was 3.12 (95% confidence interval 1.04-9.37, P < 0.02). CONCLUSIONS: Isolated IVS hypertrophy, even in the presence of normal LV mass is associated with HTN. Screening healthy subjects at risk for hypertension by echocardiography enables one to identify those who should be closely monitored, using among others, ABPM.