We sought to investigate the relationship between body mass index (BMI) and parameters derived from 48-h ambulatory blood pressure monitoring (ABPM) as well as organ damage in human hypertension.
A total of 658 consecutive outpatients with grade 1 and 2 hypertension, never treated with antihypertensive medications underwent the following procedures: (i) routine examination, (ii) 24-h urine collection for microalbuminuria, (iii) ABPM over two 24-h periods within 4 weeks, (iv) echocardiography and (v) carotid ultrasonography. Each patient was classified as lean (BMI<25 kg/m2) or overweight/obese (≥25 kg/m2) and according to the consistency of the dipping or nondipping status in the first and second ABPM period, as dipper (DD), nondipper and variable dipper.
Mean 48-h, daytime and nighttime systolic BP or diastolic BP were superimposable in the lean (n=314) and overweight (n=344) group. Overweight patients had a reduced nocturnal BP drop compared with their lean counterparts; the prevalence of DD pattern, indeed, was 15% lower in the overweight group as a whole, with a 17% difference in men and 13% in women. The prevalence of left ventricular hypertrophy was higher in overweight than in lean patients (31.8 vs. 15.9% in men and 48.7 vs. 15.6% in women, P<0.01); this more pronounced cardiac involvement was associated with structural carotid alterations.
This study, the first to investigate the relationship between BMI and nocturnal BP patterns as assessed by two ABPM sessions, shows that overweight hypertensive patients are more likely to have a reduced nocturnal fall in BP and a greater cardiac and extracardiac organ damage as compared with their lean counterparts despite a similar overall BP load.